const le16 *begin;
};
+#define BITBUF_NBITS (8 * sizeof(bitbuf_t))
+
/* Bookkeeping information for an adaptive Huffman code */
struct lzms_huffman_rebuild_info {
unsigned num_syms_until_rebuild;
/* States and probability entries for item type disambiguation */
u32 main_state;
- struct lzms_probability_entry main_probs[LZMS_NUM_MAIN_PROBS];
-
u32 match_state;
- struct lzms_probability_entry match_probs[LZMS_NUM_MATCH_PROBS];
-
u32 lz_state;
- struct lzms_probability_entry lz_probs[LZMS_NUM_LZ_PROBS];
-
u32 delta_state;
- struct lzms_probability_entry delta_probs[LZMS_NUM_DELTA_PROBS];
-
u32 lz_rep_states[LZMS_NUM_LZ_REP_DECISIONS];
+ u32 delta_rep_states[LZMS_NUM_DELTA_REP_DECISIONS];
+
+ struct lzms_probability_entry main_probs[LZMS_NUM_MAIN_PROBS];
+ struct lzms_probability_entry match_probs[LZMS_NUM_MATCH_PROBS];
+ struct lzms_probability_entry lz_probs[LZMS_NUM_LZ_PROBS];
+ struct lzms_probability_entry delta_probs[LZMS_NUM_DELTA_PROBS];
struct lzms_probability_entry lz_rep_probs[LZMS_NUM_LZ_REP_DECISIONS]
[LZMS_NUM_LZ_REP_PROBS];
-
- u32 delta_rep_states[LZMS_NUM_DELTA_REP_DECISIONS];
struct lzms_probability_entry delta_rep_probs[LZMS_NUM_DELTA_REP_DECISIONS]
[LZMS_NUM_DELTA_REP_PROBS];
static inline void
lzms_ensure_bits(struct lzms_input_bitstream *is, unsigned num_bits)
{
+ unsigned avail;
+
if (is->bitsleft >= num_bits)
return;
- if (likely(is->next != is->begin))
- is->bitbuf |= (bitbuf_t)le16_to_cpu(*--is->next)
- << (sizeof(is->bitbuf) * 8 - is->bitsleft - 16);
- is->bitsleft += 16;
+ avail = BITBUF_NBITS - is->bitsleft;
- if (likely(is->next != is->begin))
- is->bitbuf |= (bitbuf_t)le16_to_cpu(*--is->next)
- << (sizeof(is->bitbuf) * 8 - is->bitsleft - 16);
- is->bitsleft += 16;
+ if (UNALIGNED_ACCESS_IS_FAST && CPU_IS_LITTLE_ENDIAN &&
+ WORDSIZE == 8 && likely((u8 *)is->next - (u8 *)is->begin >= 8))
+ {
+ is->next -= avail >> 4;
+ is->bitbuf |= load_u64_unaligned(is->next) << (avail & 15);
+ is->bitsleft += avail & ~15;
+ } else {
+ if (likely(is->next != is->begin))
+ is->bitbuf |= (bitbuf_t)le16_to_cpu(*--is->next)
+ << (avail - 16);
+ if (likely(is->next != is->begin))
+ is->bitbuf |=(bitbuf_t)le16_to_cpu(*--is->next)
+ << (avail - 32);
+ is->bitsleft += 32;
+ }
}
/* Get @num_bits bits from the bitbuffer variable. */
static inline bitbuf_t
lzms_peek_bits(struct lzms_input_bitstream *is, unsigned num_bits)
{
- return (is->bitbuf >> 1) >> (sizeof(is->bitbuf) * 8 - num_bits - 1);
+ return (is->bitbuf >> 1) >> (BITBUF_NBITS - num_bits - 1);
}
/* Remove @num_bits bits from the bitbuffer variable. */
}
/*
- * Decode and return the next bit from the range decoder.
- *
- * @prob is the probability out of LZMS_PROBABILITY_DENOMINATOR that the next
- * bit is 0 rather than 1.
+ * Decode a bit using the range coder. The current state specifies the
+ * probability entry to use. The state and probability entry will be updated
+ * based on the decoded bit.
*/
static inline int
-lzms_range_decode_bit(struct lzms_range_decoder *rd, u32 prob)
+lzms_decode_bit(struct lzms_range_decoder *rd, u32 *state_p, u32 num_states,
+ struct lzms_probability_entry *probs)
{
+ struct lzms_probability_entry *prob_entry;
+ u32 prob;
u32 bound;
+ /* Load the probability entry corresponding to the current state. */
+ prob_entry = &probs[*state_p];
+
+ /* Get the probability (out of LZMS_PROBABILITY_DENOMINATOR) that the
+ * next bit is 0. */
+ prob = lzms_get_probability(prob_entry);
+
/* Normalize if needed. */
if (rd->range <= 0xffff) {
rd->range <<= 16;
if (rd->code < bound) {
/* Current code is in the 0-bit region of the range. */
rd->range = bound;
+
+ /* Update the state and probability entry based on the decoded bit. */
+ *state_p = ((*state_p << 1) | 0) & (num_states - 1);
+ lzms_update_probability_entry(prob_entry, 0);
return 0;
} else {
/* Current code is in the 1-bit region of the range. */
rd->range -= bound;
rd->code -= bound;
+
+ /* Update the state and probability entry based on the decoded bit. */
+ *state_p = ((*state_p << 1) | 1) & (num_states - 1);
+ lzms_update_probability_entry(prob_entry, 1);
return 1;
}
}
-/*
- * Decode a bit. This wraps around lzms_range_decode_bit() to handle using and
- * updating the state and its corresponding probability entry.
- */
-static inline int
-lzms_decode_bit(struct lzms_range_decoder *rd, u32 *state_p, u32 num_states,
- struct lzms_probability_entry *probs)
-{
- struct lzms_probability_entry *prob_entry;
- u32 prob;
- int bit;
-
- /* Load the probability entry corresponding to the current state. */
- prob_entry = &probs[*state_p];
-
- /* Get the probability that the next bit is 0. */
- prob = lzms_get_probability(prob_entry);
-
- /* Decode the next bit. */
- bit = lzms_range_decode_bit(rd, prob);
-
- /* Update the state and probability entry based on the decoded bit. */
- *state_p = ((*state_p << 1) | bit) & (num_states - 1);
- lzms_update_probability_entry(prob_entry, bit);
-
- /* Return the decoded bit. */
- return bit;
-}
-
static int
lzms_decode_main_bit(struct lzms_decompressor *d)
{
git://wimlib.net / wimlib / blobdiff