block-sha1: split the different "hacks" to be individually selected
[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
b8e48a89
LT
12#if defined(__i386__) || defined(__x86_64__)
13
dc52fd29
NP
14/*
15 * Force usage of rol or ror by selecting the one with the smaller constant.
16 * It _can_ generate slightly smaller code (a constant of 1 is special), but
17 * perhaps more importantly it's possibly faster on any uarch that does a
18 * rotate with a loop.
19 */
20
fd536d34 21#define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })
b8e48a89
LT
22#define SHA_ROL(x,n) SHA_ASM("rol", x, n)
23#define SHA_ROR(x,n) SHA_ASM("ror", x, n)
24
25#else
26
fd536d34 27#define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r)))
b8e48a89
LT
28#define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))
29#define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)
30
31#endif
d7c208a9 32
926172c5
LT
33/*
34 * If you have 32 registers or more, the compiler can (and should)
35 * try to change the array[] accesses into registers. However, on
36 * machines with less than ~25 registers, that won't really work,
37 * and at least gcc will make an unholy mess of it.
38 *
39 * So to avoid that mess which just slows things down, we force
40 * the stores to memory to actually happen (we might be better off
41 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
42 * suggested by Artur Skawina - that will also make gcc unable to
43 * try to do the silly "optimize away loads" part because it won't
44 * see what the value will be).
45 *
46 * Ben Herrenschmidt reports that on PPC, the C version comes close
47 * to the optimized asm with this (ie on PPC you don't want that
48 * 'volatile', since there are lots of registers).
dc52fd29
NP
49 *
50 * On ARM we get the best code generation by forcing a full memory barrier
51 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
52 * the stack frame size simply explode and performance goes down the drain.
926172c5 53 */
dc52fd29
NP
54
55#if defined(__i386__) || defined(__x86_64__)
926172c5 56 #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
dc52fd29
NP
57#elif defined(__arm__)
58 #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
926172c5
LT
59#else
60 #define setW(x, val) (W(x) = (val))
61#endif
ab14c823 62
dc52fd29
NP
63/* This "rolls" over the 512-bit array */
64#define W(x) (array[(x)&15])
65
ab14c823
LT
66/*
67 * Where do we get the source from? The first 16 iterations get it from
68 * the input data, the next mix it from the 512-bit array.
69 */
70#define SHA_SRC(t) htonl(data[t])
71#define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
72
30d12d4c 73#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
66c9c6c0
LT
74 unsigned int TEMP = input(t); setW(t, TEMP); \
75 E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
76 B = SHA_ROR(B, 2); } while (0)
ab14c823 77
30d12d4c
LT
78#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 )
79#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 )
80#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
81#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 )
82#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
ab14c823 83
30ba0de7 84static void blk_SHA1_Block(blk_SHA_CTX *ctx, const unsigned int *data)
d7c208a9 85{
30d12d4c 86 unsigned int A,B,C,D,E;
7b5075fc 87 unsigned int array[16];
d7c208a9 88
d7c208a9
LT
89 A = ctx->H[0];
90 B = ctx->H[1];
91 C = ctx->H[2];
92 D = ctx->H[3];
93 E = ctx->H[4];
94
ab14c823 95 /* Round 1 - iterations 0-16 take their input from 'data' */
30d12d4c
LT
96 T_0_15( 0, A, B, C, D, E);
97 T_0_15( 1, E, A, B, C, D);
98 T_0_15( 2, D, E, A, B, C);
99 T_0_15( 3, C, D, E, A, B);
100 T_0_15( 4, B, C, D, E, A);
101 T_0_15( 5, A, B, C, D, E);
102 T_0_15( 6, E, A, B, C, D);
103 T_0_15( 7, D, E, A, B, C);
104 T_0_15( 8, C, D, E, A, B);
105 T_0_15( 9, B, C, D, E, A);
106 T_0_15(10, A, B, C, D, E);
107 T_0_15(11, E, A, B, C, D);
108 T_0_15(12, D, E, A, B, C);
109 T_0_15(13, C, D, E, A, B);
110 T_0_15(14, B, C, D, E, A);
111 T_0_15(15, A, B, C, D, E);
139e3456 112
ab14c823 113 /* Round 1 - tail. Input from 512-bit mixing array */
30d12d4c
LT
114 T_16_19(16, E, A, B, C, D);
115 T_16_19(17, D, E, A, B, C);
116 T_16_19(18, C, D, E, A, B);
117 T_16_19(19, B, C, D, E, A);
d7c208a9 118
ab14c823 119 /* Round 2 */
30d12d4c
LT
120 T_20_39(20, A, B, C, D, E);
121 T_20_39(21, E, A, B, C, D);
122 T_20_39(22, D, E, A, B, C);
123 T_20_39(23, C, D, E, A, B);
124 T_20_39(24, B, C, D, E, A);
125 T_20_39(25, A, B, C, D, E);
126 T_20_39(26, E, A, B, C, D);
127 T_20_39(27, D, E, A, B, C);
128 T_20_39(28, C, D, E, A, B);
129 T_20_39(29, B, C, D, E, A);
130 T_20_39(30, A, B, C, D, E);
131 T_20_39(31, E, A, B, C, D);
132 T_20_39(32, D, E, A, B, C);
133 T_20_39(33, C, D, E, A, B);
134 T_20_39(34, B, C, D, E, A);
135 T_20_39(35, A, B, C, D, E);
136 T_20_39(36, E, A, B, C, D);
137 T_20_39(37, D, E, A, B, C);
138 T_20_39(38, C, D, E, A, B);
139 T_20_39(39, B, C, D, E, A);
d7c208a9 140
ab14c823 141 /* Round 3 */
30d12d4c
LT
142 T_40_59(40, A, B, C, D, E);
143 T_40_59(41, E, A, B, C, D);
144 T_40_59(42, D, E, A, B, C);
145 T_40_59(43, C, D, E, A, B);
146 T_40_59(44, B, C, D, E, A);
147 T_40_59(45, A, B, C, D, E);
148 T_40_59(46, E, A, B, C, D);
149 T_40_59(47, D, E, A, B, C);
150 T_40_59(48, C, D, E, A, B);
151 T_40_59(49, B, C, D, E, A);
152 T_40_59(50, A, B, C, D, E);
153 T_40_59(51, E, A, B, C, D);
154 T_40_59(52, D, E, A, B, C);
155 T_40_59(53, C, D, E, A, B);
156 T_40_59(54, B, C, D, E, A);
157 T_40_59(55, A, B, C, D, E);
158 T_40_59(56, E, A, B, C, D);
159 T_40_59(57, D, E, A, B, C);
160 T_40_59(58, C, D, E, A, B);
161 T_40_59(59, B, C, D, E, A);
d7c208a9 162
ab14c823 163 /* Round 4 */
30d12d4c
LT
164 T_60_79(60, A, B, C, D, E);
165 T_60_79(61, E, A, B, C, D);
166 T_60_79(62, D, E, A, B, C);
167 T_60_79(63, C, D, E, A, B);
168 T_60_79(64, B, C, D, E, A);
169 T_60_79(65, A, B, C, D, E);
170 T_60_79(66, E, A, B, C, D);
171 T_60_79(67, D, E, A, B, C);
172 T_60_79(68, C, D, E, A, B);
173 T_60_79(69, B, C, D, E, A);
174 T_60_79(70, A, B, C, D, E);
175 T_60_79(71, E, A, B, C, D);
176 T_60_79(72, D, E, A, B, C);
177 T_60_79(73, C, D, E, A, B);
178 T_60_79(74, B, C, D, E, A);
179 T_60_79(75, A, B, C, D, E);
180 T_60_79(76, E, A, B, C, D);
181 T_60_79(77, D, E, A, B, C);
182 T_60_79(78, C, D, E, A, B);
183 T_60_79(79, B, C, D, E, A);
d7c208a9
LT
184
185 ctx->H[0] += A;
186 ctx->H[1] += B;
187 ctx->H[2] += C;
188 ctx->H[3] += D;
189 ctx->H[4] += E;
190}
30ba0de7
NP
191
192void blk_SHA1_Init(blk_SHA_CTX *ctx)
193{
194 ctx->size = 0;
195
196 /* Initialize H with the magic constants (see FIPS180 for constants) */
197 ctx->H[0] = 0x67452301;
198 ctx->H[1] = 0xefcdab89;
199 ctx->H[2] = 0x98badcfe;
200 ctx->H[3] = 0x10325476;
201 ctx->H[4] = 0xc3d2e1f0;
202}
203
204void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
205{
206 int lenW = ctx->size & 63;
207
208 ctx->size += len;
209
210 /* Read the data into W and process blocks as they get full */
211 if (lenW) {
212 int left = 64 - lenW;
213 if (len < left)
214 left = len;
215 memcpy(lenW + (char *)ctx->W, data, left);
216 lenW = (lenW + left) & 63;
217 len -= left;
218 data += left;
219 if (lenW)
220 return;
221 blk_SHA1_Block(ctx, ctx->W);
222 }
223 while (len >= 64) {
224 blk_SHA1_Block(ctx, data);
225 data += 64;
226 len -= 64;
227 }
228 if (len)
229 memcpy(ctx->W, data, len);
230}
231
232void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
233{
234 static const unsigned char pad[64] = { 0x80 };
235 unsigned int padlen[2];
236 int i;
237
238 /* Pad with a binary 1 (ie 0x80), then zeroes, then length */
239 padlen[0] = htonl(ctx->size >> 29);
240 padlen[1] = htonl(ctx->size << 3);
241
242 i = ctx->size & 63;
243 blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - i)));
244 blk_SHA1_Update(ctx, padlen, 8);
245
246 /* Output hash */
247 for (i = 0; i < 5; i++)
248 ((unsigned int *)hashout)[i] = htonl(ctx->H[i]);
249}