lib/uzlib/tinflate: Implement more compact lookup tables.
Saves 68 bytes on PYBV11. This work was funded through GitHub Sponsors. Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
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Jim Mussared
Damien George
parent
d75a3cd861
commit
ef5061fefd
@ -7,6 +7,9 @@
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*
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* Copyright (c) 2014-2018 by Paul Sokolovsky
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*
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* Optimised for MicroPython:
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* Copyright (c) 2023 by Jim Mussared
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*
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* This software is provided 'as-is', without any express
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* or implied warranty. In no event will the authors be
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* held liable for any damages arising from the use of
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@ -51,45 +54,45 @@ uint32_t tinf_get_be_uint32(uzlib_uncomp_t *d);
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* -- uninitialized global data (static structures) -- *
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* --------------------------------------------------- */
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#ifdef RUNTIME_BITS_TABLES
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typedef struct {
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unsigned char length_bits : 3;
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unsigned short length_base : 9;
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unsigned char dist_bits : 4;
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unsigned short dist_base : 15;
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} lookup_table_entry_t;
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/* extra bits and base tables for length codes */
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unsigned char length_bits[30];
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unsigned short length_base[30];
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/* extra bits and base tables for distance codes */
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unsigned char dist_bits[30];
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unsigned short dist_base[30];
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#else
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const unsigned char length_bits[30] = {
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0, 0, 0, 0, 0, 0, 0, 0,
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1, 1, 1, 1, 2, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 4,
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5, 5, 5, 5
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const lookup_table_entry_t lookup_table[30] = {
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{0, 3, 0, 1},
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{0, 4, 0, 2},
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{0, 5, 0, 3},
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{0, 6, 0, 4},
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{0, 7, 1, 5},
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{0, 8, 1, 7},
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{0, 9, 2, 9},
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{0, 10, 2, 13},
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{1, 11, 3, 17},
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{1, 13, 3, 25},
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{1, 15, 4, 33},
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{1, 17, 4, 49},
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{2, 19, 5, 65},
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{2, 23, 5, 97},
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{2, 27, 6, 129},
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{2, 31, 6, 193},
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{3, 35, 7, 257},
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{3, 43, 7, 385},
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{3, 51, 8, 513},
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{3, 59, 8, 769},
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{4, 67, 9, 1025},
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{4, 83, 9, 1537},
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{4, 99, 10, 2049},
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{4, 115, 10, 3073},
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{5, 131, 11, 4097},
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{5, 163, 11, 6145},
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{5, 195, 12, 8193},
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{5, 227, 12, 12289},
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{0, 258, 13, 16385},
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{0, 0, 13, 24577},
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};
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const unsigned short length_base[30] = {
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3, 4, 5, 6, 7, 8, 9, 10,
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11, 13, 15, 17, 19, 23, 27, 31,
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35, 43, 51, 59, 67, 83, 99, 115,
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131, 163, 195, 227, 258
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};
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const unsigned char dist_bits[30] = {
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0, 0, 0, 0, 1, 1, 2, 2,
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3, 3, 4, 4, 5, 5, 6, 6,
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7, 7, 8, 8, 9, 9, 10, 10,
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11, 11, 12, 12, 13, 13
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};
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const unsigned short dist_base[30] = {
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1, 2, 3, 4, 5, 7, 9, 13,
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17, 25, 33, 49, 65, 97, 129, 193,
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257, 385, 513, 769, 1025, 1537, 2049, 3073,
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4097, 6145, 8193, 12289, 16385, 24577
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};
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#endif
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/* special ordering of code length codes */
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const unsigned char clcidx[] = {
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@ -102,25 +105,6 @@ const unsigned char clcidx[] = {
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* -- utility functions -- *
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* ----------------------- */
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#ifdef RUNTIME_BITS_TABLES
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/* build extra bits and base tables */
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static void tinf_build_bits_base(unsigned char *bits, unsigned short *base, int delta, int first)
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{
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int i, sum;
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/* build bits table */
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for (i = 0; i < delta; ++i) bits[i] = 0;
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for (i = 0; i < 30 - delta; ++i) bits[i + delta] = i / delta;
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/* build base table */
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for (sum = first, i = 0; i < 30; ++i)
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{
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base[i] = sum;
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sum += 1 << bits[i];
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}
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}
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#endif
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/* build the fixed huffman trees */
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static void tinf_build_fixed_trees(TINF_TREE *lt, TINF_TREE *dt)
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{
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@ -433,7 +417,7 @@ static int tinf_inflate_block_data(uzlib_uncomp_t *d, TINF_TREE *lt, TINF_TREE *
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}
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/* possibly get more bits from length code */
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d->curlen = tinf_read_bits(d, length_bits[sym], length_base[sym]);
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d->curlen = tinf_read_bits(d, lookup_table[sym].length_bits, lookup_table[sym].length_base);
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dist = tinf_decode_symbol(d, dt);
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if (dist >= 30) {
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@ -441,7 +425,7 @@ static int tinf_inflate_block_data(uzlib_uncomp_t *d, TINF_TREE *lt, TINF_TREE *
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}
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/* possibly get more bits from distance code */
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offs = tinf_read_bits(d, dist_bits[dist], dist_base[dist]);
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offs = tinf_read_bits(d, lookup_table[dist].dist_bits, lookup_table[dist].dist_base);
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/* calculate and validate actual LZ offset to use */
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if (d->dict_ring) {
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@ -521,20 +505,6 @@ static int tinf_inflate_uncompressed_block(uzlib_uncomp_t *d)
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* -- public functions -- *
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* ---------------------- */
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/* initialize global (static) data */
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void uzlib_init(void)
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{
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#ifdef RUNTIME_BITS_TABLES
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/* build extra bits and base tables */
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tinf_build_bits_base(length_bits, length_base, 4, 3);
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tinf_build_bits_base(dist_bits, dist_base, 2, 1);
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/* fix a special case */
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length_bits[28] = 0;
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length_base[28] = 258;
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#endif
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}
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/* initialize decompression structure */
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void uzlib_uncompress_init(uzlib_uncomp_t *d, void *dict, unsigned int dictLen)
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{
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@ -125,7 +125,6 @@ unsigned char uzlib_get_byte(uzlib_uncomp_t *d);
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/* Decompression API */
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void uzlib_init(void);
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void uzlib_uncompress_init(uzlib_uncomp_t *d, void *dict, unsigned int dictLen);
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int uzlib_uncompress(uzlib_uncomp_t *d);
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int uzlib_uncompress_chksum(uzlib_uncomp_t *d);
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