/* * Copyright (c) 2017 Thomas Pornin * * 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))); }