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Implemented streaming Huffman compression in chunks of 256 bytes

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DieHertz 2017-07-20 00:19:33 +03:00 • committed by Andrey Mironov
parent 213d9d976d
commit b0cc2b670d
9 changed files with 235 additions and 24 deletions
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49
src/main/common/huffman.c
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@ -18,6 +18,10 @@
#include <stdbool.h>
#include <stdint.h>
#include "platform.h"
#ifdef USE_HUFFMAN
#include "huffman.h"
@ -28,15 +32,18 @@ int huffmanEncodeBuf(uint8_t *outBuf, int outBufLen, const uint8_t *inBuf, int i
uint8_t *outByte = outBuf;
*outByte = 0;
uint8_t outBit = 0x80;
for (int ii = 0; ii< inLen; ++ii) {
for (int ii = 0; ii < inLen; ++ii) {
const int huffCodeLen = huffmanTable[*inBuf].codeLen;
const uint16_t huffCode = huffmanTable[*inBuf].code;
++inBuf;
uint16_t testBit = 0x8000;
for (int jj = 0; jj < huffCodeLen; ++jj) {
if (huffCode & testBit) {
*outByte |= outBit;
}
testBit >>= 1;
outBit >>= 1;
if (outBit == 0) {
@ -45,7 +52,8 @@ int huffmanEncodeBuf(uint8_t *outBuf, int outBufLen, const uint8_t *inBuf, int i
*outByte = 0;
++ret;
}
if (ret >= outBufLen) {
if (ret >= outBufLen && ii < inLen - 1 && jj < huffCodeLen - 1) {
return -1;
}
}
@ -57,3 +65,40 @@ int huffmanEncodeBuf(uint8_t *outBuf, int outBufLen, const uint8_t *inBuf, int i
return ret;
}
int huffmanEncodeBufStreaming(huffmanState_t *state, const uint8_t *inBuf, int inLen, const huffmanTable_t *huffmanTable)
{
uint8_t *savedOutBytePtr = state->outByte;
uint8_t savedOutByte = *savedOutBytePtr;
for (const uint8_t *pos = inBuf, *end = inBuf + inLen; pos < end; ++pos) {
const int huffCodeLen = huffmanTable[*pos].codeLen;
const uint16_t huffCode = huffmanTable[*pos].code;
uint16_t testBit = 0x8000;
for (int jj = 0; jj < huffCodeLen; ++jj) {
if (huffCode & testBit) {
*state->outByte |= state->outBit;
}
testBit >>= 1;
state->outBit >>= 1;
if (state->outBit == 0) {
state->outBit = 0x80;
++state->outByte;
*state->outByte = 0;
++state->bytesWritten;
}
// if buffer is filled and we haven't finished compressing
if (state->bytesWritten >= state->outBufLen && (pos < end - 1 || jj < huffCodeLen - 1)) {
// restore savedOutByte
*savedOutBytePtr = savedOutByte;
return -1;
}
}
}
return 0;
}
#endif