src/main/common/huffman.h

   1 /*
   2  * This file is part of Cleanflight and Betaflight.
   3  *
   4  * Cleanflight and Betaflight are free software. You can redistribute
   5  * this software and/or modify this software under the terms of the
   6  * GNU General Public License as published by the Free Software
   7  * Foundation, either version 3 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * Cleanflight and Betaflight are distributed in the hope that they
  11  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  12  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  13  * See the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this software.
  17  *
  18  * If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #pragma once
  22
  23 #include <stdint.h>
  24
  25 #define HUFFMAN_TABLE_SIZE 257 // 256 characters plus EOF
  26 typedef struct huffmanTable_s {
  27     uint16_t    codeLen:4;
  28     uint16_t    code:12;
  29 } huffmanTable_t;
  30
  31 typedef struct huffmanState_s {
  32     uint8_t     *outByte;
  33     uint16_t    bytesWritten;
  34     uint16_t    outBufLen;
  35     uint8_t     outBit;
  36 } huffmanState_t;
  37
  38 extern const huffmanTable_t huffmanTable[HUFFMAN_TABLE_SIZE];
  39
  40 struct huffmanInfo_s {
  41     uint16_t uncompressedByteCount;
  42 };
  43
  44 #define HUFFMAN_INFO_SIZE sizeof(struct huffmanInfo_s)
  45
  46 int huffmanEncodeBuf(uint8_t *outBuf, int outBufLen, const uint8_t *inBuf, int inLen, const huffmanTable_t *huffmanTable);
  47 int huffmanEncodeBufStreaming(huffmanState_t *state, const uint8_t *inBuf, int inLen, const huffmanTable_t *huffmanTable);