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Commit 8f1603bd78a31f52927d398f600e47e2452997a6

Authored by Jonathan Gray
Committed by Tom Rini
1 parent e090579d0a
Exists in smarc_8mq_lf_v2020.04 and in 17 other branches 8qm-imx_v2020.04_5.4.70_2.3.0, emb_lf_v2022.04, pitx_8mp_lf_v2020.04, smarc-8m-android-10.0.0_2.6.0, smarc-8m-android-11.0.0_2.0.0, smarc-8mp-android-11.0.0_2.0.0, smarc-imx6_v2018.03_4.14.98_2.0.0_ga, smarc-imx7_v2018.03_4.14.98_2.0.0_ga, smarc-imx_v2018.03_4.14.78_1.0.0_ga, smarc_8m-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8m-imx_v2019.04_4.19.35_1.1.0, smarc_8m_00d0-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2019.04_4.19.35_1.1.0, smarc_8mm-imx_v2020.04_5.4.24_2.1.0, smarc_8mp_lf_v2020.04, smarc_8mq-imx_v2020.04_5.4.24_2.1.0

bch: don't use __BSD_VISIBLE to test for fls 

Commit 4ecc988301bc8e981e6d7538c57cdb3aa82f7c1d assumes fls is in libc
if __BSD_VISIBLE is defined.  This appears to only be true on FreeBSD
and DragonFlyBSD.  OpenBSD defines __BSD_VISIBLE and does not have fls
in strings.h/libc.

Switch the test for __BSD_VISIBLE to one for __DragonFly__ and
__FreeBSD__ to unbreak the build on OpenBSD.

Signed-off-by: Jonathan Gray <jsg@jsg.id.au>

Showing 1 changed file with 1 additions and 1 deletions Inline Diff

1 /* 1 /*
2 * Generic binary BCH encoding/decoding library 2 * Generic binary BCH encoding/decoding library
3 * 3 *
4 * SPDX-License-Identifier: GPL-2.0 4 * SPDX-License-Identifier: GPL-2.0
5 * 5 *
6 * Copyright © 2011 Parrot S.A. 6 * Copyright © 2011 Parrot S.A.
7 * 7 *
8 * Author: Ivan Djelic <ivan.djelic@parrot.com> 8 * Author: Ivan Djelic <ivan.djelic@parrot.com>
9 * 9 *
10 * Description: 10 * Description:
11 * 11 *
12 * This library provides runtime configurable encoding/decoding of binary 12 * This library provides runtime configurable encoding/decoding of binary
13 * Bose-Chaudhuri-Hocquenghem (BCH) codes. 13 * Bose-Chaudhuri-Hocquenghem (BCH) codes.
14 * 14 *
15 * Call init_bch to get a pointer to a newly allocated bch_control structure for 15 * Call init_bch to get a pointer to a newly allocated bch_control structure for
16 * the given m (Galois field order), t (error correction capability) and 16 * the given m (Galois field order), t (error correction capability) and
17 * (optional) primitive polynomial parameters. 17 * (optional) primitive polynomial parameters.
18 * 18 *
19 * Call encode_bch to compute and store ecc parity bytes to a given buffer. 19 * Call encode_bch to compute and store ecc parity bytes to a given buffer.
20 * Call decode_bch to detect and locate errors in received data. 20 * Call decode_bch to detect and locate errors in received data.
21 * 21 *
22 * On systems supporting hw BCH features, intermediate results may be provided 22 * On systems supporting hw BCH features, intermediate results may be provided
23 * to decode_bch in order to skip certain steps. See decode_bch() documentation 23 * to decode_bch in order to skip certain steps. See decode_bch() documentation
24 * for details. 24 * for details.
25 * 25 *
26 * Option CONFIG_BCH_CONST_PARAMS can be used to force fixed values of 26 * Option CONFIG_BCH_CONST_PARAMS can be used to force fixed values of
27 * parameters m and t; thus allowing extra compiler optimizations and providing 27 * parameters m and t; thus allowing extra compiler optimizations and providing
28 * better (up to 2x) encoding performance. Using this option makes sense when 28 * better (up to 2x) encoding performance. Using this option makes sense when
29 * (m,t) are fixed and known in advance, e.g. when using BCH error correction 29 * (m,t) are fixed and known in advance, e.g. when using BCH error correction
30 * on a particular NAND flash device. 30 * on a particular NAND flash device.
31 * 31 *
32 * Algorithmic details: 32 * Algorithmic details:
33 * 33 *
34 * Encoding is performed by processing 32 input bits in parallel, using 4 34 * Encoding is performed by processing 32 input bits in parallel, using 4
35 * remainder lookup tables. 35 * remainder lookup tables.
36 * 36 *
37 * The final stage of decoding involves the following internal steps: 37 * The final stage of decoding involves the following internal steps:
38 * a. Syndrome computation 38 * a. Syndrome computation
39 * b. Error locator polynomial computation using Berlekamp-Massey algorithm 39 * b. Error locator polynomial computation using Berlekamp-Massey algorithm
40 * c. Error locator root finding (by far the most expensive step) 40 * c. Error locator root finding (by far the most expensive step)
41 * 41 *
42 * In this implementation, step c is not performed using the usual Chien search. 42 * In this implementation, step c is not performed using the usual Chien search.
43 * Instead, an alternative approach described in [1] is used. It consists in 43 * Instead, an alternative approach described in [1] is used. It consists in
44 * factoring the error locator polynomial using the Berlekamp Trace algorithm 44 * factoring the error locator polynomial using the Berlekamp Trace algorithm
45 * (BTA) down to a certain degree (4), after which ad hoc low-degree polynomial 45 * (BTA) down to a certain degree (4), after which ad hoc low-degree polynomial
46 * solving techniques [2] are used. The resulting algorithm, called BTZ, yields 46 * solving techniques [2] are used. The resulting algorithm, called BTZ, yields
47 * much better performance than Chien search for usual (m,t) values (typically 47 * much better performance than Chien search for usual (m,t) values (typically
48 * m >= 13, t < 32, see [1]). 48 * m >= 13, t < 32, see [1]).
49 * 49 *
50 * [1] B. Biswas, V. Herbert. Efficient root finding of polynomials over fields 50 * [1] B. Biswas, V. Herbert. Efficient root finding of polynomials over fields
51 * of characteristic 2, in: Western European Workshop on Research in Cryptology 51 * of characteristic 2, in: Western European Workshop on Research in Cryptology
52 * - WEWoRC 2009, Graz, Austria, LNCS, Springer, July 2009, to appear. 52 * - WEWoRC 2009, Graz, Austria, LNCS, Springer, July 2009, to appear.
53 * [2] [Zin96] V.A. Zinoviev. On the solution of equations of degree 10 over 53 * [2] [Zin96] V.A. Zinoviev. On the solution of equations of degree 10 over
54 * finite fields GF(2^q). In Rapport de recherche INRIA no 2829, 1996. 54 * finite fields GF(2^q). In Rapport de recherche INRIA no 2829, 1996.
55 */ 55 */
56 56
57 #ifndef USE_HOSTCC 57 #ifndef USE_HOSTCC
58 #include <common.h> 58 #include <common.h>
59 #include <ubi_uboot.h> 59 #include <ubi_uboot.h>
60 60
61 #include <linux/bitops.h> 61 #include <linux/bitops.h>
62 #else 62 #else
63 #include <errno.h> 63 #include <errno.h>
64 #if defined(__FreeBSD__) 64 #if defined(__FreeBSD__)
65 #include <sys/endian.h> 65 #include <sys/endian.h>
66 #else 66 #else
67 #include <endian.h> 67 #include <endian.h>
68 #endif 68 #endif
69 #include <stdint.h> 69 #include <stdint.h>
70 #include <stdlib.h> 70 #include <stdlib.h>
71 #include <string.h> 71 #include <string.h>
72 72
73 #undef cpu_to_be32 73 #undef cpu_to_be32
74 #define cpu_to_be32 htobe32 74 #define cpu_to_be32 htobe32
75 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) 75 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
76 #define kmalloc(size, flags) malloc(size) 76 #define kmalloc(size, flags) malloc(size)
77 #define kzalloc(size, flags) calloc(1, size) 77 #define kzalloc(size, flags) calloc(1, size)
78 #define kfree free 78 #define kfree free
79 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) 79 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
80 #endif 80 #endif
81 81
82 #include <asm/byteorder.h> 82 #include <asm/byteorder.h>
83 #include <linux/bch.h> 83 #include <linux/bch.h>
84 84
85 #if defined(CONFIG_BCH_CONST_PARAMS) 85 #if defined(CONFIG_BCH_CONST_PARAMS)
86 #define GF_M(_p) (CONFIG_BCH_CONST_M) 86 #define GF_M(_p) (CONFIG_BCH_CONST_M)
87 #define GF_T(_p) (CONFIG_BCH_CONST_T) 87 #define GF_T(_p) (CONFIG_BCH_CONST_T)
88 #define GF_N(_p) ((1 << (CONFIG_BCH_CONST_M))-1) 88 #define GF_N(_p) ((1 << (CONFIG_BCH_CONST_M))-1)
89 #else 89 #else
90 #define GF_M(_p) ((_p)->m) 90 #define GF_M(_p) ((_p)->m)
91 #define GF_T(_p) ((_p)->t) 91 #define GF_T(_p) ((_p)->t)
92 #define GF_N(_p) ((_p)->n) 92 #define GF_N(_p) ((_p)->n)
93 #endif 93 #endif
94 94
95 #define BCH_ECC_WORDS(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 32) 95 #define BCH_ECC_WORDS(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 32)
96 #define BCH_ECC_BYTES(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 8) 96 #define BCH_ECC_BYTES(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 8)
97 97
98 #ifndef dbg 98 #ifndef dbg
99 #define dbg(_fmt, args...) do {} while (0) 99 #define dbg(_fmt, args...) do {} while (0)
100 #endif 100 #endif
101 101
102 /* 102 /*
103 * represent a polynomial over GF(2^m) 103 * represent a polynomial over GF(2^m)
104 */ 104 */
105 struct gf_poly { 105 struct gf_poly {
106 unsigned int deg; /* polynomial degree */ 106 unsigned int deg; /* polynomial degree */
107 unsigned int c[0]; /* polynomial terms */ 107 unsigned int c[0]; /* polynomial terms */
108 }; 108 };
109 109
110 /* given its degree, compute a polynomial size in bytes */ 110 /* given its degree, compute a polynomial size in bytes */
111 #define GF_POLY_SZ(_d) (sizeof(struct gf_poly)+((_d)+1)*sizeof(unsigned int)) 111 #define GF_POLY_SZ(_d) (sizeof(struct gf_poly)+((_d)+1)*sizeof(unsigned int))
112 112
113 /* polynomial of degree 1 */ 113 /* polynomial of degree 1 */
114 struct gf_poly_deg1 { 114 struct gf_poly_deg1 {
115 struct gf_poly poly; 115 struct gf_poly poly;
116 unsigned int c[2]; 116 unsigned int c[2];
117 }; 117 };
118 118
119 #ifdef USE_HOSTCC 119 #ifdef USE_HOSTCC
120 #ifndef __BSD_VISIBLE 120 #if !defined(__DragonFly__) && !defined(__FreeBSD__)
121 static int fls(int x) 121 static int fls(int x)
122 { 122 {
123 int r = 32; 123 int r = 32;
124 124
125 if (!x) 125 if (!x)
126 return 0; 126 return 0;
127 if (!(x & 0xffff0000u)) { 127 if (!(x & 0xffff0000u)) {
128 x <<= 16; 128 x <<= 16;
129 r -= 16; 129 r -= 16;
130 } 130 }
131 if (!(x & 0xff000000u)) { 131 if (!(x & 0xff000000u)) {
132 x <<= 8; 132 x <<= 8;
133 r -= 8; 133 r -= 8;
134 } 134 }
135 if (!(x & 0xf0000000u)) { 135 if (!(x & 0xf0000000u)) {
136 x <<= 4; 136 x <<= 4;
137 r -= 4; 137 r -= 4;
138 } 138 }
139 if (!(x & 0xc0000000u)) { 139 if (!(x & 0xc0000000u)) {
140 x <<= 2; 140 x <<= 2;
141 r -= 2; 141 r -= 2;
142 } 142 }
143 if (!(x & 0x80000000u)) { 143 if (!(x & 0x80000000u)) {
144 x <<= 1; 144 x <<= 1;
145 r -= 1; 145 r -= 1;
146 } 146 }
147 return r; 147 return r;
148 } 148 }
149 #endif 149 #endif
150 #endif 150 #endif
151 151
152 /* 152 /*
153 * same as encode_bch(), but process input data one byte at a time 153 * same as encode_bch(), but process input data one byte at a time
154 */ 154 */
155 static void encode_bch_unaligned(struct bch_control *bch, 155 static void encode_bch_unaligned(struct bch_control *bch,
156 const unsigned char *data, unsigned int len, 156 const unsigned char *data, unsigned int len,
157 uint32_t *ecc) 157 uint32_t *ecc)
158 { 158 {
159 int i; 159 int i;
160 const uint32_t *p; 160 const uint32_t *p;
161 const int l = BCH_ECC_WORDS(bch)-1; 161 const int l = BCH_ECC_WORDS(bch)-1;
162 162
163 while (len--) { 163 while (len--) {
164 p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(*data++)) & 0xff); 164 p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(*data++)) & 0xff);
165 165
166 for (i = 0; i < l; i++) 166 for (i = 0; i < l; i++)
167 ecc[i] = ((ecc[i] << 8)|(ecc[i+1] >> 24))^(*p++); 167 ecc[i] = ((ecc[i] << 8)|(ecc[i+1] >> 24))^(*p++);
168 168
169 ecc[l] = (ecc[l] << 8)^(*p); 169 ecc[l] = (ecc[l] << 8)^(*p);
170 } 170 }
171 } 171 }
172 172
173 /* 173 /*
174 * convert ecc bytes to aligned, zero-padded 32-bit ecc words 174 * convert ecc bytes to aligned, zero-padded 32-bit ecc words
175 */ 175 */
176 static void load_ecc8(struct bch_control *bch, uint32_t *dst, 176 static void load_ecc8(struct bch_control *bch, uint32_t *dst,
177 const uint8_t *src) 177 const uint8_t *src)
178 { 178 {
179 uint8_t pad[4] = {0, 0, 0, 0}; 179 uint8_t pad[4] = {0, 0, 0, 0};
180 unsigned int i, nwords = BCH_ECC_WORDS(bch)-1; 180 unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
181 181
182 for (i = 0; i < nwords; i++, src += 4) 182 for (i = 0; i < nwords; i++, src += 4)
183 dst[i] = (src[0] << 24)|(src[1] << 16)|(src[2] << 8)|src[3]; 183 dst[i] = (src[0] << 24)|(src[1] << 16)|(src[2] << 8)|src[3];
184 184
185 memcpy(pad, src, BCH_ECC_BYTES(bch)-4*nwords); 185 memcpy(pad, src, BCH_ECC_BYTES(bch)-4*nwords);
186 dst[nwords] = (pad[0] << 24)|(pad[1] << 16)|(pad[2] << 8)|pad[3]; 186 dst[nwords] = (pad[0] << 24)|(pad[1] << 16)|(pad[2] << 8)|pad[3];
187 } 187 }
188 188
189 /* 189 /*
190 * convert 32-bit ecc words to ecc bytes 190 * convert 32-bit ecc words to ecc bytes
191 */ 191 */
192 static void store_ecc8(struct bch_control *bch, uint8_t *dst, 192 static void store_ecc8(struct bch_control *bch, uint8_t *dst,
193 const uint32_t *src) 193 const uint32_t *src)
194 { 194 {
195 uint8_t pad[4]; 195 uint8_t pad[4];
196 unsigned int i, nwords = BCH_ECC_WORDS(bch)-1; 196 unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
197 197
198 for (i = 0; i < nwords; i++) { 198 for (i = 0; i < nwords; i++) {
199 *dst++ = (src[i] >> 24); 199 *dst++ = (src[i] >> 24);
200 *dst++ = (src[i] >> 16) & 0xff; 200 *dst++ = (src[i] >> 16) & 0xff;
201 *dst++ = (src[i] >> 8) & 0xff; 201 *dst++ = (src[i] >> 8) & 0xff;
202 *dst++ = (src[i] >> 0) & 0xff; 202 *dst++ = (src[i] >> 0) & 0xff;
203 } 203 }
204 pad[0] = (src[nwords] >> 24); 204 pad[0] = (src[nwords] >> 24);
205 pad[1] = (src[nwords] >> 16) & 0xff; 205 pad[1] = (src[nwords] >> 16) & 0xff;
206 pad[2] = (src[nwords] >> 8) & 0xff; 206 pad[2] = (src[nwords] >> 8) & 0xff;
207 pad[3] = (src[nwords] >> 0) & 0xff; 207 pad[3] = (src[nwords] >> 0) & 0xff;
208 memcpy(dst, pad, BCH_ECC_BYTES(bch)-4*nwords); 208 memcpy(dst, pad, BCH_ECC_BYTES(bch)-4*nwords);
209 } 209 }
210 210
211 /** 211 /**
212 * encode_bch - calculate BCH ecc parity of data 212 * encode_bch - calculate BCH ecc parity of data
213 * @bch: BCH control structure 213 * @bch: BCH control structure
214 * @data: data to encode 214 * @data: data to encode
215 * @len: data length in bytes 215 * @len: data length in bytes
216 * @ecc: ecc parity data, must be initialized by caller 216 * @ecc: ecc parity data, must be initialized by caller
217 * 217 *
218 * The @ecc parity array is used both as input and output parameter, in order to 218 * The @ecc parity array is used both as input and output parameter, in order to
219 * allow incremental computations. It should be of the size indicated by member 219 * allow incremental computations. It should be of the size indicated by member
220 * @ecc_bytes of @bch, and should be initialized to 0 before the first call. 220 * @ecc_bytes of @bch, and should be initialized to 0 before the first call.
221 * 221 *
222 * The exact number of computed ecc parity bits is given by member @ecc_bits of 222 * The exact number of computed ecc parity bits is given by member @ecc_bits of
223 * @bch; it may be less than m*t for large values of t. 223 * @bch; it may be less than m*t for large values of t.
224 */ 224 */
225 void encode_bch(struct bch_control *bch, const uint8_t *data, 225 void encode_bch(struct bch_control *bch, const uint8_t *data,
226 unsigned int len, uint8_t *ecc) 226 unsigned int len, uint8_t *ecc)
227 { 227 {
228 const unsigned int l = BCH_ECC_WORDS(bch)-1; 228 const unsigned int l = BCH_ECC_WORDS(bch)-1;
229 unsigned int i, mlen; 229 unsigned int i, mlen;
230 unsigned long m; 230 unsigned long m;
231 uint32_t w, r[l+1]; 231 uint32_t w, r[l+1];
232 const uint32_t * const tab0 = bch->mod8_tab; 232 const uint32_t * const tab0 = bch->mod8_tab;
233 const uint32_t * const tab1 = tab0 + 256*(l+1); 233 const uint32_t * const tab1 = tab0 + 256*(l+1);
234 const uint32_t * const tab2 = tab1 + 256*(l+1); 234 const uint32_t * const tab2 = tab1 + 256*(l+1);
235 const uint32_t * const tab3 = tab2 + 256*(l+1); 235 const uint32_t * const tab3 = tab2 + 256*(l+1);
236 const uint32_t *pdata, *p0, *p1, *p2, *p3; 236 const uint32_t *pdata, *p0, *p1, *p2, *p3;
237 237
238 if (ecc) { 238 if (ecc) {
239 /* load ecc parity bytes into internal 32-bit buffer */ 239 /* load ecc parity bytes into internal 32-bit buffer */
240 load_ecc8(bch, bch->ecc_buf, ecc); 240 load_ecc8(bch, bch->ecc_buf, ecc);
241 } else { 241 } else {
242 memset(bch->ecc_buf, 0, sizeof(r)); 242 memset(bch->ecc_buf, 0, sizeof(r));
243 } 243 }
244 244
245 /* process first unaligned data bytes */ 245 /* process first unaligned data bytes */
246 m = ((unsigned long)data) & 3; 246 m = ((unsigned long)data) & 3;
247 if (m) { 247 if (m) {
248 mlen = (len < (4-m)) ? len : 4-m; 248 mlen = (len < (4-m)) ? len : 4-m;
249 encode_bch_unaligned(bch, data, mlen, bch->ecc_buf); 249 encode_bch_unaligned(bch, data, mlen, bch->ecc_buf);
250 data += mlen; 250 data += mlen;
251 len -= mlen; 251 len -= mlen;
252 } 252 }
253 253
254 /* process 32-bit aligned data words */ 254 /* process 32-bit aligned data words */
255 pdata = (uint32_t *)data; 255 pdata = (uint32_t *)data;
256 mlen = len/4; 256 mlen = len/4;
257 data += 4*mlen; 257 data += 4*mlen;
258 len -= 4*mlen; 258 len -= 4*mlen;
259 memcpy(r, bch->ecc_buf, sizeof(r)); 259 memcpy(r, bch->ecc_buf, sizeof(r));
260 260
261 /* 261 /*
262 * split each 32-bit word into 4 polynomials of weight 8 as follows: 262 * split each 32-bit word into 4 polynomials of weight 8 as follows:
263 * 263 *
264 * 31 ...24 23 ...16 15 ... 8 7 ... 0 264 * 31 ...24 23 ...16 15 ... 8 7 ... 0
265 * xxxxxxxx yyyyyyyy zzzzzzzz tttttttt 265 * xxxxxxxx yyyyyyyy zzzzzzzz tttttttt
266 * tttttttt mod g = r0 (precomputed) 266 * tttttttt mod g = r0 (precomputed)
267 * zzzzzzzz 00000000 mod g = r1 (precomputed) 267 * zzzzzzzz 00000000 mod g = r1 (precomputed)
268 * yyyyyyyy 00000000 00000000 mod g = r2 (precomputed) 268 * yyyyyyyy 00000000 00000000 mod g = r2 (precomputed)
269 * xxxxxxxx 00000000 00000000 00000000 mod g = r3 (precomputed) 269 * xxxxxxxx 00000000 00000000 00000000 mod g = r3 (precomputed)
270 * xxxxxxxx yyyyyyyy zzzzzzzz tttttttt mod g = r0^r1^r2^r3 270 * xxxxxxxx yyyyyyyy zzzzzzzz tttttttt mod g = r0^r1^r2^r3
271 */ 271 */
272 while (mlen--) { 272 while (mlen--) {
273 /* input data is read in big-endian format */ 273 /* input data is read in big-endian format */
274 w = r[0]^cpu_to_be32(*pdata++); 274 w = r[0]^cpu_to_be32(*pdata++);
275 p0 = tab0 + (l+1)*((w >> 0) & 0xff); 275 p0 = tab0 + (l+1)*((w >> 0) & 0xff);
276 p1 = tab1 + (l+1)*((w >> 8) & 0xff); 276 p1 = tab1 + (l+1)*((w >> 8) & 0xff);
277 p2 = tab2 + (l+1)*((w >> 16) & 0xff); 277 p2 = tab2 + (l+1)*((w >> 16) & 0xff);
278 p3 = tab3 + (l+1)*((w >> 24) & 0xff); 278 p3 = tab3 + (l+1)*((w >> 24) & 0xff);
279 279
280 for (i = 0; i < l; i++) 280 for (i = 0; i < l; i++)
281 r[i] = r[i+1]^p0[i]^p1[i]^p2[i]^p3[i]; 281 r[i] = r[i+1]^p0[i]^p1[i]^p2[i]^p3[i];
282 282
283 r[l] = p0[l]^p1[l]^p2[l]^p3[l]; 283 r[l] = p0[l]^p1[l]^p2[l]^p3[l];
284 } 284 }
285 memcpy(bch->ecc_buf, r, sizeof(r)); 285 memcpy(bch->ecc_buf, r, sizeof(r));
286 286
287 /* process last unaligned bytes */ 287 /* process last unaligned bytes */
288 if (len) 288 if (len)
289 encode_bch_unaligned(bch, data, len, bch->ecc_buf); 289 encode_bch_unaligned(bch, data, len, bch->ecc_buf);
290 290
291 /* store ecc parity bytes into original parity buffer */ 291 /* store ecc parity bytes into original parity buffer */
292 if (ecc) 292 if (ecc)
293 store_ecc8(bch, ecc, bch->ecc_buf); 293 store_ecc8(bch, ecc, bch->ecc_buf);
294 } 294 }
295 295
296 static inline int modulo(struct bch_control *bch, unsigned int v) 296 static inline int modulo(struct bch_control *bch, unsigned int v)
297 { 297 {
298 const unsigned int n = GF_N(bch); 298 const unsigned int n = GF_N(bch);
299 while (v >= n) { 299 while (v >= n) {
300 v -= n; 300 v -= n;
301 v = (v & n) + (v >> GF_M(bch)); 301 v = (v & n) + (v >> GF_M(bch));
302 } 302 }
303 return v; 303 return v;
304 } 304 }
305 305
306 /* 306 /*
307 * shorter and faster modulo function, only works when v < 2N. 307 * shorter and faster modulo function, only works when v < 2N.
308 */ 308 */
309 static inline int mod_s(struct bch_control *bch, unsigned int v) 309 static inline int mod_s(struct bch_control *bch, unsigned int v)
310 { 310 {
311 const unsigned int n = GF_N(bch); 311 const unsigned int n = GF_N(bch);
312 return (v < n) ? v : v-n; 312 return (v < n) ? v : v-n;
313 } 313 }
314 314
315 static inline int deg(unsigned int poly) 315 static inline int deg(unsigned int poly)
316 { 316 {
317 /* polynomial degree is the most-significant bit index */ 317 /* polynomial degree is the most-significant bit index */
318 return fls(poly)-1; 318 return fls(poly)-1;
319 } 319 }
320 320
321 static inline int parity(unsigned int x) 321 static inline int parity(unsigned int x)
322 { 322 {
323 /* 323 /*
324 * public domain code snippet, lifted from 324 * public domain code snippet, lifted from
325 * http://www-graphics.stanford.edu/~seander/bithacks.html 325 * http://www-graphics.stanford.edu/~seander/bithacks.html
326 */ 326 */
327 x ^= x >> 1; 327 x ^= x >> 1;
328 x ^= x >> 2; 328 x ^= x >> 2;
329 x = (x & 0x11111111U) * 0x11111111U; 329 x = (x & 0x11111111U) * 0x11111111U;
330 return (x >> 28) & 1; 330 return (x >> 28) & 1;
331 } 331 }
332 332
333 /* Galois field basic operations: multiply, divide, inverse, etc. */ 333 /* Galois field basic operations: multiply, divide, inverse, etc. */
334 334
335 static inline unsigned int gf_mul(struct bch_control *bch, unsigned int a, 335 static inline unsigned int gf_mul(struct bch_control *bch, unsigned int a,
336 unsigned int b) 336 unsigned int b)
337 { 337 {
338 return (a && b) ? bch->a_pow_tab[mod_s(bch, bch->a_log_tab[a]+ 338 return (a && b) ? bch->a_pow_tab[mod_s(bch, bch->a_log_tab[a]+
339 bch->a_log_tab[b])] : 0; 339 bch->a_log_tab[b])] : 0;
340 } 340 }
341 341
342 static inline unsigned int gf_sqr(struct bch_control *bch, unsigned int a) 342 static inline unsigned int gf_sqr(struct bch_control *bch, unsigned int a)
343 { 343 {
344 return a ? bch->a_pow_tab[mod_s(bch, 2*bch->a_log_tab[a])] : 0; 344 return a ? bch->a_pow_tab[mod_s(bch, 2*bch->a_log_tab[a])] : 0;
345 } 345 }
346 346
347 static inline unsigned int gf_div(struct bch_control *bch, unsigned int a, 347 static inline unsigned int gf_div(struct bch_control *bch, unsigned int a,
348 unsigned int b) 348 unsigned int b)
349 { 349 {
350 return a ? bch->a_pow_tab[mod_s(bch, bch->a_log_tab[a]+ 350 return a ? bch->a_pow_tab[mod_s(bch, bch->a_log_tab[a]+
351 GF_N(bch)-bch->a_log_tab[b])] : 0; 351 GF_N(bch)-bch->a_log_tab[b])] : 0;
352 } 352 }
353 353
354 static inline unsigned int gf_inv(struct bch_control *bch, unsigned int a) 354 static inline unsigned int gf_inv(struct bch_control *bch, unsigned int a)
355 { 355 {
356 return bch->a_pow_tab[GF_N(bch)-bch->a_log_tab[a]]; 356 return bch->a_pow_tab[GF_N(bch)-bch->a_log_tab[a]];
357 } 357 }
358 358
359 static inline unsigned int a_pow(struct bch_control *bch, int i) 359 static inline unsigned int a_pow(struct bch_control *bch, int i)
360 { 360 {
361 return bch->a_pow_tab[modulo(bch, i)]; 361 return bch->a_pow_tab[modulo(bch, i)];
362 } 362 }
363 363
364 static inline int a_log(struct bch_control *bch, unsigned int x) 364 static inline int a_log(struct bch_control *bch, unsigned int x)
365 { 365 {
366 return bch->a_log_tab[x]; 366 return bch->a_log_tab[x];
367 } 367 }
368 368
369 static inline int a_ilog(struct bch_control *bch, unsigned int x) 369 static inline int a_ilog(struct bch_control *bch, unsigned int x)
370 { 370 {
371 return mod_s(bch, GF_N(bch)-bch->a_log_tab[x]); 371 return mod_s(bch, GF_N(bch)-bch->a_log_tab[x]);
372 } 372 }
373 373
374 /* 374 /*
375 * compute 2t syndromes of ecc polynomial, i.e. ecc(a^j) for j=1..2t 375 * compute 2t syndromes of ecc polynomial, i.e. ecc(a^j) for j=1..2t
376 */ 376 */
377 static void compute_syndromes(struct bch_control *bch, uint32_t *ecc, 377 static void compute_syndromes(struct bch_control *bch, uint32_t *ecc,
378 unsigned int *syn) 378 unsigned int *syn)
379 { 379 {
380 int i, j, s; 380 int i, j, s;
381 unsigned int m; 381 unsigned int m;
382 uint32_t poly; 382 uint32_t poly;
383 const int t = GF_T(bch); 383 const int t = GF_T(bch);
384 384
385 s = bch->ecc_bits; 385 s = bch->ecc_bits;
386 386
387 /* make sure extra bits in last ecc word are cleared */ 387 /* make sure extra bits in last ecc word are cleared */
388 m = ((unsigned int)s) & 31; 388 m = ((unsigned int)s) & 31;
389 if (m) 389 if (m)
390 ecc[s/32] &= ~((1u << (32-m))-1); 390 ecc[s/32] &= ~((1u << (32-m))-1);
391 memset(syn, 0, 2*t*sizeof(*syn)); 391 memset(syn, 0, 2*t*sizeof(*syn));
392 392
393 /* compute v(a^j) for j=1 .. 2t-1 */ 393 /* compute v(a^j) for j=1 .. 2t-1 */
394 do { 394 do {
395 poly = *ecc++; 395 poly = *ecc++;
396 s -= 32; 396 s -= 32;
397 while (poly) { 397 while (poly) {
398 i = deg(poly); 398 i = deg(poly);
399 for (j = 0; j < 2*t; j += 2) 399 for (j = 0; j < 2*t; j += 2)
400 syn[j] ^= a_pow(bch, (j+1)*(i+s)); 400 syn[j] ^= a_pow(bch, (j+1)*(i+s));
401 401
402 poly ^= (1 << i); 402 poly ^= (1 << i);
403 } 403 }
404 } while (s > 0); 404 } while (s > 0);
405 405
406 /* v(a^(2j)) = v(a^j)^2 */ 406 /* v(a^(2j)) = v(a^j)^2 */
407 for (j = 0; j < t; j++) 407 for (j = 0; j < t; j++)
408 syn[2*j+1] = gf_sqr(bch, syn[j]); 408 syn[2*j+1] = gf_sqr(bch, syn[j]);
409 } 409 }
410 410
411 static void gf_poly_copy(struct gf_poly *dst, struct gf_poly *src) 411 static void gf_poly_copy(struct gf_poly *dst, struct gf_poly *src)
412 { 412 {
413 memcpy(dst, src, GF_POLY_SZ(src->deg)); 413 memcpy(dst, src, GF_POLY_SZ(src->deg));
414 } 414 }
415 415
416 static int compute_error_locator_polynomial(struct bch_control *bch, 416 static int compute_error_locator_polynomial(struct bch_control *bch,
417 const unsigned int *syn) 417 const unsigned int *syn)
418 { 418 {
419 const unsigned int t = GF_T(bch); 419 const unsigned int t = GF_T(bch);
420 const unsigned int n = GF_N(bch); 420 const unsigned int n = GF_N(bch);
421 unsigned int i, j, tmp, l, pd = 1, d = syn[0]; 421 unsigned int i, j, tmp, l, pd = 1, d = syn[0];
422 struct gf_poly *elp = bch->elp; 422 struct gf_poly *elp = bch->elp;
423 struct gf_poly *pelp = bch->poly_2t[0]; 423 struct gf_poly *pelp = bch->poly_2t[0];
424 struct gf_poly *elp_copy = bch->poly_2t[1]; 424 struct gf_poly *elp_copy = bch->poly_2t[1];
425 int k, pp = -1; 425 int k, pp = -1;
426 426
427 memset(pelp, 0, GF_POLY_SZ(2*t)); 427 memset(pelp, 0, GF_POLY_SZ(2*t));
428 memset(elp, 0, GF_POLY_SZ(2*t)); 428 memset(elp, 0, GF_POLY_SZ(2*t));
429 429
430 pelp->deg = 0; 430 pelp->deg = 0;
431 pelp->c[0] = 1; 431 pelp->c[0] = 1;
432 elp->deg = 0; 432 elp->deg = 0;
433 elp->c[0] = 1; 433 elp->c[0] = 1;
434 434
435 /* use simplified binary Berlekamp-Massey algorithm */ 435 /* use simplified binary Berlekamp-Massey algorithm */
436 for (i = 0; (i < t) && (elp->deg <= t); i++) { 436 for (i = 0; (i < t) && (elp->deg <= t); i++) {
437 if (d) { 437 if (d) {
438 k = 2*i-pp; 438 k = 2*i-pp;
439 gf_poly_copy(elp_copy, elp); 439 gf_poly_copy(elp_copy, elp);
440 /* e[i+1](X) = e[i](X)+di*dp^-1*X^2(i-p)*e[p](X) */ 440 /* e[i+1](X) = e[i](X)+di*dp^-1*X^2(i-p)*e[p](X) */
441 tmp = a_log(bch, d)+n-a_log(bch, pd); 441 tmp = a_log(bch, d)+n-a_log(bch, pd);
442 for (j = 0; j <= pelp->deg; j++) { 442 for (j = 0; j <= pelp->deg; j++) {
443 if (pelp->c[j]) { 443 if (pelp->c[j]) {
444 l = a_log(bch, pelp->c[j]); 444 l = a_log(bch, pelp->c[j]);
445 elp->c[j+k] ^= a_pow(bch, tmp+l); 445 elp->c[j+k] ^= a_pow(bch, tmp+l);
446 } 446 }
447 } 447 }
448 /* compute l[i+1] = max(l[i]->c[l[p]+2*(i-p]) */ 448 /* compute l[i+1] = max(l[i]->c[l[p]+2*(i-p]) */
449 tmp = pelp->deg+k; 449 tmp = pelp->deg+k;
450 if (tmp > elp->deg) { 450 if (tmp > elp->deg) {
451 elp->deg = tmp; 451 elp->deg = tmp;
452 gf_poly_copy(pelp, elp_copy); 452 gf_poly_copy(pelp, elp_copy);
453 pd = d; 453 pd = d;
454 pp = 2*i; 454 pp = 2*i;
455 } 455 }
456 } 456 }
457 /* di+1 = S(2i+3)+elp[i+1].1*S(2i+2)+...+elp[i+1].lS(2i+3-l) */ 457 /* di+1 = S(2i+3)+elp[i+1].1*S(2i+2)+...+elp[i+1].lS(2i+3-l) */
458 if (i < t-1) { 458 if (i < t-1) {
459 d = syn[2*i+2]; 459 d = syn[2*i+2];
460 for (j = 1; j <= elp->deg; j++) 460 for (j = 1; j <= elp->deg; j++)
461 d ^= gf_mul(bch, elp->c[j], syn[2*i+2-j]); 461 d ^= gf_mul(bch, elp->c[j], syn[2*i+2-j]);
462 } 462 }
463 } 463 }
464 dbg("elp=%s\n", gf_poly_str(elp)); 464 dbg("elp=%s\n", gf_poly_str(elp));
465 return (elp->deg > t) ? -1 : (int)elp->deg; 465 return (elp->deg > t) ? -1 : (int)elp->deg;
466 } 466 }
467 467
468 /* 468 /*
469 * solve a m x m linear system in GF(2) with an expected number of solutions, 469 * solve a m x m linear system in GF(2) with an expected number of solutions,
470 * and return the number of found solutions 470 * and return the number of found solutions
471 */ 471 */
472 static int solve_linear_system(struct bch_control *bch, unsigned int *rows, 472 static int solve_linear_system(struct bch_control *bch, unsigned int *rows,
473 unsigned int *sol, int nsol) 473 unsigned int *sol, int nsol)
474 { 474 {
475 const int m = GF_M(bch); 475 const int m = GF_M(bch);
476 unsigned int tmp, mask; 476 unsigned int tmp, mask;
477 int rem, c, r, p, k, param[m]; 477 int rem, c, r, p, k, param[m];
478 478
479 k = 0; 479 k = 0;
480 mask = 1 << m; 480 mask = 1 << m;
481 481
482 /* Gaussian elimination */ 482 /* Gaussian elimination */
483 for (c = 0; c < m; c++) { 483 for (c = 0; c < m; c++) {
484 rem = 0; 484 rem = 0;
485 p = c-k; 485 p = c-k;
486 /* find suitable row for elimination */ 486 /* find suitable row for elimination */
487 for (r = p; r < m; r++) { 487 for (r = p; r < m; r++) {
488 if (rows[r] & mask) { 488 if (rows[r] & mask) {
489 if (r != p) { 489 if (r != p) {
490 tmp = rows[r]; 490 tmp = rows[r];
491 rows[r] = rows[p]; 491 rows[r] = rows[p];
492 rows[p] = tmp; 492 rows[p] = tmp;
493 } 493 }
494 rem = r+1; 494 rem = r+1;
495 break; 495 break;
496 } 496 }
497 } 497 }
498 if (rem) { 498 if (rem) {
499 /* perform elimination on remaining rows */ 499 /* perform elimination on remaining rows */
500 tmp = rows[p]; 500 tmp = rows[p];
501 for (r = rem; r < m; r++) { 501 for (r = rem; r < m; r++) {
502 if (rows[r] & mask) 502 if (rows[r] & mask)
503 rows[r] ^= tmp; 503 rows[r] ^= tmp;
504 } 504 }
505 } else { 505 } else {
506 /* elimination not needed, store defective row index */ 506 /* elimination not needed, store defective row index */
507 param[k++] = c; 507 param[k++] = c;
508 } 508 }
509 mask >>= 1; 509 mask >>= 1;
510 } 510 }
511 /* rewrite system, inserting fake parameter rows */ 511 /* rewrite system, inserting fake parameter rows */
512 if (k > 0) { 512 if (k > 0) {
513 p = k; 513 p = k;
514 for (r = m-1; r >= 0; r--) { 514 for (r = m-1; r >= 0; r--) {
515 if ((r > m-1-k) && rows[r]) 515 if ((r > m-1-k) && rows[r])
516 /* system has no solution */ 516 /* system has no solution */
517 return 0; 517 return 0;
518 518
519 rows[r] = (p && (r == param[p-1])) ? 519 rows[r] = (p && (r == param[p-1])) ?
520 p--, 1u << (m-r) : rows[r-p]; 520 p--, 1u << (m-r) : rows[r-p];
521 } 521 }
522 } 522 }
523 523
524 if (nsol != (1 << k)) 524 if (nsol != (1 << k))
525 /* unexpected number of solutions */ 525 /* unexpected number of solutions */
526 return 0; 526 return 0;
527 527
528 for (p = 0; p < nsol; p++) { 528 for (p = 0; p < nsol; p++) {
529 /* set parameters for p-th solution */ 529 /* set parameters for p-th solution */
530 for (c = 0; c < k; c++) 530 for (c = 0; c < k; c++)
531 rows[param[c]] = (rows[param[c]] & ~1)|((p >> c) & 1); 531 rows[param[c]] = (rows[param[c]] & ~1)|((p >> c) & 1);
532 532
533 /* compute unique solution */ 533 /* compute unique solution */
534 tmp = 0; 534 tmp = 0;
535 for (r = m-1; r >= 0; r--) { 535 for (r = m-1; r >= 0; r--) {
536 mask = rows[r] & (tmp|1); 536 mask = rows[r] & (tmp|1);
537 tmp |= parity(mask) << (m-r); 537 tmp |= parity(mask) << (m-r);
538 } 538 }
539 sol[p] = tmp >> 1; 539 sol[p] = tmp >> 1;
540 } 540 }
541 return nsol; 541 return nsol;
542 } 542 }
543 543
544 /* 544 /*
545 * this function builds and solves a linear system for finding roots of a degree 545 * this function builds and solves a linear system for finding roots of a degree
546 * 4 affine monic polynomial X^4+aX^2+bX+c over GF(2^m). 546 * 4 affine monic polynomial X^4+aX^2+bX+c over GF(2^m).
547 */ 547 */
548 static int find_affine4_roots(struct bch_control *bch, unsigned int a, 548 static int find_affine4_roots(struct bch_control *bch, unsigned int a,
549 unsigned int b, unsigned int c, 549 unsigned int b, unsigned int c,
550 unsigned int *roots) 550 unsigned int *roots)
551 { 551 {
552 int i, j, k; 552 int i, j, k;
553 const int m = GF_M(bch); 553 const int m = GF_M(bch);
554 unsigned int mask = 0xff, t, rows[16] = {0,}; 554 unsigned int mask = 0xff, t, rows[16] = {0,};
555 555
556 j = a_log(bch, b); 556 j = a_log(bch, b);
557 k = a_log(bch, a); 557 k = a_log(bch, a);
558 rows[0] = c; 558 rows[0] = c;
559 559
560 /* buid linear system to solve X^4+aX^2+bX+c = 0 */ 560 /* buid linear system to solve X^4+aX^2+bX+c = 0 */
561 for (i = 0; i < m; i++) { 561 for (i = 0; i < m; i++) {
562 rows[i+1] = bch->a_pow_tab[4*i]^ 562 rows[i+1] = bch->a_pow_tab[4*i]^
563 (a ? bch->a_pow_tab[mod_s(bch, k)] : 0)^ 563 (a ? bch->a_pow_tab[mod_s(bch, k)] : 0)^
564 (b ? bch->a_pow_tab[mod_s(bch, j)] : 0); 564 (b ? bch->a_pow_tab[mod_s(bch, j)] : 0);
565 j++; 565 j++;
566 k += 2; 566 k += 2;
567 } 567 }
568 /* 568 /*
569 * transpose 16x16 matrix before passing it to linear solver 569 * transpose 16x16 matrix before passing it to linear solver
570 * warning: this code assumes m < 16 570 * warning: this code assumes m < 16
571 */ 571 */
572 for (j = 8; j != 0; j >>= 1, mask ^= (mask << j)) { 572 for (j = 8; j != 0; j >>= 1, mask ^= (mask << j)) {
573 for (k = 0; k < 16; k = (k+j+1) & ~j) { 573 for (k = 0; k < 16; k = (k+j+1) & ~j) {
574 t = ((rows[k] >> j)^rows[k+j]) & mask; 574 t = ((rows[k] >> j)^rows[k+j]) & mask;
575 rows[k] ^= (t << j); 575 rows[k] ^= (t << j);
576 rows[k+j] ^= t; 576 rows[k+j] ^= t;
577 } 577 }
578 } 578 }
579 return solve_linear_system(bch, rows, roots, 4); 579 return solve_linear_system(bch, rows, roots, 4);
580 } 580 }
581 581
582 /* 582 /*
583 * compute root r of a degree 1 polynomial over GF(2^m) (returned as log(1/r)) 583 * compute root r of a degree 1 polynomial over GF(2^m) (returned as log(1/r))
584 */ 584 */
585 static int find_poly_deg1_roots(struct bch_control *bch, struct gf_poly *poly, 585 static int find_poly_deg1_roots(struct bch_control *bch, struct gf_poly *poly,
586 unsigned int *roots) 586 unsigned int *roots)
587 { 587 {
588 int n = 0; 588 int n = 0;
589 589
590 if (poly->c[0]) 590 if (poly->c[0])
591 /* poly[X] = bX+c with c!=0, root=c/b */ 591 /* poly[X] = bX+c with c!=0, root=c/b */
592 roots[n++] = mod_s(bch, GF_N(bch)-bch->a_log_tab[poly->c[0]]+ 592 roots[n++] = mod_s(bch, GF_N(bch)-bch->a_log_tab[poly->c[0]]+
593 bch->a_log_tab[poly->c[1]]); 593 bch->a_log_tab[poly->c[1]]);
594 return n; 594 return n;
595 } 595 }
596 596
597 /* 597 /*
598 * compute roots of a degree 2 polynomial over GF(2^m) 598 * compute roots of a degree 2 polynomial over GF(2^m)
599 */ 599 */
600 static int find_poly_deg2_roots(struct bch_control *bch, struct gf_poly *poly, 600 static int find_poly_deg2_roots(struct bch_control *bch, struct gf_poly *poly,
601 unsigned int *roots) 601 unsigned int *roots)
602 { 602 {
603 int n = 0, i, l0, l1, l2; 603 int n = 0, i, l0, l1, l2;
604 unsigned int u, v, r; 604 unsigned int u, v, r;
605 605
606 if (poly->c[0] && poly->c[1]) { 606 if (poly->c[0] && poly->c[1]) {
607 607
608 l0 = bch->a_log_tab[poly->c[0]]; 608 l0 = bch->a_log_tab[poly->c[0]];
609 l1 = bch->a_log_tab[poly->c[1]]; 609 l1 = bch->a_log_tab[poly->c[1]];
610 l2 = bch->a_log_tab[poly->c[2]]; 610 l2 = bch->a_log_tab[poly->c[2]];
611 611
612 /* using z=a/bX, transform aX^2+bX+c into z^2+z+u (u=ac/b^2) */ 612 /* using z=a/bX, transform aX^2+bX+c into z^2+z+u (u=ac/b^2) */
613 u = a_pow(bch, l0+l2+2*(GF_N(bch)-l1)); 613 u = a_pow(bch, l0+l2+2*(GF_N(bch)-l1));
614 /* 614 /*
615 * let u = sum(li.a^i) i=0..m-1; then compute r = sum(li.xi): 615 * let u = sum(li.a^i) i=0..m-1; then compute r = sum(li.xi):
616 * r^2+r = sum(li.(xi^2+xi)) = sum(li.(a^i+Tr(a^i).a^k)) = 616 * r^2+r = sum(li.(xi^2+xi)) = sum(li.(a^i+Tr(a^i).a^k)) =
617 * u + sum(li.Tr(a^i).a^k) = u+a^k.Tr(sum(li.a^i)) = u+a^k.Tr(u) 617 * u + sum(li.Tr(a^i).a^k) = u+a^k.Tr(sum(li.a^i)) = u+a^k.Tr(u)
618 * i.e. r and r+1 are roots iff Tr(u)=0 618 * i.e. r and r+1 are roots iff Tr(u)=0
619 */ 619 */
620 r = 0; 620 r = 0;
621 v = u; 621 v = u;
622 while (v) { 622 while (v) {
623 i = deg(v); 623 i = deg(v);
624 r ^= bch->xi_tab[i]; 624 r ^= bch->xi_tab[i];
625 v ^= (1 << i); 625 v ^= (1 << i);
626 } 626 }
627 /* verify root */ 627 /* verify root */
628 if ((gf_sqr(bch, r)^r) == u) { 628 if ((gf_sqr(bch, r)^r) == u) {
629 /* reverse z=a/bX transformation and compute log(1/r) */ 629 /* reverse z=a/bX transformation and compute log(1/r) */
630 roots[n++] = modulo(bch, 2*GF_N(bch)-l1- 630 roots[n++] = modulo(bch, 2*GF_N(bch)-l1-
631 bch->a_log_tab[r]+l2); 631 bch->a_log_tab[r]+l2);
632 roots[n++] = modulo(bch, 2*GF_N(bch)-l1- 632 roots[n++] = modulo(bch, 2*GF_N(bch)-l1-
633 bch->a_log_tab[r^1]+l2); 633 bch->a_log_tab[r^1]+l2);
634 } 634 }
635 } 635 }
636 return n; 636 return n;
637 } 637 }
638 638
639 /* 639 /*
640 * compute roots of a degree 3 polynomial over GF(2^m) 640 * compute roots of a degree 3 polynomial over GF(2^m)
641 */ 641 */
642 static int find_poly_deg3_roots(struct bch_control *bch, struct gf_poly *poly, 642 static int find_poly_deg3_roots(struct bch_control *bch, struct gf_poly *poly,
643 unsigned int *roots) 643 unsigned int *roots)
644 { 644 {
645 int i, n = 0; 645 int i, n = 0;
646 unsigned int a, b, c, a2, b2, c2, e3, tmp[4]; 646 unsigned int a, b, c, a2, b2, c2, e3, tmp[4];
647 647
648 if (poly->c[0]) { 648 if (poly->c[0]) {
649 /* transform polynomial into monic X^3 + a2X^2 + b2X + c2 */ 649 /* transform polynomial into monic X^3 + a2X^2 + b2X + c2 */
650 e3 = poly->c[3]; 650 e3 = poly->c[3];
651 c2 = gf_div(bch, poly->c[0], e3); 651 c2 = gf_div(bch, poly->c[0], e3);
652 b2 = gf_div(bch, poly->c[1], e3); 652 b2 = gf_div(bch, poly->c[1], e3);
653 a2 = gf_div(bch, poly->c[2], e3); 653 a2 = gf_div(bch, poly->c[2], e3);
654 654
655 /* (X+a2)(X^3+a2X^2+b2X+c2) = X^4+aX^2+bX+c (affine) */ 655 /* (X+a2)(X^3+a2X^2+b2X+c2) = X^4+aX^2+bX+c (affine) */
656 c = gf_mul(bch, a2, c2); /* c = a2c2 */ 656 c = gf_mul(bch, a2, c2); /* c = a2c2 */
657 b = gf_mul(bch, a2, b2)^c2; /* b = a2b2 + c2 */ 657 b = gf_mul(bch, a2, b2)^c2; /* b = a2b2 + c2 */
658 a = gf_sqr(bch, a2)^b2; /* a = a2^2 + b2 */ 658 a = gf_sqr(bch, a2)^b2; /* a = a2^2 + b2 */
659 659
660 /* find the 4 roots of this affine polynomial */ 660 /* find the 4 roots of this affine polynomial */
661 if (find_affine4_roots(bch, a, b, c, tmp) == 4) { 661 if (find_affine4_roots(bch, a, b, c, tmp) == 4) {
662 /* remove a2 from final list of roots */ 662 /* remove a2 from final list of roots */
663 for (i = 0; i < 4; i++) { 663 for (i = 0; i < 4; i++) {
664 if (tmp[i] != a2) 664 if (tmp[i] != a2)
665 roots[n++] = a_ilog(bch, tmp[i]); 665 roots[n++] = a_ilog(bch, tmp[i]);
666 } 666 }
667 } 667 }
668 } 668 }
669 return n; 669 return n;
670 } 670 }
671 671
672 /* 672 /*
673 * compute roots of a degree 4 polynomial over GF(2^m) 673 * compute roots of a degree 4 polynomial over GF(2^m)
674 */ 674 */
675 static int find_poly_deg4_roots(struct bch_control *bch, struct gf_poly *poly, 675 static int find_poly_deg4_roots(struct bch_control *bch, struct gf_poly *poly,
676 unsigned int *roots) 676 unsigned int *roots)
677 { 677 {
678 int i, l, n = 0; 678 int i, l, n = 0;
679 unsigned int a, b, c, d, e = 0, f, a2, b2, c2, e4; 679 unsigned int a, b, c, d, e = 0, f, a2, b2, c2, e4;
680 680
681 if (poly->c[0] == 0) 681 if (poly->c[0] == 0)
682 return 0; 682 return 0;
683 683
684 /* transform polynomial into monic X^4 + aX^3 + bX^2 + cX + d */ 684 /* transform polynomial into monic X^4 + aX^3 + bX^2 + cX + d */
685 e4 = poly->c[4]; 685 e4 = poly->c[4];
686 d = gf_div(bch, poly->c[0], e4); 686 d = gf_div(bch, poly->c[0], e4);
687 c = gf_div(bch, poly->c[1], e4); 687 c = gf_div(bch, poly->c[1], e4);
688 b = gf_div(bch, poly->c[2], e4); 688 b = gf_div(bch, poly->c[2], e4);
689 a = gf_div(bch, poly->c[3], e4); 689 a = gf_div(bch, poly->c[3], e4);
690 690
691 /* use Y=1/X transformation to get an affine polynomial */ 691 /* use Y=1/X transformation to get an affine polynomial */
692 if (a) { 692 if (a) {
693 /* first, eliminate cX by using z=X+e with ae^2+c=0 */ 693 /* first, eliminate cX by using z=X+e with ae^2+c=0 */
694 if (c) { 694 if (c) {
695 /* compute e such that e^2 = c/a */ 695 /* compute e such that e^2 = c/a */
696 f = gf_div(bch, c, a); 696 f = gf_div(bch, c, a);
697 l = a_log(bch, f); 697 l = a_log(bch, f);
698 l += (l & 1) ? GF_N(bch) : 0; 698 l += (l & 1) ? GF_N(bch) : 0;
699 e = a_pow(bch, l/2); 699 e = a_pow(bch, l/2);
700 /* 700 /*
701 * use transformation z=X+e: 701 * use transformation z=X+e:
702 * z^4+e^4 + a(z^3+ez^2+e^2z+e^3) + b(z^2+e^2) +cz+ce+d 702 * z^4+e^4 + a(z^3+ez^2+e^2z+e^3) + b(z^2+e^2) +cz+ce+d
703 * z^4 + az^3 + (ae+b)z^2 + (ae^2+c)z+e^4+be^2+ae^3+ce+d 703 * z^4 + az^3 + (ae+b)z^2 + (ae^2+c)z+e^4+be^2+ae^3+ce+d
704 * z^4 + az^3 + (ae+b)z^2 + e^4+be^2+d 704 * z^4 + az^3 + (ae+b)z^2 + e^4+be^2+d
705 * z^4 + az^3 + b'z^2 + d' 705 * z^4 + az^3 + b'z^2 + d'
706 */ 706 */
707 d = a_pow(bch, 2*l)^gf_mul(bch, b, f)^d; 707 d = a_pow(bch, 2*l)^gf_mul(bch, b, f)^d;
708 b = gf_mul(bch, a, e)^b; 708 b = gf_mul(bch, a, e)^b;
709 } 709 }
710 /* now, use Y=1/X to get Y^4 + b/dY^2 + a/dY + 1/d */ 710 /* now, use Y=1/X to get Y^4 + b/dY^2 + a/dY + 1/d */
711 if (d == 0) 711 if (d == 0)
712 /* assume all roots have multiplicity 1 */ 712 /* assume all roots have multiplicity 1 */
713 return 0; 713 return 0;
714 714
715 c2 = gf_inv(bch, d); 715 c2 = gf_inv(bch, d);
716 b2 = gf_div(bch, a, d); 716 b2 = gf_div(bch, a, d);
717 a2 = gf_div(bch, b, d); 717 a2 = gf_div(bch, b, d);
718 } else { 718 } else {
719 /* polynomial is already affine */ 719 /* polynomial is already affine */
720 c2 = d; 720 c2 = d;
721 b2 = c; 721 b2 = c;
722 a2 = b; 722 a2 = b;
723 } 723 }
724 /* find the 4 roots of this affine polynomial */ 724 /* find the 4 roots of this affine polynomial */
725 if (find_affine4_roots(bch, a2, b2, c2, roots) == 4) { 725 if (find_affine4_roots(bch, a2, b2, c2, roots) == 4) {
726 for (i = 0; i < 4; i++) { 726 for (i = 0; i < 4; i++) {
727 /* post-process roots (reverse transformations) */ 727 /* post-process roots (reverse transformations) */
728 f = a ? gf_inv(bch, roots[i]) : roots[i]; 728 f = a ? gf_inv(bch, roots[i]) : roots[i];
729 roots[i] = a_ilog(bch, f^e); 729 roots[i] = a_ilog(bch, f^e);
730 } 730 }
731 n = 4; 731 n = 4;
732 } 732 }
733 return n; 733 return n;
734 } 734 }
735 735
736 /* 736 /*
737 * build monic, log-based representation of a polynomial 737 * build monic, log-based representation of a polynomial
738 */ 738 */
739 static void gf_poly_logrep(struct bch_control *bch, 739 static void gf_poly_logrep(struct bch_control *bch,
740 const struct gf_poly *a, int *rep) 740 const struct gf_poly *a, int *rep)
741 { 741 {
742 int i, d = a->deg, l = GF_N(bch)-a_log(bch, a->c[a->deg]); 742 int i, d = a->deg, l = GF_N(bch)-a_log(bch, a->c[a->deg]);
743 743
744 /* represent 0 values with -1; warning, rep[d] is not set to 1 */ 744 /* represent 0 values with -1; warning, rep[d] is not set to 1 */
745 for (i = 0; i < d; i++) 745 for (i = 0; i < d; i++)
746 rep[i] = a->c[i] ? mod_s(bch, a_log(bch, a->c[i])+l) : -1; 746 rep[i] = a->c[i] ? mod_s(bch, a_log(bch, a->c[i])+l) : -1;
747 } 747 }
748 748
749 /* 749 /*
750 * compute polynomial Euclidean division remainder in GF(2^m)[X] 750 * compute polynomial Euclidean division remainder in GF(2^m)[X]
751 */ 751 */
752 static void gf_poly_mod(struct bch_control *bch, struct gf_poly *a, 752 static void gf_poly_mod(struct bch_control *bch, struct gf_poly *a,
753 const struct gf_poly *b, int *rep) 753 const struct gf_poly *b, int *rep)
754 { 754 {
755 int la, p, m; 755 int la, p, m;
756 unsigned int i, j, *c = a->c; 756 unsigned int i, j, *c = a->c;
757 const unsigned int d = b->deg; 757 const unsigned int d = b->deg;
758 758
759 if (a->deg < d) 759 if (a->deg < d)
760 return; 760 return;
761 761
762 /* reuse or compute log representation of denominator */ 762 /* reuse or compute log representation of denominator */
763 if (!rep) { 763 if (!rep) {
764 rep = bch->cache; 764 rep = bch->cache;
765 gf_poly_logrep(bch, b, rep); 765 gf_poly_logrep(bch, b, rep);
766 } 766 }
767 767
768 for (j = a->deg; j >= d; j--) { 768 for (j = a->deg; j >= d; j--) {
769 if (c[j]) { 769 if (c[j]) {
770 la = a_log(bch, c[j]); 770 la = a_log(bch, c[j]);
771 p = j-d; 771 p = j-d;
772 for (i = 0; i < d; i++, p++) { 772 for (i = 0; i < d; i++, p++) {
773 m = rep[i]; 773 m = rep[i];
774 if (m >= 0) 774 if (m >= 0)
775 c[p] ^= bch->a_pow_tab[mod_s(bch, 775 c[p] ^= bch->a_pow_tab[mod_s(bch,
776 m+la)]; 776 m+la)];
777 } 777 }
778 } 778 }
779 } 779 }
780 a->deg = d-1; 780 a->deg = d-1;
781 while (!c[a->deg] && a->deg) 781 while (!c[a->deg] && a->deg)
782 a->deg--; 782 a->deg--;
783 } 783 }
784 784
785 /* 785 /*
786 * compute polynomial Euclidean division quotient in GF(2^m)[X] 786 * compute polynomial Euclidean division quotient in GF(2^m)[X]
787 */ 787 */
788 static void gf_poly_div(struct bch_control *bch, struct gf_poly *a, 788 static void gf_poly_div(struct bch_control *bch, struct gf_poly *a,
789 const struct gf_poly *b, struct gf_poly *q) 789 const struct gf_poly *b, struct gf_poly *q)
790 { 790 {
791 if (a->deg >= b->deg) { 791 if (a->deg >= b->deg) {
792 q->deg = a->deg-b->deg; 792 q->deg = a->deg-b->deg;
793 /* compute a mod b (modifies a) */ 793 /* compute a mod b (modifies a) */
794 gf_poly_mod(bch, a, b, NULL); 794 gf_poly_mod(bch, a, b, NULL);
795 /* quotient is stored in upper part of polynomial a */ 795 /* quotient is stored in upper part of polynomial a */
796 memcpy(q->c, &a->c[b->deg], (1+q->deg)*sizeof(unsigned int)); 796 memcpy(q->c, &a->c[b->deg], (1+q->deg)*sizeof(unsigned int));
797 } else { 797 } else {
798 q->deg = 0; 798 q->deg = 0;
799 q->c[0] = 0; 799 q->c[0] = 0;
800 } 800 }
801 } 801 }
802 802
803 /* 803 /*
804 * compute polynomial GCD (Greatest Common Divisor) in GF(2^m)[X] 804 * compute polynomial GCD (Greatest Common Divisor) in GF(2^m)[X]
805 */ 805 */
806 static struct gf_poly *gf_poly_gcd(struct bch_control *bch, struct gf_poly *a, 806 static struct gf_poly *gf_poly_gcd(struct bch_control *bch, struct gf_poly *a,
807 struct gf_poly *b) 807 struct gf_poly *b)
808 { 808 {
809 struct gf_poly *tmp; 809 struct gf_poly *tmp;
810 810
811 dbg("gcd(%s,%s)=", gf_poly_str(a), gf_poly_str(b)); 811 dbg("gcd(%s,%s)=", gf_poly_str(a), gf_poly_str(b));
812 812
813 if (a->deg < b->deg) { 813 if (a->deg < b->deg) {
814 tmp = b; 814 tmp = b;
815 b = a; 815 b = a;
816 a = tmp; 816 a = tmp;
817 } 817 }
818 818
819 while (b->deg > 0) { 819 while (b->deg > 0) {
820 gf_poly_mod(bch, a, b, NULL); 820 gf_poly_mod(bch, a, b, NULL);
821 tmp = b; 821 tmp = b;
822 b = a; 822 b = a;
823 a = tmp; 823 a = tmp;
824 } 824 }
825 825
826 dbg("%s\n", gf_poly_str(a)); 826 dbg("%s\n", gf_poly_str(a));
827 827
828 return a; 828 return a;
829 } 829 }
830 830
831 /* 831 /*
832 * Given a polynomial f and an integer k, compute Tr(a^kX) mod f 832 * Given a polynomial f and an integer k, compute Tr(a^kX) mod f
833 * This is used in Berlekamp Trace algorithm for splitting polynomials 833 * This is used in Berlekamp Trace algorithm for splitting polynomials
834 */ 834 */
835 static void compute_trace_bk_mod(struct bch_control *bch, int k, 835 static void compute_trace_bk_mod(struct bch_control *bch, int k,
836 const struct gf_poly *f, struct gf_poly *z, 836 const struct gf_poly *f, struct gf_poly *z,
837 struct gf_poly *out) 837 struct gf_poly *out)
838 { 838 {
839 const int m = GF_M(bch); 839 const int m = GF_M(bch);
840 int i, j; 840 int i, j;
841 841
842 /* z contains z^2j mod f */ 842 /* z contains z^2j mod f */
843 z->deg = 1; 843 z->deg = 1;
844 z->c[0] = 0; 844 z->c[0] = 0;
845 z->c[1] = bch->a_pow_tab[k]; 845 z->c[1] = bch->a_pow_tab[k];
846 846
847 out->deg = 0; 847 out->deg = 0;
848 memset(out, 0, GF_POLY_SZ(f->deg)); 848 memset(out, 0, GF_POLY_SZ(f->deg));
849 849
850 /* compute f log representation only once */ 850 /* compute f log representation only once */
851 gf_poly_logrep(bch, f, bch->cache); 851 gf_poly_logrep(bch, f, bch->cache);
852 852
853 for (i = 0; i < m; i++) { 853 for (i = 0; i < m; i++) {
854 /* add a^(k*2^i)(z^(2^i) mod f) and compute (z^(2^i) mod f)^2 */ 854 /* add a^(k*2^i)(z^(2^i) mod f) and compute (z^(2^i) mod f)^2 */
855 for (j = z->deg; j >= 0; j--) { 855 for (j = z->deg; j >= 0; j--) {
856 out->c[j] ^= z->c[j]; 856 out->c[j] ^= z->c[j];
857 z->c[2*j] = gf_sqr(bch, z->c[j]); 857 z->c[2*j] = gf_sqr(bch, z->c[j]);
858 z->c[2*j+1] = 0; 858 z->c[2*j+1] = 0;
859 } 859 }
860 if (z->deg > out->deg) 860 if (z->deg > out->deg)
861 out->deg = z->deg; 861 out->deg = z->deg;
862 862
863 if (i < m-1) { 863 if (i < m-1) {
864 z->deg *= 2; 864 z->deg *= 2;
865 /* z^(2(i+1)) mod f = (z^(2^i) mod f)^2 mod f */ 865 /* z^(2(i+1)) mod f = (z^(2^i) mod f)^2 mod f */
866 gf_poly_mod(bch, z, f, bch->cache); 866 gf_poly_mod(bch, z, f, bch->cache);
867 } 867 }
868 } 868 }
869 while (!out->c[out->deg] && out->deg) 869 while (!out->c[out->deg] && out->deg)
870 out->deg--; 870 out->deg--;
871 871
872 dbg("Tr(a^%d.X) mod f = %s\n", k, gf_poly_str(out)); 872 dbg("Tr(a^%d.X) mod f = %s\n", k, gf_poly_str(out));
873 } 873 }
874 874
875 /* 875 /*
876 * factor a polynomial using Berlekamp Trace algorithm (BTA) 876 * factor a polynomial using Berlekamp Trace algorithm (BTA)
877 */ 877 */
878 static void factor_polynomial(struct bch_control *bch, int k, struct gf_poly *f, 878 static void factor_polynomial(struct bch_control *bch, int k, struct gf_poly *f,
879 struct gf_poly **g, struct gf_poly **h) 879 struct gf_poly **g, struct gf_poly **h)
880 { 880 {
881 struct gf_poly *f2 = bch->poly_2t[0]; 881 struct gf_poly *f2 = bch->poly_2t[0];
882 struct gf_poly *q = bch->poly_2t[1]; 882 struct gf_poly *q = bch->poly_2t[1];
883 struct gf_poly *tk = bch->poly_2t[2]; 883 struct gf_poly *tk = bch->poly_2t[2];
884 struct gf_poly *z = bch->poly_2t[3]; 884 struct gf_poly *z = bch->poly_2t[3];
885 struct gf_poly *gcd; 885 struct gf_poly *gcd;
886 886
887 dbg("factoring %s...\n", gf_poly_str(f)); 887 dbg("factoring %s...\n", gf_poly_str(f));
888 888
889 *g = f; 889 *g = f;
890 *h = NULL; 890 *h = NULL;
891 891
892 /* tk = Tr(a^k.X) mod f */ 892 /* tk = Tr(a^k.X) mod f */
893 compute_trace_bk_mod(bch, k, f, z, tk); 893 compute_trace_bk_mod(bch, k, f, z, tk);
894 894
895 if (tk->deg > 0) { 895 if (tk->deg > 0) {
896 /* compute g = gcd(f, tk) (destructive operation) */ 896 /* compute g = gcd(f, tk) (destructive operation) */
897 gf_poly_copy(f2, f); 897 gf_poly_copy(f2, f);
898 gcd = gf_poly_gcd(bch, f2, tk); 898 gcd = gf_poly_gcd(bch, f2, tk);
899 if (gcd->deg < f->deg) { 899 if (gcd->deg < f->deg) {
900 /* compute h=f/gcd(f,tk); this will modify f and q */ 900 /* compute h=f/gcd(f,tk); this will modify f and q */
901 gf_poly_div(bch, f, gcd, q); 901 gf_poly_div(bch, f, gcd, q);
902 /* store g and h in-place (clobbering f) */ 902 /* store g and h in-place (clobbering f) */
903 *h = &((struct gf_poly_deg1 *)f)[gcd->deg].poly; 903 *h = &((struct gf_poly_deg1 *)f)[gcd->deg].poly;
904 gf_poly_copy(*g, gcd); 904 gf_poly_copy(*g, gcd);
905 gf_poly_copy(*h, q); 905 gf_poly_copy(*h, q);
906 } 906 }
907 } 907 }
908 } 908 }
909 909
910 /* 910 /*
911 * find roots of a polynomial, using BTZ algorithm; see the beginning of this 911 * find roots of a polynomial, using BTZ algorithm; see the beginning of this
912 * file for details 912 * file for details
913 */ 913 */
914 static int find_poly_roots(struct bch_control *bch, unsigned int k, 914 static int find_poly_roots(struct bch_control *bch, unsigned int k,
915 struct gf_poly *poly, unsigned int *roots) 915 struct gf_poly *poly, unsigned int *roots)
916 { 916 {
917 int cnt; 917 int cnt;
918 struct gf_poly *f1, *f2; 918 struct gf_poly *f1, *f2;
919 919
920 switch (poly->deg) { 920 switch (poly->deg) {
921 /* handle low degree polynomials with ad hoc techniques */ 921 /* handle low degree polynomials with ad hoc techniques */
922 case 1: 922 case 1:
923 cnt = find_poly_deg1_roots(bch, poly, roots); 923 cnt = find_poly_deg1_roots(bch, poly, roots);
924 break; 924 break;
925 case 2: 925 case 2:
926 cnt = find_poly_deg2_roots(bch, poly, roots); 926 cnt = find_poly_deg2_roots(bch, poly, roots);
927 break; 927 break;
928 case 3: 928 case 3:
929 cnt = find_poly_deg3_roots(bch, poly, roots); 929 cnt = find_poly_deg3_roots(bch, poly, roots);
930 break; 930 break;
931 case 4: 931 case 4:
932 cnt = find_poly_deg4_roots(bch, poly, roots); 932 cnt = find_poly_deg4_roots(bch, poly, roots);
933 break; 933 break;
934 default: 934 default:
935 /* factor polynomial using Berlekamp Trace Algorithm (BTA) */ 935 /* factor polynomial using Berlekamp Trace Algorithm (BTA) */
936 cnt = 0; 936 cnt = 0;
937 if (poly->deg && (k <= GF_M(bch))) { 937 if (poly->deg && (k <= GF_M(bch))) {
938 factor_polynomial(bch, k, poly, &f1, &f2); 938 factor_polynomial(bch, k, poly, &f1, &f2);
939 if (f1) 939 if (f1)
940 cnt += find_poly_roots(bch, k+1, f1, roots); 940 cnt += find_poly_roots(bch, k+1, f1, roots);
941 if (f2) 941 if (f2)
942 cnt += find_poly_roots(bch, k+1, f2, roots+cnt); 942 cnt += find_poly_roots(bch, k+1, f2, roots+cnt);
943 } 943 }
944 break; 944 break;
945 } 945 }
946 return cnt; 946 return cnt;
947 } 947 }
948 948
949 #if defined(USE_CHIEN_SEARCH) 949 #if defined(USE_CHIEN_SEARCH)
950 /* 950 /*
951 * exhaustive root search (Chien) implementation - not used, included only for 951 * exhaustive root search (Chien) implementation - not used, included only for
952 * reference/comparison tests 952 * reference/comparison tests
953 */ 953 */
954 static int chien_search(struct bch_control *bch, unsigned int len, 954 static int chien_search(struct bch_control *bch, unsigned int len,
955 struct gf_poly *p, unsigned int *roots) 955 struct gf_poly *p, unsigned int *roots)
956 { 956 {
957 int m; 957 int m;
958 unsigned int i, j, syn, syn0, count = 0; 958 unsigned int i, j, syn, syn0, count = 0;
959 const unsigned int k = 8*len+bch->ecc_bits; 959 const unsigned int k = 8*len+bch->ecc_bits;
960 960
961 /* use a log-based representation of polynomial */ 961 /* use a log-based representation of polynomial */
962 gf_poly_logrep(bch, p, bch->cache); 962 gf_poly_logrep(bch, p, bch->cache);
963 bch->cache[p->deg] = 0; 963 bch->cache[p->deg] = 0;
964 syn0 = gf_div(bch, p->c[0], p->c[p->deg]); 964 syn0 = gf_div(bch, p->c[0], p->c[p->deg]);
965 965
966 for (i = GF_N(bch)-k+1; i <= GF_N(bch); i++) { 966 for (i = GF_N(bch)-k+1; i <= GF_N(bch); i++) {
967 /* compute elp(a^i) */ 967 /* compute elp(a^i) */
968 for (j = 1, syn = syn0; j <= p->deg; j++) { 968 for (j = 1, syn = syn0; j <= p->deg; j++) {
969 m = bch->cache[j]; 969 m = bch->cache[j];
970 if (m >= 0) 970 if (m >= 0)
971 syn ^= a_pow(bch, m+j*i); 971 syn ^= a_pow(bch, m+j*i);
972 } 972 }
973 if (syn == 0) { 973 if (syn == 0) {
974 roots[count++] = GF_N(bch)-i; 974 roots[count++] = GF_N(bch)-i;
975 if (count == p->deg) 975 if (count == p->deg)
976 break; 976 break;
977 } 977 }
978 } 978 }
979 return (count == p->deg) ? count : 0; 979 return (count == p->deg) ? count : 0;
980 } 980 }
981 #define find_poly_roots(_p, _k, _elp, _loc) chien_search(_p, len, _elp, _loc) 981 #define find_poly_roots(_p, _k, _elp, _loc) chien_search(_p, len, _elp, _loc)
982 #endif /* USE_CHIEN_SEARCH */ 982 #endif /* USE_CHIEN_SEARCH */
983 983
984 /** 984 /**
985 * decode_bch - decode received codeword and find bit error locations 985 * decode_bch - decode received codeword and find bit error locations
986 * @bch: BCH control structure 986 * @bch: BCH control structure
987 * @data: received data, ignored if @calc_ecc is provided 987 * @data: received data, ignored if @calc_ecc is provided
988 * @len: data length in bytes, must always be provided 988 * @len: data length in bytes, must always be provided
989 * @recv_ecc: received ecc, if NULL then assume it was XORed in @calc_ecc 989 * @recv_ecc: received ecc, if NULL then assume it was XORed in @calc_ecc
990 * @calc_ecc: calculated ecc, if NULL then calc_ecc is computed from @data 990 * @calc_ecc: calculated ecc, if NULL then calc_ecc is computed from @data
991 * @syn: hw computed syndrome data (if NULL, syndrome is calculated) 991 * @syn: hw computed syndrome data (if NULL, syndrome is calculated)
992 * @errloc: output array of error locations 992 * @errloc: output array of error locations
993 * 993 *
994 * Returns: 994 * Returns:
995 * The number of errors found, or -EBADMSG if decoding failed, or -EINVAL if 995 * The number of errors found, or -EBADMSG if decoding failed, or -EINVAL if
996 * invalid parameters were provided 996 * invalid parameters were provided
997 * 997 *
998 * Depending on the available hw BCH support and the need to compute @calc_ecc 998 * Depending on the available hw BCH support and the need to compute @calc_ecc
999 * separately (using encode_bch()), this function should be called with one of 999 * separately (using encode_bch()), this function should be called with one of
1000 * the following parameter configurations - 1000 * the following parameter configurations -
1001 * 1001 *
1002 * by providing @data and @recv_ecc only: 1002 * by providing @data and @recv_ecc only:
1003 * decode_bch(@bch, @data, @len, @recv_ecc, NULL, NULL, @errloc) 1003 * decode_bch(@bch, @data, @len, @recv_ecc, NULL, NULL, @errloc)
1004 * 1004 *
1005 * by providing @recv_ecc and @calc_ecc: 1005 * by providing @recv_ecc and @calc_ecc:
1006 * decode_bch(@bch, NULL, @len, @recv_ecc, @calc_ecc, NULL, @errloc) 1006 * decode_bch(@bch, NULL, @len, @recv_ecc, @calc_ecc, NULL, @errloc)
1007 * 1007 *
1008 * by providing ecc = recv_ecc XOR calc_ecc: 1008 * by providing ecc = recv_ecc XOR calc_ecc:
1009 * decode_bch(@bch, NULL, @len, NULL, ecc, NULL, @errloc) 1009 * decode_bch(@bch, NULL, @len, NULL, ecc, NULL, @errloc)
1010 * 1010 *
1011 * by providing syndrome results @syn: 1011 * by providing syndrome results @syn:
1012 * decode_bch(@bch, NULL, @len, NULL, NULL, @syn, @errloc) 1012 * decode_bch(@bch, NULL, @len, NULL, NULL, @syn, @errloc)
1013 * 1013 *
1014 * Once decode_bch() has successfully returned with a positive value, error 1014 * Once decode_bch() has successfully returned with a positive value, error
1015 * locations returned in array @errloc should be interpreted as follows - 1015 * locations returned in array @errloc should be interpreted as follows -
1016 * 1016 *
1017 * if (errloc[n] >= 8*len), then n-th error is located in ecc (no need for 1017 * if (errloc[n] >= 8*len), then n-th error is located in ecc (no need for
1018 * data correction) 1018 * data correction)
1019 * 1019 *
1020 * if (errloc[n] < 8*len), then n-th error is located in data and can be 1020 * if (errloc[n] < 8*len), then n-th error is located in data and can be
1021 * corrected with statement data[errloc[n]/8] ^= 1 << (errloc[n] % 8); 1021 * corrected with statement data[errloc[n]/8] ^= 1 << (errloc[n] % 8);
1022 * 1022 *
1023 * Note that this function does not perform any data correction by itself, it 1023 * Note that this function does not perform any data correction by itself, it
1024 * merely indicates error locations. 1024 * merely indicates error locations.
1025 */ 1025 */
1026 int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len, 1026 int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
1027 const uint8_t *recv_ecc, const uint8_t *calc_ecc, 1027 const uint8_t *recv_ecc, const uint8_t *calc_ecc,
1028 const unsigned int *syn, unsigned int *errloc) 1028 const unsigned int *syn, unsigned int *errloc)
1029 { 1029 {
1030 const unsigned int ecc_words = BCH_ECC_WORDS(bch); 1030 const unsigned int ecc_words = BCH_ECC_WORDS(bch);
1031 unsigned int nbits; 1031 unsigned int nbits;
1032 int i, err, nroots; 1032 int i, err, nroots;
1033 uint32_t sum; 1033 uint32_t sum;
1034 1034
1035 /* sanity check: make sure data length can be handled */ 1035 /* sanity check: make sure data length can be handled */
1036 if (8*len > (bch->n-bch->ecc_bits)) 1036 if (8*len > (bch->n-bch->ecc_bits))
1037 return -EINVAL; 1037 return -EINVAL;
1038 1038
1039 /* if caller does not provide syndromes, compute them */ 1039 /* if caller does not provide syndromes, compute them */
1040 if (!syn) { 1040 if (!syn) {
1041 if (!calc_ecc) { 1041 if (!calc_ecc) {
1042 /* compute received data ecc into an internal buffer */ 1042 /* compute received data ecc into an internal buffer */
1043 if (!data || !recv_ecc) 1043 if (!data || !recv_ecc)
1044 return -EINVAL; 1044 return -EINVAL;
1045 encode_bch(bch, data, len, NULL); 1045 encode_bch(bch, data, len, NULL);
1046 } else { 1046 } else {
1047 /* load provided calculated ecc */ 1047 /* load provided calculated ecc */
1048 load_ecc8(bch, bch->ecc_buf, calc_ecc); 1048 load_ecc8(bch, bch->ecc_buf, calc_ecc);
1049 } 1049 }
1050 /* load received ecc or assume it was XORed in calc_ecc */ 1050 /* load received ecc or assume it was XORed in calc_ecc */
1051 if (recv_ecc) { 1051 if (recv_ecc) {
1052 load_ecc8(bch, bch->ecc_buf2, recv_ecc); 1052 load_ecc8(bch, bch->ecc_buf2, recv_ecc);
1053 /* XOR received and calculated ecc */ 1053 /* XOR received and calculated ecc */
1054 for (i = 0, sum = 0; i < (int)ecc_words; i++) { 1054 for (i = 0, sum = 0; i < (int)ecc_words; i++) {
1055 bch->ecc_buf[i] ^= bch->ecc_buf2[i]; 1055 bch->ecc_buf[i] ^= bch->ecc_buf2[i];
1056 sum |= bch->ecc_buf[i]; 1056 sum |= bch->ecc_buf[i];
1057 } 1057 }
1058 if (!sum) 1058 if (!sum)
1059 /* no error found */ 1059 /* no error found */
1060 return 0; 1060 return 0;
1061 } 1061 }
1062 compute_syndromes(bch, bch->ecc_buf, bch->syn); 1062 compute_syndromes(bch, bch->ecc_buf, bch->syn);
1063 syn = bch->syn; 1063 syn = bch->syn;
1064 } 1064 }
1065 1065
1066 err = compute_error_locator_polynomial(bch, syn); 1066 err = compute_error_locator_polynomial(bch, syn);
1067 if (err > 0) { 1067 if (err > 0) {
1068 nroots = find_poly_roots(bch, 1, bch->elp, errloc); 1068 nroots = find_poly_roots(bch, 1, bch->elp, errloc);
1069 if (err != nroots) 1069 if (err != nroots)
1070 err = -1; 1070 err = -1;
1071 } 1071 }
1072 if (err > 0) { 1072 if (err > 0) {
1073 /* post-process raw error locations for easier correction */ 1073 /* post-process raw error locations for easier correction */
1074 nbits = (len*8)+bch->ecc_bits; 1074 nbits = (len*8)+bch->ecc_bits;
1075 for (i = 0; i < err; i++) { 1075 for (i = 0; i < err; i++) {
1076 if (errloc[i] >= nbits) { 1076 if (errloc[i] >= nbits) {
1077 err = -1; 1077 err = -1;
1078 break; 1078 break;
1079 } 1079 }
1080 errloc[i] = nbits-1-errloc[i]; 1080 errloc[i] = nbits-1-errloc[i];
1081 errloc[i] = (errloc[i] & ~7)|(7-(errloc[i] & 7)); 1081 errloc[i] = (errloc[i] & ~7)|(7-(errloc[i] & 7));
1082 } 1082 }
1083 } 1083 }
1084 return (err >= 0) ? err : -EBADMSG; 1084 return (err >= 0) ? err : -EBADMSG;
1085 } 1085 }
1086 1086
1087 /* 1087 /*
1088 * generate Galois field lookup tables 1088 * generate Galois field lookup tables
1089 */ 1089 */
1090 static int build_gf_tables(struct bch_control *bch, unsigned int poly) 1090 static int build_gf_tables(struct bch_control *bch, unsigned int poly)
1091 { 1091 {
1092 unsigned int i, x = 1; 1092 unsigned int i, x = 1;
1093 const unsigned int k = 1 << deg(poly); 1093 const unsigned int k = 1 << deg(poly);
1094 1094
1095 /* primitive polynomial must be of degree m */ 1095 /* primitive polynomial must be of degree m */
1096 if (k != (1u << GF_M(bch))) 1096 if (k != (1u << GF_M(bch)))
1097 return -1; 1097 return -1;
1098 1098
1099 for (i = 0; i < GF_N(bch); i++) { 1099 for (i = 0; i < GF_N(bch); i++) {
1100 bch->a_pow_tab[i] = x; 1100 bch->a_pow_tab[i] = x;
1101 bch->a_log_tab[x] = i; 1101 bch->a_log_tab[x] = i;
1102 if (i && (x == 1)) 1102 if (i && (x == 1))
1103 /* polynomial is not primitive (a^i=1 with 0<i<2^m-1) */ 1103 /* polynomial is not primitive (a^i=1 with 0<i<2^m-1) */
1104 return -1; 1104 return -1;
1105 x <<= 1; 1105 x <<= 1;
1106 if (x & k) 1106 if (x & k)
1107 x ^= poly; 1107 x ^= poly;
1108 } 1108 }
1109 bch->a_pow_tab[GF_N(bch)] = 1; 1109 bch->a_pow_tab[GF_N(bch)] = 1;
1110 bch->a_log_tab[0] = 0; 1110 bch->a_log_tab[0] = 0;
1111 1111
1112 return 0; 1112 return 0;
1113 } 1113 }
1114 1114
1115 /* 1115 /*
1116 * compute generator polynomial remainder tables for fast encoding 1116 * compute generator polynomial remainder tables for fast encoding
1117 */ 1117 */
1118 static void build_mod8_tables(struct bch_control *bch, const uint32_t *g) 1118 static void build_mod8_tables(struct bch_control *bch, const uint32_t *g)
1119 { 1119 {
1120 int i, j, b, d; 1120 int i, j, b, d;
1121 uint32_t data, hi, lo, *tab; 1121 uint32_t data, hi, lo, *tab;
1122 const int l = BCH_ECC_WORDS(bch); 1122 const int l = BCH_ECC_WORDS(bch);
1123 const int plen = DIV_ROUND_UP(bch->ecc_bits+1, 32); 1123 const int plen = DIV_ROUND_UP(bch->ecc_bits+1, 32);
1124 const int ecclen = DIV_ROUND_UP(bch->ecc_bits, 32); 1124 const int ecclen = DIV_ROUND_UP(bch->ecc_bits, 32);
1125 1125
1126 memset(bch->mod8_tab, 0, 4*256*l*sizeof(*bch->mod8_tab)); 1126 memset(bch->mod8_tab, 0, 4*256*l*sizeof(*bch->mod8_tab));
1127 1127
1128 for (i = 0; i < 256; i++) { 1128 for (i = 0; i < 256; i++) {
1129 /* p(X)=i is a small polynomial of weight <= 8 */ 1129 /* p(X)=i is a small polynomial of weight <= 8 */
1130 for (b = 0; b < 4; b++) { 1130 for (b = 0; b < 4; b++) {
1131 /* we want to compute (p(X).X^(8*b+deg(g))) mod g(X) */ 1131 /* we want to compute (p(X).X^(8*b+deg(g))) mod g(X) */
1132 tab = bch->mod8_tab + (b*256+i)*l; 1132 tab = bch->mod8_tab + (b*256+i)*l;
1133 data = i << (8*b); 1133 data = i << (8*b);
1134 while (data) { 1134 while (data) {
1135 d = deg(data); 1135 d = deg(data);
1136 /* subtract X^d.g(X) from p(X).X^(8*b+deg(g)) */ 1136 /* subtract X^d.g(X) from p(X).X^(8*b+deg(g)) */
1137 data ^= g[0] >> (31-d); 1137 data ^= g[0] >> (31-d);
1138 for (j = 0; j < ecclen; j++) { 1138 for (j = 0; j < ecclen; j++) {
1139 hi = (d < 31) ? g[j] << (d+1) : 0; 1139 hi = (d < 31) ? g[j] << (d+1) : 0;
1140 lo = (j+1 < plen) ? 1140 lo = (j+1 < plen) ?
1141 g[j+1] >> (31-d) : 0; 1141 g[j+1] >> (31-d) : 0;
1142 tab[j] ^= hi|lo; 1142 tab[j] ^= hi|lo;
1143 } 1143 }
1144 } 1144 }
1145 } 1145 }
1146 } 1146 }
1147 } 1147 }
1148 1148
1149 /* 1149 /*
1150 * build a base for factoring degree 2 polynomials 1150 * build a base for factoring degree 2 polynomials
1151 */ 1151 */
1152 static int build_deg2_base(struct bch_control *bch) 1152 static int build_deg2_base(struct bch_control *bch)
1153 { 1153 {
1154 const int m = GF_M(bch); 1154 const int m = GF_M(bch);
1155 int i, j, r; 1155 int i, j, r;
1156 unsigned int sum, x, y, remaining, ak = 0, xi[m]; 1156 unsigned int sum, x, y, remaining, ak = 0, xi[m];
1157 1157
1158 /* find k s.t. Tr(a^k) = 1 and 0 <= k < m */ 1158 /* find k s.t. Tr(a^k) = 1 and 0 <= k < m */
1159 for (i = 0; i < m; i++) { 1159 for (i = 0; i < m; i++) {
1160 for (j = 0, sum = 0; j < m; j++) 1160 for (j = 0, sum = 0; j < m; j++)
1161 sum ^= a_pow(bch, i*(1 << j)); 1161 sum ^= a_pow(bch, i*(1 << j));
1162 1162
1163 if (sum) { 1163 if (sum) {
1164 ak = bch->a_pow_tab[i]; 1164 ak = bch->a_pow_tab[i];
1165 break; 1165 break;
1166 } 1166 }
1167 } 1167 }
1168 /* find xi, i=0..m-1 such that xi^2+xi = a^i+Tr(a^i).a^k */ 1168 /* find xi, i=0..m-1 such that xi^2+xi = a^i+Tr(a^i).a^k */
1169 remaining = m; 1169 remaining = m;
1170 memset(xi, 0, sizeof(xi)); 1170 memset(xi, 0, sizeof(xi));
1171 1171
1172 for (x = 0; (x <= GF_N(bch)) && remaining; x++) { 1172 for (x = 0; (x <= GF_N(bch)) && remaining; x++) {
1173 y = gf_sqr(bch, x)^x; 1173 y = gf_sqr(bch, x)^x;
1174 for (i = 0; i < 2; i++) { 1174 for (i = 0; i < 2; i++) {
1175 r = a_log(bch, y); 1175 r = a_log(bch, y);
1176 if (y && (r < m) && !xi[r]) { 1176 if (y && (r < m) && !xi[r]) {
1177 bch->xi_tab[r] = x; 1177 bch->xi_tab[r] = x;
1178 xi[r] = 1; 1178 xi[r] = 1;
1179 remaining--; 1179 remaining--;
1180 dbg("x%d = %x\n", r, x); 1180 dbg("x%d = %x\n", r, x);
1181 break; 1181 break;
1182 } 1182 }
1183 y ^= ak; 1183 y ^= ak;
1184 } 1184 }
1185 } 1185 }
1186 /* should not happen but check anyway */ 1186 /* should not happen but check anyway */
1187 return remaining ? -1 : 0; 1187 return remaining ? -1 : 0;
1188 } 1188 }
1189 1189
1190 static void *bch_alloc(size_t size, int *err) 1190 static void *bch_alloc(size_t size, int *err)
1191 { 1191 {
1192 void *ptr; 1192 void *ptr;
1193 1193
1194 ptr = kmalloc(size, GFP_KERNEL); 1194 ptr = kmalloc(size, GFP_KERNEL);
1195 if (ptr == NULL) 1195 if (ptr == NULL)
1196 *err = 1; 1196 *err = 1;
1197 return ptr; 1197 return ptr;
1198 } 1198 }
1199 1199
1200 /* 1200 /*
1201 * compute generator polynomial for given (m,t) parameters. 1201 * compute generator polynomial for given (m,t) parameters.
1202 */ 1202 */
1203 static uint32_t *compute_generator_polynomial(struct bch_control *bch) 1203 static uint32_t *compute_generator_polynomial(struct bch_control *bch)
1204 { 1204 {
1205 const unsigned int m = GF_M(bch); 1205 const unsigned int m = GF_M(bch);
1206 const unsigned int t = GF_T(bch); 1206 const unsigned int t = GF_T(bch);
1207 int n, err = 0; 1207 int n, err = 0;
1208 unsigned int i, j, nbits, r, word, *roots; 1208 unsigned int i, j, nbits, r, word, *roots;
1209 struct gf_poly *g; 1209 struct gf_poly *g;
1210 uint32_t *genpoly; 1210 uint32_t *genpoly;
1211 1211
1212 g = bch_alloc(GF_POLY_SZ(m*t), &err); 1212 g = bch_alloc(GF_POLY_SZ(m*t), &err);
1213 roots = bch_alloc((bch->n+1)*sizeof(*roots), &err); 1213 roots = bch_alloc((bch->n+1)*sizeof(*roots), &err);
1214 genpoly = bch_alloc(DIV_ROUND_UP(m*t+1, 32)*sizeof(*genpoly), &err); 1214 genpoly = bch_alloc(DIV_ROUND_UP(m*t+1, 32)*sizeof(*genpoly), &err);
1215 1215
1216 if (err) { 1216 if (err) {
1217 kfree(genpoly); 1217 kfree(genpoly);
1218 genpoly = NULL; 1218 genpoly = NULL;
1219 goto finish; 1219 goto finish;
1220 } 1220 }
1221 1221
1222 /* enumerate all roots of g(X) */ 1222 /* enumerate all roots of g(X) */
1223 memset(roots , 0, (bch->n+1)*sizeof(*roots)); 1223 memset(roots , 0, (bch->n+1)*sizeof(*roots));
1224 for (i = 0; i < t; i++) { 1224 for (i = 0; i < t; i++) {
1225 for (j = 0, r = 2*i+1; j < m; j++) { 1225 for (j = 0, r = 2*i+1; j < m; j++) {
1226 roots[r] = 1; 1226 roots[r] = 1;
1227 r = mod_s(bch, 2*r); 1227 r = mod_s(bch, 2*r);
1228 } 1228 }
1229 } 1229 }
1230 /* build generator polynomial g(X) */ 1230 /* build generator polynomial g(X) */
1231 g->deg = 0; 1231 g->deg = 0;
1232 g->c[0] = 1; 1232 g->c[0] = 1;
1233 for (i = 0; i < GF_N(bch); i++) { 1233 for (i = 0; i < GF_N(bch); i++) {
1234 if (roots[i]) { 1234 if (roots[i]) {
1235 /* multiply g(X) by (X+root) */ 1235 /* multiply g(X) by (X+root) */
1236 r = bch->a_pow_tab[i]; 1236 r = bch->a_pow_tab[i];
1237 g->c[g->deg+1] = 1; 1237 g->c[g->deg+1] = 1;
1238 for (j = g->deg; j > 0; j--) 1238 for (j = g->deg; j > 0; j--)
1239 g->c[j] = gf_mul(bch, g->c[j], r)^g->c[j-1]; 1239 g->c[j] = gf_mul(bch, g->c[j], r)^g->c[j-1];
1240 1240
1241 g->c[0] = gf_mul(bch, g->c[0], r); 1241 g->c[0] = gf_mul(bch, g->c[0], r);
1242 g->deg++; 1242 g->deg++;
1243 } 1243 }
1244 } 1244 }
1245 /* store left-justified binary representation of g(X) */ 1245 /* store left-justified binary representation of g(X) */
1246 n = g->deg+1; 1246 n = g->deg+1;
1247 i = 0; 1247 i = 0;
1248 1248
1249 while (n > 0) { 1249 while (n > 0) {
1250 nbits = (n > 32) ? 32 : n; 1250 nbits = (n > 32) ? 32 : n;
1251 for (j = 0, word = 0; j < nbits; j++) { 1251 for (j = 0, word = 0; j < nbits; j++) {
1252 if (g->c[n-1-j]) 1252 if (g->c[n-1-j])
1253 word |= 1u << (31-j); 1253 word |= 1u << (31-j);
1254 } 1254 }
1255 genpoly[i++] = word; 1255 genpoly[i++] = word;
1256 n -= nbits; 1256 n -= nbits;
1257 } 1257 }
1258 bch->ecc_bits = g->deg; 1258 bch->ecc_bits = g->deg;
1259 1259
1260 finish: 1260 finish:
1261 kfree(g); 1261 kfree(g);
1262 kfree(roots); 1262 kfree(roots);
1263 1263
1264 return genpoly; 1264 return genpoly;
1265 } 1265 }
1266 1266
1267 /** 1267 /**
1268 * init_bch - initialize a BCH encoder/decoder 1268 * init_bch - initialize a BCH encoder/decoder
1269 * @m: Galois field order, should be in the range 5-15 1269 * @m: Galois field order, should be in the range 5-15
1270 * @t: maximum error correction capability, in bits 1270 * @t: maximum error correction capability, in bits
1271 * @prim_poly: user-provided primitive polynomial (or 0 to use default) 1271 * @prim_poly: user-provided primitive polynomial (or 0 to use default)
1272 * 1272 *
1273 * Returns: 1273 * Returns:
1274 * a newly allocated BCH control structure if successful, NULL otherwise 1274 * a newly allocated BCH control structure if successful, NULL otherwise
1275 * 1275 *
1276 * This initialization can take some time, as lookup tables are built for fast 1276 * This initialization can take some time, as lookup tables are built for fast
1277 * encoding/decoding; make sure not to call this function from a time critical 1277 * encoding/decoding; make sure not to call this function from a time critical
1278 * path. Usually, init_bch() should be called on module/driver init and 1278 * path. Usually, init_bch() should be called on module/driver init and
1279 * free_bch() should be called to release memory on exit. 1279 * free_bch() should be called to release memory on exit.
1280 * 1280 *
1281 * You may provide your own primitive polynomial of degree @m in argument 1281 * You may provide your own primitive polynomial of degree @m in argument
1282 * @prim_poly, or let init_bch() use its default polynomial. 1282 * @prim_poly, or let init_bch() use its default polynomial.
1283 * 1283 *
1284 * Once init_bch() has successfully returned a pointer to a newly allocated 1284 * Once init_bch() has successfully returned a pointer to a newly allocated
1285 * BCH control structure, ecc length in bytes is given by member @ecc_bytes of 1285 * BCH control structure, ecc length in bytes is given by member @ecc_bytes of
1286 * the structure. 1286 * the structure.
1287 */ 1287 */
1288 struct bch_control *init_bch(int m, int t, unsigned int prim_poly) 1288 struct bch_control *init_bch(int m, int t, unsigned int prim_poly)
1289 { 1289 {
1290 int err = 0; 1290 int err = 0;
1291 unsigned int i, words; 1291 unsigned int i, words;
1292 uint32_t *genpoly; 1292 uint32_t *genpoly;
1293 struct bch_control *bch = NULL; 1293 struct bch_control *bch = NULL;
1294 1294
1295 const int min_m = 5; 1295 const int min_m = 5;
1296 const int max_m = 15; 1296 const int max_m = 15;
1297 1297
1298 /* default primitive polynomials */ 1298 /* default primitive polynomials */
1299 static const unsigned int prim_poly_tab[] = { 1299 static const unsigned int prim_poly_tab[] = {
1300 0x25, 0x43, 0x83, 0x11d, 0x211, 0x409, 0x805, 0x1053, 0x201b, 1300 0x25, 0x43, 0x83, 0x11d, 0x211, 0x409, 0x805, 0x1053, 0x201b,
1301 0x402b, 0x8003, 1301 0x402b, 0x8003,
1302 }; 1302 };
1303 1303
1304 #if defined(CONFIG_BCH_CONST_PARAMS) 1304 #if defined(CONFIG_BCH_CONST_PARAMS)
1305 if ((m != (CONFIG_BCH_CONST_M)) || (t != (CONFIG_BCH_CONST_T))) { 1305 if ((m != (CONFIG_BCH_CONST_M)) || (t != (CONFIG_BCH_CONST_T))) {
1306 printk(KERN_ERR "bch encoder/decoder was configured to support " 1306 printk(KERN_ERR "bch encoder/decoder was configured to support "
1307 "parameters m=%d, t=%d only!\n", 1307 "parameters m=%d, t=%d only!\n",
1308 CONFIG_BCH_CONST_M, CONFIG_BCH_CONST_T); 1308 CONFIG_BCH_CONST_M, CONFIG_BCH_CONST_T);
1309 goto fail; 1309 goto fail;
1310 } 1310 }
1311 #endif 1311 #endif
1312 if ((m < min_m) || (m > max_m)) 1312 if ((m < min_m) || (m > max_m))
1313 /* 1313 /*
1314 * values of m greater than 15 are not currently supported; 1314 * values of m greater than 15 are not currently supported;
1315 * supporting m > 15 would require changing table base type 1315 * supporting m > 15 would require changing table base type
1316 * (uint16_t) and a small patch in matrix transposition 1316 * (uint16_t) and a small patch in matrix transposition
1317 */ 1317 */
1318 goto fail; 1318 goto fail;
1319 1319
1320 /* sanity checks */ 1320 /* sanity checks */
1321 if ((t < 1) || (m*t >= ((1 << m)-1))) 1321 if ((t < 1) || (m*t >= ((1 << m)-1)))
1322 /* invalid t value */ 1322 /* invalid t value */
1323 goto fail; 1323 goto fail;
1324 1324
1325 /* select a primitive polynomial for generating GF(2^m) */ 1325 /* select a primitive polynomial for generating GF(2^m) */
1326 if (prim_poly == 0) 1326 if (prim_poly == 0)
1327 prim_poly = prim_poly_tab[m-min_m]; 1327 prim_poly = prim_poly_tab[m-min_m];
1328 1328
1329 bch = kzalloc(sizeof(*bch), GFP_KERNEL); 1329 bch = kzalloc(sizeof(*bch), GFP_KERNEL);
1330 if (bch == NULL) 1330 if (bch == NULL)
1331 goto fail; 1331 goto fail;
1332 1332
1333 bch->m = m; 1333 bch->m = m;
1334 bch->t = t; 1334 bch->t = t;
1335 bch->n = (1 << m)-1; 1335 bch->n = (1 << m)-1;
1336 words = DIV_ROUND_UP(m*t, 32); 1336 words = DIV_ROUND_UP(m*t, 32);
1337 bch->ecc_bytes = DIV_ROUND_UP(m*t, 8); 1337 bch->ecc_bytes = DIV_ROUND_UP(m*t, 8);
1338 bch->a_pow_tab = bch_alloc((1+bch->n)*sizeof(*bch->a_pow_tab), &err); 1338 bch->a_pow_tab = bch_alloc((1+bch->n)*sizeof(*bch->a_pow_tab), &err);
1339 bch->a_log_tab = bch_alloc((1+bch->n)*sizeof(*bch->a_log_tab), &err); 1339 bch->a_log_tab = bch_alloc((1+bch->n)*sizeof(*bch->a_log_tab), &err);
1340 bch->mod8_tab = bch_alloc(words*1024*sizeof(*bch->mod8_tab), &err); 1340 bch->mod8_tab = bch_alloc(words*1024*sizeof(*bch->mod8_tab), &err);
1341 bch->ecc_buf = bch_alloc(words*sizeof(*bch->ecc_buf), &err); 1341 bch->ecc_buf = bch_alloc(words*sizeof(*bch->ecc_buf), &err);
1342 bch->ecc_buf2 = bch_alloc(words*sizeof(*bch->ecc_buf2), &err); 1342 bch->ecc_buf2 = bch_alloc(words*sizeof(*bch->ecc_buf2), &err);
1343 bch->xi_tab = bch_alloc(m*sizeof(*bch->xi_tab), &err); 1343 bch->xi_tab = bch_alloc(m*sizeof(*bch->xi_tab), &err);
1344 bch->syn = bch_alloc(2*t*sizeof(*bch->syn), &err); 1344 bch->syn = bch_alloc(2*t*sizeof(*bch->syn), &err);
1345 bch->cache = bch_alloc(2*t*sizeof(*bch->cache), &err); 1345 bch->cache = bch_alloc(2*t*sizeof(*bch->cache), &err);
1346 bch->elp = bch_alloc((t+1)*sizeof(struct gf_poly_deg1), &err); 1346 bch->elp = bch_alloc((t+1)*sizeof(struct gf_poly_deg1), &err);
1347 1347
1348 for (i = 0; i < ARRAY_SIZE(bch->poly_2t); i++) 1348 for (i = 0; i < ARRAY_SIZE(bch->poly_2t); i++)
1349 bch->poly_2t[i] = bch_alloc(GF_POLY_SZ(2*t), &err); 1349 bch->poly_2t[i] = bch_alloc(GF_POLY_SZ(2*t), &err);
1350 1350
1351 if (err) 1351 if (err)
1352 goto fail; 1352 goto fail;
1353 1353
1354 err = build_gf_tables(bch, prim_poly); 1354 err = build_gf_tables(bch, prim_poly);
1355 if (err) 1355 if (err)
1356 goto fail; 1356 goto fail;
1357 1357
1358 /* use generator polynomial for computing encoding tables */ 1358 /* use generator polynomial for computing encoding tables */
1359 genpoly = compute_generator_polynomial(bch); 1359 genpoly = compute_generator_polynomial(bch);
1360 if (genpoly == NULL) 1360 if (genpoly == NULL)
1361 goto fail; 1361 goto fail;
1362 1362
1363 build_mod8_tables(bch, genpoly); 1363 build_mod8_tables(bch, genpoly);
1364 kfree(genpoly); 1364 kfree(genpoly);
1365 1365
1366 err = build_deg2_base(bch); 1366 err = build_deg2_base(bch);
1367 if (err) 1367 if (err)
1368 goto fail; 1368 goto fail;
1369 1369
1370 return bch; 1370 return bch;
1371 1371
1372 fail: 1372 fail:
1373 free_bch(bch); 1373 free_bch(bch);
1374 return NULL; 1374 return NULL;
1375 } 1375 }
1376 1376
1377 /** 1377 /**
1378 * free_bch - free the BCH control structure 1378 * free_bch - free the BCH control structure
1379 * @bch: BCH control structure to release 1379 * @bch: BCH control structure to release
1380 */ 1380 */
1381 void free_bch(struct bch_control *bch) 1381 void free_bch(struct bch_control *bch)
1382 { 1382 {
1383 unsigned int i; 1383 unsigned int i;
1384 1384
1385 if (bch) { 1385 if (bch) {
1386 kfree(bch->a_pow_tab); 1386 kfree(bch->a_pow_tab);
1387 kfree(bch->a_log_tab); 1387 kfree(bch->a_log_tab);
1388 kfree(bch->mod8_tab); 1388 kfree(bch->mod8_tab);
1389 kfree(bch->ecc_buf); 1389 kfree(bch->ecc_buf);
1390 kfree(bch->ecc_buf2); 1390 kfree(bch->ecc_buf2);
1391 kfree(bch->xi_tab); 1391 kfree(bch->xi_tab);
1392 kfree(bch->syn); 1392 kfree(bch->syn);
1393 kfree(bch->cache); 1393 kfree(bch->cache);
1394 kfree(bch->elp); 1394 kfree(bch->elp);
1395 1395
1396 for (i = 0; i < ARRAY_SIZE(bch->poly_2t); i++) 1396 for (i = 0; i < ARRAY_SIZE(bch->poly_2t); i++)
1397 kfree(bch->poly_2t[i]); 1397 kfree(bch->poly_2t[i]);
1398 1398
1399 kfree(bch); 1399 kfree(bch);
1400 } 1400 }
1401 } 1401 }
1402 1402