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53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
/*
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* This file is part of Espruino, a JavaScript interpreter for Microcontrollers
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*
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* Copyright (C) 2013 Gordon Williams <gw@pur3.co.uk>
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* ----------------------------------------------------------------------------
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* Simple RLE EncoderDecoder
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* ----------------------------------------------------------------------------
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*/
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#include "compress_rle.h"
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// gets data from array, writes to callback
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void rle_encode(unsigned char *data, size_t dataLen, void (*callback)(unsigned char ch, uint32_t *cbdata), uint32_t *cbdata) {
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int lastCh = -1; // not a valid char
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while (dataLen) {
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unsigned char ch = *(data++);
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dataLen--;
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callback(ch, cbdata);
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if (ch==lastCh) {
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int cnt = 0;
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while (dataLen && lastCh==*data && cnt<255) {
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data++;
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dataLen--;
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cnt++;
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}
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callback((unsigned char)cnt, cbdata);
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}
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lastCh = ch;
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}
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}
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// gets data from callback, writes it into array
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void rle_decode(int (*callback)(uint32_t *cbdata), uint32_t *cbdata, unsigned char *data) {
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int lastCh = -256; // not a valid char
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while (true) {
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int ch = callback(cbdata);
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if (ch<0) return;
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*(data++) = (unsigned char)ch;
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if (ch==lastCh) {
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int cnt = callback(cbdata);
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while (cnt-->0) {
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*(data++) = (unsigned char)ch;
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}
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}
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lastCh = ch;
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}
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}
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