108 lines
3.1 KiB
C
108 lines
3.1 KiB
C
/*
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* This file is part of Cleanflight and Betaflight.
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*
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* Cleanflight and Betaflight are free software. You can redistribute
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* this software and/or modify this software under the terms of the
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* 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)
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* any later version.
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*
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* Cleanflight and Betaflight are distributed in the hope that they
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* will be useful, but WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the 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 this software.
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*
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "platform.h"
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#ifdef USE_HUFFMAN
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#include "huffman.h"
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int huffmanEncodeBuf(uint8_t *outBuf, int outBufLen, const uint8_t *inBuf, int inLen, const huffmanTable_t *huffmanTable)
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{
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int ret = 0;
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uint8_t *outByte = outBuf;
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*outByte = 0;
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uint8_t outBit = 0x80;
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for (int ii = 0; ii < inLen; ++ii) {
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const int huffCodeLen = huffmanTable[*inBuf].codeLen;
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const uint16_t huffCode = huffmanTable[*inBuf].code;
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++inBuf;
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uint16_t testBit = 0x8000;
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for (int jj = 0; jj < huffCodeLen; ++jj) {
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if (huffCode & testBit) {
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*outByte |= outBit;
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}
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testBit >>= 1;
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outBit >>= 1;
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if (outBit == 0) {
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outBit = 0x80;
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++outByte;
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*outByte = 0;
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++ret;
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}
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if (ret >= outBufLen && ii < inLen - 1 && jj < huffCodeLen - 1) {
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return -1;
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}
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}
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}
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if (outBit != 0x80) {
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// ensure last character in output buffer is counted
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++ret;
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}
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return ret;
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}
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int huffmanEncodeBufStreaming(huffmanState_t *state, const uint8_t *inBuf, int inLen, const huffmanTable_t *huffmanTable)
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{
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uint8_t *savedOutBytePtr = state->outByte;
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uint8_t savedOutByte = *savedOutBytePtr;
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for (const uint8_t *pos = inBuf, *end = inBuf + inLen; pos < end; ++pos) {
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const int huffCodeLen = huffmanTable[*pos].codeLen;
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const uint16_t huffCode = huffmanTable[*pos].code;
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uint16_t testBit = 0x8000;
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for (int jj = 0; jj < huffCodeLen; ++jj) {
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if (huffCode & testBit) {
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*state->outByte |= state->outBit;
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}
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testBit >>= 1;
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state->outBit >>= 1;
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if (state->outBit == 0) {
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state->outBit = 0x80;
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++state->outByte;
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*state->outByte = 0;
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++state->bytesWritten;
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}
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// if buffer is filled and we haven't finished compressing
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if (state->bytesWritten >= state->outBufLen && (pos < end - 1 || jj < huffCodeLen - 1)) {
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// restore savedOutByte
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*savedOutBytePtr = savedOutByte;
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return -1;
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}
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}
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}
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return 0;
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}
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#endif
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