extend() should not need sign extension for the bits parameter.

[fjl] / dehuff.h

diff --git a/dehuff.h b/dehuff.h
index a6a431a8139440a7052ce1dadd39b182ee5566b4..f29b815631752e213d6a9867b728e33c9438c60d 100644 (file)
--- a/dehuff.h
+++ b/dehuff.h
@@ -48,10 +48,10 @@ void read_huffman_tables(huffman_tables_t* dst, input_func_t* input_func, void*
 unsigned read_huffman_symbol_slow_path(const struct huffman_table* table,
                                        struct bit_source* source);
 
-static inline unsigned read_huffman_symbol(const struct huffman_table* table,
-                                           struct bit_source* source)
+static inline unsigned read_huffman_symbol_no_refill(
+       const struct huffman_table* table,
+       struct bit_source* source)
 {
-       possibly_refill(source, DEHUF_TABLE_BITS);
        assert(source->bits_available >= DEHUF_TABLE_BITS);
        unsigned lookup = peek_bits(source, DEHUF_TABLE_BITS);
        int code = table->lookup_table_codes[lookup];
@@ -65,6 +65,13 @@ static inline unsigned read_huffman_symbol(const struct huffman_table* table,
        return code;
 }
 
+static inline unsigned read_huffman_symbol(const struct huffman_table* table,
+                                           struct bit_source* source)
+{
+       possibly_refill(source, DEHUF_TABLE_BITS);
+       return read_huffman_symbol_no_refill(table, source);
+}
+
 // procedure EXTEND (figure F.12)
 
 // Fast lookup table for (1 << (bits - 1)).
@@ -74,7 +81,7 @@ static const int bit_thresholds[16] = {
        0, 1 << 0, 1 << 1, 1 << 2, 1 << 3, 1 << 4, 1 << 5, 1 << 6, 1 << 7, 1 << 8, 1 << 9, 1 << 10, 1 << 11, 1 << 12, 1 << 13, 1 << 14
 };
 
-static inline unsigned extend(int val, int bits)
+static inline unsigned extend(int val, unsigned bits)
 {
        if (val < bit_thresholds[bits]) {
                return val + (-1 << bits) + 1;