c3fff877e — BusyBox

Subject

unlzma: if !LZMA_FAST, save ~200 more bytes (Pascal Bellard )

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

archival/libunarchive/decompress_unlzma.c +36 -24

archival/libunarchive/decompress_unlzma.c+36 -24

@@ -282,14 +282,16 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	while (global_pos + buffer_pos < header.dst_size) {
	int pos_state = (buffer_pos + global_pos) & pos_state_mask;

-	prob =
-	p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
+	prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
	if (rc_is_bit_0(rc, prob)) {
	mi = 1;
	rc_update_bit_0(rc, prob);
-	prob = (p + LZMA_LITERAL + (LZMA_LIT_SIZE
-	* ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
-	+ (previous_byte >> (8 - lc)))));
+	prob = (p + LZMA_LITERAL
+	+ (LZMA_LIT_SIZE * ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
+	+ (previous_byte >> (8 - lc))
+	)
+	)
+	);

	if (state >= LZMA_NUM_LIT_STATES) {
	int match_byte;
@@ -317,8 +319,15 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	prob_lit = prob + mi;
	rc_get_bit(rc, prob_lit, &mi);
	}
-	previous_byte = (uint8_t) mi;

+	state -= 3;
+	if (state < 4-3)
+	state = 0;
+	if (state >= 10-3)
+	state -= 6-3;
+
+	previous_byte = (uint8_t) mi;
+	#if ENABLE_FEATURE_LZMA_FAST
	buffer[buffer_pos++] = previous_byte;
	if (buffer_pos == header.dict_size) {
	buffer_pos = 0;
@@ -327,12 +336,10 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	goto bad;
	USE_DESKTOP(total_written += header.dict_size;)
	}
-	if (state < 4)
-	state = 0;
-	else if (state < 10)
-	state -= 3;
-	else
-	state -= 6;
+	#else
+	len = 1;
+	goto one_byte;
+	#endif
	} else {
	int offset;
	uint16_t *prob_len;
@@ -352,11 +359,14 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);
	prob = (p + LZMA_IS_REP_0_LONG
-	+ (state << LZMA_NUM_POS_BITS_MAX) + pos_state);
+	+ (state << LZMA_NUM_POS_BITS_MAX)
+	+ pos_state
+	);
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);

	state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
+	#if ENABLE_FEATURE_LZMA_FAST
	pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
@@ -370,6 +380,10 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	USE_DESKTOP(total_written += header.dict_size;)
	}
	continue;
+	#else
+	len = 1;
+	goto string;
+	#endif
	} else {
	rc_update_bit_1(rc, prob);
	}
@@ -405,7 +419,7 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	if (rc_is_bit_0(rc, prob_len)) {
	rc_update_bit_0(rc, prob_len);
	prob_len = (prob + LZMA_LEN_LOW
-	+ (pos_state << LZMA_LEN_NUM_LOW_BITS));
+	+ (pos_state << LZMA_LEN_NUM_LOW_BITS));
	offset = 0;
	num_bits = LZMA_LEN_NUM_LOW_BITS;
	} else {
@@ -414,14 +428,14 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	if (rc_is_bit_0(rc, prob_len)) {
	rc_update_bit_0(rc, prob_len);
	prob_len = (prob + LZMA_LEN_MID
-	+ (pos_state << LZMA_LEN_NUM_MID_BITS));
+	+ (pos_state << LZMA_LEN_NUM_MID_BITS));
	offset = 1 << LZMA_LEN_NUM_LOW_BITS;
	num_bits = LZMA_LEN_NUM_MID_BITS;
	} else {
	rc_update_bit_1(rc, prob_len);
	prob_len = prob + LZMA_LEN_HIGH;
	offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
-	+ (1 << LZMA_LEN_NUM_MID_BITS));
+	+ (1 << LZMA_LEN_NUM_MID_BITS));
	num_bits = LZMA_LEN_NUM_HIGH_BITS;
	}
	}
@@ -432,12 +446,10 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	int pos_slot;

	state += LZMA_NUM_LIT_STATES;
-	prob =
-	p + LZMA_POS_SLOT +
-	((len <
-	LZMA_NUM_LEN_TO_POS_STATES ? len :
-	LZMA_NUM_LEN_TO_POS_STATES - 1)
-	<< LZMA_NUM_POS_SLOT_BITS);
+	prob = p + LZMA_POS_SLOT +
+	((len < LZMA_NUM_LEN_TO_POS_STATES ? len :
+	LZMA_NUM_LEN_TO_POS_STATES - 1)
+	<< LZMA_NUM_POS_SLOT_BITS);
	rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
	&pos_slot);
	if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
@@ -468,12 +480,13 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	}

	len += LZMA_MATCH_MIN_LEN;
-
+	SKIP_FEATURE_LZMA_FAST(string:)
	do {
	pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	previous_byte = buffer[pos];
+	SKIP_FEATURE_LZMA_FAST(one_byte:)
	buffer[buffer_pos++] = previous_byte;
	if (buffer_pos == header.dict_size) {
	buffer_pos = 0;
@@ -487,7 +500,6 @@ unpack_lzma_stream(int src_fd, int dst_fd)
	}
	}

-
	if (full_write(dst_fd, buffer, buffer_pos) != buffer_pos) {
	bad:
	rc_free(rc);