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prefix_coding.hpp
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prefix_coding.hpp
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#ifndef PREFIX_CODING_HEADER
#define PREFIX_CODING_HEADER
#include "rans_byte.h"
#include "symbolstats.hpp"
#include "numerics.hpp"
/*
0 0
1 1
2 2
3 3
4 4-5 1 100-101 6
5 6-7 1 110-111 6
6 8-11 2 1000-1011 8
7 12-15 2 1100-1111 8
8 16-23 3 10000-10111 10
9 24-31 3 11000-11111 10
10 32-47 4 100000-101111 12
11 48-63 4 110000-111111 12
12 64 5
13 96 5
14 128 6
15 192 6
16 256 7
17 384 7
18 512 8
19 8
20 1024 9
21 9
22 2048 10
23 10
24 4096 11
25 11
26 8192 12
27 12
28 16384 13
29 13
30 32768 14
31 14
32 65536 15
33 15
34 131072 16
35 16
36 262144 17
37 17
38 524288 18
39 18
40 1048576 19
41 19
42 2097152 20
43 20
44 4194304 21
45 21
*/
struct lz_triple{
uint32_t val_backref;
uint32_t val_matchlen;
uint32_t val_future;
};
struct lz_triple_c{
uint8_t backref;
uint8_t matchlen;
uint8_t future;
uint32_t backref_bits;
uint32_t matchlen_bits;
uint32_t future_bits;
};
int8_t lut_x[120] = {
0, 1, 1, -1, 0, 2, 1, -1,
2, -2, 2, -2, 0, 3, 1, -1,
3, -3, 2, -2, 3, -3, 0, 4,
1, -1, 4, -4, 3, -3, 2, -2,
4, -4, 0, 3, -3, 4, -4, 5,
1, -1, 5, -5, 2, -2, 5, -5,
4, -4, 3, -3, 5, -5, 0, 6,
1, -1, 6, -6, 2, -2, 6, -6,
4, -4, 5, -5, 3, -3, 6, -6,
0, 7, 1, -1, 5, -5, 7, -7,
4, -4, 6, -6, 2, -2, 7, -7,
3, -3, 7, -7, 5, -5, 6, -6,
8, 4, -4, 7, -7, 8, 8, 6,
-6, 8, 5, -5, 7, -7, 8, 6,
-6, 7, -7, 8, 7, -7, 8, 8};
int8_t lut_y[120] = {
1, 0, 1, 1, 2, 0, 2, 2,
1, 1, 2, 2, 3, 0, 3, 3,
1, 1, 3, 3, 2, 2, 4, 0,
4, 4, 1, 1, 3, 3, 4, 4,
2, 2, 5, 4, 4, 3, 3, 0,
5, 5, 1, 1, 5, 5, 2, 2,
4, 4, 5, 5, 3, 3, 6, 0,
6, 6, 1, 1, 6, 6, 2, 2,
5, 5, 4, 4, 6, 6, 3, 3,
7, 0, 7, 7, 5, 5, 1, 1,
6, 6, 4, 4, 7, 7, 2, 2,
7, 7, 3, 3, 6, 6, 5, 5,
0, 7, 7, 4, 4, 1, 2, 6,
6, 3, 7, 7, 5, 5, 4, 7,
7, 6, 6, 5, 7, 7, 6, 7};
uint8_t reverse_lut[120] = {
119,116,111,106, 97, 88, 84, 74, 72, 75, 85, 89, 98,107,112,117,
118,113,103, 92, 80, 68, 60, 56, 54, 57, 61, 69, 81, 93,104,114,
115,108, 94, 76, 64, 50, 44, 40, 34, 41, 45, 51, 65, 77, 95,109,
110, 99, 82, 66, 48, 35, 30, 24, 22, 25, 31, 36, 49, 67, 83,100,
105, 90, 70, 52, 37, 28, 18, 14, 12, 15, 19, 29, 38, 53, 71, 91,
102, 86, 62, 46, 32, 20, 10, 6, 4, 7, 11, 21, 33, 47, 63, 87,
101, 78, 58, 42, 26, 16, 8, 2, 0, 3, 9, 17, 27, 43, 59, 79,
96, 73, 55, 39, 23, 13, 5, 1
};
uint8_t read_prefixcode(RansState& rans, RansDecSymbol* sym, SymbolStats stats, uint8_t*& fileIndex){
uint32_t cumFreq = RansDecGet(&rans, 16);
uint8_t s = 0;
for(size_t j=0;j<256;j++){
if(stats.cum_freqs[j + 1] > cumFreq){
s = j;
break;
}
}
RansDecAdvanceSymbol(&rans, &fileIndex, &sym[s], 16);
return s;
}
/*
uint8_t inverse_prefix(size_t value){
if(value < 5){
return (uint8_t)value;
}
uint8_t magnitude = log2_plus(value);
uint8_t magnitude2 = log2_plus(value - (1 << (magnitude - 1)));
uint8_t halfcode = magnitude*2;
if(magnitude2 + 1 == magnitude){
return halfcode - 1;
}
else{
return halfcode - 2;
}
}
uint8_t extrabits_from_prefix(uint8_t prefix){
if(prefix < 4){
return 0;
}
else{
return prefix/2 - 1;
}
}
uint32_t prefix_extrabits(size_t value){
if(value < 4){
return 0;
}
uint8_t magnitude = log2_plus(value);
uint8_t magnitude2 = log2_plus(value - (1 << (magnitude - 1)));
if(magnitude2 + 1 == magnitude){
return value - (1 << (magnitude - 1)) - (1 << (magnitude2 - 1));
}
else{
return value - (1 << (magnitude - 1));
}
}
uint32_t prefix_to_val(
uint8_t prefix,
RansState& rans,
uint8_t*& fileIndex,
RansDecSymbol decode_binary_zero,
RansDecSymbol decode_binary_one
){
if(prefix < 4){
return (uint32_t)prefix;
}
uint32_t value = (1 << (prefix/2));
if(prefix % 2){
value += (value >> 1);
}
uint8_t extrabits = extrabits_from_prefix(prefix);
for(size_t shift = 0;shift < extrabits;shift++){
uint32_t cumFreq = RansDecGet(&rans, 16);
if(cumFreq < (1 << 15)){
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_zero, 16);
}
else{
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_one, 16);
value += (1 << (extrabits - shift - 1));
}
}
return value;
}
*/
uint8_t native_inverse_prefix(size_t value){
if(value < 5){
return (uint8_t)value;
}
uint8_t magnitude = log2_plus(value);
uint8_t magnitude2 = log2_plus(value - (1 << (magnitude - 1)));
uint8_t halfcode = magnitude*2;
if(magnitude2 + 1 == magnitude){
return halfcode - 1;
}
else{
return halfcode - 2;
}
}
uint8_t native_extrabits_from_prefix(uint8_t prefix){
if(prefix < 4){
return 0;
}
else{
return prefix/2 - 1;
}
}
uint32_t native_prefix_extrabits(size_t value){
if(value < 4){
return 0;
}
uint8_t magnitude = log2_plus(value);
uint8_t magnitude2 = log2_plus(value - (1 << (magnitude - 1)));
if(magnitude2 + 1 == magnitude){
return value - (1 << (magnitude - 1)) - (1 << (magnitude2 - 1));
}
else{
return value - (1 << (magnitude - 1));
}
}
uint32_t native_prefix_to_val(
uint8_t prefix,
RansState& rans,
uint8_t*& fileIndex,
RansDecSymbol decode_binary_zero,
RansDecSymbol decode_binary_one
){
if(prefix < 4){
return (uint32_t)prefix;
}
uint32_t value = (1 << (prefix/2));
if(prefix % 2){
value += (value >> 1);
}
uint8_t extrabits = native_extrabits_from_prefix(prefix);
for(size_t shift = 0;shift < extrabits;shift++){
uint32_t cumFreq = RansDecGet(&rans, 16);
if(cumFreq < (1 << 15)){
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_zero, 16);
}
else{
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_one, 16);
value += (1 << (extrabits - shift - 1));
}
}
return value;
}
size_t extra_offset = 4;
uint8_t inverse_prefix(size_t value){
if(value < extra_offset){
return (uint8_t)value;
}
else{
return extra_offset + native_inverse_prefix(value - extra_offset);
}
}
uint8_t extrabits_from_prefix(uint8_t prefix){
if(prefix < extra_offset){
return 0;
}
else{
return native_extrabits_from_prefix(prefix - extra_offset);
}
}
uint32_t prefix_extrabits(size_t value){
if(value < extra_offset){
return 0;
}
else{
return native_prefix_extrabits(value - extra_offset);
}
}
uint32_t prefix_to_val(
uint8_t prefix,
RansState& rans,
uint8_t*& fileIndex,
RansDecSymbol decode_binary_zero,
RansDecSymbol decode_binary_one
){
if(prefix < extra_offset){
return (uint32_t)prefix;
}
else{
return extra_offset + native_prefix_to_val(
prefix - extra_offset,
rans,
fileIndex,
decode_binary_zero,
decode_binary_one
);
}
}
uint8_t read32(
RansState& rans,
uint8_t*& fileIndex,
RansDecSymbol decode_binary_zero,
RansDecSymbol decode_binary_one
){
uint8_t value = 0;
for(size_t shift = 0;shift < 5;shift++){
uint32_t cumFreq = RansDecGet(&rans, 16);
if(cumFreq < (1 << 15)){
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_zero, 16);
}
else{
RansDecAdvanceSymbol(&rans, &fileIndex, &decode_binary_one, 16);
value += (1 << (4 - shift));
}
}
return value;
}
#endif //PREFIX_CODING