1 /* SPDX-License-Identifier: 0BSD */
7  *          Igor Pavlov <https://7-zip.org/>
22  * Maximum number of position states. A position state is the lowest pb
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.
59 /* The lowest 7 states indicate that the previous state was a literal. */
63 static inline void lzma_state_literal(enum lzma_state *state)  in lzma_state_literal()  argument
65 	if (*state <= STATE_SHORTREP_LIT_LIT)  in lzma_state_literal()
66 		*state = STATE_LIT_LIT;  in lzma_state_literal()
67 	else if (*state <= STATE_LIT_SHORTREP)  in lzma_state_literal()
68 		*state -= 3;  in lzma_state_literal()
70 		*state -= 6;  in lzma_state_literal()
74 static inline void lzma_state_match(enum lzma_state *state)  in lzma_state_match()  argument
76 	*state = *state < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH;  in lzma_state_match()
79 /* Indicate that the latest state was a long repeated match. */
80 static inline void lzma_state_long_rep(enum lzma_state *state)  in lzma_state_long_rep()  argument
82 	*state = *state < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP;  in lzma_state_long_rep()
86 static inline void lzma_state_short_rep(enum lzma_state *state)  in lzma_state_short_rep()  argument
88 	*state = *state < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP;  in lzma_state_short_rep()
92 static inline bool lzma_state_is_literal(enum lzma_state state)  in lzma_state_is_literal()  argument
94 	return state < LIT_STATES;  in lzma_state_is_literal()
97 /* Each literal coder is divided in three sections:
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
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.
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.
191 #define ALIGN_MASK (ALIGN_SIZE - 1)
198  * distances tends to take less space than re-encoding the actual