/*
   * Keyed 32-bit hash function using TEA in a Davis-Meyer function
   *   H0 = Key
   *   Hi = E Mi(Hi-1) + Hi-1
   *
   * (see Applied Cryptography, 2nd edition, p448).
   *
   * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998

   *

   * Jeremy has agreed to the contents of reiserfs/README. -Hans
   * Yura's function is added (04/07/2000)
   */
  
  //
  // keyed_hash
  // yura_hash
  // r5_hash
  //
  
  #include <linux/kernel.h>

  #include <linux/reiserfs_fs.h>

  #include <asm/types.h>

  #define DELTA 0x9E3779B9
  #define FULLROUNDS 10		/* 32 is overkill, 16 is strong crypto */
  #define PARTROUNDS 6		/* 6 gets complete mixing */
  
  /* a, b, c, d - data; h0, h1 - accumulated hash */
  #define TEACORE(rounds)							\
  	do {								\
  		u32 sum = 0;						\
  		int n = rounds;						\
  		u32 b0, b1;						\
  									\
  		b0 = h0;						\
  		b1 = h1;						\
  									\
  		do							\
  		{							\
  			sum += DELTA;					\
  			b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);	\
  			b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);	\
  		} while(--n);						\
  									\
  		h0 += b0;						\
  		h1 += b1;						\
  	} while(0)

  u32 keyed_hash(const signed char *msg, int len)
  {

  	u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };

  
  	u32 h0 = k[0], h1 = k[1];
  	u32 a, b, c, d;
  	u32 pad;
  	int i;

  	//      assert(len >= 0 && len < 256);
  
  	pad = (u32) len | ((u32) len << 8);

  	pad |= pad << 16;

  	while (len >= 16) {
  		a = (u32) msg[0] |
  		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  		b = (u32) msg[4] |
  		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
  		c = (u32) msg[8] |
  		    (u32) msg[9] << 8 |
  		    (u32) msg[10] << 16 | (u32) msg[11] << 24;
  		d = (u32) msg[12] |
  		    (u32) msg[13] << 8 |
  		    (u32) msg[14] << 16 | (u32) msg[15] << 24;

  		TEACORE(PARTROUNDS);
  
  		len -= 16;
  		msg += 16;
  	}

  	if (len >= 12) {
  		a = (u32) msg[0] |
  		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  		b = (u32) msg[4] |
  		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
  		c = (u32) msg[8] |
  		    (u32) msg[9] << 8 |
  		    (u32) msg[10] << 16 | (u32) msg[11] << 24;

  
  		d = pad;

  		for (i = 12; i < len; i++) {

  			d <<= 8;
  			d |= msg[i];
  		}

  	} else if (len >= 8) {
  		a = (u32) msg[0] |
  		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
  		b = (u32) msg[4] |
  		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;

  
  		c = d = pad;

  		for (i = 8; i < len; i++) {

  			c <<= 8;
  			c |= msg[i];
  		}

  	} else if (len >= 4) {
  		a = (u32) msg[0] |
  		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;

  
  		b = c = d = pad;

  		for (i = 4; i < len; i++) {

  			b <<= 8;
  			b |= msg[i];
  		}

  	} else {

  		a = b = c = d = pad;

  		for (i = 0; i < len; i++) {

  			a <<= 8;
  			a |= msg[i];
  		}
  	}
  
  	TEACORE(FULLROUNDS);
  
  /*	return 0;*/

  	return h0 ^ h1;

  }
  
  /* What follows in this file is copyright 2000 by Hans Reiser, and the
   * licensing of what follows is governed by reiserfs/README */

  u32 yura_hash(const signed char *msg, int len)

  {

  	int j, pow;
  	u32 a, c;
  	int i;
  
  	for (pow = 1, i = 1; i < len; i++)
  		pow = pow * 10;
  
  	if (len == 1)
  		a = msg[0] - 48;
  	else
  		a = (msg[0] - 48) * pow;
  
  	for (i = 1; i < len; i++) {
  		c = msg[i] - 48;
  		for (pow = 1, j = i; j < len - 1; j++)
  			pow = pow * 10;
  		a = a + c * pow;
  	}
  
  	for (; i < 40; i++) {
  		c = '0' - 48;
  		for (pow = 1, j = i; j < len - 1; j++)
  			pow = pow * 10;
  		a = a + c * pow;
  	}
  
  	for (; i < 256; i++) {
  		c = i;
  		for (pow = 1, j = i; j < len - 1; j++)
  			pow = pow * 10;
  		a = a + c * pow;
  	}
  
  	a = a << 7;
  	return a;

  }

  u32 r5_hash(const signed char *msg, int len)

  {

  	u32 a = 0;
  	while (*msg) {
  		a += *msg << 4;
  		a += *msg >> 4;
  		a *= 11;
  		msg++;
  	}
  	return a;

  }