diff options
Diffstat (limited to 'third_party/git/block-sha1/sha1.c')
| -rw-r--r-- | third_party/git/block-sha1/sha1.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/third_party/git/block-sha1/sha1.c b/third_party/git/block-sha1/sha1.c new file mode 100644 index 000000000000..22b125cf8c12 --- /dev/null +++ b/third_party/git/block-sha1/sha1.c @@ -0,0 +1,251 @@ +/* + * 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" + +#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) + +/* + * Force usage of rol or ror by selecting the one with the smaller constant. + * It _can_ generate slightly smaller code (a constant of 1 is special), but + * perhaps more importantly it's possibly faster on any uarch that does a + * rotate with a loop. + */ + +#define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; }) +#define SHA_ROL(x,n) SHA_ASM("rol", x, n) +#define SHA_ROR(x,n) SHA_ASM("ror", x, n) + +#else + +#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) + +#endif + +/* + * 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, unsigned long 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]); +} |