Added generic API for date range validation (with callbacks).
[BearSSL] / int / i15_montmul.c
1 /*
2 * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 #include "inner.h"
26
27 /* see inner.h */
28 void
29 br_i15_montymul(uint16_t *d, const uint16_t *x, const uint16_t *y,
30 const uint16_t *m, uint16_t m0i)
31 {
32 size_t len, len4, u, v;
33 uint32_t dh;
34
35 len = (m[0] + 15) >> 4;
36 len4 = len & ~(size_t)3;
37 br_i15_zero(d, m[0]);
38 dh = 0;
39 for (u = 0; u < len; u ++) {
40 uint32_t f, xu, r, zh;
41
42 xu = x[u + 1];
43 f = MUL15((d[1] + MUL15(x[u + 1], y[1])) & 0x7FFF, m0i)
44 & 0x7FFF;
45 #if BR_ARMEL_CORTEXM_GCC
46 if (len4 != 0) {
47 uint16_t *limit;
48
49 limit = d + len4;
50 asm volatile (
51 "\n\
52 @ carry: r=r2 \n\
53 @ multipliers: xu=r3 f=r4 \n\
54 @ base registers: d+v=r5 y+v=r6 m+v=r7 \n\
55 @ r8 contains 0x7FFF \n\
56 @ r9 contains d+len4 \n\
57 ldr r0, %[limit] \n\
58 ldr r3, %[xu] \n\
59 mov r9, r0 \n\
60 ldr r4, %[f] \n\
61 eor r2, r2 \n\
62 ldr r5, %[d] \n\
63 sub r1, r2, #1 \n\
64 ldr r6, %[y] \n\
65 lsr r1, r1, #17 \n\
66 ldr r7, %[m] \n\
67 mov r8, r1 \n\
68 loop%=: \n\
69 ldrh r0, [r6, #2] \n\
70 ldrh r1, [r7, #2] \n\
71 mul r0, r3 \n\
72 mul r1, r4 \n\
73 add r2, r0, r2 \n\
74 ldrh r0, [r5, #2] \n\
75 add r2, r1, r2 \n\
76 mov r1, r8 \n\
77 add r2, r0, r2 \n\
78 and r1, r2 \n\
79 lsr r2, r2, #15 \n\
80 strh r1, [r5, #0] \n\
81 \n\
82 ldrh r0, [r6, #4] \n\
83 ldrh r1, [r7, #4] \n\
84 mul r0, r3 \n\
85 mul r1, r4 \n\
86 add r2, r0, r2 \n\
87 ldrh r0, [r5, #4] \n\
88 add r2, r1, r2 \n\
89 mov r1, r8 \n\
90 add r2, r0, r2 \n\
91 and r1, r2 \n\
92 lsr r2, r2, #15 \n\
93 strh r1, [r5, #2] \n\
94 \n\
95 ldrh r0, [r6, #6] \n\
96 ldrh r1, [r7, #6] \n\
97 mul r0, r3 \n\
98 mul r1, r4 \n\
99 add r2, r0, r2 \n\
100 ldrh r0, [r5, #6] \n\
101 add r2, r1, r2 \n\
102 mov r1, r8 \n\
103 add r2, r0, r2 \n\
104 and r1, r2 \n\
105 lsr r2, r2, #15 \n\
106 strh r1, [r5, #4] \n\
107 \n\
108 ldrh r0, [r6, #8] \n\
109 ldrh r1, [r7, #8] \n\
110 mul r0, r3 \n\
111 mul r1, r4 \n\
112 add r2, r0, r2 \n\
113 ldrh r0, [r5, #8] \n\
114 add r2, r1, r2 \n\
115 mov r1, r8 \n\
116 add r2, r0, r2 \n\
117 and r1, r2 \n\
118 lsr r2, r2, #15 \n\
119 strh r1, [r5, #6] \n\
120 \n\
121 add r5, r5, #8 \n\
122 add r6, r6, #8 \n\
123 add r7, r7, #8 \n\
124 cmp r5, r9 \n\
125 bne loop%= \n\
126 \n\
127 str r2, %[carry] \n\
128 "
129 : [carry] "=m" (r)
130 : [xu] "m" (xu), [f] "m" (f), [d] "m" (d), [y] "m" (y),
131 [m] "m" (m), [limit] "m" (limit)
132 : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9" );
133 } else {
134 r = 0;
135 }
136 v = len4;
137 #else
138 r = 0;
139 for (v = 0; v < len4; v += 4) {
140 uint32_t z;
141
142 z = d[v + 1] + MUL15(xu, y[v + 1])
143 + MUL15(f, m[v + 1]) + r;
144 r = z >> 15;
145 d[v + 0] = z & 0x7FFF;
146 z = d[v + 2] + MUL15(xu, y[v + 2])
147 + MUL15(f, m[v + 2]) + r;
148 r = z >> 15;
149 d[v + 1] = z & 0x7FFF;
150 z = d[v + 3] + MUL15(xu, y[v + 3])
151 + MUL15(f, m[v + 3]) + r;
152 r = z >> 15;
153 d[v + 2] = z & 0x7FFF;
154 z = d[v + 4] + MUL15(xu, y[v + 4])
155 + MUL15(f, m[v + 4]) + r;
156 r = z >> 15;
157 d[v + 3] = z & 0x7FFF;
158 }
159 #endif
160 for (; v < len; v ++) {
161 uint32_t z;
162
163 z = d[v + 1] + MUL15(xu, y[v + 1])
164 + MUL15(f, m[v + 1]) + r;
165 r = z >> 15;
166 d[v + 0] = z & 0x7FFF;
167 }
168
169 zh = dh + r;
170 d[len] = zh & 0x7FFF;
171 dh = zh >> 15;
172 }
173
174 /*
175 * Restore the bit length (it was overwritten in the loop above).
176 */
177 d[0] = m[0];
178
179 /*
180 * d[] may be greater than m[], but it is still lower than twice
181 * the modulus.
182 */
183 br_i15_sub(d, m, NEQ(dh, 0) | NOT(br_i15_sub(d, m, 0)));
184 }