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micropython/extmod/uzlib/tinflate.c

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/*
* tinflate - tiny inflate
*
* Copyright (c) 2003 by Joergen Ibsen / Jibz
* All Rights Reserved
* http://www.ibsensoftware.com/
*
* Copyright (c) 2014 by Paul Sokolovsky
*
* This software is provided 'as-is', without any express
* or implied warranty. In no event will the authors be
* held liable for any damages arising from the use of
* this software.
*
* Permission is granted to anyone to use this software
* for any purpose, including commercial applications,
* and to alter it and redistribute it freely, subject to
* the following restrictions:
*
* 1. The origin of this software must not be
* misrepresented; you must not claim that you
* wrote the original software. If you use this
* software in a product, an acknowledgment in
* the product documentation would be appreciated
* but is not required.
*
* 2. Altered source versions must be plainly marked
* as such, and must not be misrepresented as
* being the original software.
*
* 3. This notice may not be removed or altered from
* any source distribution.
*/
#include "tinf.h"
/* --------------------------------------------------- *
* -- uninitialized global data (static structures) -- *
* --------------------------------------------------- */
#ifdef RUNTIME_BITS_TABLES
/* extra bits and base tables for length codes */
unsigned char length_bits[30];
unsigned short length_base[30];
/* extra bits and base tables for distance codes */
unsigned char dist_bits[30];
unsigned short dist_base[30];
#else
const unsigned char length_bits[30] = {
0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4,
5, 5, 5, 5
};
const unsigned short length_base[30] = {
3, 4, 5, 6, 7, 8, 9, 10,
11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115,
131, 163, 195, 227, 258
};
const unsigned char dist_bits[30] = {
0, 0, 0, 0, 1, 1, 2, 2,
3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10,
11, 11, 12, 12, 13, 13
};
const unsigned short dist_base[30] = {
1, 2, 3, 4, 5, 7, 9, 13,
17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073,
4097, 6145, 8193, 12289, 16385, 24577
};
#endif
/* special ordering of code length codes */
const unsigned char clcidx[] = {
16, 17, 18, 0, 8, 7, 9, 6,
10, 5, 11, 4, 12, 3, 13, 2,
14, 1, 15
};
/* ----------------------- *
* -- utility functions -- *
* ----------------------- */
/* Execute callback to grow destination buffer */
static int tinf_grow_dest_buf(TINF_DATA *d, unsigned int lastAlloc)
{
unsigned int oldsize = d->dest - d->destStart;
/* This will update only destStart and destSize */
if (!d->destGrow)
{
return TINF_DEST_OVERFLOW;
}
d->destGrow(d, lastAlloc);
d->dest = d->destStart + oldsize;
d->destRemaining = d->destSize - oldsize;
return 0;
}
#ifdef RUNTIME_BITS_TABLES
/* build extra bits and base tables */
static void tinf_build_bits_base(unsigned char *bits, unsigned short *base, int delta, int first)
{
int i, sum;
/* build bits table */
for (i = 0; i < delta; ++i) bits[i] = 0;
for (i = 0; i < 30 - delta; ++i) bits[i + delta] = i / delta;
/* build base table */
for (sum = first, i = 0; i < 30; ++i)
{
base[i] = sum;
sum += 1 << bits[i];
}
}
#endif
/* build the fixed huffman trees */
static void tinf_build_fixed_trees(TINF_TREE *lt, TINF_TREE *dt)
{
int i;
/* build fixed length tree */
for (i = 0; i < 7; ++i) lt->table[i] = 0;
lt->table[7] = 24;
lt->table[8] = 152;
lt->table[9] = 112;
for (i = 0; i < 24; ++i) lt->trans[i] = 256 + i;
for (i = 0; i < 144; ++i) lt->trans[24 + i] = i;
for (i = 0; i < 8; ++i) lt->trans[24 + 144 + i] = 280 + i;
for (i = 0; i < 112; ++i) lt->trans[24 + 144 + 8 + i] = 144 + i;
/* build fixed distance tree */
for (i = 0; i < 5; ++i) dt->table[i] = 0;
dt->table[5] = 32;
for (i = 0; i < 32; ++i) dt->trans[i] = i;
}
/* given an array of code lengths, build a tree */
static void tinf_build_tree(TINF_TREE *t, const unsigned char *lengths, unsigned int num)
{
unsigned short offs[16];
unsigned int i, sum;
/* clear code length count table */
for (i = 0; i < 16; ++i) t->table[i] = 0;
/* scan symbol lengths, and sum code length counts */
for (i = 0; i < num; ++i) t->table[lengths[i]]++;
t->table[0] = 0;
/* compute offset table for distribution sort */
for (sum = 0, i = 0; i < 16; ++i)
{
offs[i] = sum;
sum += t->table[i];
}
/* create code->symbol translation table (symbols sorted by code) */
for (i = 0; i < num; ++i)
{
if (lengths[i]) t->trans[offs[lengths[i]]++] = i;
}
}
/* ---------------------- *
* -- decode functions -- *
* ---------------------- */
/* get one bit from source stream */
static int tinf_getbit(TINF_DATA *d)
{
unsigned int bit;
/* check if tag is empty */
if (!d->bitcount--)
{
/* load next tag */
d->tag = *d->source++;
d->bitcount = 7;
}
/* shift bit out of tag */
bit = d->tag & 0x01;
d->tag >>= 1;
return bit;
}
/* read a num bit value from a stream and add base */
static unsigned int tinf_read_bits(TINF_DATA *d, int num, int base)
{
unsigned int val = 0;
/* read num bits */
if (num)
{
unsigned int limit = 1 << (num);
unsigned int mask;
for (mask = 1; mask < limit; mask *= 2)
if (tinf_getbit(d)) val += mask;
}
return val + base;
}
/* given a data stream and a tree, decode a symbol */
static int tinf_decode_symbol(TINF_DATA *d, TINF_TREE *t)
{
int sum = 0, cur = 0, len = 0;
/* get more bits while code value is above sum */
do {
cur = 2*cur + tinf_getbit(d);
++len;
sum += t->table[len];
cur -= t->table[len];
} while (cur >= 0);
return t->trans[sum + cur];
}
/* given a data stream, decode dynamic trees from it */
static void tinf_decode_trees(TINF_DATA *d, TINF_TREE *lt, TINF_TREE *dt)
{
unsigned char lengths[288+32];
unsigned int hlit, hdist, hclen;
unsigned int i, num, length;
/* get 5 bits HLIT (257-286) */
hlit = tinf_read_bits(d, 5, 257);
/* get 5 bits HDIST (1-32) */
hdist = tinf_read_bits(d, 5, 1);
/* get 4 bits HCLEN (4-19) */
hclen = tinf_read_bits(d, 4, 4);
for (i = 0; i < 19; ++i) lengths[i] = 0;
/* read code lengths for code length alphabet */
for (i = 0; i < hclen; ++i)
{
/* get 3 bits code length (0-7) */
unsigned int clen = tinf_read_bits(d, 3, 0);
lengths[clcidx[i]] = clen;
}
/* build code length tree, temporarily use length tree */
tinf_build_tree(lt, lengths, 19);
/* decode code lengths for the dynamic trees */
for (num = 0; num < hlit + hdist; )
{
int sym = tinf_decode_symbol(d, lt);
switch (sym)
{
case 16:
/* copy previous code length 3-6 times (read 2 bits) */
{
unsigned char prev = lengths[num - 1];
for (length = tinf_read_bits(d, 2, 3); length; --length)
{
lengths[num++] = prev;
}
}
break;
case 17:
/* repeat code length 0 for 3-10 times (read 3 bits) */
for (length = tinf_read_bits(d, 3, 3); length; --length)
{
lengths[num++] = 0;
}
break;
case 18:
/* repeat code length 0 for 11-138 times (read 7 bits) */
for (length = tinf_read_bits(d, 7, 11); length; --length)
{
lengths[num++] = 0;
}
break;
default:
/* values 0-15 represent the actual code lengths */
lengths[num++] = sym;
break;
}
}
/* build dynamic trees */
tinf_build_tree(lt, lengths, hlit);
tinf_build_tree(dt, lengths + hlit, hdist);
}
/* ----------------------------- *
* -- block inflate functions -- *
* ----------------------------- */
/* given a stream and two trees, inflate a block of data */
static int tinf_inflate_block_data(TINF_DATA *d, TINF_TREE *lt, TINF_TREE *dt)
{
while (1)
{
int sym = tinf_decode_symbol(d, lt);
/* check for end of block */
if (sym == 256)
{
return TINF_OK;
}
if (sym < 256)
{
if (d->destRemaining == 0)
{
int res = tinf_grow_dest_buf(d, 1);
if (res) return res;
}
*d->dest++ = sym;
d->destRemaining--;
} else {
int length, dist, offs;
int i;
sym -= 257;
/* possibly get more bits from length code */
length = tinf_read_bits(d, length_bits[sym], length_base[sym]);
dist = tinf_decode_symbol(d, dt);
/* possibly get more bits from distance code */
offs = tinf_read_bits(d, dist_bits[dist], dist_base[dist]);
if (d->destRemaining < length)
{
int res = tinf_grow_dest_buf(d, length);
if (res) return res;
}
/* copy match */
for (i = 0; i < length; ++i)
{
d->dest[i] = d->dest[i - offs];
}
d->dest += length;
d->destRemaining -= length;
}
}
}
/* inflate an uncompressed block of data */
static int tinf_inflate_uncompressed_block(TINF_DATA *d)
{
unsigned int length, invlength;
unsigned int i;
/* get length */
length = d->source[1];
length = 256*length + d->source[0];
/* get one's complement of length */
invlength = d->source[3];
invlength = 256*invlength + d->source[2];
/* check length */
if (length != (~invlength & 0x0000ffff)) return TINF_DATA_ERROR;
if (d->destRemaining < length)
{
int res = tinf_grow_dest_buf(d, length);
if (res) return res;
}
d->source += 4;
/* copy block */
for (i = length; i; --i) *d->dest++ = *d->source++;
d->destRemaining -= length;
/* make sure we start next block on a byte boundary */
d->bitcount = 0;
return TINF_OK;
}
/* inflate a block of data compressed with fixed huffman trees */
static int tinf_inflate_fixed_block(TINF_DATA *d)
{
/* build fixed huffman trees */
tinf_build_fixed_trees(&d->ltree, &d->dtree);
/* decode block using fixed trees */
return tinf_inflate_block_data(d, &d->ltree, &d->dtree);
}
/* inflate a block of data compressed with dynamic huffman trees */
static int tinf_inflate_dynamic_block(TINF_DATA *d)
{
/* decode trees from stream */
tinf_decode_trees(d, &d->ltree, &d->dtree);
/* decode block using decoded trees */
return tinf_inflate_block_data(d, &d->ltree, &d->dtree);
}
/* ---------------------- *
* -- public functions -- *
* ---------------------- */
/* initialize global (static) data */
void tinf_init()
{
#ifdef RUNTIME_BITS_TABLES
/* build extra bits and base tables */
tinf_build_bits_base(length_bits, length_base, 4, 3);
tinf_build_bits_base(dist_bits, dist_base, 2, 1);
/* fix a special case */
length_bits[28] = 0;
length_base[28] = 258;
#endif
}
/* inflate stream from source to dest */
int tinf_uncompress(void *dest, unsigned int *destLen,
const void *source, unsigned int sourceLen)
{
TINF_DATA d;
int res;
/* initialise data */
d.source = (const unsigned char *)source;
d.destStart = (unsigned char *)dest;
d.destRemaining = *destLen;
res = tinf_uncompress_dyn(&d);
*destLen = d.dest - d.destStart;
return res;
}
/* inflate stream from source to dest */
int tinf_uncompress_dyn(TINF_DATA *d)
{
int bfinal;
/* initialise data */
d->bitcount = 0;
d->dest = d->destStart;
d->destRemaining = d->destSize;
do {
unsigned int btype;
int res;
/* read final block flag */
bfinal = tinf_getbit(d);
/* read block type (2 bits) */
btype = tinf_read_bits(d, 2, 0);
/* decompress block */
switch (btype)
{
case 0:
/* decompress uncompressed block */
res = tinf_inflate_uncompressed_block(d);
break;
case 1:
/* decompress block with fixed huffman trees */
res = tinf_inflate_fixed_block(d);
break;
case 2:
/* decompress block with dynamic huffman trees */
res = tinf_inflate_dynamic_block(d);
break;
default:
return TINF_DATA_ERROR;
}
if (res != TINF_OK) return TINF_DATA_ERROR;
} while (!bfinal);
return TINF_OK;
}
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