block-sha1: get rid of redundant 'lenW' context
[git/git.git] / block-sha1 / sha1.c
CommitLineData
d7c208a9
LT
1/*
2 * Based on the Mozilla SHA1 (see mozilla-sha1/sha1.c),
3 * optimized to do word accesses rather than byte accesses,
4 * and to avoid unnecessary copies into the context array.
5 */
6
7#include <string.h>
8#include <arpa/inet.h>
9
10#include "sha1.h"
11
12/* Hash one 64-byte block of data */
13static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data);
14
15void blk_SHA1_Init(blk_SHA_CTX *ctx)
16{
d7c208a9
LT
17 ctx->size = 0;
18
19 /* Initialize H with the magic constants (see FIPS180 for constants)
20 */
21 ctx->H[0] = 0x67452301;
22 ctx->H[1] = 0xefcdab89;
23 ctx->H[2] = 0x98badcfe;
24 ctx->H[3] = 0x10325476;
25 ctx->H[4] = 0xc3d2e1f0;
26}
27
28
29void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
30{
5d5210c3 31 int lenW = ctx->size & 63;
d7c208a9 32
5d5210c3 33 ctx->size += len;
d7c208a9
LT
34
35 /* Read the data into W and process blocks as they get full
36 */
37 if (lenW) {
38 int left = 64 - lenW;
39 if (len < left)
40 left = len;
41 memcpy(lenW + (char *)ctx->W, data, left);
42 lenW = (lenW + left) & 63;
43 len -= left;
44 data += left;
d7c208a9
LT
45 if (lenW)
46 return;
47 blk_SHA1Block(ctx, ctx->W);
48 }
49 while (len >= 64) {
50 blk_SHA1Block(ctx, data);
51 data += 64;
52 len -= 64;
53 }
5d5210c3 54 if (len)
d7c208a9 55 memcpy(ctx->W, data, len);
d7c208a9
LT
56}
57
58
59void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
60{
61 static const unsigned char pad[64] = { 0x80 };
62 unsigned int padlen[2];
63 int i;
64
65 /* Pad with a binary 1 (ie 0x80), then zeroes, then length
66 */
5d5210c3
LT
67 padlen[0] = htonl(ctx->size >> 29);
68 padlen[1] = htonl(ctx->size << 3);
d7c208a9 69
5d5210c3
LT
70 i = ctx->size & 63;
71 blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - i)));
d7c208a9
LT
72 blk_SHA1_Update(ctx, padlen, 8);
73
74 /* Output hash
75 */
76 for (i = 0; i < 5; i++)
77 ((unsigned int *)hashout)[i] = htonl(ctx->H[i]);
78}
79
b8e48a89
LT
80#if defined(__i386__) || defined(__x86_64__)
81
fd536d34 82#define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })
b8e48a89
LT
83#define SHA_ROL(x,n) SHA_ASM("rol", x, n)
84#define SHA_ROR(x,n) SHA_ASM("ror", x, n)
85
86#else
87
fd536d34 88#define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r)))
b8e48a89
LT
89#define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))
90#define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)
91
92#endif
d7c208a9 93
ab14c823
LT
94/* This "rolls" over the 512-bit array */
95#define W(x) (array[(x)&15])
96
97/*
98 * Where do we get the source from? The first 16 iterations get it from
99 * the input data, the next mix it from the 512-bit array.
100 */
101#define SHA_SRC(t) htonl(data[t])
102#define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
103
104#define SHA_ROUND(t, input, fn, constant) \
105 TEMP = input(t); W(t) = TEMP; \
106 TEMP += SHA_ROL(A,5) + (fn) + E + (constant); \
107 E = D; D = C; C = SHA_ROR(B, 2); B = A; A = TEMP
108
109#define T_0_15(t) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999 )
110#define T_16_19(t) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999 )
111#define T_20_39(t) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1 )
e869e113 112#define T_40_59(t) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc )
ab14c823
LT
113#define T_60_79(t) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6 )
114
d7c208a9
LT
115static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data)
116{
d7c208a9 117 unsigned int A,B,C,D,E,TEMP;
7b5075fc 118 unsigned int array[16];
d7c208a9 119
d7c208a9
LT
120 A = ctx->H[0];
121 B = ctx->H[1];
122 C = ctx->H[2];
123 D = ctx->H[3];
124 E = ctx->H[4];
125
ab14c823 126 /* Round 1 - iterations 0-16 take their input from 'data' */
139e3456
LT
127 T_0_15( 0); T_0_15( 1); T_0_15( 2); T_0_15( 3); T_0_15( 4);
128 T_0_15( 5); T_0_15( 6); T_0_15( 7); T_0_15( 8); T_0_15( 9);
129 T_0_15(10); T_0_15(11); T_0_15(12); T_0_15(13); T_0_15(14);
130 T_0_15(15);
131
ab14c823 132 /* Round 1 - tail. Input from 512-bit mixing array */
139e3456 133 T_16_19(16); T_16_19(17); T_16_19(18); T_16_19(19);
d7c208a9 134
ab14c823 135 /* Round 2 */
d7c208a9
LT
136 T_20_39(20); T_20_39(21); T_20_39(22); T_20_39(23); T_20_39(24);
137 T_20_39(25); T_20_39(26); T_20_39(27); T_20_39(28); T_20_39(29);
138 T_20_39(30); T_20_39(31); T_20_39(32); T_20_39(33); T_20_39(34);
139 T_20_39(35); T_20_39(36); T_20_39(37); T_20_39(38); T_20_39(39);
140
ab14c823 141 /* Round 3 */
d7c208a9
LT
142 T_40_59(40); T_40_59(41); T_40_59(42); T_40_59(43); T_40_59(44);
143 T_40_59(45); T_40_59(46); T_40_59(47); T_40_59(48); T_40_59(49);
144 T_40_59(50); T_40_59(51); T_40_59(52); T_40_59(53); T_40_59(54);
145 T_40_59(55); T_40_59(56); T_40_59(57); T_40_59(58); T_40_59(59);
146
ab14c823 147 /* Round 4 */
d7c208a9
LT
148 T_60_79(60); T_60_79(61); T_60_79(62); T_60_79(63); T_60_79(64);
149 T_60_79(65); T_60_79(66); T_60_79(67); T_60_79(68); T_60_79(69);
150 T_60_79(70); T_60_79(71); T_60_79(72); T_60_79(73); T_60_79(74);
151 T_60_79(75); T_60_79(76); T_60_79(77); T_60_79(78); T_60_79(79);
152
153 ctx->H[0] += A;
154 ctx->H[1] += B;
155 ctx->H[2] += C;
156 ctx->H[3] += D;
157 ctx->H[4] += E;
158}