[git commit master] Revert "unlzma: speedup, by Pascal Bellard (pascal.bellard AT ads-lu.com)"
Denys Vlasenko
vda.linux at googlemail.com
Mon Sep 7 11:19:17 UTC 2009
commit: http://git.busybox.net/busybox/commit/?id=3de3f57c6d0200b49a5e31e80421e36272035e15
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
https://bugs.busybox.net/show_bug.cgi?id=599
This reverts commit 9ac3dc764a78b51fe8fdcd1b4682850de098733b.
---
archival/Config.in | 4 +-
archival/libunarchive/decompress_unlzma.c | 154 ++++++++++++++++++-----------
2 files changed, 98 insertions(+), 60 deletions(-)
diff --git a/archival/Config.in b/archival/Config.in
index cae7f20..71b9538 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -298,8 +298,8 @@ config FEATURE_LZMA_FAST
default n
depends on UNLZMA
help
- This option reduces decompression time by about 25% at the cost of
- a 1K bigger binary.
+ This option reduces decompression time by about 33% at the cost of
+ a 2K bigger binary.
config UNZIP
bool "unzip"
diff --git a/archival/libunarchive/decompress_unlzma.c b/archival/libunarchive/decompress_unlzma.c
index 68085d6..33e5cd6 100644
--- a/archival/libunarchive/decompress_unlzma.c
+++ b/archival/libunarchive/decompress_unlzma.c
@@ -8,15 +8,14 @@
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
+
#include "libbb.h"
#include "unarchive.h"
#if ENABLE_FEATURE_LZMA_FAST
# define speed_inline ALWAYS_INLINE
-# define size_inline
#else
# define speed_inline
-# define size_inline ALWAYS_INLINE
#endif
@@ -45,8 +44,8 @@ typedef struct {
#define RC_MODEL_TOTAL_BITS 11
-/* Called twice: once at startup (LZMA_FAST only) and once in rc_normalize() */
-static size_inline void rc_read(rc_t *rc)
+/* Called twice: once at startup and once in rc_normalize() */
+static void rc_read(rc_t *rc)
{
int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
if (buffer_size <= 0)
@@ -55,17 +54,8 @@ static size_inline void rc_read(rc_t *rc)
rc->buffer_end = RC_BUFFER + buffer_size;
}
-/* Called twice, but one callsite is in speed_inline'd rc_is_bit_1() */
-static void rc_do_normalize(rc_t *rc)
-{
- if (rc->ptr >= rc->buffer_end)
- rc_read(rc);
- rc->range <<= 8;
- rc->code = (rc->code << 8) | *rc->ptr++;
-}
-
/* Called once */
-static ALWAYS_INLINE rc_t* rc_init(int fd) /*, int buffer_size) */
+static rc_t* rc_init(int fd) /*, int buffer_size) */
{
int i;
rc_t *rc;
@@ -73,18 +63,17 @@ static ALWAYS_INLINE rc_t* rc_init(int fd) /*, int buffer_size) */
rc = xmalloc(sizeof(*rc) + RC_BUFFER_SIZE);
rc->fd = fd;
+ /* rc->buffer_size = buffer_size; */
+ rc->buffer_end = RC_BUFFER + RC_BUFFER_SIZE;
rc->ptr = rc->buffer_end;
+ rc->code = 0;
+ rc->range = 0xFFFFFFFF;
for (i = 0; i < 5; i++) {
-#if ENABLE_FEATURE_LZMA_FAST
if (rc->ptr >= rc->buffer_end)
rc_read(rc);
rc->code = (rc->code << 8) | *rc->ptr++;
-#else
- rc_do_normalize(rc);
-#endif
}
- rc->range = 0xFFFFFFFF;
return rc;
}
@@ -94,6 +83,14 @@ static ALWAYS_INLINE void rc_free(rc_t *rc)
free(rc);
}
+/* Called twice, but one callsite is in speed_inline'd rc_is_bit_0_helper() */
+static void rc_do_normalize(rc_t *rc)
+{
+ if (rc->ptr >= rc->buffer_end)
+ rc_read(rc);
+ rc->range <<= 8;
+ rc->code = (rc->code << 8) | *rc->ptr++;
+}
static ALWAYS_INLINE void rc_normalize(rc_t *rc)
{
if (rc->range < (1 << RC_TOP_BITS)) {
@@ -101,28 +98,49 @@ static ALWAYS_INLINE void rc_normalize(rc_t *rc)
}
}
-/* rc_is_bit_1 is called 9 times */
-static speed_inline int rc_is_bit_1(rc_t *rc, uint16_t *p)
+/* rc_is_bit_0 is called 9 times */
+/* Why rc_is_bit_0_helper exists?
+ * Because we want to always expose (rc->code < rc->bound) to optimizer.
+ * Thus rc_is_bit_0 is always inlined, and rc_is_bit_0_helper is inlined
+ * only if we compile for speed.
+ */
+static speed_inline uint32_t rc_is_bit_0_helper(rc_t *rc, uint16_t *p)
{
rc_normalize(rc);
rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
- if (rc->code < rc->bound) {
- rc->range = rc->bound;
- *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
- return 0;
- }
+ return rc->bound;
+}
+static ALWAYS_INLINE int rc_is_bit_0(rc_t *rc, uint16_t *p)
+{
+ uint32_t t = rc_is_bit_0_helper(rc, p);
+ return rc->code < t;
+}
+
+/* Called ~10 times, but very small, thus inlined */
+static speed_inline void rc_update_bit_0(rc_t *rc, uint16_t *p)
+{
+ rc->range = rc->bound;
+ *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
+}
+static speed_inline void rc_update_bit_1(rc_t *rc, uint16_t *p)
+{
rc->range -= rc->bound;
rc->code -= rc->bound;
*p -= *p >> RC_MOVE_BITS;
- return 1;
}
/* Called 4 times in unlzma loop */
-static speed_inline int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
+static int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
{
- int ret = rc_is_bit_1(rc, p);
- *symbol = *symbol * 2 + ret;
- return ret;
+ if (rc_is_bit_0(rc, p)) {
+ rc_update_bit_0(rc, p);
+ *symbol *= 2;
+ return 0;
+ } else {
+ rc_update_bit_1(rc, p);
+ *symbol = *symbol * 2 + 1;
+ return 1;
+ }
}
/* Called once */
@@ -248,13 +266,13 @@ unpack_lzma_stream(int src_fd, int dst_fd)
header.dst_size = SWAP_LE64(header.dst_size);
if (header.dict_size == 0)
- header.dict_size++;
+ header.dict_size = 1;
buffer = xmalloc(MIN(header.dst_size, header.dict_size));
num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
p = xmalloc(num_probs * sizeof(*p));
- num_probs += LZMA_LITERAL - LZMA_BASE_SIZE;
+ num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
for (i = 0; i < num_probs; i++)
p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
@@ -264,8 +282,9 @@ unpack_lzma_stream(int src_fd, int dst_fd)
int pos_state = (buffer_pos + global_pos) & pos_state_mask;
prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
- if (!rc_is_bit_1(rc, prob)) {
+ 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))
@@ -321,21 +340,27 @@ unpack_lzma_stream(int src_fd, int dst_fd)
int offset;
uint16_t *prob_len;
+ rc_update_bit_1(rc, prob);
prob = p + LZMA_IS_REP + state;
- if (!rc_is_bit_1(rc, prob)) {
+ if (rc_is_bit_0(rc, prob)) {
+ rc_update_bit_0(rc, prob);
rep3 = rep2;
rep2 = rep1;
rep1 = rep0;
state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
prob = p + LZMA_LEN_CODER;
} else {
- prob += LZMA_IS_REP_G0 - LZMA_IS_REP;
- if (!rc_is_bit_1(rc, prob)) {
+ rc_update_bit_1(rc, prob);
+ prob = p + LZMA_IS_REP_G0 + state;
+ 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
);
- if (!rc_is_bit_1(rc, prob)) {
+ 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;
@@ -347,16 +372,25 @@ unpack_lzma_stream(int src_fd, int dst_fd)
len = 1;
goto string;
#endif
+ } else {
+ rc_update_bit_1(rc, prob);
}
} else {
uint32_t distance;
- prob += LZMA_IS_REP_G1 - LZMA_IS_REP_G0;
- distance = rep1;
- if (rc_is_bit_1(rc, prob)) {
- prob += LZMA_IS_REP_G2 - LZMA_IS_REP_G1;
- distance = rep2;
- if (rc_is_bit_1(rc, prob)) {
+ rc_update_bit_1(rc, prob);
+ prob = p + LZMA_IS_REP_G1 + state;
+ if (rc_is_bit_0(rc, prob)) {
+ rc_update_bit_0(rc, prob);
+ distance = rep1;
+ } else {
+ rc_update_bit_1(rc, prob);
+ prob = p + LZMA_IS_REP_G2 + state;
+ if (rc_is_bit_0(rc, prob)) {
+ rc_update_bit_0(rc, prob);
+ distance = rep2;
+ } else {
+ rc_update_bit_1(rc, prob);
distance = rep3;
rep3 = rep2;
}
@@ -370,20 +404,24 @@ unpack_lzma_stream(int src_fd, int dst_fd)
}
prob_len = prob + LZMA_LEN_CHOICE;
- if (!rc_is_bit_1(rc, prob_len)) {
- prob_len += LZMA_LEN_LOW - LZMA_LEN_CHOICE
- + (pos_state << LZMA_LEN_NUM_LOW_BITS);
+ 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));
offset = 0;
num_bits = LZMA_LEN_NUM_LOW_BITS;
} else {
- prob_len += LZMA_LEN_CHOICE_2 - LZMA_LEN_CHOICE;
- if (!rc_is_bit_1(rc, prob_len)) {
- prob_len += LZMA_LEN_MID - LZMA_LEN_CHOICE_2
- + (pos_state << LZMA_LEN_NUM_MID_BITS);
+ rc_update_bit_1(rc, prob_len);
+ prob_len = prob + LZMA_LEN_CHOICE_2;
+ 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));
offset = 1 << LZMA_LEN_NUM_LOW_BITS;
num_bits = LZMA_LEN_NUM_MID_BITS;
} else {
- prob_len += LZMA_LEN_HIGH - LZMA_LEN_CHOICE_2;
+ 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));
num_bits = LZMA_LEN_NUM_HIGH_BITS;
@@ -400,20 +438,19 @@ unpack_lzma_stream(int src_fd, int dst_fd)
((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);
- rep0 = pos_slot;
+ rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
+ &pos_slot);
if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
num_bits = (pos_slot >> 1) - 1;
rep0 = 2 | (pos_slot & 1);
- prob = p + LZMA_ALIGN;
if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
rep0 <<= num_bits;
- prob += LZMA_SPEC_POS - LZMA_ALIGN - 1 + rep0 - pos_slot;
+ prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
} else {
num_bits -= LZMA_NUM_ALIGN_BITS;
while (num_bits--)
rep0 = (rep0 << 1) | rc_direct_bit(rc);
+ prob = p + LZMA_ALIGN;
rep0 <<= LZMA_NUM_ALIGN_BITS;
num_bits = LZMA_NUM_ALIGN_BITS;
}
@@ -424,7 +461,8 @@ unpack_lzma_stream(int src_fd, int dst_fd)
rep0 |= i;
i <<= 1;
}
- }
+ } else
+ rep0 = pos_slot;
if (++rep0 == 0)
break;
}
--
1.6.3.3
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