/* Lzma decompressor for Linux kernel. Shamelessly snarfed
   *from busybox 1.1.1
   *
   *Linux kernel adaptation
   *Copyright (C) 2006  Alain < alain@knaff.lu >
   *
   *Based on small lzma deflate implementation/Small range coder
   *implementation for lzma.
   *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
   *

   *Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)

   *Copyright (C) 1999-2005  Igor Pavlov
   *
   *Copyrights of the parts, see headers below.
   *
   *
   *This program is free software; you can redistribute it and/or
   *modify it under the terms of the GNU Lesser General Public
   *License as published by the Free Software Foundation; either
   *version 2.1 of the License, or (at your option) any later version.
   *
   *This program is distributed in the hope that it will be useful,
   *but WITHOUT ANY WARRANTY; without even the implied warranty of
   *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *Lesser General Public License for more details.
   *
   *You should have received a copy of the GNU Lesser General Public
   *License along with this library; if not, write to the Free Software
   *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */

  #ifdef STATIC
  #define PREBOOT
  #else

  #include <linux/decompress/unlzma.h>
  #endif /* STATIC */
  
  #include <linux/decompress/mm.h>
  
  #define	MIN(a, b) (((a) < (b)) ? (a) : (b))
  
  static long long INIT read_int(unsigned char *ptr, int size)
  {
  	int i;
  	long long ret = 0;
  
  	for (i = 0; i < size; i++)
  		ret = (ret << 8) | ptr[size-i-1];
  	return ret;
  }
  
  #define ENDIAN_CONVERT(x) \
    x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
  
  
  /* Small range coder implementation for lzma.
   *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
   *

   *Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)

   *Copyright (c) 1999-2005  Igor Pavlov
   */
  
  #include <linux/compiler.h>
  
  #define LZMA_IOBUF_SIZE	0x10000
  
  struct rc {

  	long (*fill)(void*, unsigned long);

  	uint8_t *ptr;
  	uint8_t *buffer;
  	uint8_t *buffer_end;

  	long buffer_size;

  	uint32_t code;
  	uint32_t range;
  	uint32_t bound;

  	void (*error)(char *);

  };
  
  
  #define RC_TOP_BITS 24
  #define RC_MOVE_BITS 5
  #define RC_MODEL_TOTAL_BITS 11

  static long INIT nofill(void *buffer, unsigned long len)

  {
  	return -1;
  }

  /* Called twice: once at startup and once in rc_normalize() */
  static void INIT rc_read(struct rc *rc)
  {
  	rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
  	if (rc->buffer_size <= 0)

  		rc->error("unexpected EOF");

  	rc->ptr = rc->buffer;
  	rc->buffer_end = rc->buffer + rc->buffer_size;
  }
  
  /* Called once */
  static inline void INIT rc_init(struct rc *rc,

  				       long (*fill)(void*, unsigned long),
  				       char *buffer, long buffer_size)

  {

  	if (fill)
  		rc->fill = fill;
  	else
  		rc->fill = nofill;

  	rc->buffer = (uint8_t *)buffer;
  	rc->buffer_size = buffer_size;
  	rc->buffer_end = rc->buffer + rc->buffer_size;
  	rc->ptr = rc->buffer;
  
  	rc->code = 0;
  	rc->range = 0xFFFFFFFF;
  }
  
  static inline void INIT rc_init_code(struct rc *rc)
  {
  	int i;
  
  	for (i = 0; i < 5; i++) {
  		if (rc->ptr >= rc->buffer_end)
  			rc_read(rc);
  		rc->code = (rc->code << 8) | *rc->ptr++;
  	}
  }

  /* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
  static void INIT rc_do_normalize(struct rc *rc)
  {
  	if (rc->ptr >= rc->buffer_end)
  		rc_read(rc);
  	rc->range <<= 8;
  	rc->code = (rc->code << 8) | *rc->ptr++;
  }
  static inline void INIT rc_normalize(struct rc *rc)
  {
  	if (rc->range < (1 << RC_TOP_BITS))
  		rc_do_normalize(rc);
  }
  
  /* Called 9 times */
  /* Why rc_is_bit_0_helper exists?
   *Because we want to always expose (rc->code < rc->bound) to optimizer
   */
  static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
  {
  	rc_normalize(rc);
  	rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
  	return rc->bound;
  }
  static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
  {
  	uint32_t t = rc_is_bit_0_helper(rc, p);
  	return rc->code < t;
  }
  
  /* Called ~10 times, but very small, thus inlined */
  static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
  {
  	rc->range = rc->bound;
  	*p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
  }

  static inline void INIT rc_update_bit_1(struct rc *rc, uint16_t *p)

  {
  	rc->range -= rc->bound;
  	rc->code -= rc->bound;
  	*p -= *p >> RC_MOVE_BITS;
  }
  
  /* Called 4 times in unlzma loop */
  static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
  {
  	if (rc_is_bit_0(rc, p)) {
  		rc_update_bit_0(rc, p);
  		*symbol *= 2;
  		return 0;
  	} else {
  		rc_update_bit_1(rc, p);
  		*symbol = *symbol * 2 + 1;
  		return 1;
  	}
  }
  
  /* Called once */
  static inline int INIT rc_direct_bit(struct rc *rc)
  {
  	rc_normalize(rc);
  	rc->range >>= 1;
  	if (rc->code >= rc->range) {
  		rc->code -= rc->range;
  		return 1;
  	}
  	return 0;
  }
  
  /* Called twice */
  static inline void INIT
  rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
  {
  	int i = num_levels;
  
  	*symbol = 1;
  	while (i--)
  		rc_get_bit(rc, p + *symbol, symbol);
  	*symbol -= 1 << num_levels;
  }
  
  
  /*
   * Small lzma deflate implementation.
   * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
   *

   * Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)

   * Copyright (C) 1999-2005  Igor Pavlov
   */
  
  
  struct lzma_header {
  	uint8_t pos;
  	uint32_t dict_size;
  	uint64_t dst_size;
  } __attribute__ ((packed)) ;
  
  
  #define LZMA_BASE_SIZE 1846
  #define LZMA_LIT_SIZE 768
  
  #define LZMA_NUM_POS_BITS_MAX 4
  
  #define LZMA_LEN_NUM_LOW_BITS 3
  #define LZMA_LEN_NUM_MID_BITS 3
  #define LZMA_LEN_NUM_HIGH_BITS 8
  
  #define LZMA_LEN_CHOICE 0
  #define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
  #define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
  #define LZMA_LEN_MID (LZMA_LEN_LOW \
  		      + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
  #define LZMA_LEN_HIGH (LZMA_LEN_MID \
  		       +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
  #define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))
  
  #define LZMA_NUM_STATES 12
  #define LZMA_NUM_LIT_STATES 7
  
  #define LZMA_START_POS_MODEL_INDEX 4
  #define LZMA_END_POS_MODEL_INDEX 14
  #define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))
  
  #define LZMA_NUM_POS_SLOT_BITS 6
  #define LZMA_NUM_LEN_TO_POS_STATES 4
  
  #define LZMA_NUM_ALIGN_BITS 4
  
  #define LZMA_MATCH_MIN_LEN 2
  
  #define LZMA_IS_MATCH 0
  #define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
  #define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
  #define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
  #define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
  #define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
  #define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
  		       + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
  #define LZMA_SPEC_POS (LZMA_POS_SLOT \
  		       +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
  #define LZMA_ALIGN (LZMA_SPEC_POS \
  		    + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
  #define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
  #define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
  #define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
  
  
  struct writer {
  	uint8_t *buffer;
  	uint8_t previous_byte;
  	size_t buffer_pos;
  	int bufsize;
  	size_t global_pos;

  	long (*flush)(void*, unsigned long);

  	struct lzma_header *header;
  };
  
  struct cstate {
  	int state;
  	uint32_t rep0, rep1, rep2, rep3;
  };
  
  static inline size_t INIT get_pos(struct writer *wr)
  {
  	return
  		wr->global_pos + wr->buffer_pos;
  }
  
  static inline uint8_t INIT peek_old_byte(struct writer *wr,
  						uint32_t offs)
  {
  	if (!wr->flush) {
  		int32_t pos;
  		while (offs > wr->header->dict_size)
  			offs -= wr->header->dict_size;
  		pos = wr->buffer_pos - offs;
  		return wr->buffer[pos];
  	} else {
  		uint32_t pos = wr->buffer_pos - offs;
  		while (pos >= wr->header->dict_size)
  			pos += wr->header->dict_size;
  		return wr->buffer[pos];
  	}
  
  }

  static inline int INIT write_byte(struct writer *wr, uint8_t byte)

  {
  	wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
  	if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
  		wr->buffer_pos = 0;
  		wr->global_pos += wr->header->dict_size;

  		if (wr->flush((char *)wr->buffer, wr->header->dict_size)
  				!= wr->header->dict_size)
  			return -1;

  	}

  	return 0;

  }

  static inline int INIT copy_byte(struct writer *wr, uint32_t offs)

  {

  	return write_byte(wr, peek_old_byte(wr, offs));

  }

  static inline int INIT copy_bytes(struct writer *wr,

  					 uint32_t rep0, int len)
  {
  	do {

  		if (copy_byte(wr, rep0))
  			return -1;

  		len--;
  	} while (len != 0 && wr->buffer_pos < wr->header->dst_size);

  
  	return len;

  }

  static inline int INIT process_bit0(struct writer *wr, struct rc *rc,

  				     struct cstate *cst, uint16_t *p,
  				     int pos_state, uint16_t *prob,
  				     int lc, uint32_t literal_pos_mask) {
  	int mi = 1;
  	rc_update_bit_0(rc, prob);
  	prob = (p + LZMA_LITERAL +
  		(LZMA_LIT_SIZE
  		 * (((get_pos(wr) & literal_pos_mask) << lc)
  		    + (wr->previous_byte >> (8 - lc))))
  		);
  
  	if (cst->state >= LZMA_NUM_LIT_STATES) {
  		int match_byte = peek_old_byte(wr, cst->rep0);
  		do {
  			int bit;
  			uint16_t *prob_lit;
  
  			match_byte <<= 1;
  			bit = match_byte & 0x100;
  			prob_lit = prob + 0x100 + bit + mi;
  			if (rc_get_bit(rc, prob_lit, &mi)) {
  				if (!bit)
  					break;
  			} else {
  				if (bit)
  					break;
  			}
  		} while (mi < 0x100);
  	}
  	while (mi < 0x100) {
  		uint16_t *prob_lit = prob + mi;
  		rc_get_bit(rc, prob_lit, &mi);
  	}

  	if (cst->state < 4)
  		cst->state = 0;
  	else if (cst->state < 10)
  		cst->state -= 3;
  	else
  		cst->state -= 6;

  
  	return write_byte(wr, mi);

  }

  static inline int INIT process_bit1(struct writer *wr, struct rc *rc,

  					    struct cstate *cst, uint16_t *p,
  					    int pos_state, uint16_t *prob) {
    int offset;
  	uint16_t *prob_len;
  	int num_bits;
  	int len;
  
  	rc_update_bit_1(rc, prob);
  	prob = p + LZMA_IS_REP + cst->state;
  	if (rc_is_bit_0(rc, prob)) {
  		rc_update_bit_0(rc, prob);
  		cst->rep3 = cst->rep2;
  		cst->rep2 = cst->rep1;
  		cst->rep1 = cst->rep0;
  		cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
  		prob = p + LZMA_LEN_CODER;
  	} else {
  		rc_update_bit_1(rc, prob);
  		prob = p + LZMA_IS_REP_G0 + cst->state;
  		if (rc_is_bit_0(rc, prob)) {
  			rc_update_bit_0(rc, prob);
  			prob = (p + LZMA_IS_REP_0_LONG
  				+ (cst->state <<
  				   LZMA_NUM_POS_BITS_MAX) +
  				pos_state);
  			if (rc_is_bit_0(rc, prob)) {
  				rc_update_bit_0(rc, prob);
  
  				cst->state = cst->state < LZMA_NUM_LIT_STATES ?
  					9 : 11;

  				return copy_byte(wr, cst->rep0);

  			} else {
  				rc_update_bit_1(rc, prob);
  			}
  		} else {
  			uint32_t distance;
  
  			rc_update_bit_1(rc, prob);
  			prob = p + LZMA_IS_REP_G1 + cst->state;
  			if (rc_is_bit_0(rc, prob)) {
  				rc_update_bit_0(rc, prob);
  				distance = cst->rep1;
  			} else {
  				rc_update_bit_1(rc, prob);
  				prob = p + LZMA_IS_REP_G2 + cst->state;
  				if (rc_is_bit_0(rc, prob)) {
  					rc_update_bit_0(rc, prob);
  					distance = cst->rep2;
  				} else {
  					rc_update_bit_1(rc, prob);
  					distance = cst->rep3;
  					cst->rep3 = cst->rep2;
  				}
  				cst->rep2 = cst->rep1;
  			}
  			cst->rep1 = cst->rep0;
  			cst->rep0 = distance;
  		}
  		cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
  		prob = p + LZMA_REP_LEN_CODER;
  	}
  
  	prob_len = prob + LZMA_LEN_CHOICE;
  	if (rc_is_bit_0(rc, prob_len)) {
  		rc_update_bit_0(rc, prob_len);
  		prob_len = (prob + LZMA_LEN_LOW
  			    + (pos_state <<
  			       LZMA_LEN_NUM_LOW_BITS));
  		offset = 0;
  		num_bits = LZMA_LEN_NUM_LOW_BITS;
  	} else {
  		rc_update_bit_1(rc, prob_len);
  		prob_len = prob + LZMA_LEN_CHOICE_2;
  		if (rc_is_bit_0(rc, prob_len)) {
  			rc_update_bit_0(rc, prob_len);
  			prob_len = (prob + LZMA_LEN_MID
  				    + (pos_state <<
  				       LZMA_LEN_NUM_MID_BITS));
  			offset = 1 << LZMA_LEN_NUM_LOW_BITS;
  			num_bits = LZMA_LEN_NUM_MID_BITS;
  		} else {
  			rc_update_bit_1(rc, prob_len);
  			prob_len = prob + LZMA_LEN_HIGH;
  			offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
  				  + (1 << LZMA_LEN_NUM_MID_BITS));
  			num_bits = LZMA_LEN_NUM_HIGH_BITS;
  		}
  	}
  
  	rc_bit_tree_decode(rc, prob_len, num_bits, &len);
  	len += offset;
  
  	if (cst->state < 4) {
  		int pos_slot;
  
  		cst->state += LZMA_NUM_LIT_STATES;
  		prob =
  			p + LZMA_POS_SLOT +
  			((len <
  			  LZMA_NUM_LEN_TO_POS_STATES ? len :
  			  LZMA_NUM_LEN_TO_POS_STATES - 1)
  			 << LZMA_NUM_POS_SLOT_BITS);
  		rc_bit_tree_decode(rc, prob,
  				   LZMA_NUM_POS_SLOT_BITS,
  				   &pos_slot);
  		if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
  			int i, mi;
  			num_bits = (pos_slot >> 1) - 1;
  			cst->rep0 = 2 | (pos_slot & 1);
  			if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
  				cst->rep0 <<= num_bits;
  				prob = p + LZMA_SPEC_POS +
  					cst->rep0 - pos_slot - 1;
  			} else {
  				num_bits -= LZMA_NUM_ALIGN_BITS;
  				while (num_bits--)
  					cst->rep0 = (cst->rep0 << 1) |
  						rc_direct_bit(rc);
  				prob = p + LZMA_ALIGN;
  				cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
  				num_bits = LZMA_NUM_ALIGN_BITS;
  			}
  			i = 1;
  			mi = 1;
  			while (num_bits--) {
  				if (rc_get_bit(rc, prob + mi, &mi))
  					cst->rep0 |= i;
  				i <<= 1;
  			}
  		} else
  			cst->rep0 = pos_slot;
  		if (++(cst->rep0) == 0)

  			return 0;

  		if (cst->rep0 > wr->header->dict_size
  				|| cst->rep0 > get_pos(wr))
  			return -1;

  	}
  
  	len += LZMA_MATCH_MIN_LEN;

  	return copy_bytes(wr, cst->rep0, len);

  }

  STATIC inline int INIT unlzma(unsigned char *buf, long in_len,
  			      long (*fill)(void*, unsigned long),
  			      long (*flush)(void*, unsigned long),

  			      unsigned char *output,

  			      long *posp,

  			      void(*error)(char *x)

  	)
  {
  	struct lzma_header header;
  	int lc, pb, lp;
  	uint32_t pos_state_mask;
  	uint32_t literal_pos_mask;
  	uint16_t *p;
  	int num_probs;
  	struct rc rc;
  	int i, mi;
  	struct writer wr;
  	struct cstate cst;
  	unsigned char *inbuf;
  	int ret = -1;

  	rc.error = error;

  	if (buf)
  		inbuf = buf;
  	else
  		inbuf = malloc(LZMA_IOBUF_SIZE);
  	if (!inbuf) {

  		error("Could not allocate input buffer");

  		goto exit_0;
  	}
  
  	cst.state = 0;
  	cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
  
  	wr.header = &header;
  	wr.flush = flush;
  	wr.global_pos = 0;
  	wr.previous_byte = 0;
  	wr.buffer_pos = 0;
  
  	rc_init(&rc, fill, inbuf, in_len);
  
  	for (i = 0; i < sizeof(header); i++) {
  		if (rc.ptr >= rc.buffer_end)
  			rc_read(&rc);
  		((unsigned char *)&header)[i] = *rc.ptr++;
  	}

  	if (header.pos >= (9 * 5 * 5)) {

  		error("bad header");

  		goto exit_1;
  	}

  
  	mi = 0;
  	lc = header.pos;
  	while (lc >= 9) {
  		mi++;
  		lc -= 9;
  	}
  	pb = 0;
  	lp = mi;
  	while (lp >= 5) {
  		pb++;
  		lp -= 5;
  	}
  	pos_state_mask = (1 << pb) - 1;
  	literal_pos_mask = (1 << lp) - 1;
  
  	ENDIAN_CONVERT(header.dict_size);
  	ENDIAN_CONVERT(header.dst_size);
  
  	if (header.dict_size == 0)
  		header.dict_size = 1;
  
  	if (output)
  		wr.buffer = output;
  	else {
  		wr.bufsize = MIN(header.dst_size, header.dict_size);
  		wr.buffer = large_malloc(wr.bufsize);
  	}
  	if (wr.buffer == NULL)
  		goto exit_1;
  
  	num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
  	p = (uint16_t *) large_malloc(num_probs * sizeof(*p));

  	if (p == NULL)

  		goto exit_2;
  	num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
  	for (i = 0; i < num_probs; i++)
  		p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
  
  	rc_init_code(&rc);
  
  	while (get_pos(&wr) < header.dst_size) {
  		int pos_state =	get_pos(&wr) & pos_state_mask;
  		uint16_t *prob = p + LZMA_IS_MATCH +
  			(cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;

  		if (rc_is_bit_0(&rc, prob)) {
  			if (process_bit0(&wr, &rc, &cst, p, pos_state, prob,
  					lc, literal_pos_mask)) {
  				error("LZMA data is corrupt");
  				goto exit_3;
  			}
  		} else {
  			if (process_bit1(&wr, &rc, &cst, p, pos_state, prob)) {
  				error("LZMA data is corrupt");
  				goto exit_3;
  			}

  			if (cst.rep0 == 0)
  				break;
  		}

  		if (rc.buffer_size <= 0)
  			goto exit_3;

  	}
  
  	if (posp)
  		*posp = rc.ptr-rc.buffer;

  	if (!wr.flush || wr.flush(wr.buffer, wr.buffer_pos) == wr.buffer_pos)
  		ret = 0;

  exit_3:

  	large_free(p);
  exit_2:
  	if (!output)
  		large_free(wr.buffer);
  exit_1:
  	if (!buf)
  		free(inbuf);
  exit_0:
  	return ret;
  }

  #ifdef PREBOOT

  STATIC int INIT __decompress(unsigned char *buf, long in_len,

  			      long (*fill)(void*, unsigned long),
  			      long (*flush)(void*, unsigned long),

  			      unsigned char *output, long out_len,

  			      long *posp,

  			      void (*error)(char *x))

  {

  	return unlzma(buf, in_len - 4, fill, flush, output, posp, error);

  }
  #endif