block-sha1/sha1.c - jrn/git - Git at Google

 /*
  * SHA1 routine optimized to do word accesses rather than byte accesses,
  * and to avoid unnecessary copies into the context array.
  *
  * This was initially based on the Mozilla SHA1 implementation, although
  * none of the original Mozilla code remains.
  */

 /* this is only to get definitions for memcpy(), ntohl() and htonl() */
 #include "../git-compat-util.h"

 #include "sha1.h"

 #define SHA_ROT(X,l,r)	(((X) << (l)) | ((X) >> (r)))
 #define SHA_ROL(X,n)	SHA_ROT(X,n,32-(n))
 #define SHA_ROR(X,n)	SHA_ROT(X,32-(n),n)

 /*
  * If you have 32 registers or more, the compiler can (and should)
  * try to change the array[] accesses into registers. However, on
  * machines with less than ~25 registers, that won't really work,
  * and at least gcc will make an unholy mess of it.
  *
  * So to avoid that mess which just slows things down, we force
  * the stores to memory to actually happen (we might be better off
  * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
  * suggested by Artur Skawina - that will also make gcc unable to
  * try to do the silly "optimize away loads" part because it won't
  * see what the value will be).
  *
  * Ben Herrenschmidt reports that on PPC, the C version comes close
  * to the optimized asm with this (ie on PPC you don't want that
  * 'volatile', since there are lots of registers).
  *
  * On ARM we get the best code generation by forcing a full memory barrier
  * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
  * the stack frame size simply explode and performance goes down the drain.
  */

 #if defined(__i386__) || defined(__x86_64__)
   #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
 #elif defined(__GNUC__) && defined(__arm__)
   #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
 #else
   #define setW(x, val) (W(x) = (val))
 #endif

 /* This "rolls" over the 512-bit array */
 #define W(x) (array[(x)&15])

 /*
  * Where do we get the source from? The first 16 iterations get it from
  * the input data, the next mix it from the 512-bit array.
  */
 #define SHA_SRC(t) get_be32((unsigned char *) block + (t)*4)
 #define SHA_MIX(t) SHA_ROL(W((t)+13) ^ W((t)+8) ^ W((t)+2) ^ W(t), 1)

 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
 	unsigned int TEMP = input(t); setW(t, TEMP); \
 	E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
 	B = SHA_ROR(B, 2); } while (0)

 #define T_0_15(t, A, B, C, D, E)  SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
 #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
 #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )

 static void blk_SHA1_Block(blk_SHA_CTX *ctx, const void *block)
 {
 	unsigned int A,B,C,D,E;
 	unsigned int array[16];

 	A = ctx->H[0];
 	B = ctx->H[1];
 	C = ctx->H[2];
 	D = ctx->H[3];
 	E = ctx->H[4];

 	/* Round 1 - iterations 0-16 take their input from 'block' */
 	T_0_15( 0, A, B, C, D, E);
 	T_0_15( 1, E, A, B, C, D);
 	T_0_15( 2, D, E, A, B, C);
 	T_0_15( 3, C, D, E, A, B);
 	T_0_15( 4, B, C, D, E, A);
 	T_0_15( 5, A, B, C, D, E);
 	T_0_15( 6, E, A, B, C, D);
 	T_0_15( 7, D, E, A, B, C);
 	T_0_15( 8, C, D, E, A, B);
 	T_0_15( 9, B, C, D, E, A);
 	T_0_15(10, A, B, C, D, E);
 	T_0_15(11, E, A, B, C, D);
 	T_0_15(12, D, E, A, B, C);
 	T_0_15(13, C, D, E, A, B);
 	T_0_15(14, B, C, D, E, A);
 	T_0_15(15, A, B, C, D, E);

 	/* Round 1 - tail. Input from 512-bit mixing array */
 	T_16_19(16, E, A, B, C, D);
 	T_16_19(17, D, E, A, B, C);
 	T_16_19(18, C, D, E, A, B);
 	T_16_19(19, B, C, D, E, A);

 	/* Round 2 */
 	T_20_39(20, A, B, C, D, E);
 	T_20_39(21, E, A, B, C, D);
 	T_20_39(22, D, E, A, B, C);
 	T_20_39(23, C, D, E, A, B);
 	T_20_39(24, B, C, D, E, A);
 	T_20_39(25, A, B, C, D, E);
 	T_20_39(26, E, A, B, C, D);
 	T_20_39(27, D, E, A, B, C);
 	T_20_39(28, C, D, E, A, B);
 	T_20_39(29, B, C, D, E, A);
 	T_20_39(30, A, B, C, D, E);
 	T_20_39(31, E, A, B, C, D);
 	T_20_39(32, D, E, A, B, C);
 	T_20_39(33, C, D, E, A, B);
 	T_20_39(34, B, C, D, E, A);
 	T_20_39(35, A, B, C, D, E);
 	T_20_39(36, E, A, B, C, D);
 	T_20_39(37, D, E, A, B, C);
 	T_20_39(38, C, D, E, A, B);
 	T_20_39(39, B, C, D, E, A);

 	/* Round 3 */
 	T_40_59(40, A, B, C, D, E);
 	T_40_59(41, E, A, B, C, D);
 	T_40_59(42, D, E, A, B, C);
 	T_40_59(43, C, D, E, A, B);
 	T_40_59(44, B, C, D, E, A);
 	T_40_59(45, A, B, C, D, E);
 	T_40_59(46, E, A, B, C, D);
 	T_40_59(47, D, E, A, B, C);
 	T_40_59(48, C, D, E, A, B);
 	T_40_59(49, B, C, D, E, A);
 	T_40_59(50, A, B, C, D, E);
 	T_40_59(51, E, A, B, C, D);
 	T_40_59(52, D, E, A, B, C);
 	T_40_59(53, C, D, E, A, B);
 	T_40_59(54, B, C, D, E, A);
 	T_40_59(55, A, B, C, D, E);
 	T_40_59(56, E, A, B, C, D);
 	T_40_59(57, D, E, A, B, C);
 	T_40_59(58, C, D, E, A, B);
 	T_40_59(59, B, C, D, E, A);

 	/* Round 4 */
 	T_60_79(60, A, B, C, D, E);
 	T_60_79(61, E, A, B, C, D);
 	T_60_79(62, D, E, A, B, C);
 	T_60_79(63, C, D, E, A, B);
 	T_60_79(64, B, C, D, E, A);
 	T_60_79(65, A, B, C, D, E);
 	T_60_79(66, E, A, B, C, D);
 	T_60_79(67, D, E, A, B, C);
 	T_60_79(68, C, D, E, A, B);
 	T_60_79(69, B, C, D, E, A);
 	T_60_79(70, A, B, C, D, E);
 	T_60_79(71, E, A, B, C, D);
 	T_60_79(72, D, E, A, B, C);
 	T_60_79(73, C, D, E, A, B);
 	T_60_79(74, B, C, D, E, A);
 	T_60_79(75, A, B, C, D, E);
 	T_60_79(76, E, A, B, C, D);
 	T_60_79(77, D, E, A, B, C);
 	T_60_79(78, C, D, E, A, B);
 	T_60_79(79, B, C, D, E, A);

 	ctx->H[0] += A;
 	ctx->H[1] += B;
 	ctx->H[2] += C;
 	ctx->H[3] += D;
 	ctx->H[4] += E;
 }

 void blk_SHA1_Init(blk_SHA_CTX *ctx)
 {
 	ctx->size = 0;

 	/* Initialize H with the magic constants (see FIPS180 for constants) */
 	ctx->H[0] = 0x67452301;
 	ctx->H[1] = 0xefcdab89;
 	ctx->H[2] = 0x98badcfe;
 	ctx->H[3] = 0x10325476;
 	ctx->H[4] = 0xc3d2e1f0;
 }

 void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, size_t len)
 {
 	unsigned int lenW = ctx->size & 63;

 	ctx->size += len;

 	/* Read the data into W and process blocks as they get full */
 	if (lenW) {
 		unsigned int left = 64 - lenW;
 		if (len < left)
 			left = len;
 		memcpy(lenW + (char *)ctx->W, data, left);
 		lenW = (lenW + left) & 63;
 		len -= left;
 		data = ((const char *)data + left);
 		if (lenW)
 			return;
 		blk_SHA1_Block(ctx, ctx->W);
 	}
 	while (len >= 64) {
 		blk_SHA1_Block(ctx, data);
 		data = ((const char *)data + 64);
 		len -= 64;
 	}
 	if (len)
 		memcpy(ctx->W, data, len);
 }

 void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
 {
 	static const unsigned char pad[64] = { 0x80 };
 	unsigned int padlen[2];
 	int i;

 	/* Pad with a binary 1 (ie 0x80), then zeroes, then length */
 	padlen[0] = htonl((uint32_t)(ctx->size >> 29));
 	padlen[1] = htonl((uint32_t)(ctx->size << 3));

 	i = ctx->size & 63;
 	blk_SHA1_Update(ctx, pad, 1 + (63 & (55 - i)));
 	blk_SHA1_Update(ctx, padlen, 8);

 	/* Output hash */
 	for (i = 0; i < 5; i++)
 		put_be32(hashout + i * 4, ctx->H[i]);
 }
	/*
	* SHA1 routine optimized to do word accesses rather than byte accesses,
	* and to avoid unnecessary copies into the context array.
	*
	* This was initially based on the Mozilla SHA1 implementation, although
	* none of the original Mozilla code remains.
	*/

	/* this is only to get definitions for memcpy(), ntohl() and htonl() */
	#include "../git-compat-util.h"

	#include "sha1.h"

	#define SHA_ROT(X,l,r) (((X) << (l)) \| ((X) >> (r)))
	#define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))
	#define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)

	/*
	* If you have 32 registers or more, the compiler can (and should)
	* try to change the array[] accesses into registers. However, on
	* machines with less than ~25 registers, that won't really work,
	* and at least gcc will make an unholy mess of it.
	*
	* So to avoid that mess which just slows things down, we force
	* the stores to memory to actually happen (we might be better off
	* with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
	* suggested by Artur Skawina - that will also make gcc unable to
	* try to do the silly "optimize away loads" part because it won't
	* see what the value will be).
	*
	* Ben Herrenschmidt reports that on PPC, the C version comes close
	* to the optimized asm with this (ie on PPC you don't want that
	* 'volatile', since there are lots of registers).
	*
	* On ARM we get the best code generation by forcing a full memory barrier
	* between each SHA_ROUND, otherwise gcc happily get wild with spilling and
	* the stack frame size simply explode and performance goes down the drain.
	*/

	#if defined(__i386__) \|\| defined(__x86_64__)
	#define setW(x, val) ((volatile unsigned int )&W(x) = (val))
	#elif defined(__GNUC__) && defined(__arm__)
	#define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
	#else
	#define setW(x, val) (W(x) = (val))
	#endif

	/* This "rolls" over the 512-bit array */
	#define W(x) (array[(x)&15])

	/*
	* Where do we get the source from? The first 16 iterations get it from
	* the input data, the next mix it from the 512-bit array.
	*/
	#define SHA_SRC(t) get_be32((unsigned char ) block + (t)4)
	#define SHA_MIX(t) SHA_ROL(W((t)+13) ^ W((t)+8) ^ W((t)+2) ^ W(t), 1)

	#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
	unsigned int TEMP = input(t); setW(t, TEMP); \
	E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
	B = SHA_ROR(B, 2); } while (0)

	#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
	#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
	#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
	#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
	#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )

	static void blk_SHA1_Block(blk_SHA_CTX ctx, const void block)
	{
	unsigned int A,B,C,D,E;
	unsigned int array[16];

	A = ctx->H[0];
	B = ctx->H[1];
	C = ctx->H[2];
	D = ctx->H[3];
	E = ctx->H[4];

	/* Round 1 - iterations 0-16 take their input from 'block' */
	T_0_15( 0, A, B, C, D, E);
	T_0_15( 1, E, A, B, C, D);
	T_0_15( 2, D, E, A, B, C);
	T_0_15( 3, C, D, E, A, B);
	T_0_15( 4, B, C, D, E, A);
	T_0_15( 5, A, B, C, D, E);
	T_0_15( 6, E, A, B, C, D);
	T_0_15( 7, D, E, A, B, C);
	T_0_15( 8, C, D, E, A, B);
	T_0_15( 9, B, C, D, E, A);
	T_0_15(10, A, B, C, D, E);
	T_0_15(11, E, A, B, C, D);
	T_0_15(12, D, E, A, B, C);
	T_0_15(13, C, D, E, A, B);
	T_0_15(14, B, C, D, E, A);
	T_0_15(15, A, B, C, D, E);

	/* Round 1 - tail. Input from 512-bit mixing array */
	T_16_19(16, E, A, B, C, D);
	T_16_19(17, D, E, A, B, C);
	T_16_19(18, C, D, E, A, B);
	T_16_19(19, B, C, D, E, A);

	/* Round 2 */
	T_20_39(20, A, B, C, D, E);
	T_20_39(21, E, A, B, C, D);
	T_20_39(22, D, E, A, B, C);
	T_20_39(23, C, D, E, A, B);
	T_20_39(24, B, C, D, E, A);
	T_20_39(25, A, B, C, D, E);
	T_20_39(26, E, A, B, C, D);
	T_20_39(27, D, E, A, B, C);
	T_20_39(28, C, D, E, A, B);
	T_20_39(29, B, C, D, E, A);
	T_20_39(30, A, B, C, D, E);
	T_20_39(31, E, A, B, C, D);
	T_20_39(32, D, E, A, B, C);
	T_20_39(33, C, D, E, A, B);
	T_20_39(34, B, C, D, E, A);
	T_20_39(35, A, B, C, D, E);
	T_20_39(36, E, A, B, C, D);
	T_20_39(37, D, E, A, B, C);
	T_20_39(38, C, D, E, A, B);
	T_20_39(39, B, C, D, E, A);

	/* Round 3 */
	T_40_59(40, A, B, C, D, E);
	T_40_59(41, E, A, B, C, D);
	T_40_59(42, D, E, A, B, C);
	T_40_59(43, C, D, E, A, B);
	T_40_59(44, B, C, D, E, A);
	T_40_59(45, A, B, C, D, E);
	T_40_59(46, E, A, B, C, D);
	T_40_59(47, D, E, A, B, C);
	T_40_59(48, C, D, E, A, B);
	T_40_59(49, B, C, D, E, A);
	T_40_59(50, A, B, C, D, E);
	T_40_59(51, E, A, B, C, D);
	T_40_59(52, D, E, A, B, C);
	T_40_59(53, C, D, E, A, B);
	T_40_59(54, B, C, D, E, A);
	T_40_59(55, A, B, C, D, E);
	T_40_59(56, E, A, B, C, D);
	T_40_59(57, D, E, A, B, C);
	T_40_59(58, C, D, E, A, B);
	T_40_59(59, B, C, D, E, A);

	/* Round 4 */
	T_60_79(60, A, B, C, D, E);
	T_60_79(61, E, A, B, C, D);
	T_60_79(62, D, E, A, B, C);
	T_60_79(63, C, D, E, A, B);
	T_60_79(64, B, C, D, E, A);
	T_60_79(65, A, B, C, D, E);
	T_60_79(66, E, A, B, C, D);
	T_60_79(67, D, E, A, B, C);
	T_60_79(68, C, D, E, A, B);
	T_60_79(69, B, C, D, E, A);
	T_60_79(70, A, B, C, D, E);
	T_60_79(71, E, A, B, C, D);
	T_60_79(72, D, E, A, B, C);
	T_60_79(73, C, D, E, A, B);
	T_60_79(74, B, C, D, E, A);
	T_60_79(75, A, B, C, D, E);
	T_60_79(76, E, A, B, C, D);
	T_60_79(77, D, E, A, B, C);
	T_60_79(78, C, D, E, A, B);
	T_60_79(79, B, C, D, E, A);

	ctx->H[0] += A;
	ctx->H[1] += B;
	ctx->H[2] += C;
	ctx->H[3] += D;
	ctx->H[4] += E;
	}

	void blk_SHA1_Init(blk_SHA_CTX *ctx)
	{
	ctx->size = 0;

	/* Initialize H with the magic constants (see FIPS180 for constants) */
	ctx->H[0] = 0x67452301;
	ctx->H[1] = 0xefcdab89;
	ctx->H[2] = 0x98badcfe;
	ctx->H[3] = 0x10325476;
	ctx->H[4] = 0xc3d2e1f0;
	}

	void blk_SHA1_Update(blk_SHA_CTX ctx, const void data, size_t len)
	{
	unsigned int lenW = ctx->size & 63;

	ctx->size += len;

	/* Read the data into W and process blocks as they get full */
	if (lenW) {
	unsigned int left = 64 - lenW;
	if (len < left)
	left = len;
	memcpy(lenW + (char *)ctx->W, data, left);
	lenW = (lenW + left) & 63;
	len -= left;
	data = ((const char *)data + left);
	if (lenW)
	return;
	blk_SHA1_Block(ctx, ctx->W);
	}
	while (len >= 64) {
	blk_SHA1_Block(ctx, data);
	data = ((const char *)data + 64);
	len -= 64;
	}
	if (len)
	memcpy(ctx->W, data, len);
	}

	void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
	{
	static const unsigned char pad[64] = { 0x80 };
	unsigned int padlen[2];
	int i;

	/* Pad with a binary 1 (ie 0x80), then zeroes, then length */
	padlen[0] = htonl((uint32_t)(ctx->size >> 29));
	padlen[1] = htonl((uint32_t)(ctx->size << 3));

	i = ctx->size & 63;
	blk_SHA1_Update(ctx, pad, 1 + (63 & (55 - i)));
	blk_SHA1_Update(ctx, padlen, 8);

	/* Output hash */
	for (i = 0; i < 5; i++)
	put_be32(hashout + i * 4, ctx->H[i]);
	}