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GPMF_bitstream.h
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GPMF_bitstream.h
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/*! @file GPMF_bitstream.h
*
* @brief GPMF Parser library include
*
* Some GPMF streams may contain compressed data, this is useful for high frequency
* sensor data that is highly correlated like IMU data. The compression is Huffman
* coding of the delta between samples, with addition codewords for runs of zeros,
* and optional quantization. The compression scheme is similar to the Huffman coding
* in JPEG. As it intended for lossless compression (with quantize set to 1) it can
* only compress/decompress integer based streams.
*
* @version 1.2.0
*
* (C) Copyright 2017 GoPro Inc (http://gopro.com/).
*
* Licensed under either:
* - Apache License, Version 2.0, http://www.apache.org/licenses/LICENSE-2.0
* - MIT license, http://opensource.org/licenses/MIT
* at your option.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef _GPMF_BITSTREAM_H
#define _GPMF_BITSTREAM_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdint.h>
typedef struct rlv { // Codebook entries for arbitrary runs
uint16_t size; // Size of code word in bits
uint16_t bits; // Code word bits right justified
uint16_t count; // Run length for zeros
int16_t value; // Value for difference
} RLV;
typedef const struct {
int length; // Number of entries in the code book
RLV entries[39];
} RLVTABLE;
#define BITSTREAM_WORD_TYPE uint16_t // use 16-bit buffer for compression
#define BITSTREAM_WORD_SIZE 16 // use 16-bit buffer for compression
#define BITSTREAM_ERROR_OVERFLOW 1
#define BITMASK(n) _bitmask[n]
#define _BITMASK(n) ((((BITSTREAM_WORD_TYPE )1 << (n))) - 1)
static const BITSTREAM_WORD_TYPE _bitmask[] =
{
_BITMASK(0), _BITMASK(1), _BITMASK(2), _BITMASK(3),
_BITMASK(4), _BITMASK(5), _BITMASK(6), _BITMASK(7),
_BITMASK(8), _BITMASK(9), _BITMASK(10), _BITMASK(11),
_BITMASK(12), _BITMASK(13), _BITMASK(14), _BITMASK(15),
0xFFFF
};
typedef struct bitstream
{
int32_t error; // Error parsing the bitstream
int32_t bitsFree; // Number of bits available in the current word
uint8_t *lpCurrentWord; // Pointer to next word in block
int32_t wordsUsed; // Number of words used in the block
int32_t dwBlockLength; // Number of entries in the block
uint16_t wBuffer; // Current word bit buffer
uint16_t bits_per_src_word; // Bitused in the source word. e.g. 's' = 16-bits
} BITSTREAM;
static RLVTABLE enchuftable = {
39,
{
{ 1, 0b0, 1, 0 }, // m0
{ 2, 0b10, 1, 1 }, // m1
{ 4, 0b1100, 1, 2 }, // m2
{ 5, 0b11011, 1, 3 }, // m3
{ 5, 0b11101, 1, 4 }, // m4
{ 6, 0b110100, 1, 5 }, // m5
{ 6, 0b110101, 1, 6 }, // m6
{ 6, 0b111110, 1, 7 }, // m7
{ 7, 0b1110000, 1, 8 }, // m8
{ 7, 0b1110011, 1, 9 }, // m9
{ 7, 0b1111000, 1, 10 }, // m10
{ 7, 0b1111001, 1, 11 }, // m11
{ 7, 0b1111011, 1, 12 }, // m12
{ 8, 0b11100100, 1, 13 }, // m13
{ 8, 0b11100101, 1, 14 }, // m14
{ 8, 0b11110100, 1, 15 }, // m15
{ 9, 0b111000101, 1, 16 }, // m16
{ 9, 0b111000110, 1, 17 }, // m17
{ 9, 0b111101010, 1, 18 }, // m18
{ 10, 0b1110001000, 1, 19 }, // m19
{ 10, 0b1110001110, 1, 20 }, // m20
{ 10, 0b1111010110, 1, 21 }, // m21
{ 10, 0b1111111100, 1, 22 }, // m22
{ 11, 0b11100010010, 1, 23 }, // m23
{ 11, 0b11100011111, 1, 24 }, // m24
{ 11, 0b11110101110, 1, 25 }, // m25
{ 12, 0b111000100111, 1, 26 }, // m26
{ 12, 0b111000111101, 1, 27 }, // m27
{ 12, 0b111101011111, 1, 28 }, // m28
{ 13, 0b1110001001101, 1, 29 }, // m29
{ 13, 0b1110001111001, 1, 30 }, // m30
{ 13, 0b1111010111101, 1, 31 }, // m31
{ 14, 0b11100010011000, 1, 32 }, // m32
{ 14, 0b11100011110000, 1, 33 }, // m33
{ 14, 0b11110101111000, 1, 34 }, // m34
{ 14, 0b11110101111001, 1, 35 }, // m35
{ 15, 0b111000100110010, 1, 36 }, // m36
{ 15, 0b111000100110011, 1, 37 }, // m37
{ 15, 0b111000111100011, 1, 38 }, // m38
}
};
static RLVTABLE enczerorunstable = {
4,
{
{ 7, 0b1111110, 16, 0 }, // z16
{ 8, 0b11111110, 32, 0 }, // z32
{ 9, 0b111111111, 64, 0 }, // z64
{ 10,0b1111111101, 128, 0 }, // z128
}
};
#define HUFF_ESC_CODE_ENTRY 0
#define HUFF_END_CODE_ENTRY 1
static RLVTABLE enccontrolcodestable = {
2,
{
{ 16, 0b1110001111000100, 0, 0 }, // escape code for direct data <ESC><data>Continue
{ 16, 0b1110001111000101, 0, 0 }, // end code. Ends each compressed stream
}
};
#ifdef __cplusplus
}
#endif
#endif