lib/xz/xz_lzma2.h

1 /* SPDX-License-Identifier: 0BSD */
7  *          Igor Pavlov <https://7-zip.org/>
33  *  - Literal: One 8-bit byte
34  *  - Match: Repeat a chunk of data at some distance
35  *  - Long repeat: Multi-byte match at a recently seen distance
36  *  - Short repeat: One-byte repeat at a recently seen distance
39  * either short or long repeated match, and NONLIT means any non-literal.
68 		*state -= 3;  in lzma_state_literal()
70 		*state -= 6;  in lzma_state_literal()
98  *   - 0x001-0x0FF: Without match byte
99  *   - 0x101-0x1FF: With match byte; match bit is 0
100  *   - 0x201-0x2FF: With match byte; match bit is 1
105 #define LITERAL_CODER_SIZE 0x300
116  *  2-9      4 = Choice=0 + 3 bits
117  * 10-17     5 = Choice=1 + Choice2=0 + 3 bits
118  * 18-273   10 = Choice=1 + Choice2=1 + 8 bits
132 #define MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1)
149 			? len - MATCH_LEN_MIN : DIST_STATES - 1;  in lzma_get_dist_state()
153  * The highest two bits of a 32-bit match distance are encoded using six bits.
154  * This six-bit value is called a distance slot. This way encoding a 32-bit
155  * value takes 6-36 bits, larger values taking more bits.
160 /* Match distances up to 127 are fully encoded using probabilities. Since
162  * the distances 0-3 don't need any additional bits to encode, since the
170  * Match distances greater than 127 are encoded in three pieces:
171  *   - distance slot: the highest two bits
172  *   - direct bits: 2-26 bits below the highest two bits
173  *   - alignment bits: four lowest bits
177  * The distance slot value of 14 is for distances 128-191.
181 /* Distance slots that indicate a distance <= 127. */
186  * For match distances greater than 127, only the highest two bits and the
191 #define ALIGN_MASK (ALIGN_SIZE - 1)
198  * distances tends to take less space than re-encoding the actual