aboutsummaryrefslogtreecommitdiff
path: root/src
diff options
context:
space:
mode:
Diffstat (limited to 'src')
-rw-r--r--src/liblzma/lzma/lzma_decoder.c108
-rw-r--r--src/liblzma/rangecoder/range_decoder.h77
2 files changed, 82 insertions, 103 deletions
diff --git a/src/liblzma/lzma/lzma_decoder.c b/src/liblzma/lzma/lzma_decoder.c
index cf437d88..2e8393d6 100644
--- a/src/liblzma/lzma/lzma_decoder.c
+++ b/src/liblzma/lzma/lzma_decoder.c
@@ -25,21 +25,13 @@
#ifdef HAVE_SMALL
// Macros for (somewhat) size-optimized code.
-#define seq_4(seq) seq
-
-#define seq_6(seq) seq
-
-#define seq_8(seq) seq
-
-#define seq_len(seq) \
- seq ## _CHOICE, \
- seq ## _CHOICE2, \
- seq ## _BITTREE
-
+// This is used to decode the match length (how many bytes must be repeated
+// from the dictionary). This version is used in the Resumable mode and
+// does not unroll any loops.
#define len_decode(target, ld, pos_state, seq) \
do { \
case seq ## _CHOICE: \
- rc_if_0(ld.choice, seq ## _CHOICE) { \
+ rc_if_0_safe(ld.choice, seq ## _CHOICE) { \
rc_update_0(ld.choice); \
probs = ld.low[pos_state];\
limit = LEN_LOW_SYMBOLS; \
@@ -47,7 +39,7 @@ case seq ## _CHOICE: \
} else { \
rc_update_1(ld.choice); \
case seq ## _CHOICE2: \
- rc_if_0(ld.choice2, seq ## _CHOICE2) { \
+ rc_if_0_safe(ld.choice2, seq ## _CHOICE2) { \
rc_update_0(ld.choice2); \
probs = ld.mid[pos_state]; \
limit = LEN_MID_SYMBOLS; \
@@ -63,89 +55,42 @@ case seq ## _CHOICE2: \
symbol = 1; \
case seq ## _BITTREE: \
do { \
- rc_bit(probs[symbol], , , seq ## _BITTREE); \
+ rc_bit_safe(probs[symbol], , , seq ## _BITTREE); \
} while (symbol < limit); \
target += symbol - limit; \
} while (0)
-#else // HAVE_SMALL
-
-// Unrolled versions
-#define seq_4(seq) \
- seq ## 0, \
- seq ## 1, \
- seq ## 2, \
- seq ## 3
-
-#define seq_6(seq) \
- seq ## 0, \
- seq ## 1, \
- seq ## 2, \
- seq ## 3, \
- seq ## 4, \
- seq ## 5
-
-#define seq_8(seq) \
- seq ## 0, \
- seq ## 1, \
- seq ## 2, \
- seq ## 3, \
- seq ## 4, \
- seq ## 5, \
- seq ## 6, \
- seq ## 7
-
-#define seq_len(seq) \
- seq ## _CHOICE, \
- seq ## _LOW0, \
- seq ## _LOW1, \
- seq ## _LOW2, \
- seq ## _CHOICE2, \
- seq ## _MID0, \
- seq ## _MID1, \
- seq ## _MID2, \
- seq ## _HIGH0, \
- seq ## _HIGH1, \
- seq ## _HIGH2, \
- seq ## _HIGH3, \
- seq ## _HIGH4, \
- seq ## _HIGH5, \
- seq ## _HIGH6, \
- seq ## _HIGH7
-#define len_decode(target, ld, pos_state, seq) \
+// This is the faster version of the match length decoder that does not
+// worry about being resumable. It unrolls the bittree decoding loop.
+#define len_decode_fast(target, ld, pos_state) \
do { \
symbol = 1; \
-case seq ## _CHOICE: \
- rc_if_0(ld.choice, seq ## _CHOICE) { \
+ rc_if_0(ld.choice) { \
rc_update_0(ld.choice); \
- rc_bit_case(ld.low[pos_state][symbol], , , seq ## _LOW0); \
- rc_bit_case(ld.low[pos_state][symbol], , , seq ## _LOW1); \
- rc_bit_case(ld.low[pos_state][symbol], , , seq ## _LOW2); \
+ rc_bit(ld.low[pos_state][symbol], , ); \
+ rc_bit(ld.low[pos_state][symbol], , ); \
+ rc_bit(ld.low[pos_state][symbol], , ); \
target = symbol - LEN_LOW_SYMBOLS + MATCH_LEN_MIN; \
} else { \
rc_update_1(ld.choice); \
-case seq ## _CHOICE2: \
- rc_if_0(ld.choice2, seq ## _CHOICE2) { \
+ rc_if_0(ld.choice2) { \
rc_update_0(ld.choice2); \
- rc_bit_case(ld.mid[pos_state][symbol], , , \
- seq ## _MID0); \
- rc_bit_case(ld.mid[pos_state][symbol], , , \
- seq ## _MID1); \
- rc_bit_case(ld.mid[pos_state][symbol], , , \
- seq ## _MID2); \
+ rc_bit(ld.mid[pos_state][symbol], , ); \
+ rc_bit(ld.mid[pos_state][symbol], , ); \
+ rc_bit(ld.mid[pos_state][symbol], , ); \
target = symbol - LEN_MID_SYMBOLS \
+ MATCH_LEN_MIN + LEN_LOW_SYMBOLS; \
} else { \
rc_update_1(ld.choice2); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH0); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH1); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH2); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH3); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH4); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH5); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH6); \
- rc_bit_case(ld.high[symbol], , , seq ## _HIGH7); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
+ rc_bit(ld.high[symbol], , ); \
target = symbol - LEN_HIGH_SYMBOLS \
+ MATCH_LEN_MIN \
+ LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS; \
@@ -153,8 +98,6 @@ case seq ## _CHOICE2: \
} \
} while (0)
-#endif // HAVE_SMALL
-
/// Length decoder probabilities; see comments in lzma_common.h.
typedef struct {
@@ -889,7 +832,6 @@ out:
}
-
static void
lzma_decoder_uncompressed(void *coder_ptr, lzma_vli uncompressed_size,
bool allow_eopm)
diff --git a/src/liblzma/rangecoder/range_decoder.h b/src/liblzma/rangecoder/range_decoder.h
index a38e6aa3..5e813f56 100644
--- a/src/liblzma/rangecoder/range_decoder.h
+++ b/src/liblzma/rangecoder/range_decoder.h
@@ -80,10 +80,22 @@ do { \
((range_decoder).code == 0)
-/// Read the next input byte if needed. If more input is needed but there is
+// Read the next input byte if needed.
+#define rc_normalize() \
+do { \
+ if (rc.range < RC_TOP_VALUE) { \
+ rc.range <<= RC_SHIFT_BITS; \
+ rc.code = (rc.code << RC_SHIFT_BITS) | in[rc_in_pos++]; \
+ } \
+} while (0)
+
+
+/// If more input is needed but there is
/// no more input available, "goto out" is used to jump out of the main
-/// decoder loop.
-#define rc_normalize(seq) \
+/// decoder loop. The "_safe" macros are used in the Resumable decoder
+/// mode in order to save the sequence to continue decoding from that
+/// point later.
+#define rc_normalize_safe(seq) \
do { \
if (rc.range < RC_TOP_VALUE) { \
if (unlikely(rc_in_pos == in_size)) { \
@@ -99,7 +111,7 @@ do { \
/// Start decoding a bit. This must be used together with rc_update_0()
/// and rc_update_1():
///
-/// rc_if_0(prob, seq) {
+/// rc_if_0(prob) {
/// rc_update_0(prob);
/// // Do something
/// } else {
@@ -107,8 +119,14 @@ do { \
/// // Do something else
/// }
///
-#define rc_if_0(prob, seq) \
- rc_normalize(seq); \
+#define rc_if_0(prob) \
+ rc_normalize(); \
+ rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * (prob); \
+ if (rc.code < rc_bound)
+
+
+#define rc_if_0_safe(prob, seq) \
+ rc_normalize_safe(seq); \
rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * (prob); \
if (rc.code < rc_bound)
@@ -136,9 +154,21 @@ do { \
/// This macro is used as the last step in bittree reverse decoders since
/// those don't use "symbol" for anything else than indexing the probability
/// arrays.
-#define rc_bit_last(prob, action0, action1, seq) \
+#define rc_bit_last(prob, action0, action1) \
do { \
- rc_if_0(prob, seq) { \
+ rc_if_0(prob) { \
+ rc_update_0(prob); \
+ action0; \
+ } else { \
+ rc_update_1(prob); \
+ action1; \
+ } \
+} while (0)
+
+
+#define rc_bit_last_safe(prob, action0, action1, seq) \
+do { \
+ rc_if_0_safe(prob, seq) { \
rc_update_0(prob); \
action0; \
} else { \
@@ -150,26 +180,33 @@ do { \
/// Decodes one bit, updates "symbol", and runs action0 or action1 depending
/// on the decoded bit.
-#define rc_bit(prob, action0, action1, seq) \
+#define rc_bit(prob, action0, action1) \
rc_bit_last(prob, \
symbol <<= 1; action0, \
+ symbol = (symbol << 1) + 1; action1);
+
+
+#define rc_bit_safe(prob, action0, action1, seq) \
+ rc_bit_last_safe(prob, \
+ symbol <<= 1; action0, \
symbol = (symbol << 1) + 1; action1, \
seq);
-
-/// Like rc_bit() but add "case seq:" as a prefix. This makes the unrolled
-/// loops more readable because the code isn't littered with "case"
-/// statements. On the other hand this also makes it less readable, since
-/// spotting the places where the decoder loop may be restarted is less
-/// obvious.
-#define rc_bit_case(prob, action0, action1, seq) \
- case seq: rc_bit(prob, action0, action1, seq)
+/// Decode a bit without using a probability.
+#define rc_direct(dest) \
+do { \
+ rc_normalize(); \
+ rc.range >>= 1; \
+ rc.code -= rc.range; \
+ rc_bound = UINT32_C(0) - (rc.code >> 31); \
+ rc.code += rc.range & rc_bound; \
+ dest = (dest << 1) + (rc_bound + 1); \
+} while (0)
-/// Decode a bit without using a probability.
-#define rc_direct(dest, seq) \
+#define rc_direct_safe(dest, seq) \
do { \
- rc_normalize(seq); \
+ rc_normalize_safe(seq); \
rc.range >>= 1; \
rc.code -= rc.range; \
rc_bound = UINT32_C(0) - (rc.code >> 31); \
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-20 04:15:22 +0000