mirror of
https://github.com/libretro/beetle-pce-fast-libretro.git
synced 2024-11-23 07:50:03 +00:00
505 lines
16 KiB
C
505 lines
16 KiB
C
// license:BSD-3-Clause
|
|
// copyright-holders:Aaron Giles
|
|
/***************************************************************************
|
|
|
|
huffman.c
|
|
|
|
Static Huffman compression and decompression helpers.
|
|
|
|
****************************************************************************
|
|
|
|
Maximum codelength is officially (alphabetsize - 1). This would be 255 bits
|
|
(since we use 1 byte values). However, it is also dependent upon the number
|
|
of samples used, as follows:
|
|
|
|
2 bits -> 3..4 samples
|
|
3 bits -> 5..7 samples
|
|
4 bits -> 8..12 samples
|
|
5 bits -> 13..20 samples
|
|
6 bits -> 21..33 samples
|
|
7 bits -> 34..54 samples
|
|
8 bits -> 55..88 samples
|
|
9 bits -> 89..143 samples
|
|
10 bits -> 144..232 samples
|
|
11 bits -> 233..376 samples
|
|
12 bits -> 377..609 samples
|
|
13 bits -> 610..986 samples
|
|
14 bits -> 987..1596 samples
|
|
15 bits -> 1597..2583 samples
|
|
16 bits -> 2584..4180 samples -> note that a 4k data size guarantees codelength <= 16 bits
|
|
17 bits -> 4181..6764 samples
|
|
18 bits -> 6765..10945 samples
|
|
19 bits -> 10946..17710 samples
|
|
20 bits -> 17711..28656 samples
|
|
21 bits -> 28657..46367 samples
|
|
22 bits -> 46368..75024 samples
|
|
23 bits -> 75025..121392 samples
|
|
24 bits -> 121393..196417 samples
|
|
25 bits -> 196418..317810 samples
|
|
26 bits -> 317811..514228 samples
|
|
27 bits -> 514229..832039 samples
|
|
28 bits -> 832040..1346268 samples
|
|
29 bits -> 1346269..2178308 samples
|
|
30 bits -> 2178309..3524577 samples
|
|
31 bits -> 3524578..5702886 samples
|
|
32 bits -> 5702887..9227464 samples
|
|
|
|
Looking at it differently, here is where powers of 2 fall into these buckets:
|
|
|
|
256 samples -> 11 bits max
|
|
512 samples -> 12 bits max
|
|
1k samples -> 14 bits max
|
|
2k samples -> 15 bits max
|
|
4k samples -> 16 bits max
|
|
8k samples -> 18 bits max
|
|
16k samples -> 19 bits max
|
|
32k samples -> 21 bits max
|
|
64k samples -> 22 bits max
|
|
128k samples -> 24 bits max
|
|
256k samples -> 25 bits max
|
|
512k samples -> 27 bits max
|
|
1M samples -> 28 bits max
|
|
2M samples -> 29 bits max
|
|
4M samples -> 31 bits max
|
|
8M samples -> 32 bits max
|
|
|
|
****************************************************************************
|
|
|
|
Delta-RLE encoding works as follows:
|
|
|
|
Starting value is assumed to be 0. All data is encoded as a delta
|
|
from the previous value, such that final[i] = final[i - 1] + delta.
|
|
Long runs of 0s are RLE-encoded as follows:
|
|
|
|
0x100 = repeat count of 8
|
|
0x101 = repeat count of 9
|
|
0x102 = repeat count of 10
|
|
0x103 = repeat count of 11
|
|
0x104 = repeat count of 12
|
|
0x105 = repeat count of 13
|
|
0x106 = repeat count of 14
|
|
0x107 = repeat count of 15
|
|
0x108 = repeat count of 16
|
|
0x109 = repeat count of 32
|
|
0x10a = repeat count of 64
|
|
0x10b = repeat count of 128
|
|
0x10c = repeat count of 256
|
|
0x10d = repeat count of 512
|
|
0x10e = repeat count of 1024
|
|
0x10f = repeat count of 2048
|
|
|
|
Note that repeat counts are reset at the end of a row, so if a 0 run
|
|
extends to the end of a row, a large repeat count may be used.
|
|
|
|
The reason for starting the run counts at 8 is that 0 is expected to
|
|
be the most common symbol, and is typically encoded in 1 or 2 bits.
|
|
|
|
***************************************************************************/
|
|
|
|
#include <stdlib.h>
|
|
#include <assert.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
#include "huffman.h"
|
|
|
|
#define MAX(x,y) ((x) > (y) ? (x) : (y))
|
|
|
|
//**************************************************************************
|
|
// MACROS
|
|
//**************************************************************************
|
|
|
|
#define MAKE_LOOKUP(code,bits) (((code) << 5) | ((bits) & 0x1f))
|
|
|
|
|
|
//**************************************************************************
|
|
// IMPLEMENTATION
|
|
//**************************************************************************
|
|
|
|
//-------------------------------------------------
|
|
// huffman_context_base - create an encoding/
|
|
// decoding context
|
|
//-------------------------------------------------
|
|
|
|
struct huffman_decoder* create_huffman_decoder(int numcodes, int maxbits)
|
|
{
|
|
// limit to 24 bits
|
|
if (maxbits > 24)
|
|
return NULL;
|
|
|
|
struct huffman_decoder* decoder = (struct huffman_decoder*)malloc(sizeof(struct huffman_decoder));
|
|
decoder->numcodes = numcodes;
|
|
decoder->maxbits = maxbits;
|
|
decoder->lookup = (lookup_value*)malloc(sizeof(lookup_value) * (1 << maxbits));
|
|
decoder->huffnode = (struct node_t*)malloc(sizeof(struct node_t) * numcodes);
|
|
decoder->datahisto = NULL;
|
|
decoder->prevdata = 0;
|
|
decoder->rleremaining = 0;
|
|
return decoder;
|
|
}
|
|
|
|
//-------------------------------------------------
|
|
// decode_one - decode a single code from the
|
|
// huffman stream
|
|
//-------------------------------------------------
|
|
|
|
uint32_t huffman_decode_one(struct huffman_decoder* decoder, struct bitstream* bitbuf)
|
|
{
|
|
// peek ahead to get maxbits worth of data
|
|
uint32_t bits = bitstream_peek(bitbuf, decoder->maxbits);
|
|
|
|
// look it up, then remove the actual number of bits for this code
|
|
lookup_value lookup = decoder->lookup[bits];
|
|
bitstream_remove(bitbuf, lookup & 0x1f);
|
|
|
|
// return the value
|
|
return lookup >> 5;
|
|
}
|
|
|
|
//-------------------------------------------------
|
|
// import_tree_rle - import an RLE-encoded
|
|
// huffman tree from a source data stream
|
|
//-------------------------------------------------
|
|
|
|
enum huffman_error huffman_import_tree_rle(struct huffman_decoder* decoder, struct bitstream* bitbuf)
|
|
{
|
|
// bits per entry depends on the maxbits
|
|
int numbits;
|
|
if (decoder->maxbits >= 16)
|
|
numbits = 5;
|
|
else if (decoder->maxbits >= 8)
|
|
numbits = 4;
|
|
else
|
|
numbits = 3;
|
|
|
|
// loop until we read all the nodes
|
|
int curnode;
|
|
for (curnode = 0; curnode < decoder->numcodes; )
|
|
{
|
|
// a non-one value is just raw
|
|
int nodebits = bitstream_read(bitbuf, numbits);
|
|
if (nodebits != 1)
|
|
decoder->huffnode[curnode++].numbits = nodebits;
|
|
|
|
// a one value is an escape code
|
|
else
|
|
{
|
|
// a double 1 is just a single 1
|
|
nodebits = bitstream_read(bitbuf, numbits);
|
|
if (nodebits == 1)
|
|
decoder->huffnode[curnode++].numbits = nodebits;
|
|
|
|
// otherwise, we need one for value for the repeat count
|
|
else
|
|
{
|
|
int repcount = bitstream_read(bitbuf, numbits) + 3;
|
|
while (repcount--)
|
|
decoder->huffnode[curnode++].numbits = nodebits;
|
|
}
|
|
}
|
|
}
|
|
|
|
// make sure we ended up with the right number
|
|
if (curnode != decoder->numcodes)
|
|
return HUFFERR_INVALID_DATA;
|
|
|
|
// assign canonical codes for all nodes based on their code lengths
|
|
enum huffman_error error = huffman_assign_canonical_codes(decoder);
|
|
if (error != HUFFERR_NONE)
|
|
return error;
|
|
|
|
// build the lookup table
|
|
huffman_build_lookup_table(decoder);
|
|
|
|
// determine final input length and report errors
|
|
return bitstream_overflow(bitbuf) ? HUFFERR_INPUT_BUFFER_TOO_SMALL : HUFFERR_NONE;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------
|
|
// import_tree_huffman - import a huffman-encoded
|
|
// huffman tree from a source data stream
|
|
//-------------------------------------------------
|
|
|
|
enum huffman_error huffman_import_tree_huffman(struct huffman_decoder* decoder, struct bitstream* bitbuf)
|
|
{
|
|
// start by parsing the lengths for the small tree
|
|
struct huffman_decoder* smallhuff = create_huffman_decoder(24, 6);
|
|
smallhuff->huffnode[0].numbits = bitstream_read(bitbuf, 3);
|
|
int start = bitstream_read(bitbuf, 3) + 1;
|
|
int count = 0;
|
|
for (int index = 1; index < 24; index++)
|
|
{
|
|
if (index < start || count == 7)
|
|
smallhuff->huffnode[index].numbits = 0;
|
|
else
|
|
{
|
|
count = bitstream_read(bitbuf, 3);
|
|
smallhuff->huffnode[index].numbits = (count == 7) ? 0 : count;
|
|
}
|
|
}
|
|
|
|
// then regenerate the tree
|
|
enum huffman_error error = huffman_assign_canonical_codes(smallhuff);
|
|
if (error != HUFFERR_NONE)
|
|
return error;
|
|
huffman_build_lookup_table(smallhuff);
|
|
|
|
// determine the maximum length of an RLE count
|
|
uint32_t temp = decoder->numcodes - 9;
|
|
uint8_t rlefullbits = 0;
|
|
while (temp != 0)
|
|
temp >>= 1, rlefullbits++;
|
|
|
|
// now process the rest of the data
|
|
int last = 0;
|
|
int curcode;
|
|
for (curcode = 0; curcode < decoder->numcodes; )
|
|
{
|
|
int value = huffman_decode_one(smallhuff, bitbuf);
|
|
if (value != 0)
|
|
decoder->huffnode[curcode++].numbits = last = value - 1;
|
|
else
|
|
{
|
|
int count = bitstream_read(bitbuf, 3) + 2;
|
|
if (count == 7+2)
|
|
count += bitstream_read(bitbuf, rlefullbits);
|
|
for ( ; count != 0 && curcode < decoder->numcodes; count--)
|
|
decoder->huffnode[curcode++].numbits = last;
|
|
}
|
|
}
|
|
|
|
// make sure we ended up with the right number
|
|
if (curcode != decoder->numcodes)
|
|
return HUFFERR_INVALID_DATA;
|
|
|
|
// assign canonical codes for all nodes based on their code lengths
|
|
error = huffman_assign_canonical_codes(decoder);
|
|
if (error != HUFFERR_NONE)
|
|
return error;
|
|
|
|
// build the lookup table
|
|
huffman_build_lookup_table(decoder);
|
|
|
|
// determine final input length and report errors
|
|
return bitstream_overflow(bitbuf) ? HUFFERR_INPUT_BUFFER_TOO_SMALL : HUFFERR_NONE;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------
|
|
// compute_tree_from_histo - common backend for
|
|
// computing a tree based on the data histogram
|
|
//-------------------------------------------------
|
|
|
|
enum huffman_error huffman_compute_tree_from_histo(struct huffman_decoder* decoder)
|
|
{
|
|
// compute the number of data items in the histogram
|
|
uint32_t sdatacount = 0;
|
|
for (int i = 0; i < decoder->numcodes; i++)
|
|
sdatacount += decoder->datahisto[i];
|
|
|
|
// binary search to achieve the optimum encoding
|
|
uint32_t lowerweight = 0;
|
|
uint32_t upperweight = sdatacount * 2;
|
|
while (1)
|
|
{
|
|
// build a tree using the current weight
|
|
uint32_t curweight = (upperweight + lowerweight) / 2;
|
|
int curmaxbits = huffman_build_tree(decoder, sdatacount, curweight);
|
|
|
|
// apply binary search here
|
|
if (curmaxbits <= decoder->maxbits)
|
|
{
|
|
lowerweight = curweight;
|
|
|
|
// early out if it worked with the raw weights, or if we're done searching
|
|
if (curweight == sdatacount || (upperweight - lowerweight) <= 1)
|
|
break;
|
|
}
|
|
else
|
|
upperweight = curweight;
|
|
}
|
|
|
|
// assign canonical codes for all nodes based on their code lengths
|
|
return huffman_assign_canonical_codes(decoder);
|
|
}
|
|
|
|
|
|
|
|
//**************************************************************************
|
|
// INTERNAL FUNCTIONS
|
|
//**************************************************************************
|
|
|
|
//-------------------------------------------------
|
|
// tree_node_compare - compare two tree nodes
|
|
// by weight
|
|
//-------------------------------------------------
|
|
|
|
static int huffman_tree_node_compare(const void *item1, const void *item2)
|
|
{
|
|
const struct node_t *node1 = *(const struct node_t **)item1;
|
|
const struct node_t *node2 = *(const struct node_t **)item2;
|
|
if (node2->weight != node1->weight)
|
|
return node2->weight - node1->weight;
|
|
if (node2->bits - node1->bits == 0)
|
|
fprintf(stderr, "identical node sort keys, should not happen!\n");
|
|
return (int)node1->bits - (int)node2->bits;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------
|
|
// build_tree - build a huffman tree based on the
|
|
// data distribution
|
|
//-------------------------------------------------
|
|
|
|
int huffman_build_tree(struct huffman_decoder* decoder, uint32_t totaldata, uint32_t totalweight)
|
|
{
|
|
// make a list of all non-zero nodes
|
|
struct node_t** list = (struct node_t**)malloc(sizeof(struct node_t*) * decoder->numcodes * 2);
|
|
int listitems = 0;
|
|
memset(decoder->huffnode, 0, decoder->numcodes * sizeof(decoder->huffnode[0]));
|
|
for (int curcode = 0; curcode < decoder->numcodes; curcode++)
|
|
if (decoder->datahisto[curcode] != 0)
|
|
{
|
|
list[listitems++] = &decoder->huffnode[curcode];
|
|
decoder->huffnode[curcode].count = decoder->datahisto[curcode];
|
|
decoder->huffnode[curcode].bits = curcode;
|
|
|
|
// scale the weight by the current effective length, ensuring we don't go to 0
|
|
decoder->huffnode[curcode].weight = ((uint64_t)decoder->datahisto[curcode]) * ((uint64_t)totalweight) / ((uint64_t)totaldata);
|
|
if (decoder->huffnode[curcode].weight == 0)
|
|
decoder->huffnode[curcode].weight = 1;
|
|
}
|
|
/*
|
|
fprintf(stderr, "Pre-sort:\n");
|
|
for (int i = 0; i < listitems; i++) {
|
|
fprintf(stderr, "weight: %d code: %d\n", list[i]->m_weight, list[i]->m_bits);
|
|
}
|
|
*/
|
|
// sort the list by weight, largest weight first
|
|
qsort(&list[0], listitems, sizeof(list[0]), huffman_tree_node_compare);
|
|
/*
|
|
fprintf(stderr, "Post-sort:\n");
|
|
for (int i = 0; i < listitems; i++) {
|
|
fprintf(stderr, "weight: %d code: %d\n", list[i]->m_weight, list[i]->m_bits);
|
|
}
|
|
fprintf(stderr, "===================\n");
|
|
*/
|
|
// now build the tree
|
|
int nextalloc = decoder->numcodes;
|
|
while (listitems > 1)
|
|
{
|
|
// remove lowest two items
|
|
struct node_t* node1 = &(*list[--listitems]);
|
|
struct node_t* node0 = &(*list[--listitems]);
|
|
|
|
// create new node
|
|
struct node_t* newnode = &decoder->huffnode[nextalloc++];
|
|
newnode->parent = NULL;
|
|
node0->parent = node1->parent = newnode;
|
|
newnode->weight = node0->weight + node1->weight;
|
|
|
|
// insert into list at appropriate location
|
|
int curitem;
|
|
for (curitem = 0; curitem < listitems; curitem++)
|
|
if (newnode->weight > list[curitem]->weight)
|
|
{
|
|
memmove(&list[curitem+1], &list[curitem], (listitems - curitem) * sizeof(list[0]));
|
|
break;
|
|
}
|
|
list[curitem] = newnode;
|
|
listitems++;
|
|
}
|
|
|
|
// compute the number of bits in each code, and fill in another histogram
|
|
int maxbits = 0;
|
|
for (int curcode = 0; curcode < decoder->numcodes; curcode++)
|
|
{
|
|
struct node_t* node = &decoder->huffnode[curcode];
|
|
node->numbits = 0;
|
|
node->bits = 0;
|
|
|
|
// if we have a non-zero weight, compute the number of bits
|
|
if (node->weight > 0)
|
|
{
|
|
// determine the number of bits for this node
|
|
for (struct node_t *curnode = node; curnode->parent != NULL; curnode = curnode->parent)
|
|
node->numbits++;
|
|
if (node->numbits == 0)
|
|
node->numbits = 1;
|
|
|
|
// keep track of the max
|
|
maxbits = MAX(maxbits, ((int)node->numbits));
|
|
}
|
|
}
|
|
return maxbits;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------
|
|
// assign_canonical_codes - assign canonical codes
|
|
// to all the nodes based on the number of bits
|
|
// in each
|
|
//-------------------------------------------------
|
|
|
|
enum huffman_error huffman_assign_canonical_codes(struct huffman_decoder* decoder)
|
|
{
|
|
// build up a histogram of bit lengths
|
|
uint32_t bithisto[33] = { 0 };
|
|
for (int curcode = 0; curcode < decoder->numcodes; curcode++)
|
|
{
|
|
struct node_t* node = &decoder->huffnode[curcode];
|
|
if (node->numbits > decoder->maxbits)
|
|
return HUFFERR_INTERNAL_INCONSISTENCY;
|
|
if (node->numbits <= 32)
|
|
bithisto[node->numbits]++;
|
|
}
|
|
|
|
// for each code length, determine the starting code number
|
|
uint32_t curstart = 0;
|
|
for (int codelen = 32; codelen > 0; codelen--)
|
|
{
|
|
uint32_t nextstart = (curstart + bithisto[codelen]) >> 1;
|
|
if (codelen != 1 && nextstart * 2 != (curstart + bithisto[codelen]))
|
|
return HUFFERR_INTERNAL_INCONSISTENCY;
|
|
bithisto[codelen] = curstart;
|
|
curstart = nextstart;
|
|
}
|
|
|
|
// now assign canonical codes
|
|
for (int curcode = 0; curcode < decoder->numcodes; curcode++)
|
|
{
|
|
struct node_t* node = &decoder->huffnode[curcode];
|
|
if (node->numbits > 0)
|
|
node->bits = bithisto[node->numbits]++;
|
|
}
|
|
return HUFFERR_NONE;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------
|
|
// build_lookup_table - build a lookup table for
|
|
// fast decoding
|
|
//-------------------------------------------------
|
|
|
|
void huffman_build_lookup_table(struct huffman_decoder* decoder)
|
|
{
|
|
// iterate over all codes
|
|
for (int curcode = 0; curcode < decoder->numcodes; curcode++)
|
|
{
|
|
// process all nodes which have non-zero bits
|
|
struct node_t* node = &decoder->huffnode[curcode];
|
|
if (node->numbits > 0)
|
|
{
|
|
// set up the entry
|
|
lookup_value value = MAKE_LOOKUP(curcode, node->numbits);
|
|
|
|
// fill all matching entries
|
|
int shift = decoder->maxbits - node->numbits;
|
|
lookup_value *dest = &decoder->lookup[node->bits << shift];
|
|
lookup_value *destend = &decoder->lookup[((node->bits + 1) << shift) - 1];
|
|
while (dest <= destend)
|
|
*dest++ = value;
|
|
}
|
|
}
|
|
} |