diff options
Diffstat (limited to 'third_party/bearssl/src/i15_montmul.c')
| -rw-r--r-- | third_party/bearssl/src/i15_montmul.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/third_party/bearssl/src/i15_montmul.c b/third_party/bearssl/src/i15_montmul.c new file mode 100644 index 0000000..e98bc32 --- /dev/null +++ b/third_party/bearssl/src/i15_montmul.c @@ -0,0 +1,184 @@ +/* + * Copyright (c) 2017 Thomas Pornin <[email protected]> + * + * Permission is hereby granted, free of charge, to any person obtaining + * a copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sublicense, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "inner.h" + +/* see inner.h */ +void +br_i15_montymul(uint16_t *d, const uint16_t *x, const uint16_t *y, + const uint16_t *m, uint16_t m0i) +{ + size_t len, len4, u, v; + uint32_t dh; + + len = (m[0] + 15) >> 4; + len4 = len & ~(size_t)3; + br_i15_zero(d, m[0]); + dh = 0; + for (u = 0; u < len; u ++) { + uint32_t f, xu, r, zh; + + xu = x[u + 1]; + f = MUL15((d[1] + MUL15(x[u + 1], y[1])) & 0x7FFF, m0i) + & 0x7FFF; +#if BR_ARMEL_CORTEXM_GCC + if (len4 != 0) { + uint16_t *limit; + + limit = d + len4; + asm volatile ( +"\n\ + @ carry: r=r2 \n\ + @ multipliers: xu=r3 f=r4 \n\ + @ base registers: d+v=r5 y+v=r6 m+v=r7 \n\ + @ r8 contains 0x7FFF \n\ + @ r9 contains d+len4 \n\ + ldr r0, %[limit] \n\ + ldr r3, %[xu] \n\ + mov r9, r0 \n\ + ldr r4, %[f] \n\ + eor r2, r2 \n\ + ldr r5, %[d] \n\ + sub r1, r2, #1 \n\ + ldr r6, %[y] \n\ + lsr r1, r1, #17 \n\ + ldr r7, %[m] \n\ + mov r8, r1 \n\ +loop%=: \n\ + ldrh r0, [r6, #2] \n\ + ldrh r1, [r7, #2] \n\ + mul r0, r3 \n\ + mul r1, r4 \n\ + add r2, r0, r2 \n\ + ldrh r0, [r5, #2] \n\ + add r2, r1, r2 \n\ + mov r1, r8 \n\ + add r2, r0, r2 \n\ + and r1, r2 \n\ + lsr r2, r2, #15 \n\ + strh r1, [r5, #0] \n\ + \n\ + ldrh r0, [r6, #4] \n\ + ldrh r1, [r7, #4] \n\ + mul r0, r3 \n\ + mul r1, r4 \n\ + add r2, r0, r2 \n\ + ldrh r0, [r5, #4] \n\ + add r2, r1, r2 \n\ + mov r1, r8 \n\ + add r2, r0, r2 \n\ + and r1, r2 \n\ + lsr r2, r2, #15 \n\ + strh r1, [r5, #2] \n\ + \n\ + ldrh r0, [r6, #6] \n\ + ldrh r1, [r7, #6] \n\ + mul r0, r3 \n\ + mul r1, r4 \n\ + add r2, r0, r2 \n\ + ldrh r0, [r5, #6] \n\ + add r2, r1, r2 \n\ + mov r1, r8 \n\ + add r2, r0, r2 \n\ + and r1, r2 \n\ + lsr r2, r2, #15 \n\ + strh r1, [r5, #4] \n\ + \n\ + ldrh r0, [r6, #8] \n\ + ldrh r1, [r7, #8] \n\ + mul r0, r3 \n\ + mul r1, r4 \n\ + add r2, r0, r2 \n\ + ldrh r0, [r5, #8] \n\ + add r2, r1, r2 \n\ + mov r1, r8 \n\ + add r2, r0, r2 \n\ + and r1, r2 \n\ + lsr r2, r2, #15 \n\ + strh r1, [r5, #6] \n\ + \n\ + add r5, r5, #8 \n\ + add r6, r6, #8 \n\ + add r7, r7, #8 \n\ + cmp r5, r9 \n\ + bne loop%= \n\ + \n\ + str r2, %[carry] \n\ +" +: [carry] "=m" (r) +: [xu] "m" (xu), [f] "m" (f), [d] "m" (d), [y] "m" (y), + [m] "m" (m), [limit] "m" (limit) +: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9" ); + } else { + r = 0; + } + v = len4; +#else + r = 0; + for (v = 0; v < len4; v += 4) { + uint32_t z; + + z = d[v + 1] + MUL15(xu, y[v + 1]) + + MUL15(f, m[v + 1]) + r; + r = z >> 15; + d[v + 0] = z & 0x7FFF; + z = d[v + 2] + MUL15(xu, y[v + 2]) + + MUL15(f, m[v + 2]) + r; + r = z >> 15; + d[v + 1] = z & 0x7FFF; + z = d[v + 3] + MUL15(xu, y[v + 3]) + + MUL15(f, m[v + 3]) + r; + r = z >> 15; + d[v + 2] = z & 0x7FFF; + z = d[v + 4] + MUL15(xu, y[v + 4]) + + MUL15(f, m[v + 4]) + r; + r = z >> 15; + d[v + 3] = z & 0x7FFF; + } +#endif + for (; v < len; v ++) { + uint32_t z; + + z = d[v + 1] + MUL15(xu, y[v + 1]) + + MUL15(f, m[v + 1]) + r; + r = z >> 15; + d[v + 0] = z & 0x7FFF; + } + + zh = dh + r; + d[len] = zh & 0x7FFF; + dh = zh >> 15; + } + + /* + * Restore the bit length (it was overwritten in the loop above). + */ + d[0] = m[0]; + + /* + * d[] may be greater than m[], but it is still lower than twice + * the modulus. + */ + br_i15_sub(d, m, NEQ(dh, 0) | NOT(br_i15_sub(d, m, 0))); +} |