mirror of
https://github.com/godotengine/godot.git
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5167c9186a
Upstream development restarted after 13 years. Changes:
2020-02-02: Version 0.5.0
Minor speed improvement on the decompressor.
Prevent memory violation when decompressing corrupted input.
2020-01-10: Version 0.4.0
Only code & infrastructure clean-up, no new functionality.
592 lines
15 KiB
C
592 lines
15 KiB
C
/*
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FastLZ - Byte-aligned LZ77 compression library
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Copyright (C) 2005-2020 Ariya Hidayat <ariya.hidayat@gmail.com>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#include "fastlz.h"
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#include <stdint.h>
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/*
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* Always check for bound when decompressing.
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* Generally it is best to leave it defined.
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*/
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#define FASTLZ_SAFE
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#if defined(FASTLZ_USE_SAFE_DECOMPRESSOR) && (FASTLZ_USE_SAFE_DECOMPRESSOR == 0)
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#undef FASTLZ_SAFE
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#endif
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/*
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* Give hints to the compiler for branch prediction optimization.
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*/
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#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ > 2))
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#define FASTLZ_LIKELY(c) (__builtin_expect(!!(c), 1))
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#define FASTLZ_UNLIKELY(c) (__builtin_expect(!!(c), 0))
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#else
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#define FASTLZ_LIKELY(c) (c)
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#define FASTLZ_UNLIKELY(c) (c)
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#endif
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#if defined(FASTLZ_SAFE)
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#define FASTLZ_BOUND_CHECK(cond) \
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if (FASTLZ_UNLIKELY(!(cond))) return 0;
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#else
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#define FASTLZ_BOUND_CHECK(cond) \
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do { \
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} while (0)
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#endif
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#define MAX_COPY 32
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#define MAX_LEN 264 /* 256 + 8 */
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#define MAX_L1_DISTANCE 8192
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#define MAX_L2_DISTANCE 8191
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#define MAX_FARDISTANCE (65535 + MAX_L2_DISTANCE - 1)
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#define FASTLZ_READU16(p) ((p)[0] | (p)[1] << 8)
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#define HASH_LOG 13
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#define HASH_SIZE (1 << HASH_LOG)
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#define HASH_MASK (HASH_SIZE - 1)
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#define HASH_FUNCTION(v, p) \
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{ \
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v = FASTLZ_READU16(p); \
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v ^= FASTLZ_READU16(p + 1) ^ (v >> (16 - HASH_LOG)); \
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v &= HASH_MASK; \
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}
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int fastlz1_compress(const void* input, int length, void* output) {
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const uint8_t* ip = (const uint8_t*)input;
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const uint8_t* ip_bound = ip + length - 2;
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const uint8_t* ip_limit = ip + length - 12 - 1;
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uint8_t* op = (uint8_t*)output;
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const uint8_t* htab[HASH_SIZE];
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uint32_t hval;
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uint32_t copy;
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/* sanity check */
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if (FASTLZ_UNLIKELY(length < 4)) {
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if (length) {
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/* create literal copy only */
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*op++ = length - 1;
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ip_bound++;
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while (ip <= ip_bound) *op++ = *ip++;
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return length + 1;
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} else
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return 0;
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}
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/* initializes hash table */
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for (hval = 0; hval < HASH_SIZE; ++hval) htab[hval] = ip;
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/* we start with literal copy */
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copy = 2;
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*op++ = MAX_COPY - 1;
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*op++ = *ip++;
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*op++ = *ip++;
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/* main loop */
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while (FASTLZ_LIKELY(ip < ip_limit)) {
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const uint8_t* ref;
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uint32_t distance;
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/* minimum match length */
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uint32_t len = 3;
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/* comparison starting-point */
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const uint8_t* anchor = ip;
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/* find potential match */
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HASH_FUNCTION(hval, ip);
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ref = htab[hval];
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/* update hash table */
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htab[hval] = anchor;
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/* calculate distance to the match */
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distance = anchor - ref;
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/* is this a match? check the first 3 bytes */
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if (distance == 0 || (distance >= MAX_L1_DISTANCE) || *ref++ != *ip++ ||
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*ref++ != *ip++ || *ref++ != *ip++)
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goto literal;
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/* last matched byte */
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ip = anchor + len;
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/* distance is biased */
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distance--;
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if (!distance) {
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/* zero distance means a run */
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uint8_t x = ip[-1];
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while (ip < ip_bound)
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if (*ref++ != x)
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break;
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else
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ip++;
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} else
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for (;;) {
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/* safe because the outer check against ip limit */
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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while (ip < ip_bound)
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if (*ref++ != *ip++) break;
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break;
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}
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/* if we have copied something, adjust the copy count */
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if (copy) /* copy is biased, '0' means 1 byte copy */
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*(op - copy - 1) = copy - 1;
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else
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/* back, to overwrite the copy count */
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op--;
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/* reset literal counter */
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copy = 0;
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/* length is biased, '1' means a match of 3 bytes */
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ip -= 3;
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len = ip - anchor;
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/* encode the match */
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if (FASTLZ_UNLIKELY(len > MAX_LEN - 2))
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while (len > MAX_LEN - 2) {
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*op++ = (7 << 5) + (distance >> 8);
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*op++ = MAX_LEN - 2 - 7 - 2;
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*op++ = (distance & 255);
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len -= MAX_LEN - 2;
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}
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if (len < 7) {
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*op++ = (len << 5) + (distance >> 8);
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*op++ = (distance & 255);
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} else {
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*op++ = (7 << 5) + (distance >> 8);
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*op++ = len - 7;
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*op++ = (distance & 255);
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}
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/* update the hash at match boundary */
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HASH_FUNCTION(hval, ip);
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htab[hval] = ip++;
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HASH_FUNCTION(hval, ip);
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htab[hval] = ip++;
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/* assuming literal copy */
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*op++ = MAX_COPY - 1;
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continue;
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literal:
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*op++ = *anchor++;
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ip = anchor;
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copy++;
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if (FASTLZ_UNLIKELY(copy == MAX_COPY)) {
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copy = 0;
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*op++ = MAX_COPY - 1;
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}
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}
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/* left-over as literal copy */
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ip_bound++;
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while (ip <= ip_bound) {
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*op++ = *ip++;
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copy++;
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if (copy == MAX_COPY) {
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copy = 0;
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*op++ = MAX_COPY - 1;
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}
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}
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/* if we have copied something, adjust the copy length */
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if (copy)
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*(op - copy - 1) = copy - 1;
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else
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op--;
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return op - (uint8_t*)output;
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}
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#if defined(FASTLZ_USE_MEMMOVE) && (FASTLZ_USE_MEMMOVE == 0)
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static void fastlz_memmove(uint8_t* dest, const uint8_t* src, uint32_t count) {
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do {
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*dest++ = *src++;
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} while (--count);
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}
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static void fastlz_memcpy(uint8_t* dest, const uint8_t* src, uint32_t count) {
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return fastlz_memmove(dest, src, count);
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}
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#else
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#include <string.h>
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static void fastlz_memmove(uint8_t* dest, const uint8_t* src, uint32_t count) {
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if ((count > 4) && (dest >= src + count)) {
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memmove(dest, src, count);
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} else {
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switch (count) {
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default:
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do {
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*dest++ = *src++;
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} while (--count);
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break;
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case 3:
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*dest++ = *src++;
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case 2:
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*dest++ = *src++;
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case 1:
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*dest++ = *src++;
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case 0:
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break;
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}
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}
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}
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static void fastlz_memcpy(uint8_t* dest, const uint8_t* src, uint32_t count) {
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memcpy(dest, src, count);
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}
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#endif
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int fastlz1_decompress(const void* input, int length, void* output,
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int maxout) {
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const uint8_t* ip = (const uint8_t*)input;
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const uint8_t* ip_limit = ip + length;
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const uint8_t* ip_bound = ip_limit - 2;
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uint8_t* op = (uint8_t*)output;
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uint8_t* op_limit = op + maxout;
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uint32_t ctrl = (*ip++) & 31;
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while (1) {
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if (ctrl >= 32) {
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uint32_t len = (ctrl >> 5) - 1;
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uint32_t ofs = (ctrl & 31) << 8;
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const uint8_t* ref = op - ofs - 1;
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if (len == 7 - 1) {
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FASTLZ_BOUND_CHECK(ip <= ip_bound);
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len += *ip++;
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}
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ref -= *ip++;
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len += 3;
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FASTLZ_BOUND_CHECK(op + len <= op_limit);
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FASTLZ_BOUND_CHECK(ref >= (uint8_t*)output);
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fastlz_memmove(op, ref, len);
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op += len;
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} else {
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ctrl++;
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FASTLZ_BOUND_CHECK(op + ctrl <= op_limit);
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FASTLZ_BOUND_CHECK(ip + ctrl <= ip_limit);
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fastlz_memcpy(op, ip, ctrl);
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ip += ctrl;
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op += ctrl;
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}
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if (FASTLZ_UNLIKELY(ip > ip_bound)) break;
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ctrl = *ip++;
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}
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return op - (uint8_t*)output;
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}
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int fastlz2_compress(const void* input, int length, void* output) {
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const uint8_t* ip = (const uint8_t*)input;
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const uint8_t* ip_bound = ip + length - 2;
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const uint8_t* ip_limit = ip + length - 12 - 1;
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uint8_t* op = (uint8_t*)output;
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const uint8_t* htab[HASH_SIZE];
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uint32_t hval;
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uint32_t copy;
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/* sanity check */
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if (FASTLZ_UNLIKELY(length < 4)) {
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if (length) {
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/* create literal copy only */
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*op++ = length - 1;
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ip_bound++;
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while (ip <= ip_bound) *op++ = *ip++;
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return length + 1;
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} else
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return 0;
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}
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/* initializes hash table */
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for (hval = 0; hval < HASH_SIZE; ++hval) htab[hval] = ip;
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/* we start with literal copy */
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copy = 2;
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*op++ = MAX_COPY - 1;
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*op++ = *ip++;
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*op++ = *ip++;
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/* main loop */
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while (FASTLZ_LIKELY(ip < ip_limit)) {
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const uint8_t* ref;
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uint32_t distance;
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/* minimum match length */
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uint32_t len = 3;
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/* comparison starting-point */
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const uint8_t* anchor = ip;
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/* check for a run */
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if (ip[0] == ip[-1] && ip[0] == ip[1] && ip[1] == ip[2]) {
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distance = 1;
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ip += 3;
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ref = anchor - 1 + 3;
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goto match;
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}
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/* find potential match */
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HASH_FUNCTION(hval, ip);
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ref = htab[hval];
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/* update hash table */
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htab[hval] = anchor;
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/* calculate distance to the match */
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distance = anchor - ref;
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/* is this a match? check the first 3 bytes */
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if (distance == 0 || (distance >= MAX_FARDISTANCE) || *ref++ != *ip++ ||
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*ref++ != *ip++ || *ref++ != *ip++)
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goto literal;
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/* far, needs at least 5-byte match */
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if (distance >= MAX_L2_DISTANCE) {
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if (*ip++ != *ref++ || *ip++ != *ref++) goto literal;
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len += 2;
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}
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match:
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/* last matched byte */
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ip = anchor + len;
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/* distance is biased */
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distance--;
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if (!distance) {
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/* zero distance means a run */
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uint8_t x = ip[-1];
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while (ip < ip_bound)
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if (*ref++ != x)
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break;
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else
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ip++;
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} else
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for (;;) {
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/* safe because the outer check against ip limit */
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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if (*ref++ != *ip++) break;
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while (ip < ip_bound)
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if (*ref++ != *ip++) break;
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break;
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}
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/* if we have copied something, adjust the copy count */
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if (copy) /* copy is biased, '0' means 1 byte copy */
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*(op - copy - 1) = copy - 1;
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else
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/* back, to overwrite the copy count */
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op--;
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/* reset literal counter */
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copy = 0;
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/* length is biased, '1' means a match of 3 bytes */
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ip -= 3;
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len = ip - anchor;
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/* encode the match */
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if (distance < MAX_L2_DISTANCE) {
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if (len < 7) {
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*op++ = (len << 5) + (distance >> 8);
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*op++ = (distance & 255);
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} else {
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*op++ = (7 << 5) + (distance >> 8);
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for (len -= 7; len >= 255; len -= 255) *op++ = 255;
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*op++ = len;
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*op++ = (distance & 255);
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}
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} else {
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/* far away, but not yet in the another galaxy... */
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if (len < 7) {
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distance -= MAX_L2_DISTANCE;
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*op++ = (len << 5) + 31;
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*op++ = 255;
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*op++ = distance >> 8;
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*op++ = distance & 255;
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} else {
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distance -= MAX_L2_DISTANCE;
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*op++ = (7 << 5) + 31;
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for (len -= 7; len >= 255; len -= 255) *op++ = 255;
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*op++ = len;
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*op++ = 255;
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*op++ = distance >> 8;
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*op++ = distance & 255;
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}
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}
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/* update the hash at match boundary */
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HASH_FUNCTION(hval, ip);
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htab[hval] = ip++;
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HASH_FUNCTION(hval, ip);
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htab[hval] = ip++;
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/* assuming literal copy */
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*op++ = MAX_COPY - 1;
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continue;
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literal:
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*op++ = *anchor++;
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ip = anchor;
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copy++;
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if (FASTLZ_UNLIKELY(copy == MAX_COPY)) {
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copy = 0;
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*op++ = MAX_COPY - 1;
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}
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}
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/* left-over as literal copy */
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ip_bound++;
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while (ip <= ip_bound) {
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*op++ = *ip++;
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copy++;
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if (copy == MAX_COPY) {
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copy = 0;
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*op++ = MAX_COPY - 1;
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}
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}
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/* if we have copied something, adjust the copy length */
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if (copy)
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*(op - copy - 1) = copy - 1;
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else
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op--;
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/* marker for fastlz2 */
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*(uint8_t*)output |= (1 << 5);
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return op - (uint8_t*)output;
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}
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int fastlz2_decompress(const void* input, int length, void* output,
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int maxout) {
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const uint8_t* ip = (const uint8_t*)input;
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const uint8_t* ip_limit = ip + length;
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const uint8_t* ip_bound = ip_limit - 2;
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uint8_t* op = (uint8_t*)output;
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uint8_t* op_limit = op + maxout;
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uint32_t ctrl = (*ip++) & 31;
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while (1) {
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if (ctrl >= 32) {
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uint32_t len = (ctrl >> 5) - 1;
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uint32_t ofs = (ctrl & 31) << 8;
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const uint8_t* ref = op - ofs - 1;
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uint8_t code;
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if (len == 7 - 1) do {
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FASTLZ_BOUND_CHECK(ip <= ip_bound);
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code = *ip++;
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len += code;
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} while (code == 255);
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code = *ip++;
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ref -= code;
|
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len += 3;
|
|
|
|
/* match from 16-bit distance */
|
|
if (FASTLZ_UNLIKELY(code == 255))
|
|
if (FASTLZ_LIKELY(ofs == (31 << 8))) {
|
|
FASTLZ_BOUND_CHECK(ip < ip_bound);
|
|
ofs = (*ip++) << 8;
|
|
ofs += *ip++;
|
|
ref = op - ofs - MAX_L2_DISTANCE - 1;
|
|
}
|
|
|
|
FASTLZ_BOUND_CHECK(op + len <= op_limit);
|
|
FASTLZ_BOUND_CHECK(ref >= (uint8_t*)output);
|
|
fastlz_memmove(op, ref, len);
|
|
op += len;
|
|
} else {
|
|
ctrl++;
|
|
FASTLZ_BOUND_CHECK(op + ctrl <= op_limit);
|
|
FASTLZ_BOUND_CHECK(ip + ctrl <= ip_limit);
|
|
fastlz_memcpy(op, ip, ctrl);
|
|
ip += ctrl;
|
|
op += ctrl;
|
|
}
|
|
|
|
if (FASTLZ_UNLIKELY(ip >= ip_limit)) break;
|
|
ctrl = *ip++;
|
|
}
|
|
|
|
return op - (uint8_t*)output;
|
|
}
|
|
|
|
int fastlz_compress(const void* input, int length, void* output) {
|
|
/* for short block, choose fastlz1 */
|
|
if (length < 65536) return fastlz1_compress(input, length, output);
|
|
|
|
/* else... */
|
|
return fastlz2_compress(input, length, output);
|
|
}
|
|
|
|
int fastlz_decompress(const void* input, int length, void* output, int maxout) {
|
|
/* magic identifier for compression level */
|
|
int level = ((*(const uint8_t*)input) >> 5) + 1;
|
|
|
|
if (level == 1) return fastlz1_decompress(input, length, output, maxout);
|
|
if (level == 2) return fastlz2_decompress(input, length, output, maxout);
|
|
|
|
/* unknown level, trigger error */
|
|
return 0;
|
|
}
|
|
|
|
int fastlz_compress_level(int level, const void* input, int length,
|
|
void* output) {
|
|
if (level == 1) return fastlz1_compress(input, length, output);
|
|
if (level == 2) return fastlz2_compress(input, length, output);
|
|
|
|
return 0;
|
|
}
|