decompress.h: Add likely(), unlikely() uses
authorEric Biggers <ebiggers3@gmail.com>
Sat, 18 May 2013 02:19:24 +0000 (21:19 -0500)
committerEric Biggers <ebiggers3@gmail.com>
Sat, 18 May 2013 02:19:24 +0000 (21:19 -0500)
include/wimlib/decompress.h

index 059e182..7d0d385 100644 (file)
@@ -72,7 +72,7 @@ bitstream_ensure_bits(struct input_bitstream *istream, unsigned num_bits)
 #else
        if (istream->bitsleft < num_bits) {
 #endif
-               if (istream->data_bytes_left >= 2) {
+               if (likely(istream->data_bytes_left >= 2)) {
                        unsigned shift = sizeof(input_bitbuf_t) * 8 - 16 -
                                         istream->bitsleft;
                        istream->bitbuf |= (input_bitbuf_t)le16_to_cpu(
@@ -95,7 +95,7 @@ bitstream_peek_bits(const struct input_bitstream *istream, unsigned num_bits)
 {
        wimlib_assert2(istream->bitsleft >= num_bits);
        int ret;
-       if (num_bits == 0)
+       if (unlikely(num_bits == 0))
                ret = 0;
        else
                ret = istream->bitbuf >> (sizeof(input_bitbuf_t) * 8 - num_bits);
@@ -121,7 +121,7 @@ bitstream_read_bits(struct input_bitstream *istream,
 {
        wimlib_assert2(num_bits <= 16);
        int ret = bitstream_ensure_bits(istream, num_bits);
-       if (ret == 0) {
+       if (likely(ret == 0)) {
                *n = bitstream_peek_bits(istream, num_bits);
                bitstream_remove_bits(istream, num_bits);
        } else {
@@ -143,7 +143,7 @@ bitstream_read_byte(struct input_bitstream *istream)
        wimlib_assert2(istream->bitsleft < 32);
        int ret;
 
-       if (istream->data_bytes_left == 0) {
+       if (unlikely(istream->data_bytes_left == 0)) {
                ERROR("bitstream_read_byte(): Input buffer exhausted");
                ret = -1;
        } else {
@@ -189,7 +189,7 @@ read_huffsym_near_end_of_input(struct input_bitstream *istream,
  *                             directory in the decode_table, as the
  *                             decode_table contains 2**table_bits entries.
  */
-static _always_inline_attribute int
+static inline int
 read_huffsym(struct input_bitstream *istream,
             const u16 decode_table[],
             const u8 lens[],
@@ -202,7 +202,7 @@ read_huffsym(struct input_bitstream *istream,
 
        /* In the most common case, there are at least max_codeword_len bits
         * remaining in the stream. */
-       if (bitstream_ensure_bits(istream, max_codeword_len) == 0) {
+       if (likely(bitstream_ensure_bits(istream, max_codeword_len) == 0)) {
 
                /* Use the next table_bits of the input as an index into the
                 * decode_table. */
@@ -212,7 +212,10 @@ read_huffsym(struct input_bitstream *istream,
 
                /* If the entry in the decode table is not a valid symbol, it is
                 * the offset of the root of its Huffman subtree. */
-               if (sym >= num_syms) {
+               if (likely(sym < num_syms)) {
+                       wimlib_assert2(lens[sym] <= table_bits);
+                       bitstream_remove_bits(istream, lens[sym]);
+               } else {
                        bitstream_remove_bits(istream, table_bits);
                        do {
                                key_bits = sym + bitstream_peek_bits(istream, 1);
@@ -221,9 +224,6 @@ read_huffsym(struct input_bitstream *istream,
                                wimlib_assert2(key_bits < num_syms * 2 +
                                               (1 << table_bits));
                        } while ((sym = decode_table[key_bits]) >= num_syms);
-               } else {
-                       wimlib_assert2(lens[sym] <= table_bits);
-                       bitstream_remove_bits(istream, lens[sym]);
                }
                *n = sym;
                ret = 0;
@@ -242,6 +242,8 @@ make_huffman_decode_table(u16 decode_table[], unsigned num_syms,
                          unsigned num_bits, const u8 lengths[],
                          unsigned max_codeword_len);
 
+/* Minimum alignment for the decode_table parameter to
+ * make_huffman_decode_table(). */
 #define DECODE_TABLE_ALIGNMENT 16
 
 #endif /* _WIMLIB_DECOMPRESS_H */