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-rw-r--r--src/liblzma/lzma/lzma_decoder.c5
-rw-r--r--src/liblzma/rangecoder/range_decoder.h10
2 files changed, 11 insertions, 4 deletions
diff --git a/src/liblzma/lzma/lzma_decoder.c b/src/liblzma/lzma/lzma_decoder.c
index 66d2818d..f7323061 100644
--- a/src/liblzma/lzma/lzma_decoder.c
+++ b/src/liblzma/lzma/lzma_decoder.c
@@ -261,7 +261,7 @@ lzma_decode(void *coder_ptr, lzma_dict *restrict dictptr,
const size_t dict_start = dict.pos;
// Range decoder
- rc_to_local(coder->rc, *in_pos);
+ rc_to_local(coder->rc, *in_pos, LZMA_IN_REQUIRED);
// State
uint32_t state = coder->state;
@@ -340,8 +340,7 @@ lzma_decode(void *coder_ptr, lzma_dict *restrict dictptr,
// If there is not enough room for another LZMA symbol
// go to Resumable mode.
- if (unlikely(rc_in_end - rc_in_ptr < LZMA_IN_REQUIRED
- || dict.pos == dict.limit))
+ if (unlikely(!rc_is_fast_allowed() || dict.pos == dict.limit))
goto slow;
// Decode the first bit from the next LZMA symbol.
diff --git a/src/liblzma/rangecoder/range_decoder.h b/src/liblzma/rangecoder/range_decoder.h
index 40de80c0..8cc78e6a 100644
--- a/src/liblzma/rangecoder/range_decoder.h
+++ b/src/liblzma/rangecoder/range_decoder.h
@@ -61,13 +61,21 @@ rc_read_init(lzma_range_decoder *rc, const uint8_t *restrict in,
/// Makes local copies of range decoder and *in_pos variables. Doing this
/// improves speed significantly. The range decoder macros expect also
/// variables 'in' and 'in_size' to be defined.
-#define rc_to_local(range_decoder, in_pos) \
+#define rc_to_local(range_decoder, in_pos, fast_mode_in_required) \
lzma_range_decoder rc = range_decoder; \
const uint8_t *rc_in_ptr = in + (in_pos); \
const uint8_t *rc_in_end = in + in_size; \
+ const uint8_t *rc_in_fast_end \
+ = (rc_in_end - rc_in_ptr) <= (fast_mode_in_required) \
+ ? rc_in_ptr \
+ : rc_in_end - (fast_mode_in_required); \
uint32_t rc_bound
+/// Evaluates to true if there is enough input remaining to use fast mode.
+#define rc_is_fast_allowed() (rc_in_ptr < rc_in_fast_end)
+
+
/// Stores the local copes back to the range decoder structure.
#define rc_from_local(range_decoder, in_pos) \
do { \