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_encode(void *dst, size_t len, const uint32_t *x) 30 { 31 unsigned char *buf; 32 size_t k, xlen; 33 uint32_t acc; 34 int acc_len; 35 36 xlen = (x[0] + 31) >> 5; 37 if (xlen == 0) { 38 memset(dst, 0, len); 39 return; 40 } 41 buf = (unsigned char *)dst + len; 42 k = 1; 43 acc = 0; 44 acc_len = 0; 45 while (len != 0) { 46 uint32_t w; 47 48 w = (k <= xlen) ? x[k] : 0; 49 k ++; 50 if (acc_len == 0) { 51 acc = w; 52 acc_len = 31; 53 } else { 54 uint32_t z; 55 56 z = acc | (w << acc_len); 57 acc_len --; 58 acc = w >> (31 - acc_len); 59 if (len >= 4) { 60 buf -= 4; 61 len -= 4; 62 br_enc32be(buf, z); 63 } else { 64 switch (len) { 65 case 3: 66 buf[-3] = (unsigned char)(z >> 16); 67 /* fall through */ 68 case 2: 69 buf[-2] = (unsigned char)(z >> 8); 70 /* fall through */ 71 case 1: 72 buf[-1] = (unsigned char)z; 73 break; 74 } 75 return; 76 } 77 } 78 } 79 } 80