52 lines
1.4 KiB
C++
52 lines
1.4 KiB
C++
/* Copyright (C) 2009 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* base32 conversion
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*/
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#include "precompiled.h"
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// big endian!
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void base32(const size_t in_len, const u8* in, u8* out)
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{
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u32 pool = 0; // of bits from buffer
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size_t pool_bits = 0; // # bits currently in buffer
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static const u8 tbl[33] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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size_t in_bytes_left = in_len; // to avoid overrunning input buffer
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const size_t out_chars = (in_len*8 + 4) / 5; // = ceil(# 5-bit blocks)
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for(size_t i = 0; i < out_chars; i++)
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{
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if(pool_bits < 5 && in_bytes_left)
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{
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pool <<= 8;
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pool |= *in++;
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pool_bits += 8;
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in_bytes_left--;
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}
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pool_bits -= 5;
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const size_t c = (pool >> pool_bits) & 31;
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*out++ = tbl[c];
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}
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*out++ = '\0';
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}
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