1*0957b409SSimon J. Gerraty /* 2*0957b409SSimon J. Gerraty * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org> 3*0957b409SSimon J. Gerraty * 4*0957b409SSimon J. Gerraty * Permission is hereby granted, free of charge, to any person obtaining 5*0957b409SSimon J. Gerraty * a copy of this software and associated documentation files (the 6*0957b409SSimon J. Gerraty * "Software"), to deal in the Software without restriction, including 7*0957b409SSimon J. Gerraty * without limitation the rights to use, copy, modify, merge, publish, 8*0957b409SSimon J. Gerraty * distribute, sublicense, and/or sell copies of the Software, and to 9*0957b409SSimon J. Gerraty * permit persons to whom the Software is furnished to do so, subject to 10*0957b409SSimon J. Gerraty * the following conditions: 11*0957b409SSimon J. Gerraty * 12*0957b409SSimon J. Gerraty * The above copyright notice and this permission notice shall be 13*0957b409SSimon J. Gerraty * included in all copies or substantial portions of the Software. 14*0957b409SSimon J. Gerraty * 15*0957b409SSimon J. Gerraty * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16*0957b409SSimon J. Gerraty * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17*0957b409SSimon J. Gerraty * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18*0957b409SSimon J. Gerraty * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19*0957b409SSimon J. Gerraty * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20*0957b409SSimon J. Gerraty * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21*0957b409SSimon J. Gerraty * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22*0957b409SSimon J. Gerraty * SOFTWARE. 23*0957b409SSimon J. Gerraty */ 24*0957b409SSimon J. Gerraty 25*0957b409SSimon J. Gerraty #include "inner.h" 26*0957b409SSimon J. Gerraty 27*0957b409SSimon J. Gerraty /* see inner.h */ 28*0957b409SSimon J. Gerraty void 29*0957b409SSimon J. Gerraty br_i31_encode(void *dst, size_t len, const uint32_t *x) 30*0957b409SSimon J. Gerraty { 31*0957b409SSimon J. Gerraty unsigned char *buf; 32*0957b409SSimon J. Gerraty size_t k, xlen; 33*0957b409SSimon J. Gerraty uint32_t acc; 34*0957b409SSimon J. Gerraty int acc_len; 35*0957b409SSimon J. Gerraty 36*0957b409SSimon J. Gerraty xlen = (x[0] + 31) >> 5; 37*0957b409SSimon J. Gerraty if (xlen == 0) { 38*0957b409SSimon J. Gerraty memset(dst, 0, len); 39*0957b409SSimon J. Gerraty return; 40*0957b409SSimon J. Gerraty } 41*0957b409SSimon J. Gerraty buf = (unsigned char *)dst + len; 42*0957b409SSimon J. Gerraty k = 1; 43*0957b409SSimon J. Gerraty acc = 0; 44*0957b409SSimon J. Gerraty acc_len = 0; 45*0957b409SSimon J. Gerraty while (len != 0) { 46*0957b409SSimon J. Gerraty uint32_t w; 47*0957b409SSimon J. Gerraty 48*0957b409SSimon J. Gerraty w = (k <= xlen) ? x[k] : 0; 49*0957b409SSimon J. Gerraty k ++; 50*0957b409SSimon J. Gerraty if (acc_len == 0) { 51*0957b409SSimon J. Gerraty acc = w; 52*0957b409SSimon J. Gerraty acc_len = 31; 53*0957b409SSimon J. Gerraty } else { 54*0957b409SSimon J. Gerraty uint32_t z; 55*0957b409SSimon J. Gerraty 56*0957b409SSimon J. Gerraty z = acc | (w << acc_len); 57*0957b409SSimon J. Gerraty acc_len --; 58*0957b409SSimon J. Gerraty acc = w >> (31 - acc_len); 59*0957b409SSimon J. Gerraty if (len >= 4) { 60*0957b409SSimon J. Gerraty buf -= 4; 61*0957b409SSimon J. Gerraty len -= 4; 62*0957b409SSimon J. Gerraty br_enc32be(buf, z); 63*0957b409SSimon J. Gerraty } else { 64*0957b409SSimon J. Gerraty switch (len) { 65*0957b409SSimon J. Gerraty case 3: 66*0957b409SSimon J. Gerraty buf[-3] = (unsigned char)(z >> 16); 67*0957b409SSimon J. Gerraty /* fall through */ 68*0957b409SSimon J. Gerraty case 2: 69*0957b409SSimon J. Gerraty buf[-2] = (unsigned char)(z >> 8); 70*0957b409SSimon J. Gerraty /* fall through */ 71*0957b409SSimon J. Gerraty case 1: 72*0957b409SSimon J. Gerraty buf[-1] = (unsigned char)z; 73*0957b409SSimon J. Gerraty break; 74*0957b409SSimon J. Gerraty } 75*0957b409SSimon J. Gerraty return; 76*0957b409SSimon J. Gerraty } 77*0957b409SSimon J. Gerraty } 78*0957b409SSimon J. Gerraty } 79*0957b409SSimon J. Gerraty } 80