_ Git - BearSSL/blob - src/int/i32_decode.c

   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_i32_decode(uint32_t *x, const void *src, size_t len)
  30 {
  31         const unsigned char *buf;
  32         size_t u, v;
  33
  34         buf = src;
  35         u = len;
  36         v = 1;
  37         for (;;) {
  38                 if (u < 4) {
  39                         uint32_t w;
  40
  41                         if (u < 2) {
  42                                 if (u == 0) {
  43                                         break;
  44                                 } else {
  45                                         w = buf[0];
  46                                 }
  47                         } else {
  48                                 if (u == 2) {
  49                                         w = br_dec16be(buf);
  50                                 } else {
  51                                         w = ((uint32_t)buf[0] << 16)
  52                                                 | br_dec16be(buf + 1);
  53                                 }
  54                         }
  55                         x[v ++] = w;
  56                         break;
  57                 } else {
  58                         u -= 4;
  59                         x[v ++] = br_dec32be(buf + u);
  60                 }
  61         }
  62         x[0] = br_i32_bit_length(x + 1, v - 1);
  63 }