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1176 lines
28 KiB
1176 lines
28 KiB
/* |
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* LZMA2 decoder |
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* |
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* Authors: Lasse Collin <[email protected]> |
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* Igor Pavlov <https://7-zip.org/> |
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* |
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* This file has been put into the public domain. |
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* You can do whatever you want with this file. |
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*/ |
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|
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#include "xz_private.h" |
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#include "xz_lzma2.h" |
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|
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/* |
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* Range decoder initialization eats the first five bytes of each LZMA chunk. |
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*/ |
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#define RC_INIT_BYTES 5 |
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|
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/* |
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* Minimum number of usable input buffer to safely decode one LZMA symbol. |
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* The worst case is that we decode 22 bits using probabilities and 26 |
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* direct bits. This may decode at maximum of 20 bytes of input. However, |
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* lzma_main() does an extra normalization before returning, thus we |
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* need to put 21 here. |
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*/ |
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#define LZMA_IN_REQUIRED 21 |
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|
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/* |
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* Dictionary (history buffer) |
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* |
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* These are always true: |
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* start <= pos <= full <= end |
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* pos <= limit <= end |
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* |
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* In multi-call mode, also these are true: |
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* end == size |
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* size <= size_max |
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* allocated <= size |
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* |
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* Most of these variables are size_t to support single-call mode, |
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* in which the dictionary variables address the actual output |
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* buffer directly. |
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*/ |
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struct dictionary { |
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/* Beginning of the history buffer */ |
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uint8_t *buf; |
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|
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/* Old position in buf (before decoding more data) */ |
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size_t start; |
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|
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/* Position in buf */ |
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size_t pos; |
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|
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/* |
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* How full dictionary is. This is used to detect corrupt input that |
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* would read beyond the beginning of the uncompressed stream. |
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*/ |
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size_t full; |
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|
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/* Write limit; we don't write to buf[limit] or later bytes. */ |
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size_t limit; |
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|
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/* |
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* End of the dictionary buffer. In multi-call mode, this is |
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* the same as the dictionary size. In single-call mode, this |
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* indicates the size of the output buffer. |
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*/ |
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size_t end; |
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|
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/* |
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* Size of the dictionary as specified in Block Header. This is used |
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* together with "full" to detect corrupt input that would make us |
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* read beyond the beginning of the uncompressed stream. |
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*/ |
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uint32_t size; |
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|
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/* |
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* Maximum allowed dictionary size in multi-call mode. |
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* This is ignored in single-call mode. |
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*/ |
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uint32_t size_max; |
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|
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/* |
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* Amount of memory currently allocated for the dictionary. |
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* This is used only with XZ_DYNALLOC. (With XZ_PREALLOC, |
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* size_max is always the same as the allocated size.) |
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*/ |
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uint32_t allocated; |
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|
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/* Operation mode */ |
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enum xz_mode mode; |
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}; |
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|
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/* Range decoder */ |
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struct rc_dec { |
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uint32_t range; |
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uint32_t code; |
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|
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/* |
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* Number of initializing bytes remaining to be read |
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* by rc_read_init(). |
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*/ |
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uint32_t init_bytes_left; |
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|
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/* |
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* Buffer from which we read our input. It can be either |
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* temp.buf or the caller-provided input buffer. |
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*/ |
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const uint8_t *in; |
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size_t in_pos; |
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size_t in_limit; |
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}; |
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|
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/* Probabilities for a length decoder. */ |
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struct lzma_len_dec { |
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/* Probability of match length being at least 10 */ |
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uint16_t choice; |
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|
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/* Probability of match length being at least 18 */ |
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uint16_t choice2; |
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|
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/* Probabilities for match lengths 2-9 */ |
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uint16_t low[POS_STATES_MAX][LEN_LOW_SYMBOLS]; |
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|
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/* Probabilities for match lengths 10-17 */ |
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uint16_t mid[POS_STATES_MAX][LEN_MID_SYMBOLS]; |
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|
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/* Probabilities for match lengths 18-273 */ |
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uint16_t high[LEN_HIGH_SYMBOLS]; |
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}; |
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struct lzma_dec { |
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/* Distances of latest four matches */ |
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uint32_t rep0; |
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uint32_t rep1; |
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uint32_t rep2; |
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uint32_t rep3; |
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|
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/* Types of the most recently seen LZMA symbols */ |
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enum lzma_state state; |
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|
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/* |
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* Length of a match. This is updated so that dict_repeat can |
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* be called again to finish repeating the whole match. |
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*/ |
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uint32_t len; |
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|
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/* |
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* LZMA properties or related bit masks (number of literal |
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* context bits, a mask dervied from the number of literal |
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* position bits, and a mask dervied from the number |
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* position bits) |
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*/ |
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uint32_t lc; |
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uint32_t literal_pos_mask; /* (1 << lp) - 1 */ |
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uint32_t pos_mask; /* (1 << pb) - 1 */ |
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|
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/* If 1, it's a match. Otherwise it's a single 8-bit literal. */ |
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uint16_t is_match[STATES][POS_STATES_MAX]; |
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|
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/* If 1, it's a repeated match. The distance is one of rep0 .. rep3. */ |
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uint16_t is_rep[STATES]; |
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/* |
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* If 0, distance of a repeated match is rep0. |
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* Otherwise check is_rep1. |
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*/ |
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uint16_t is_rep0[STATES]; |
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|
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/* |
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* If 0, distance of a repeated match is rep1. |
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* Otherwise check is_rep2. |
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*/ |
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uint16_t is_rep1[STATES]; |
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|
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/* If 0, distance of a repeated match is rep2. Otherwise it is rep3. */ |
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uint16_t is_rep2[STATES]; |
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|
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/* |
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* If 1, the repeated match has length of one byte. Otherwise |
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* the length is decoded from rep_len_decoder. |
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*/ |
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uint16_t is_rep0_long[STATES][POS_STATES_MAX]; |
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|
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/* |
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* Probability tree for the highest two bits of the match |
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* distance. There is a separate probability tree for match |
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* lengths of 2 (i.e. MATCH_LEN_MIN), 3, 4, and [5, 273]. |
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*/ |
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uint16_t dist_slot[DIST_STATES][DIST_SLOTS]; |
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|
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/* |
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* Probility trees for additional bits for match distance |
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* when the distance is in the range [4, 127]. |
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*/ |
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uint16_t dist_special[FULL_DISTANCES - DIST_MODEL_END]; |
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|
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/* |
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* Probability tree for the lowest four bits of a match |
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* distance that is equal to or greater than 128. |
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*/ |
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uint16_t dist_align[ALIGN_SIZE]; |
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|
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/* Length of a normal match */ |
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struct lzma_len_dec match_len_dec; |
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|
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/* Length of a repeated match */ |
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struct lzma_len_dec rep_len_dec; |
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|
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/* Probabilities of literals */ |
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uint16_t literal[LITERAL_CODERS_MAX][LITERAL_CODER_SIZE]; |
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}; |
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struct lzma2_dec { |
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/* Position in xz_dec_lzma2_run(). */ |
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enum lzma2_seq { |
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SEQ_CONTROL, |
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SEQ_UNCOMPRESSED_1, |
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SEQ_UNCOMPRESSED_2, |
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SEQ_COMPRESSED_0, |
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SEQ_COMPRESSED_1, |
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SEQ_PROPERTIES, |
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SEQ_LZMA_PREPARE, |
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SEQ_LZMA_RUN, |
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SEQ_COPY |
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} sequence; |
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|
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/* Next position after decoding the compressed size of the chunk. */ |
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enum lzma2_seq next_sequence; |
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|
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/* Uncompressed size of LZMA chunk (2 MiB at maximum) */ |
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uint32_t uncompressed; |
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/* |
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* Compressed size of LZMA chunk or compressed/uncompressed |
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* size of uncompressed chunk (64 KiB at maximum) |
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*/ |
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uint32_t compressed; |
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/* |
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* True if dictionary reset is needed. This is false before |
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* the first chunk (LZMA or uncompressed). |
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*/ |
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bool need_dict_reset; |
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|
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/* |
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* True if new LZMA properties are needed. This is false |
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* before the first LZMA chunk. |
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*/ |
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bool need_props; |
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}; |
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|
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struct xz_dec_lzma2 { |
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/* |
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* The order below is important on x86 to reduce code size and |
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* it shouldn't hurt on other platforms. Everything up to and |
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* including lzma.pos_mask are in the first 128 bytes on x86-32, |
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* which allows using smaller instructions to access those |
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* variables. On x86-64, fewer variables fit into the first 128 |
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* bytes, but this is still the best order without sacrificing |
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* the readability by splitting the structures. |
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*/ |
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struct rc_dec rc; |
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struct dictionary dict; |
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struct lzma2_dec lzma2; |
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struct lzma_dec lzma; |
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|
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/* |
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* Temporary buffer which holds small number of input bytes between |
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* decoder calls. See lzma2_lzma() for details. |
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*/ |
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struct { |
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uint32_t size; |
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uint8_t buf[3 * LZMA_IN_REQUIRED]; |
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} temp; |
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}; |
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|
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/************** |
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* Dictionary * |
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**************/ |
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/* |
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* Reset the dictionary state. When in single-call mode, set up the beginning |
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* of the dictionary to point to the actual output buffer. |
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*/ |
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static void dict_reset(struct dictionary *dict, struct xz_buf *b) |
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{ |
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if (DEC_IS_SINGLE(dict->mode)) { |
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dict->buf = b->out + b->out_pos; |
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dict->end = b->out_size - b->out_pos; |
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} |
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dict->start = 0; |
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dict->pos = 0; |
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dict->limit = 0; |
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dict->full = 0; |
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} |
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|
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/* Set dictionary write limit */ |
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static void dict_limit(struct dictionary *dict, size_t out_max) |
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{ |
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if (dict->end - dict->pos <= out_max) |
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dict->limit = dict->end; |
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else |
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dict->limit = dict->pos + out_max; |
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} |
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|
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/* Return true if at least one byte can be written into the dictionary. */ |
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static inline bool dict_has_space(const struct dictionary *dict) |
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{ |
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return dict->pos < dict->limit; |
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} |
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|
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/* |
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* Get a byte from the dictionary at the given distance. The distance is |
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* assumed to valid, or as a special case, zero when the dictionary is |
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* still empty. This special case is needed for single-call decoding to |
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* avoid writing a '\0' to the end of the destination buffer. |
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*/ |
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static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist) |
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{ |
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size_t offset = dict->pos - dist - 1; |
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if (dist >= dict->pos) |
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offset += dict->end; |
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return dict->full > 0 ? dict->buf[offset] : 0; |
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} |
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/* |
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* Put one byte into the dictionary. It is assumed that there is space for it. |
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*/ |
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static inline void dict_put(struct dictionary *dict, uint8_t byte) |
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{ |
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dict->buf[dict->pos++] = byte; |
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if (dict->full < dict->pos) |
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dict->full = dict->pos; |
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} |
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/* |
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* Repeat given number of bytes from the given distance. If the distance is |
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* invalid, false is returned. On success, true is returned and *len is |
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* updated to indicate how many bytes were left to be repeated. |
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*/ |
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static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist) |
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{ |
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size_t back; |
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uint32_t left; |
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if (dist >= dict->full || dist >= dict->size) |
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return false; |
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left = min_t(size_t, dict->limit - dict->pos, *len); |
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*len -= left; |
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back = dict->pos - dist - 1; |
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if (dist >= dict->pos) |
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back += dict->end; |
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do { |
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dict->buf[dict->pos++] = dict->buf[back++]; |
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if (back == dict->end) |
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back = 0; |
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} while (--left > 0); |
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if (dict->full < dict->pos) |
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dict->full = dict->pos; |
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return true; |
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} |
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/* Copy uncompressed data as is from input to dictionary and output buffers. */ |
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static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b, |
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uint32_t *left) |
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{ |
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size_t copy_size; |
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|
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while (*left > 0 && b->in_pos < b->in_size |
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&& b->out_pos < b->out_size) { |
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copy_size = min(b->in_size - b->in_pos, |
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b->out_size - b->out_pos); |
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if (copy_size > dict->end - dict->pos) |
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copy_size = dict->end - dict->pos; |
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if (copy_size > *left) |
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copy_size = *left; |
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*left -= copy_size; |
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memcpy(dict->buf + dict->pos, b->in + b->in_pos, copy_size); |
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dict->pos += copy_size; |
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|
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if (dict->full < dict->pos) |
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dict->full = dict->pos; |
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|
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if (DEC_IS_MULTI(dict->mode)) { |
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if (dict->pos == dict->end) |
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dict->pos = 0; |
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|
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memcpy(b->out + b->out_pos, b->in + b->in_pos, |
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copy_size); |
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} |
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dict->start = dict->pos; |
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|
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b->out_pos += copy_size; |
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b->in_pos += copy_size; |
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} |
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} |
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|
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/* |
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* Flush pending data from dictionary to b->out. It is assumed that there is |
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* enough space in b->out. This is guaranteed because caller uses dict_limit() |
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* before decoding data into the dictionary. |
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*/ |
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static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b) |
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{ |
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size_t copy_size = dict->pos - dict->start; |
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|
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if (DEC_IS_MULTI(dict->mode)) { |
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if (dict->pos == dict->end) |
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dict->pos = 0; |
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|
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memcpy(b->out + b->out_pos, dict->buf + dict->start, |
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copy_size); |
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} |
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dict->start = dict->pos; |
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b->out_pos += copy_size; |
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return copy_size; |
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} |
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|
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/***************** |
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* Range decoder * |
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*****************/ |
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|
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/* Reset the range decoder. */ |
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static void rc_reset(struct rc_dec *rc) |
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{ |
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rc->range = (uint32_t)-1; |
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rc->code = 0; |
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rc->init_bytes_left = RC_INIT_BYTES; |
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} |
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|
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/* |
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* Read the first five initial bytes into rc->code if they haven't been |
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* read already. (Yes, the first byte gets completely ignored.) |
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*/ |
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static bool rc_read_init(struct rc_dec *rc, struct xz_buf *b) |
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{ |
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while (rc->init_bytes_left > 0) { |
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if (b->in_pos == b->in_size) |
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return false; |
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|
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rc->code = (rc->code << 8) + b->in[b->in_pos++]; |
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--rc->init_bytes_left; |
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} |
|
|
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return true; |
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} |
|
|
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/* Return true if there may not be enough input for the next decoding loop. */ |
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static inline bool rc_limit_exceeded(const struct rc_dec *rc) |
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{ |
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return rc->in_pos > rc->in_limit; |
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} |
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|
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/* |
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* Return true if it is possible (from point of view of range decoder) that |
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* we have reached the end of the LZMA chunk. |
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*/ |
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static inline bool rc_is_finished(const struct rc_dec *rc) |
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{ |
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return rc->code == 0; |
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} |
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|
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/* Read the next input byte if needed. */ |
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static __always_inline void rc_normalize(struct rc_dec *rc) |
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{ |
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if (rc->range < RC_TOP_VALUE) { |
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rc->range <<= RC_SHIFT_BITS; |
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rc->code = (rc->code << RC_SHIFT_BITS) + rc->in[rc->in_pos++]; |
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} |
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} |
|
|
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/* |
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* Decode one bit. In some versions, this function has been splitted in three |
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* functions so that the compiler is supposed to be able to more easily avoid |
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* an extra branch. In this particular version of the LZMA decoder, this |
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* doesn't seem to be a good idea (tested with GCC 3.3.6, 3.4.6, and 4.3.3 |
|
* on x86). Using a non-splitted version results in nicer looking code too. |
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* |
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* NOTE: This must return an int. Do not make it return a bool or the speed |
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* of the code generated by GCC 3.x decreases 10-15 %. (GCC 4.3 doesn't care, |
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* and it generates 10-20 % faster code than GCC 3.x from this file anyway.) |
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*/ |
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static __always_inline int rc_bit(struct rc_dec *rc, uint16_t *prob) |
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{ |
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uint32_t bound; |
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int bit; |
|
|
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rc_normalize(rc); |
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bound = (rc->range >> RC_BIT_MODEL_TOTAL_BITS) * *prob; |
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if (rc->code < bound) { |
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rc->range = bound; |
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*prob += (RC_BIT_MODEL_TOTAL - *prob) >> RC_MOVE_BITS; |
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bit = 0; |
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} else { |
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rc->range -= bound; |
|
rc->code -= bound; |
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*prob -= *prob >> RC_MOVE_BITS; |
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bit = 1; |
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} |
|
|
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return bit; |
|
} |
|
|
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/* Decode a bittree starting from the most significant bit. */ |
|
static __always_inline uint32_t rc_bittree(struct rc_dec *rc, |
|
uint16_t *probs, uint32_t limit) |
|
{ |
|
uint32_t symbol = 1; |
|
|
|
do { |
|
if (rc_bit(rc, &probs[symbol])) |
|
symbol = (symbol << 1) + 1; |
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else |
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symbol <<= 1; |
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} while (symbol < limit); |
|
|
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return symbol; |
|
} |
|
|
|
/* Decode a bittree starting from the least significant bit. */ |
|
static __always_inline void rc_bittree_reverse(struct rc_dec *rc, |
|
uint16_t *probs, |
|
uint32_t *dest, uint32_t limit) |
|
{ |
|
uint32_t symbol = 1; |
|
uint32_t i = 0; |
|
|
|
do { |
|
if (rc_bit(rc, &probs[symbol])) { |
|
symbol = (symbol << 1) + 1; |
|
*dest += 1 << i; |
|
} else { |
|
symbol <<= 1; |
|
} |
|
} while (++i < limit); |
|
} |
|
|
|
/* Decode direct bits (fixed fifty-fifty probability) */ |
|
static inline void rc_direct(struct rc_dec *rc, uint32_t *dest, uint32_t limit) |
|
{ |
|
uint32_t mask; |
|
|
|
do { |
|
rc_normalize(rc); |
|
rc->range >>= 1; |
|
rc->code -= rc->range; |
|
mask = (uint32_t)0 - (rc->code >> 31); |
|
rc->code += rc->range & mask; |
|
*dest = (*dest << 1) + (mask + 1); |
|
} while (--limit > 0); |
|
} |
|
|
|
/******** |
|
* LZMA * |
|
********/ |
|
|
|
/* Get pointer to literal coder probability array. */ |
|
static uint16_t *lzma_literal_probs(struct xz_dec_lzma2 *s) |
|
{ |
|
uint32_t prev_byte = dict_get(&s->dict, 0); |
|
uint32_t low = prev_byte >> (8 - s->lzma.lc); |
|
uint32_t high = (s->dict.pos & s->lzma.literal_pos_mask) << s->lzma.lc; |
|
return s->lzma.literal[low + high]; |
|
} |
|
|
|
/* Decode a literal (one 8-bit byte) */ |
|
static void lzma_literal(struct xz_dec_lzma2 *s) |
|
{ |
|
uint16_t *probs; |
|
uint32_t symbol; |
|
uint32_t match_byte; |
|
uint32_t match_bit; |
|
uint32_t offset; |
|
uint32_t i; |
|
|
|
probs = lzma_literal_probs(s); |
|
|
|
if (lzma_state_is_literal(s->lzma.state)) { |
|
symbol = rc_bittree(&s->rc, probs, 0x100); |
|
} else { |
|
symbol = 1; |
|
match_byte = dict_get(&s->dict, s->lzma.rep0) << 1; |
|
offset = 0x100; |
|
|
|
do { |
|
match_bit = match_byte & offset; |
|
match_byte <<= 1; |
|
i = offset + match_bit + symbol; |
|
|
|
if (rc_bit(&s->rc, &probs[i])) { |
|
symbol = (symbol << 1) + 1; |
|
offset &= match_bit; |
|
} else { |
|
symbol <<= 1; |
|
offset &= ~match_bit; |
|
} |
|
} while (symbol < 0x100); |
|
} |
|
|
|
dict_put(&s->dict, (uint8_t)symbol); |
|
lzma_state_literal(&s->lzma.state); |
|
} |
|
|
|
/* Decode the length of the match into s->lzma.len. */ |
|
static void lzma_len(struct xz_dec_lzma2 *s, struct lzma_len_dec *l, |
|
uint32_t pos_state) |
|
{ |
|
uint16_t *probs; |
|
uint32_t limit; |
|
|
|
if (!rc_bit(&s->rc, &l->choice)) { |
|
probs = l->low[pos_state]; |
|
limit = LEN_LOW_SYMBOLS; |
|
s->lzma.len = MATCH_LEN_MIN; |
|
} else { |
|
if (!rc_bit(&s->rc, &l->choice2)) { |
|
probs = l->mid[pos_state]; |
|
limit = LEN_MID_SYMBOLS; |
|
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS; |
|
} else { |
|
probs = l->high; |
|
limit = LEN_HIGH_SYMBOLS; |
|
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS |
|
+ LEN_MID_SYMBOLS; |
|
} |
|
} |
|
|
|
s->lzma.len += rc_bittree(&s->rc, probs, limit) - limit; |
|
} |
|
|
|
/* Decode a match. The distance will be stored in s->lzma.rep0. */ |
|
static void lzma_match(struct xz_dec_lzma2 *s, uint32_t pos_state) |
|
{ |
|
uint16_t *probs; |
|
uint32_t dist_slot; |
|
uint32_t limit; |
|
|
|
lzma_state_match(&s->lzma.state); |
|
|
|
s->lzma.rep3 = s->lzma.rep2; |
|
s->lzma.rep2 = s->lzma.rep1; |
|
s->lzma.rep1 = s->lzma.rep0; |
|
|
|
lzma_len(s, &s->lzma.match_len_dec, pos_state); |
|
|
|
probs = s->lzma.dist_slot[lzma_get_dist_state(s->lzma.len)]; |
|
dist_slot = rc_bittree(&s->rc, probs, DIST_SLOTS) - DIST_SLOTS; |
|
|
|
if (dist_slot < DIST_MODEL_START) { |
|
s->lzma.rep0 = dist_slot; |
|
} else { |
|
limit = (dist_slot >> 1) - 1; |
|
s->lzma.rep0 = 2 + (dist_slot & 1); |
|
|
|
if (dist_slot < DIST_MODEL_END) { |
|
s->lzma.rep0 <<= limit; |
|
probs = s->lzma.dist_special + s->lzma.rep0 |
|
- dist_slot - 1; |
|
rc_bittree_reverse(&s->rc, probs, |
|
&s->lzma.rep0, limit); |
|
} else { |
|
rc_direct(&s->rc, &s->lzma.rep0, limit - ALIGN_BITS); |
|
s->lzma.rep0 <<= ALIGN_BITS; |
|
rc_bittree_reverse(&s->rc, s->lzma.dist_align, |
|
&s->lzma.rep0, ALIGN_BITS); |
|
} |
|
} |
|
} |
|
|
|
/* |
|
* Decode a repeated match. The distance is one of the four most recently |
|
* seen matches. The distance will be stored in s->lzma.rep0. |
|
*/ |
|
static void lzma_rep_match(struct xz_dec_lzma2 *s, uint32_t pos_state) |
|
{ |
|
uint32_t tmp; |
|
|
|
if (!rc_bit(&s->rc, &s->lzma.is_rep0[s->lzma.state])) { |
|
if (!rc_bit(&s->rc, &s->lzma.is_rep0_long[ |
|
s->lzma.state][pos_state])) { |
|
lzma_state_short_rep(&s->lzma.state); |
|
s->lzma.len = 1; |
|
return; |
|
} |
|
} else { |
|
if (!rc_bit(&s->rc, &s->lzma.is_rep1[s->lzma.state])) { |
|
tmp = s->lzma.rep1; |
|
} else { |
|
if (!rc_bit(&s->rc, &s->lzma.is_rep2[s->lzma.state])) { |
|
tmp = s->lzma.rep2; |
|
} else { |
|
tmp = s->lzma.rep3; |
|
s->lzma.rep3 = s->lzma.rep2; |
|
} |
|
|
|
s->lzma.rep2 = s->lzma.rep1; |
|
} |
|
|
|
s->lzma.rep1 = s->lzma.rep0; |
|
s->lzma.rep0 = tmp; |
|
} |
|
|
|
lzma_state_long_rep(&s->lzma.state); |
|
lzma_len(s, &s->lzma.rep_len_dec, pos_state); |
|
} |
|
|
|
/* LZMA decoder core */ |
|
static bool lzma_main(struct xz_dec_lzma2 *s) |
|
{ |
|
uint32_t pos_state; |
|
|
|
/* |
|
* If the dictionary was reached during the previous call, try to |
|
* finish the possibly pending repeat in the dictionary. |
|
*/ |
|
if (dict_has_space(&s->dict) && s->lzma.len > 0) |
|
dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0); |
|
|
|
/* |
|
* Decode more LZMA symbols. One iteration may consume up to |
|
* LZMA_IN_REQUIRED - 1 bytes. |
|
*/ |
|
while (dict_has_space(&s->dict) && !rc_limit_exceeded(&s->rc)) { |
|
pos_state = s->dict.pos & s->lzma.pos_mask; |
|
|
|
if (!rc_bit(&s->rc, &s->lzma.is_match[ |
|
s->lzma.state][pos_state])) { |
|
lzma_literal(s); |
|
} else { |
|
if (rc_bit(&s->rc, &s->lzma.is_rep[s->lzma.state])) |
|
lzma_rep_match(s, pos_state); |
|
else |
|
lzma_match(s, pos_state); |
|
|
|
if (!dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0)) |
|
return false; |
|
} |
|
} |
|
|
|
/* |
|
* Having the range decoder always normalized when we are outside |
|
* this function makes it easier to correctly handle end of the chunk. |
|
*/ |
|
rc_normalize(&s->rc); |
|
|
|
return true; |
|
} |
|
|
|
/* |
|
* Reset the LZMA decoder and range decoder state. Dictionary is nore reset |
|
* here, because LZMA state may be reset without resetting the dictionary. |
|
*/ |
|
static void lzma_reset(struct xz_dec_lzma2 *s) |
|
{ |
|
uint16_t *probs; |
|
size_t i; |
|
|
|
s->lzma.state = STATE_LIT_LIT; |
|
s->lzma.rep0 = 0; |
|
s->lzma.rep1 = 0; |
|
s->lzma.rep2 = 0; |
|
s->lzma.rep3 = 0; |
|
|
|
/* |
|
* All probabilities are initialized to the same value. This hack |
|
* makes the code smaller by avoiding a separate loop for each |
|
* probability array. |
|
* |
|
* This could be optimized so that only that part of literal |
|
* probabilities that are actually required. In the common case |
|
* we would write 12 KiB less. |
|
*/ |
|
probs = s->lzma.is_match[0]; |
|
for (i = 0; i < PROBS_TOTAL; ++i) |
|
probs[i] = RC_BIT_MODEL_TOTAL / 2; |
|
|
|
rc_reset(&s->rc); |
|
} |
|
|
|
/* |
|
* Decode and validate LZMA properties (lc/lp/pb) and calculate the bit masks |
|
* from the decoded lp and pb values. On success, the LZMA decoder state is |
|
* reset and true is returned. |
|
*/ |
|
static bool lzma_props(struct xz_dec_lzma2 *s, uint8_t props) |
|
{ |
|
if (props > (4 * 5 + 4) * 9 + 8) |
|
return false; |
|
|
|
s->lzma.pos_mask = 0; |
|
while (props >= 9 * 5) { |
|
props -= 9 * 5; |
|
++s->lzma.pos_mask; |
|
} |
|
|
|
s->lzma.pos_mask = (1 << s->lzma.pos_mask) - 1; |
|
|
|
s->lzma.literal_pos_mask = 0; |
|
while (props >= 9) { |
|
props -= 9; |
|
++s->lzma.literal_pos_mask; |
|
} |
|
|
|
s->lzma.lc = props; |
|
|
|
if (s->lzma.lc + s->lzma.literal_pos_mask > 4) |
|
return false; |
|
|
|
s->lzma.literal_pos_mask = (1 << s->lzma.literal_pos_mask) - 1; |
|
|
|
lzma_reset(s); |
|
|
|
return true; |
|
} |
|
|
|
/********* |
|
* LZMA2 * |
|
*********/ |
|
|
|
/* |
|
* The LZMA decoder assumes that if the input limit (s->rc.in_limit) hasn't |
|
* been exceeded, it is safe to read up to LZMA_IN_REQUIRED bytes. This |
|
* wrapper function takes care of making the LZMA decoder's assumption safe. |
|
* |
|
* As long as there is plenty of input left to be decoded in the current LZMA |
|
* chunk, we decode directly from the caller-supplied input buffer until |
|
* there's LZMA_IN_REQUIRED bytes left. Those remaining bytes are copied into |
|
* s->temp.buf, which (hopefully) gets filled on the next call to this |
|
* function. We decode a few bytes from the temporary buffer so that we can |
|
* continue decoding from the caller-supplied input buffer again. |
|
*/ |
|
static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b) |
|
{ |
|
size_t in_avail; |
|
uint32_t tmp; |
|
|
|
in_avail = b->in_size - b->in_pos; |
|
if (s->temp.size > 0 || s->lzma2.compressed == 0) { |
|
tmp = 2 * LZMA_IN_REQUIRED - s->temp.size; |
|
if (tmp > s->lzma2.compressed - s->temp.size) |
|
tmp = s->lzma2.compressed - s->temp.size; |
|
if (tmp > in_avail) |
|
tmp = in_avail; |
|
|
|
memcpy(s->temp.buf + s->temp.size, b->in + b->in_pos, tmp); |
|
|
|
if (s->temp.size + tmp == s->lzma2.compressed) { |
|
memzero(s->temp.buf + s->temp.size + tmp, |
|
sizeof(s->temp.buf) |
|
- s->temp.size - tmp); |
|
s->rc.in_limit = s->temp.size + tmp; |
|
} else if (s->temp.size + tmp < LZMA_IN_REQUIRED) { |
|
s->temp.size += tmp; |
|
b->in_pos += tmp; |
|
return true; |
|
} else { |
|
s->rc.in_limit = s->temp.size + tmp - LZMA_IN_REQUIRED; |
|
} |
|
|
|
s->rc.in = s->temp.buf; |
|
s->rc.in_pos = 0; |
|
|
|
if (!lzma_main(s) || s->rc.in_pos > s->temp.size + tmp) |
|
return false; |
|
|
|
s->lzma2.compressed -= s->rc.in_pos; |
|
|
|
if (s->rc.in_pos < s->temp.size) { |
|
s->temp.size -= s->rc.in_pos; |
|
memmove(s->temp.buf, s->temp.buf + s->rc.in_pos, |
|
s->temp.size); |
|
return true; |
|
} |
|
|
|
b->in_pos += s->rc.in_pos - s->temp.size; |
|
s->temp.size = 0; |
|
} |
|
|
|
in_avail = b->in_size - b->in_pos; |
|
if (in_avail >= LZMA_IN_REQUIRED) { |
|
s->rc.in = b->in; |
|
s->rc.in_pos = b->in_pos; |
|
|
|
if (in_avail >= s->lzma2.compressed + LZMA_IN_REQUIRED) |
|
s->rc.in_limit = b->in_pos + s->lzma2.compressed; |
|
else |
|
s->rc.in_limit = b->in_size - LZMA_IN_REQUIRED; |
|
|
|
if (!lzma_main(s)) |
|
return false; |
|
|
|
in_avail = s->rc.in_pos - b->in_pos; |
|
if (in_avail > s->lzma2.compressed) |
|
return false; |
|
|
|
s->lzma2.compressed -= in_avail; |
|
b->in_pos = s->rc.in_pos; |
|
} |
|
|
|
in_avail = b->in_size - b->in_pos; |
|
if (in_avail < LZMA_IN_REQUIRED) { |
|
if (in_avail > s->lzma2.compressed) |
|
in_avail = s->lzma2.compressed; |
|
|
|
memcpy(s->temp.buf, b->in + b->in_pos, in_avail); |
|
s->temp.size = in_avail; |
|
b->in_pos += in_avail; |
|
} |
|
|
|
return true; |
|
} |
|
|
|
/* |
|
* Take care of the LZMA2 control layer, and forward the job of actual LZMA |
|
* decoding or copying of uncompressed chunks to other functions. |
|
*/ |
|
XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, |
|
struct xz_buf *b) |
|
{ |
|
uint32_t tmp; |
|
|
|
while (b->in_pos < b->in_size || s->lzma2.sequence == SEQ_LZMA_RUN) { |
|
switch (s->lzma2.sequence) { |
|
case SEQ_CONTROL: |
|
/* |
|
* LZMA2 control byte |
|
* |
|
* Exact values: |
|
* 0x00 End marker |
|
* 0x01 Dictionary reset followed by |
|
* an uncompressed chunk |
|
* 0x02 Uncompressed chunk (no dictionary reset) |
|
* |
|
* Highest three bits (s->control & 0xE0): |
|
* 0xE0 Dictionary reset, new properties and state |
|
* reset, followed by LZMA compressed chunk |
|
* 0xC0 New properties and state reset, followed |
|
* by LZMA compressed chunk (no dictionary |
|
* reset) |
|
* 0xA0 State reset using old properties, |
|
* followed by LZMA compressed chunk (no |
|
* dictionary reset) |
|
* 0x80 LZMA chunk (no dictionary or state reset) |
|
* |
|
* For LZMA compressed chunks, the lowest five bits |
|
* (s->control & 1F) are the highest bits of the |
|
* uncompressed size (bits 16-20). |
|
* |
|
* A new LZMA2 stream must begin with a dictionary |
|
* reset. The first LZMA chunk must set new |
|
* properties and reset the LZMA state. |
|
* |
|
* Values that don't match anything described above |
|
* are invalid and we return XZ_DATA_ERROR. |
|
*/ |
|
tmp = b->in[b->in_pos++]; |
|
|
|
if (tmp == 0x00) |
|
return XZ_STREAM_END; |
|
|
|
if (tmp >= 0xE0 || tmp == 0x01) { |
|
s->lzma2.need_props = true; |
|
s->lzma2.need_dict_reset = false; |
|
dict_reset(&s->dict, b); |
|
} else if (s->lzma2.need_dict_reset) { |
|
return XZ_DATA_ERROR; |
|
} |
|
|
|
if (tmp >= 0x80) { |
|
s->lzma2.uncompressed = (tmp & 0x1F) << 16; |
|
s->lzma2.sequence = SEQ_UNCOMPRESSED_1; |
|
|
|
if (tmp >= 0xC0) { |
|
/* |
|
* When there are new properties, |
|
* state reset is done at |
|
* SEQ_PROPERTIES. |
|
*/ |
|
s->lzma2.need_props = false; |
|
s->lzma2.next_sequence |
|
= SEQ_PROPERTIES; |
|
|
|
} else if (s->lzma2.need_props) { |
|
return XZ_DATA_ERROR; |
|
|
|
} else { |
|
s->lzma2.next_sequence |
|
= SEQ_LZMA_PREPARE; |
|
if (tmp >= 0xA0) |
|
lzma_reset(s); |
|
} |
|
} else { |
|
if (tmp > 0x02) |
|
return XZ_DATA_ERROR; |
|
|
|
s->lzma2.sequence = SEQ_COMPRESSED_0; |
|
s->lzma2.next_sequence = SEQ_COPY; |
|
} |
|
|
|
break; |
|
|
|
case SEQ_UNCOMPRESSED_1: |
|
s->lzma2.uncompressed |
|
+= (uint32_t)b->in[b->in_pos++] << 8; |
|
s->lzma2.sequence = SEQ_UNCOMPRESSED_2; |
|
break; |
|
|
|
case SEQ_UNCOMPRESSED_2: |
|
s->lzma2.uncompressed |
|
+= (uint32_t)b->in[b->in_pos++] + 1; |
|
s->lzma2.sequence = SEQ_COMPRESSED_0; |
|
break; |
|
|
|
case SEQ_COMPRESSED_0: |
|
s->lzma2.compressed |
|
= (uint32_t)b->in[b->in_pos++] << 8; |
|
s->lzma2.sequence = SEQ_COMPRESSED_1; |
|
break; |
|
|
|
case SEQ_COMPRESSED_1: |
|
s->lzma2.compressed |
|
+= (uint32_t)b->in[b->in_pos++] + 1; |
|
s->lzma2.sequence = s->lzma2.next_sequence; |
|
break; |
|
|
|
case SEQ_PROPERTIES: |
|
if (!lzma_props(s, b->in[b->in_pos++])) |
|
return XZ_DATA_ERROR; |
|
|
|
s->lzma2.sequence = SEQ_LZMA_PREPARE; |
|
|
|
fallthrough; |
|
|
|
case SEQ_LZMA_PREPARE: |
|
if (s->lzma2.compressed < RC_INIT_BYTES) |
|
return XZ_DATA_ERROR; |
|
|
|
if (!rc_read_init(&s->rc, b)) |
|
return XZ_OK; |
|
|
|
s->lzma2.compressed -= RC_INIT_BYTES; |
|
s->lzma2.sequence = SEQ_LZMA_RUN; |
|
|
|
fallthrough; |
|
|
|
case SEQ_LZMA_RUN: |
|
/* |
|
* Set dictionary limit to indicate how much we want |
|
* to be encoded at maximum. Decode new data into the |
|
* dictionary. Flush the new data from dictionary to |
|
* b->out. Check if we finished decoding this chunk. |
|
* In case the dictionary got full but we didn't fill |
|
* the output buffer yet, we may run this loop |
|
* multiple times without changing s->lzma2.sequence. |
|
*/ |
|
dict_limit(&s->dict, min_t(size_t, |
|
b->out_size - b->out_pos, |
|
s->lzma2.uncompressed)); |
|
if (!lzma2_lzma(s, b)) |
|
return XZ_DATA_ERROR; |
|
|
|
s->lzma2.uncompressed -= dict_flush(&s->dict, b); |
|
|
|
if (s->lzma2.uncompressed == 0) { |
|
if (s->lzma2.compressed > 0 || s->lzma.len > 0 |
|
|| !rc_is_finished(&s->rc)) |
|
return XZ_DATA_ERROR; |
|
|
|
rc_reset(&s->rc); |
|
s->lzma2.sequence = SEQ_CONTROL; |
|
|
|
} else if (b->out_pos == b->out_size |
|
|| (b->in_pos == b->in_size |
|
&& s->temp.size |
|
< s->lzma2.compressed)) { |
|
return XZ_OK; |
|
} |
|
|
|
break; |
|
|
|
case SEQ_COPY: |
|
dict_uncompressed(&s->dict, b, &s->lzma2.compressed); |
|
if (s->lzma2.compressed > 0) |
|
return XZ_OK; |
|
|
|
s->lzma2.sequence = SEQ_CONTROL; |
|
break; |
|
} |
|
} |
|
|
|
return XZ_OK; |
|
} |
|
|
|
XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode, |
|
uint32_t dict_max) |
|
{ |
|
struct xz_dec_lzma2 *s = kmalloc(sizeof(*s), GFP_KERNEL); |
|
if (s == NULL) |
|
return NULL; |
|
|
|
s->dict.mode = mode; |
|
s->dict.size_max = dict_max; |
|
|
|
if (DEC_IS_PREALLOC(mode)) { |
|
s->dict.buf = vmalloc(dict_max); |
|
if (s->dict.buf == NULL) { |
|
kfree(s); |
|
return NULL; |
|
} |
|
} else if (DEC_IS_DYNALLOC(mode)) { |
|
s->dict.buf = NULL; |
|
s->dict.allocated = 0; |
|
} |
|
|
|
return s; |
|
} |
|
|
|
XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props) |
|
{ |
|
/* This limits dictionary size to 3 GiB to keep parsing simpler. */ |
|
if (props > 39) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
s->dict.size = 2 + (props & 1); |
|
s->dict.size <<= (props >> 1) + 11; |
|
|
|
if (DEC_IS_MULTI(s->dict.mode)) { |
|
if (s->dict.size > s->dict.size_max) |
|
return XZ_MEMLIMIT_ERROR; |
|
|
|
s->dict.end = s->dict.size; |
|
|
|
if (DEC_IS_DYNALLOC(s->dict.mode)) { |
|
if (s->dict.allocated < s->dict.size) { |
|
s->dict.allocated = s->dict.size; |
|
vfree(s->dict.buf); |
|
s->dict.buf = vmalloc(s->dict.size); |
|
if (s->dict.buf == NULL) { |
|
s->dict.allocated = 0; |
|
return XZ_MEM_ERROR; |
|
} |
|
} |
|
} |
|
} |
|
|
|
s->lzma.len = 0; |
|
|
|
s->lzma2.sequence = SEQ_CONTROL; |
|
s->lzma2.need_dict_reset = true; |
|
|
|
s->temp.size = 0; |
|
|
|
return XZ_OK; |
|
} |
|
|
|
XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s) |
|
{ |
|
if (DEC_IS_MULTI(s->dict.mode)) |
|
vfree(s->dict.buf); |
|
|
|
kfree(s); |
|
}
|
|
|