Adjust naming of (de)compression files

[wimlib] / include / wimlib / lzms_common.h

diff --git a/include/wimlib/lzms_common.h b/include/wimlib/lzms_common.h
new file mode 100644 (file)
index 0000000..10dc4d0
--- /dev/null
+++ b/include/wimlib/lzms_common.h
@@ -0,0 +1,110 @@
+/*
+ * lzms_common.h
+ *
+ * Declarations shared between LZMS compression and decompression.
+ */
+
+#ifndef _LZMS_COMMON_H
+#define _LZMS_COMMON_H
+
+#include "wimlib/compiler.h"
+#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];
+
+/* Length slot tables  */
+extern const u32 lzms_length_slot_base[LZMS_NUM_LENGTH_SYMS + 1];
+extern const u8 lzms_extra_length_bits[LZMS_NUM_LENGTH_SYMS];
+
+extern unsigned
+lzms_get_slot(u32 value, const u32 slot_base_tab[], unsigned num_slots);
+
+/* Return the offset slot for the specified offset  */
+static inline unsigned
+lzms_get_offset_slot(u32 offset)
+{
+       return lzms_get_slot(offset, lzms_offset_slot_base, LZMS_MAX_NUM_OFFSET_SYMS);
+}
+
+/* Return the length slot for the specified length  */
+static inline unsigned
+lzms_get_length_slot(u32 length)
+{
+       return lzms_get_slot(length, lzms_length_slot_base, LZMS_NUM_LENGTH_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);
+
+extern void
+lzms_init_symbol_frequencies(u32 freqs[], size_t num_syms);
+
+/* Given a decoded bit, update the probability entry.  */
+static inline void
+lzms_update_probability_entry(struct lzms_probability_entry *prob_entry, int bit)
+{
+       s32 delta_zero_bits;
+
+       BUILD_BUG_ON(LZMS_PROBABILITY_MAX != sizeof(prob_entry->recent_bits) * 8);
+
+       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;
+}
+
+/* Given a probability entry, return the chance out of LZMS_PROBABILITY_MAX 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;
+
+       /* 0% and 100% probabilities aren't allowed.  */
+       if (prob == 0)
+               prob++;
+       if (prob == LZMS_PROBABILITY_MAX)
+               prob--;
+       return prob;
+}
+
+#endif /* _LZMS_COMMON_H */