79 lines
1.7 KiB
C++
79 lines
1.7 KiB
C++
/*
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RLE 90 compression algorithm.
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Copyright (C) 2019, Guillaume Gonnet
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This program is free software: you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "stuffit/methods/rle90.h"
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namespace maconv {
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namespace stuffit {
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// Initialize the algorithm.
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void Rle90Method::Initialize()
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{
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count = 0;
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byte = 0;
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}
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// Read the next byte.
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uint8_t Rle90Method::ReadNextByte()
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{
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// We have a byte to repeat.
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if (count != 0)
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return (count--, byte);
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// Read the next byte from the stream.
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uint8_t next = *(data++);
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if (next != 0x90)
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return (byte = next, byte);
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// The previous byte need to be repeated (if not 0x0).
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next = *(data++);
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if (next == 0x0)
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return (byte = next, byte);
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count = next - 2;
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return next;
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}
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// Read the next bytes.
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int32_t Rle90Method::ReadBytes(uint8_t *buffer, uint32_t length)
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{
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if (data == end && count == 0)
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return -1;
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uint8_t *start = buffer;
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uint8_t *end_capacity = buffer + length;
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while ((data != end || count != 0) && buffer != end_capacity)
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*(buffer++) = ReadNextByte();
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return buffer - start;
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}
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} // namespace stuffit
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} // namespace maconv
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