Line data    Source code

       1             : /* Copyright (C) 2010 Wildfire Games.
       2             :  *
       3             :  * Permission is hereby granted, free of charge, to any person obtaining
       4             :  * a copy of this software and associated documentation files (the
       5             :  * "Software"), to deal in the Software without restriction, including
       6             :  * without limitation the rights to use, copy, modify, merge, publish,
       7             :  * distribute, sublicense, and/or sell copies of the Software, and to
       8             :  * permit persons to whom the Software is furnished to do so, subject to
       9             :  * the following conditions:
      10             :  *
      11             :  * The above copyright notice and this permission notice shall be included
      12             :  * in all copies or substantial portions of the Software.
      13             :  *
      14             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
      15             :  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
      16             :  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
      17             :  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
      18             :  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
      19             :  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      20             :  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      21             :  */
      22             : 
      23             : /*
      24             :  * base32 conversion
      25             :  */
      26             : 
      27             : #include "precompiled.h"
      28             : 
      29             : 
      30             : // big endian!
      31           7 : void base32(const size_t in_len, const u8* in, u8* out)
      32             : {
      33           7 :     u32 pool = 0;   // of bits from buffer
      34           7 :     ssize_t pool_bits = 0;  // # bits currently in buffer
      35             : 
      36           7 :     static const u8 tbl[33] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
      37             : 
      38           7 :     size_t in_bytes_left = in_len;  // to avoid overrunning input buffer
      39           7 :     const size_t out_chars = (in_len*8 + 4) / 5;    // = ceil(# 5-bit blocks)
      40          58 :     for(size_t i = 0; i < out_chars; i++)
      41             :     {
      42          51 :         if(pool_bits < 5 && in_bytes_left)
      43             :         {
      44          30 :             pool <<= 8;
      45          30 :             pool |= *in++;
      46          30 :             pool_bits += 8;
      47          30 :             in_bytes_left--;
      48             :         }
      49             : 
      50          51 :         pool_bits -= 5;
      51          51 :         size_t c;
      52          51 :         if (pool_bits < 0)
      53           6 :             c = (pool << -pool_bits) & 31;
      54             :         else
      55          45 :             c = (pool >> pool_bits) & 31;
      56          51 :         *out++ = tbl[c];
      57             :     }
      58             : 
      59           7 :     *out++ = '\0';
      60           7 : }