tea_hash.c

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/* Copyright (C) 2001-2005 by Hans Reiser, licensing governed by
   reiser4progs/COPYING.
   
   tea_hash.c -- tea hash implementation. */

#ifdef ENABLE_TEA_HASH

#include <reiser4/plugin.h>

#define FULLROUNDS  10
#define PARTROUNDS  6
#define DELTA	    0x9E3779B9

#define tea_hash_core(rounds)					               \
do {								               \
        uint64_t sum = 0;						       \
        int n = rounds;						               \
        uint64_t 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)

uint64_t tea_hash_build(unsigned char *name, uint32_t len) {
	uint64_t k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3}; 

	uint64_t i;
	uint64_t pad;
	uint64_t a, b, c, d;
	uint64_t h0 = k[0], h1 = k[1];
 
	pad = (uint64_t)len | ((uint64_t)len << 8);
	pad |= pad << 16;

	while(len >= 16) {
		a = (uint64_t)name[0]      |
			(uint64_t)name[1] << 8 |
			(uint64_t)name[2] << 16|
			(uint64_t)name[3] << 24;
	
		b = (uint64_t)name[4]      |
			(uint64_t)name[5] << 8 |
			(uint64_t)name[6] << 16|
			(uint64_t)name[7] << 24;
	
		c = (uint64_t)name[8]       |
			(uint64_t)name[9] << 8  |
			(uint64_t)name[10] << 16|
			(uint64_t)name[11] << 24;
	
		d = (uint64_t)name[12]      |
			(uint64_t)name[13] << 8 |
			(uint64_t)name[14] << 16|
			(uint64_t)name[15] << 24;
	
		tea_hash_core(PARTROUNDS);
	    
		len -= 16;
		name += 16;
	}

	if (len >= 12) {
		if (len >= 16)
			*(int *)0 = 0;

		a = (uint64_t)name[ 0]      |
			(uint64_t)name[ 1] << 8 |
			(uint64_t)name[ 2] << 16|
			(uint64_t)name[ 3] << 24;
	    
		b = (uint64_t)name[ 4]      |
			(uint64_t)name[ 5] << 8 |
			(uint64_t)name[ 6] << 16|
			(uint64_t)name[ 7] << 24;
	    
		c = (uint64_t)name[ 8]      |
			(uint64_t)name[ 9] << 8 |
			(uint64_t)name[10] << 16|
			(uint64_t)name[11] << 24;

		d = pad;
		for(i = 12; i < len; i++) {
			d <<= 8;
			d |= name[i];
		}
	} else if (len >= 8) {
		if (len >= 12)
			*(int *)0 = 0;
		a = (uint64_t)name[ 0]      |
			(uint64_t)name[ 1] << 8 |
			(uint64_t)name[ 2] << 16|
			(uint64_t)name[ 3] << 24;
	
		b = (uint64_t)name[ 4]      |
			(uint64_t)name[ 5] << 8 |
			(uint64_t)name[ 6] << 16|
			(uint64_t)name[ 7] << 24;
	
		c = d = pad;
	    
		for (i = 8; i < len; i++) {
			c <<= 8;
			c |= name[i];
		}
	} else if (len >= 4) {
		if (len >= 8)
			*(int *)0 = 0;
	
		a = (uint64_t)name[ 0]      |
			(uint64_t)name[ 1] << 8 |
			(uint64_t)name[ 2] << 16|
			(uint64_t)name[ 3] << 24;
	
		b = c = d = pad;
		for (i = 4; i < len; i++) {
			b <<= 8;
			b |= name[i];
		}
	} else {
		if (len >= 4)
			*(int *)0 = 0;
	
		a = b = c = d = pad;
		for(i = 0; i < len; i++) {
			a <<= 8;
			a |= name[i];
		}
	}

	tea_hash_core(FULLROUNDS);

	return h0 ^ h1;
}

reiser4_hash_plug_t tea_hash_plug = {
	.p = {
		.id = {HASH_TEA_ID, 0, HASH_PLUG_TYPE},
#ifndef ENABLE_MINIMAL
		.label = "tea_hash",
		.desc  = "Tea hash plugin.",
#endif
	},
	
	.build = tea_hash_build
};
#endif