#include "wimlib/lzms_constants.h"
#include "wimlib/types.h"
-//#define ENABLE_LZMS_DEBUG
-#ifdef ENABLE_LZMS_DEBUG
-# define LZMS_DEBUG DEBUG
-# define LZMS_ASSERT wimlib_assert
-# include "wimlib/assert.h"
-# include "wimlib/error.h"
-#else
-# define LZMS_DEBUG(format, ...)
-# define LZMS_ASSERT(...)
-#endif
-
-extern void
-lzms_x86_filter(u8 data[], s32 size, s32 last_target_usages[], bool undo);
-
-/* Probability entry for use by the range coder when in a specific state. */
-struct lzms_probability_entry {
-
- /* Number of zeroes in the most recent LZMS_PROBABILITY_MAX bits that
- * have been coded using this probability entry. This is a cached value
- * because it can be computed as LZMS_PROBABILITY_MAX minus the number
- * of bits set in the low-order LZMS_PROBABILITY_MAX bits of
- * @recent_bits. */
- u32 num_recent_zero_bits;
-
- /* The most recent LZMS_PROBABILITY_MAX bits that have been coded using
- * this probability entry. The size of this variable, in bits, must be
- * at least LZMS_PROBABILITY_MAX. */
- u64 recent_bits;
-};
-
/* Offset slot tables */
extern const u32 lzms_offset_slot_base[LZMS_MAX_NUM_OFFSET_SYMS + 1];
extern const u8 lzms_extra_offset_bits[LZMS_MAX_NUM_OFFSET_SYMS];
extern unsigned
lzms_get_num_offset_slots(size_t uncompressed_size);
-extern void
-lzms_init_probability_entries(struct lzms_probability_entry *entries, size_t count);
+
+/* Probability entry for use by the range coder when in a specific state */
+struct lzms_probability_entry {
+
+ /* The number of zeroes in the most recent LZMS_PROBABILITY_DENOMINATOR
+ * bits that have been decoded or encoded using this probability entry.
+ * The probability of the next bit being 0 is this value over
+ * LZMS_PROBABILITY_DENOMINATOR, except for the cases where this would
+ * imply 0% or 100% probability. */
+ u32 num_recent_zero_bits;
+
+ /* The most recent LZMS_PROBABILITY_DENOMINATOR bits that have been
+ * coded using this probability entry. The bits are ordered such that
+ * low order is newest and high order is oldest. */
+ u64 recent_bits;
+};
extern void
-lzms_init_symbol_frequencies(u32 freqs[], size_t num_syms);
+lzms_init_probability_entries(struct lzms_probability_entry *entries, size_t count);
-/* Given a decoded bit, update the probability entry. */
+/* Given a decoded or encoded bit, update the probability entry. */
static inline void
-lzms_update_probability_entry(struct lzms_probability_entry *prob_entry, int bit)
+lzms_update_probability_entry(struct lzms_probability_entry *entry, int bit)
{
- s32 delta_zero_bits;
+ BUILD_BUG_ON(LZMS_PROBABILITY_DENOMINATOR != sizeof(entry->recent_bits) * 8);
- BUILD_BUG_ON(LZMS_PROBABILITY_MAX != sizeof(prob_entry->recent_bits) * 8);
+ s32 delta_zero_bits = (s32)(entry->recent_bits >>
+ (LZMS_PROBABILITY_DENOMINATOR - 1)) - bit;
- delta_zero_bits = (s32)(prob_entry->recent_bits >> (LZMS_PROBABILITY_MAX - 1)) - bit;
-
- prob_entry->num_recent_zero_bits += delta_zero_bits;
- prob_entry->recent_bits <<= 1;
- prob_entry->recent_bits |= bit;
+ entry->num_recent_zero_bits += delta_zero_bits;
+ entry->recent_bits = (entry->recent_bits << 1) | bit;
}
-/* Given a probability entry, return the chance out of LZMS_PROBABILITY_MAX that
- * the next decoded bit will be a 0. */
+/* Given a probability entry, return the chance out of
+ * LZMS_PROBABILITY_DENOMINATOR that the next decoded bit will be a 0. */
static inline u32
lzms_get_probability(const struct lzms_probability_entry *prob_entry)
{
- u32 prob;
-
- prob = prob_entry->num_recent_zero_bits;
+ u32 prob = prob_entry->num_recent_zero_bits;
/* 0% and 100% probabilities aren't allowed. */
if (prob == 0)
prob++;
- if (prob == LZMS_PROBABILITY_MAX)
+ else if (prob == LZMS_PROBABILITY_DENOMINATOR)
prob--;
return prob;
}
+extern void
+lzms_init_symbol_frequencies(u32 freqs[], unsigned num_syms);
+
+extern void
+lzms_dilute_symbol_frequencies(u32 freqs[], unsigned num_syms);
+
+/* Pre/post-processing */
+extern void
+lzms_x86_filter(u8 data[], s32 size, s32 last_target_usages[], bool undo);
+
#endif /* _LZMS_COMMON_H */