1 /* 2 * Copyright (c) 2016 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_ecdsa_i31_bits2int(uint32_t *x, 30 const void *src, size_t len, uint32_t ebitlen) 31 { 32 uint32_t bitlen, hbitlen; 33 int sc; 34 35 bitlen = ebitlen - (ebitlen >> 5); 36 hbitlen = (uint32_t)len << 3; 37 if (hbitlen > bitlen) { 38 len = (bitlen + 7) >> 3; 39 sc = (int)((hbitlen - bitlen) & 7); 40 } else { 41 sc = 0; 42 } 43 br_i31_zero(x, ebitlen); 44 br_i31_decode(x, src, len); 45 br_i31_rshift(x, sc); 46 x[0] = ebitlen; 47 } 48