lib/uzlib/defl_static: Implement some code size improvements.
This commit makes the following changes: - Replace 256-byte reverse-bits-in-byte lookup table with computation. - Replace length and distance code lookup tables with computation. - Remove comp_disabled check (it's unused). - Make the dest_write_cb take the data pointer directly, rather than the Outbuf. Saves 500 bytes on PYBV11. Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared
Damien George
parent
82db9926ed
commit
0900976384
@ -10,6 +10,9 @@ Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
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Justin Bradford, Ben Harris, Malcolm Smith, Ahmad Khalifa, Markus
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Kuhn, Colin Watson, and CORE SDI S.A.
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Optimised for MicroPython:
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Copyright (c) 2023 by Jim Mussared
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation files
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(the "Software"), to deal in the Software without restriction,
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@ -55,152 +58,44 @@ static void outbits(struct Outbuf *out, unsigned long bits, int nbits)
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out->outbits |= bits << out->noutbits;
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out->noutbits += nbits;
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while (out->noutbits >= 8) {
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out->dest_write_cb(out, out->outbits & 0xFF);
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out->dest_write_cb(out->dest_write_data, out->outbits & 0xFF);
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out->outbits >>= 8;
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out->noutbits -= 8;
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}
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}
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static const unsigned char mirrorbytes[256] = {
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0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
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0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
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0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
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0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
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0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
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0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
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0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
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0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
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0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
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0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
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0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
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0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
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0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
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0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
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0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
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0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
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0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
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0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
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0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
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0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
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0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
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0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
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0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
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0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
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0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
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0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
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0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
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0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
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0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
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0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
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0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
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0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
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static const unsigned char mirrornibbles[16] = {
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0x0, 0x8, 0x4, 0xc, 0x2, 0xa, 0x6, 0xe,
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0x1, 0x9, 0x5, 0xd, 0x3, 0xb, 0x7, 0xf,
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};
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typedef struct {
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uint8_t extrabits;
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uint8_t min, max;
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} len_coderecord;
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static unsigned int mirrorbyte(unsigned int b) {
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return mirrornibbles[b & 0xf] << 4 | mirrornibbles[b >> 4];
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}
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typedef struct {
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uint8_t code, extrabits;
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uint16_t min, max;
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} dist_coderecord;
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#define TO_LCODE(x, y) x - 3, y - 3
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#define FROM_LCODE(x) (x + 3)
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static const len_coderecord lencodes[] = {
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{0, TO_LCODE(3, 3)},
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{0, TO_LCODE(4, 4)},
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{0, TO_LCODE(5, 5)},
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{0, TO_LCODE(6, 6)},
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{0, TO_LCODE(7, 7)},
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{0, TO_LCODE(8, 8)},
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{0, TO_LCODE(9, 9)},
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{0, TO_LCODE(10, 10)},
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{1, TO_LCODE(11, 12)},
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{1, TO_LCODE(13, 14)},
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{1, TO_LCODE(15, 16)},
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{1, TO_LCODE(17, 18)},
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{2, TO_LCODE(19, 22)},
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{2, TO_LCODE(23, 26)},
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{2, TO_LCODE(27, 30)},
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{2, TO_LCODE(31, 34)},
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{3, TO_LCODE(35, 42)},
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{3, TO_LCODE(43, 50)},
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{3, TO_LCODE(51, 58)},
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{3, TO_LCODE(59, 66)},
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{4, TO_LCODE(67, 82)},
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{4, TO_LCODE(83, 98)},
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{4, TO_LCODE(99, 114)},
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{4, TO_LCODE(115, 130)},
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{5, TO_LCODE(131, 162)},
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{5, TO_LCODE(163, 194)},
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{5, TO_LCODE(195, 226)},
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{5, TO_LCODE(227, 257)},
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{0, TO_LCODE(258, 258)},
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};
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static const dist_coderecord distcodes[] = {
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{0, 0, 1, 1},
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{1, 0, 2, 2},
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{2, 0, 3, 3},
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{3, 0, 4, 4},
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{4, 1, 5, 6},
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{5, 1, 7, 8},
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{6, 2, 9, 12},
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{7, 2, 13, 16},
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{8, 3, 17, 24},
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{9, 3, 25, 32},
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{10, 4, 33, 48},
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{11, 4, 49, 64},
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{12, 5, 65, 96},
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{13, 5, 97, 128},
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{14, 6, 129, 192},
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{15, 6, 193, 256},
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{16, 7, 257, 384},
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{17, 7, 385, 512},
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{18, 8, 513, 768},
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{19, 8, 769, 1024},
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{20, 9, 1025, 1536},
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{21, 9, 1537, 2048},
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{22, 10, 2049, 3072},
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{23, 10, 3073, 4096},
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{24, 11, 4097, 6144},
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{25, 11, 6145, 8192},
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{26, 12, 8193, 12288},
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{27, 12, 12289, 16384},
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{28, 13, 16385, 24576},
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{29, 13, 24577, 32768},
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};
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static int int_log2(int x) {
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int r = 0;
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while (x >>= 1) {
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++r;
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}
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return r;
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}
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void zlib_literal(struct Outbuf *out, unsigned char c)
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{
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if (out->comp_disabled) {
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/*
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* We're in an uncompressed block, so just output the byte.
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*/
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outbits(out, c, 8);
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return;
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}
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if (c <= 143) {
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/* 0 through 143 are 8 bits long starting at 00110000. */
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outbits(out, mirrorbytes[0x30 + c], 8);
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outbits(out, mirrorbyte(0x30 + c), 8);
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} else {
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/* 144 through 255 are 9 bits long starting at 110010000. */
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outbits(out, 1 + 2 * mirrorbytes[0x90 - 144 + c], 9);
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outbits(out, 1 + 2 * mirrorbyte(0x90 - 144 + c), 9);
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}
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}
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void zlib_match(struct Outbuf *out, int distance, int len)
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{
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const dist_coderecord *d;
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const len_coderecord *l;
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int i, j, k;
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int lcode;
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assert(!out->comp_disabled);
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assert(distance >= 1 && distance <= 32768);
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distance -= 1;
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while (len > 0) {
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int thislen;
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@ -218,73 +113,56 @@ void zlib_match(struct Outbuf *out, int distance, int len)
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thislen = (len > 260 ? 258 : len <= 258 ? len : len - 3);
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len -= thislen;
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/*
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* Binary-search to find which length code we're
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* transmitting.
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*/
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i = -1;
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j = sizeof(lencodes) / sizeof(*lencodes);
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while (1) {
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assert(j - i >= 2);
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k = (j + i) / 2;
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if (thislen < FROM_LCODE(lencodes[k].min))
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j = k;
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else if (thislen > FROM_LCODE(lencodes[k].max))
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i = k;
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else {
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l = &lencodes[k];
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break; /* found it! */
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}
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}
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assert(thislen >= 3 && thislen <= 258);
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lcode = l - lencodes + 257;
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thislen -= 3;
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int lcode = 28;
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int x = int_log2(thislen);
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int y;
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if (thislen < 255) {
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if (x) {
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--x;
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}
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y = (thislen >> (x ? x - 1 : 0)) & 3;
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lcode = x * 4 + y;
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}
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/*
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* Transmit the length code. 256-279 are seven bits
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* starting at 0000000; 280-287 are eight bits starting at
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* 11000000.
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*/
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if (lcode <= 279) {
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outbits(out, mirrorbytes[(lcode - 256) * 2], 7);
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if (lcode <= 22) {
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outbits(out, mirrorbyte((lcode + 1) * 2), 7);
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} else {
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outbits(out, mirrorbytes[0xc0 - 280 + lcode], 8);
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outbits(out, mirrorbyte(lcode + 169), 8);
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}
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/*
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* Transmit the extra bits.
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*/
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if (l->extrabits)
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outbits(out, thislen - FROM_LCODE(l->min), l->extrabits);
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if (thislen < 255 && x > 1) {
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int extrabits = x - 1;
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int lmin = (thislen >> extrabits) << extrabits;
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outbits(out, thislen - lmin, extrabits);
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}
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/*
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* Binary-search to find which distance code we're
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* transmitting.
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*/
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i = -1;
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j = sizeof(distcodes) / sizeof(*distcodes);
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while (1) {
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assert(j - i >= 2);
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k = (j + i) / 2;
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if (distance < distcodes[k].min)
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j = k;
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else if (distance > distcodes[k].max)
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i = k;
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else {
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d = &distcodes[k];
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break; /* found it! */
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}
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}
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x = int_log2(distance);
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y = (distance >> (x ? x - 1 : 0)) & 1;
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/*
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* Transmit the distance code. Five bits starting at 00000.
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*/
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outbits(out, mirrorbytes[d->code * 8], 5);
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outbits(out, mirrorbyte((x * 2 + y) * 8), 5);
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/*
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* Transmit the extra bits.
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*/
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if (d->extrabits)
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outbits(out, distance - d->min, d->extrabits);
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if (x > 1) {
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int dextrabits = x - 1;
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int dmin = (distance >> dextrabits) << dextrabits;
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outbits(out, distance - dmin, dextrabits);
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}
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}
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}
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@ -32,10 +32,9 @@
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struct Outbuf {
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void *dest_write_data;
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void (*dest_write_cb)(struct Outbuf *outbuf, uint8_t byte);
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void (*dest_write_cb)(void *data, uint8_t byte);
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unsigned long outbits;
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int noutbits;
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int comp_disabled;
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};
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void zlib_start_block(struct Outbuf *ctx);
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