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_i31_decode(uint32_t *x, const void *src, size_t len) 30 { 31 const unsigned char *buf; 32 size_t u, v; 33 uint32_t acc; 34 int acc_len; 35 36 buf = src; 37 u = len; 38 v = 1; 39 acc = 0; 40 acc_len = 0; 41 while (u -- > 0) { 42 uint32_t b; 43 44 b = buf[u]; 45 acc |= (b << acc_len); 46 acc_len += 8; 47 if (acc_len >= 31) { 48 x[v ++] = acc & (uint32_t)0x7FFFFFFF; 49 acc_len -= 31; 50 acc = b >> (8 - acc_len); 51 } 52 } 53 if (acc_len != 0) { 54 x[v ++] = acc; 55 } 56 x[0] = br_i31_bit_length(x + 1, v - 1); 57 } 58