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author | Autechre | 2021-03-16 14:45:41 +0100 |
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committer | GitHub | 2021-03-16 14:45:41 +0100 |
commit | 41ed0ee3ff0f83bf53b010e4d79ca1de5389e8f2 (patch) | |
tree | 3cf574af74146252926490c2816d95e34a602a3c /deps/libchdr/src/libchdr_huffman.c | |
parent | e3e1b865f7c06f57918b97f7293b5b2959fb7b7d (diff) | |
parent | 2ff0b5124f2e17a290121e1eeecf45db1d9e2c85 (diff) | |
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Merge pull request #506 from jdgleaver/libchdr-update
Update libchdr (replace libflac with dr_flac)
Diffstat (limited to 'deps/libchdr/src/libchdr_huffman.c')
-rw-r--r-- | deps/libchdr/src/libchdr_huffman.c | 544 |
1 files changed, 544 insertions, 0 deletions
diff --git a/deps/libchdr/src/libchdr_huffman.c b/deps/libchdr/src/libchdr_huffman.c new file mode 100644 index 0000000..6a50f13 --- /dev/null +++ b/deps/libchdr/src/libchdr_huffman.c @@ -0,0 +1,544 @@ +/* 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 <libchdr/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) +{ + struct huffman_decoder* decoder = NULL; + + /* limit to 24 bits */ + if (maxbits > 24) + return NULL; + + 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; +} + +void delete_huffman_decoder(struct huffman_decoder* decoder) +{ + if (decoder != NULL) + { + if (decoder->lookup != NULL) + free(decoder->lookup); + if (decoder->huffnode != NULL) + free(decoder->huffnode); + free(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) +{ + int numbits, curnode; + enum huffman_error error; + + /* bits per entry depends on the maxbits */ + if (decoder->maxbits >= 16) + numbits = 5; + else if (decoder->maxbits >= 8) + numbits = 4; + else + numbits = 3; + + /* loop until we read all the nodes */ + 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 */ + 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) +{ + int start; + int last = 0; + int count = 0; + int index; + int curcode; + uint8_t rlefullbits = 0; + uint32_t temp; + enum huffman_error error; + /* 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); + start = bitstream_read(bitbuf, 3) + 1; + for (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 */ + 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 */ + temp = decoder->numcodes - 9; + while (temp != 0) + temp >>= 1, rlefullbits++; + + /* now process the rest of the data */ + 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) +{ + int i; + uint32_t lowerweight; + uint32_t upperweight; + /* compute the number of data items in the histogram */ + uint32_t sdatacount = 0; + for (i = 0; i < decoder->numcodes; i++) + sdatacount += decoder->datahisto[i]; + + /* binary search to achieve the optimum encoding */ + lowerweight = 0; + 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) +{ + int curcode; + int nextalloc; + int listitems = 0; + int maxbits = 0; + /* make a list of all non-zero nodes */ + struct node_t** list = (struct node_t**)malloc(sizeof(struct node_t*) * decoder->numcodes * 2); + memset(decoder->huffnode, 0, decoder->numcodes * sizeof(decoder->huffnode[0])); + for (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; + } + +#if 0 + 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); + } +#endif + + /* sort the list by weight, largest weight first */ + qsort(&list[0], listitems, sizeof(list[0]), huffman_tree_node_compare); + +#if 0 + 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"); +#endif + + /* now build the tree */ + nextalloc = decoder->numcodes; + while (listitems > 1) + { + int curitem; + /* 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 */ + 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 */ + for (curcode = 0; curcode < decoder->numcodes; curcode++) + { + struct node_t *curnode; + 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 (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) +{ + int curcode, codelen; + uint32_t curstart = 0; + /* build up a histogram of bit lengths */ + uint32_t bithisto[33] = { 0 }; + for (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 */ + for (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 (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) +{ + int curcode; + /* iterate over all codes */ + for (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) + { + int shift; + lookup_value *dest; + lookup_value *destend; + /* set up the entry */ + lookup_value value = MAKE_LOOKUP(curcode, node->numbits); + + /* fill all matching entries */ + shift = decoder->maxbits - node->numbits; + dest = &decoder->lookup[node->bits << shift]; + destend = &decoder->lookup[((node->bits + 1) << shift) - 1]; + while (dest <= destend) + *dest++ = value; + } + } +} |