Function gen_codes

extern/zlib/src/trees.c:202–231

=========================================================================== * Generate the codes for a given tree and bit counts (which need not be * optimal). * IN assertion: the array bl_count contains the bit length statistics for * the given tree and the field len is set for all tree elements. * OUT assertion: the field code is set for all tree elements of non * zero code length. */

 *     zero code length.
 */
local void gen_codes(ct_data *tree, int max_code, ushf *bl_count) {
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
    unsigned code = 0;         /* running code value */
    int bits;                  /* bit index */
    int n;                     /* code index */

    /* The distribution counts are first used to generate the code values
     * without bit reversal.
     */
    for (bits = 1; bits <= MAX_BITS; bits++) {
        code = (code + bl_count[bits - 1]) << 1;
        next_code[bits] = (ush)code;
    }
    /* Check that the bit counts in bl_count are consistent. The last code
     * must be all ones.
     */
    Assert (code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
            "inconsistent bit counts");
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

    for (n = 0;  n <= max_code; n++) {
        int len = tree[n].Len;
        if (len == 0) continue;
        /* Now reverse the bits */
        tree[n].Code = (ush)bi_reverse(next_code[len]++, len);

        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
            n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
    }
}

#ifdef GEN_TREES_H
local void gen_trees_header(void);