4 * Declarations shared between LZMS compression and decompression.
10 #include "wimlib/compiler.h"
11 #include "wimlib/lzms_constants.h"
12 #include "wimlib/types.h"
14 /* Offset slot tables */
15 extern const u32 lzms_offset_slot_base[LZMS_MAX_NUM_OFFSET_SYMS + 1];
16 extern const u8 lzms_extra_offset_bits[LZMS_MAX_NUM_OFFSET_SYMS];
18 /* Length slot tables */
19 extern const u32 lzms_length_slot_base[LZMS_NUM_LENGTH_SYMS + 1];
20 extern const u8 lzms_extra_length_bits[LZMS_NUM_LENGTH_SYMS];
23 lzms_get_slot(u32 value, const u32 slot_base_tab[], unsigned num_slots);
25 /* Return the offset slot for the specified offset */
26 static forceinline unsigned
27 lzms_get_offset_slot(u32 offset)
29 return lzms_get_slot(offset, lzms_offset_slot_base, LZMS_MAX_NUM_OFFSET_SYMS);
32 /* Return the length slot for the specified length */
33 static forceinline unsigned
34 lzms_get_length_slot(u32 length)
36 return lzms_get_slot(length, lzms_length_slot_base, LZMS_NUM_LENGTH_SYMS);
40 lzms_get_num_offset_slots(size_t uncompressed_size);
43 /* Probability entry for use by the range coder when in a specific state */
44 struct lzms_probability_entry {
46 /* The number of zeroes in the most recent LZMS_PROBABILITY_DENOMINATOR
47 * bits that have been decoded or encoded using this probability entry.
48 * The probability of the next bit being 0 is this value over
49 * LZMS_PROBABILITY_DENOMINATOR, except for the cases where this would
50 * imply 0% or 100% probability. */
51 u32 num_recent_zero_bits;
53 /* The most recent LZMS_PROBABILITY_DENOMINATOR bits that have been
54 * coded using this probability entry. The bits are ordered such that
55 * low order is newest and high order is oldest. */
59 struct lzms_probabilites {
60 struct lzms_probability_entry main[LZMS_NUM_MAIN_PROBS];
61 struct lzms_probability_entry match[LZMS_NUM_MATCH_PROBS];
62 struct lzms_probability_entry lz[LZMS_NUM_LZ_PROBS];
63 struct lzms_probability_entry delta[LZMS_NUM_DELTA_PROBS];
64 struct lzms_probability_entry lz_rep[LZMS_NUM_LZ_REP_DECISIONS]
65 [LZMS_NUM_LZ_REP_PROBS];
66 struct lzms_probability_entry delta_rep[LZMS_NUM_DELTA_REP_DECISIONS]
67 [LZMS_NUM_DELTA_REP_PROBS];
71 lzms_init_probabilities(struct lzms_probabilites *probs);
73 /* Given a decoded or encoded bit, update the probability entry. */
74 static forceinline void
75 lzms_update_probability_entry(struct lzms_probability_entry *entry, int bit)
77 STATIC_ASSERT(LZMS_PROBABILITY_DENOMINATOR == sizeof(entry->recent_bits) * 8);
80 if (__builtin_constant_p(bit)) {
81 /* Optimized implementation for x86_64 using carry flag */
83 __asm__("shlq %[recent_bits] \n"
84 "adcl $0xffffffff, %[num_recent_zero_bits] \n"
85 "orq $0x1, %[recent_bits] \n"
86 : [recent_bits] "+r" (entry->recent_bits),
87 [num_recent_zero_bits] "+mr" (entry->num_recent_zero_bits)
91 __asm__("shlq %[recent_bits] \n"
92 "adcl $0x0, %[num_recent_zero_bits] \n"
93 : [recent_bits] "+m" (entry->recent_bits),
94 [num_recent_zero_bits] "+mr" (entry->num_recent_zero_bits)
101 s32 delta_zero_bits = (s32)(entry->recent_bits >>
102 (LZMS_PROBABILITY_DENOMINATOR - 1)) - bit;
104 entry->num_recent_zero_bits += delta_zero_bits;
105 entry->recent_bits = (entry->recent_bits << 1) | bit;
109 /* Given a probability entry, return the chance out of
110 * LZMS_PROBABILITY_DENOMINATOR that the next decoded bit will be a 0. */
111 static forceinline u32
112 lzms_get_probability(const struct lzms_probability_entry *prob_entry)
114 u32 prob = prob_entry->num_recent_zero_bits;
116 /* 0% and 100% probabilities aren't allowed. */
122 prob += (u32)(prob - 1) >> 31;
125 * if (prob == LZMS_PROBABILITY_DENOMINATOR)
128 prob -= (prob >> LZMS_PROBABILITY_BITS);
134 lzms_init_symbol_frequencies(u32 freqs[], unsigned num_syms);
137 lzms_dilute_symbol_frequencies(u32 freqs[], unsigned num_syms);
139 /* Pre/post-processing */
141 lzms_x86_filter(u8 data[], s32 size, s32 last_target_usages[], bool undo);
143 #endif /* _LZMS_COMMON_H */