#include "wma.h"
#include "bitstream.h"
+/** Read an 8, 16, or 32 bit entity from a VLC table. */
#define GET_DATA(v, table, i, size) \
{\
const uint8_t *ptr = (const uint8_t *)table + i * size; \
/**
* Build VLC decoding tables suitable for use with get_vlc().
*
- * \param nb_bits Set the decoding table size (2^nb_bits)
- * entries. The bigger it is, the faster is the decoding. But
- * it should not be too big to save memory and L1 cache. '9'
- * is a good compromise.
+ * \param vlc The structure to be initialized.
+ *
+ * \param nb_bits Set the decoding table size (2^nb_bits) entries. The bigger
+ * it is, the faster is the decoding. But it should not be too big to save
+ * memory and L1 cache. '9' is a good compromise.
*
* \param nb_codes Number of vlcs codes.
*
build_table(vlc, nb_bits, nb_codes, bits, codes, codes_size, 0, 0);
}
+/**
+ * Deallocate all resources of a VLC table.
+ *
+ * \param vlc Pointer to an initialized vlc structure.
+ *
+ * The table given by \a vlc must have been initialized earlier via \ref
+ * init_vlc().
+ */
void free_vlc(struct vlc *vlc)
{
freep(&vlc->table);
}
+
+/**
+ * Parse a vlc code.
+ *
+ * \param gbc The getbit context structure.
+ *
+ * \param table The vlc tables to use.
+ *
+ * \param bits The number of bits which will be read at once, must be
+ * identical to nb_bits in init_vlc().
+ *
+ * \param max_depth The number of times bits bits must be read to completely
+ * read the longest vlc code = (max_vlc_length + bits - 1) / bits.
+ *
+ * \return The vlc code.
+ */
+int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], int bits,
+ int max_depth)
+{
+ int n, idx, nb_bits, code;
+
+ idx = show_bits(gbc, bits);
+ code = table[idx][0];
+ n = table[idx][1];
+ if (max_depth > 1 && n < 0) {
+ skip_bits(gbc, bits);
+ nb_bits = -n;
+ idx = show_bits(gbc, nb_bits) + code;
+ code = table[idx][0];
+ n = table[idx][1];
+ if (max_depth > 2 && n < 0) {
+ skip_bits(gbc, nb_bits);
+ nb_bits = -n;
+ idx = show_bits(gbc, nb_bits) + code;
+ code = table[idx][0];
+ n = table[idx][1];
+ }
+ }
+ skip_bits(gbc, n);
+ return code >= 0? code : -E_VLC;
+}