rle_row_alc.c

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/*
 * This software is copyrighted as noted below.  It may be freely copied,
 * modified, and redistributed, provided that the copyright notice is 
 * preserved on all copies.
 * 
 * There is no warranty or other guarantee of fitness for this software,
 * it is provided solely "as is".  Bug reports or fixes may be sent
 * to the author, who may or may not act on them as he desires.
 *
 * You may not include this software in a program or other software product
 * without supplying the source, or without informing the end-user that the 
 * source is available for no extra charge.
 *
 * If you modify this software, you should include a notice giving the
 * name of the person performing the modification, the date of modification,
 * and the reason for such modification.
 *
 *  Modified at BRL 16-May-88 by Mike Muuss to avoid Alliant STDC desire
 *  to have all "void" functions so declared.
 */
/* 
 * rle_row_alc.c - Allocate buffers for rle_getrow/rle_putrow.
 * 
 * Author:  Spencer W. Thomas
 *      Computer Science Dept.
 *      University of Utah
 * Date:    Fri Nov 14 1986
 * Copyright (c) 1986, Spencer W. Thomas
 */

#include <stdio.h>
#include "rle.h"

/*****************************************************************
 * TAG( rle_row_alloc )
 * 
 * Allocate buffer space for use by rle_getrow and rle_putrow.
 * Inputs:
 *  the_hdr:    Header structure for RLE file to be read or
 *          written.
 * Outputs:
 *  scanp:      Pointer to pointer to created scanline buffer.
 *          This pointer is adjusted for the alpha channel,
 *          if present.
 *  Returns 0 for success, -1 if malloc failed.
 * Assumptions:
 *  No input scanline will extend beyond the declared xmax endpoint.
 * Algorithm:
 *  Count number of channels actually used (check bitmap).
 *  Allocate nchan*rowlength pixels, allocate a buffer
 *  to hold ncolors+alpha pointers, and give each channel
 *  rowlength pixels.  Rowlength is xmax + 1, to allow for rle_getrow
 *  usage.
 */
int
rle_row_alloc( the_hdr, scanp )
rle_hdr *the_hdr;
rle_pixel ***scanp;
{
    rle_pixel ** scanbuf, * pixbuf;
    int rowlen, nchan = 0, i, ncol;

    rowlen = the_hdr->xmax + 1;
    if ( the_hdr->alpha && RLE_BIT( *the_hdr, RLE_ALPHA ) )
    nchan++;
    for ( i = 0; i < the_hdr->ncolors; i++ )
    if ( RLE_BIT( *the_hdr, i ) )
         nchan++;

    ncol = the_hdr->ncolors + the_hdr->alpha;

    if ( (scanbuf = (rle_pixel **)malloc( ncol * sizeof(rle_pixel *) )) == 0 )
    return -1;
    if ( (pixbuf = (rle_pixel *)malloc( nchan * rowlen *
                       sizeof(rle_pixel) )) == 0 )
    {
    free( scanbuf );
    return -1;
    }

    if ( the_hdr->alpha )
    scanbuf++;

    for ( i = -the_hdr->alpha; i < the_hdr->ncolors; i++ )
    if ( RLE_BIT( *the_hdr, i ) )
    {
        scanbuf[i] = pixbuf;
        pixbuf += rowlen;
    }
    else
        scanbuf[i] = 0;
    *scanp = scanbuf;

    return 0;
}


/*****************************************************************
 * TAG( rle_row_free )
 * 
 * Free storage allocated by rle_row_alloc().
 * Inputs:
 *  the_hdr:    Header structure as above.
 *  scanp:      Pointer to scanbuf above.
 * Outputs:
 *  Frees storage referenced by scanp and nrawp.
 * Assumptions:
 *  Storage was allocated by rle_row_alloc, or by use of same
 *  algorithm, at least.
 * Algorithm:
 *  free scanp[0] and scanp.
 */
void
rle_row_free( the_hdr, scanp )
rle_hdr *the_hdr;
rle_pixel **scanp;
{
    int i;

    if ( the_hdr->alpha )
    scanp--;
    for ( i = 0; i < the_hdr->ncolors + the_hdr->alpha; i++ )
    if ( scanp[i] != 0 )
    {
        free( (char *)scanp[i] );
        break;
    }
    free( (char *)scanp );
}