ghostscript-9.52/base/scfdgen.c

/* Copyright (C) 2001-2019 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,
   CA 94945, U.S.A., +1(415)492-9861, for further information.
*/


/* Generate the CCITTFaxDecode tables */
#include "stdio_.h"		/* includes std.h */
#include "scf.h"
#include "malloc_.h"
#include "memory_.h"

typedef void (*cfd_node_proc) (cfd_node *, cfd_node *, uint, int, int, int);
typedef void (*cfd_enum_proc) (cfd_node_proc, cfd_node *, cfd_node *, int);
static void cfd_build_tree(cfd_node *, cfd_enum_proc, int, FILE *);
static void cfd_enumerate_white(cfd_node_proc, cfd_node *, cfd_node *, int);
static void cfd_enumerate_black(cfd_node_proc, cfd_node *, cfd_node *, int);
static void cfd_enumerate_2d(cfd_node_proc, cfd_node *, cfd_node *, int);
static void cfd_enumerate_uncompressed(cfd_node_proc, cfd_node *, cfd_node *, int);

main()
{
    FILE *out = fopen("scfdtab.c", "w");
    cfd_node area[1 << max(cfd_white_initial_bits, cfd_black_initial_bits)];

    fputs("/* Tables for CCITTFaxDecode filter. */\n\n", out);
    fputs("/* This file was generated automatically.  It is governed by the same terms */\n", out);
    fputs("/* as the files scfetab.c and scfdgen.c from which it was derived. */\n", out);
    fputs("/* Consult those files for the licensing terms and conditions. */\n\n", out);
    fputs("#include \"std.h\"\n", out);
    fputs("#include \"scommon.h\"\t\t/* for scf.h */\n", out);
    fputs("#include \"scf.h\"\n\n", out);
    fputs("/* White decoding table. */\n", out);
    fputs("const cfd_node cf_white_decode[] = {\n", out);
    cfd_build_tree(area, cfd_enumerate_white, cfd_white_initial_bits, out);
    fputs("\n};\n\n", out);
    fputs("/* Black decoding table. */\n", out);
    fputs("const cfd_node cf_black_decode[] = {\n", out);
    cfd_build_tree(area, cfd_enumerate_black, cfd_black_initial_bits, out);
    fputs("\n};\n\n", out);
    fputs("/* 2-D decoding table. */\n", out);
    fputs("const cfd_node cf_2d_decode[] = {\n", out);
    cfd_build_tree(area, cfd_enumerate_2d, cfd_2d_initial_bits, out);
    fputs("\n};\n\n", out);
    fputs("/* Uncompresssed decoding table. */\n", out);
    fputs("const cfd_node cf_uncompressed_decode[] = {\n", out);
    cfd_build_tree(area, cfd_enumerate_uncompressed, cfd_uncompressed_initial_bits, out);
    fputs("\n};\n\n", out);
    fputs("/* Dummy executable code to pacify compilers. */\n", out);
    fputs("void scfdtab_dummy(void);\n", out);
    fputs("void\nscfdtab_dummy(void)\n{\n}\n", out);
    fclose(out);
    return 0;
}

/* Initialize first-level leaves, count second-level nodes. */
static void
cfd_count_nodes(cfd_node * tree, cfd_node * ignore_extn,
                uint code, int code_length, int run_length, int initial_bits)
{
    if (code_length <= initial_bits) {
        /* Initialize one or more first-level leaves. */
        int sh = initial_bits - code_length;
        cfd_node *np = &tree[code << sh];
        int i;

        for (i = 1 << sh; i > 0; i--, np++)
            np->run_length = run_length,
                np->code_length = code_length;
    } else {
        /* Note the need for a second level. */
        cfd_node *np = &tree[code >> (code_length - initial_bits)];

        np->code_length = max(np->code_length, code_length);
    }
}

/* Initialize second-level nodes. */
static void
cfd_init2_nodes(cfd_node * tree, cfd_node * extn,
                uint code, int code_length, int run_length, int initial_bits)
{
    int xbits = code_length - initial_bits;
    int xrep;
    cfd_node *np1, *np2;
    int i;

    if (xbits <= 0)
        return;
    np1 = &tree[code >> xbits];
    np2 = &extn[np1->run_length - (1 << initial_bits)];
    xrep = np1->code_length - code_length;
    i = 1 << xrep;
    np2 += (code & ((1 << xbits) - 1)) * i;
    for (; i > 0; i--, np2++)
        np2->run_length = run_length,
            np2->code_length = xbits;
}

/* Enumerate all the relevant white or black codes. */
static void
cfd_enumerate_codes(cfd_node_proc proc, cfd_node * tree, cfd_node * extn,
                  int initial_bits, const cfe_run * tt, const cfe_run * mut)
{
    int i;
    const cfe_run *ep;

    for (i = 0, ep = tt; i < 64; i++, ep++)
        (*proc) (tree, extn, ep->code, ep->code_length, i, initial_bits);
    for (i = 1, ep = mut + 1; i < 41; i++, ep++)
        (*proc) (tree, extn, ep->code, ep->code_length, i << 6, initial_bits);
    (*proc) (tree, extn,
             cf1_run_uncompressed.code, cf1_run_uncompressed.code_length,
             run_uncompressed, initial_bits);
    (*proc) (tree, extn,
             0, run_eol_code_length - 1,
             run_zeros, initial_bits);
}
static void
cfd_enumerate_white(cfd_node_proc proc, cfd_node * tree, cfd_node * extn,
                    int initial_bits)
{
    cfd_enumerate_codes(proc, tree, extn, initial_bits,
                        cf_white_runs.termination, cf_white_runs.make_up);
}
static void
cfd_enumerate_black(cfd_node_proc proc, cfd_node * tree, cfd_node * extn,
                    int initial_bits)
{
    cfd_enumerate_codes(proc, tree, extn, initial_bits,
                        cf_black_runs.termination, cf_black_runs.make_up);
}

/* Enumerate the 2-D codes. */
static void
cfd_enumerate_2d(cfd_node_proc proc, cfd_node * tree, cfd_node * extn,
                 int initial_bits)
{
    int i;
    const cfe_run *ep;

    (*proc) (tree, extn, cf2_run_pass.code, cf2_run_pass.code_length,
             run2_pass, initial_bits);
    (*proc) (tree, extn, cf2_run_horizontal.code, cf2_run_horizontal.code_length,
             run2_horizontal, initial_bits);
    for (i = 0; i < countof(cf2_run_vertical); i++) {
        ep = &cf2_run_vertical[i];
        (*proc) (tree, extn, ep->code, ep->code_length, i, initial_bits);
    }
    (*proc) (tree, extn, cf2_run_uncompressed.code, cf2_run_uncompressed.code_length,
             run_uncompressed, initial_bits);
    (*proc) (tree, extn, 0, run_eol_code_length - 1, run_zeros, initial_bits);
}

/* Enumerate the uncompressed codes. */
static void
cfd_enumerate_uncompressed(cfd_node_proc proc, cfd_node * tree, cfd_node * extn,
                           int initial_bits)
{
    int i;
    const cfe_run *ep;

    for (i = 0; i < countof(cf_uncompressed); i++) {
        ep = &cf_uncompressed[i];
        (*proc) (tree, extn, ep->code, ep->code_length, i, initial_bits);
    }
    for (i = 0; i < countof(cf_uncompressed_exit); i++) {
        ep = &cf_uncompressed_exit[i];
        (*proc) (tree, extn, ep->code, ep->code_length, i, initial_bits);
    }
}

/* Build and write out the table. */
static void
cfd_build_tree(cfd_node * tree, cfd_enum_proc enum_proc, int initial_bits,
               FILE * f)
{
    cfd_node *np;
    const char *prev = "";
    int i, next;
    cfd_node *extn;

    memset(tree, 0, sizeof(cfd_node) << initial_bits);
    /* Construct and write the first level of the tree. */
    (*enum_proc) (cfd_count_nodes, tree, (cfd_node *) 0, initial_bits);
    next = 0;
    for (i = 0, np = tree; i < 1 << initial_bits; i++, np++) {
        if (np->code_length > initial_bits) {	/* second level needed */
            np->run_length = next + (1 << initial_bits);
            next += 1 << (np->code_length - initial_bits);
        }
        fprintf(f, "%s\t{ %d, %d }", prev, np->run_length, np->code_length);
        prev = ",\n";
    }
    /* Construct and write the second level. */
    extn = (cfd_node *) malloc(sizeof(cfd_node) * next);
    for (i = 0, np = extn; i < next; i++, np++)
        np->run_length = run_error,
            np->code_length = 0;
    (*enum_proc) (cfd_init2_nodes, tree, extn, initial_bits);
    for (i = 0, np = extn; i < next; i++, np++)
        fprintf(f, ",\n\t{ %d, %d }", np->run_length, np->code_length);
    free((char *)extn);
}