source: trunk/src/testing/app/bitplay/libimage/rdwr.c @ 4

/******************************************************************************
 * SAGE - Scalable Adaptive Graphics Environment
 *
 * Copyright (C) 2004 Electronic Visualization Laboratory,
 * University of Illinois at Chicago
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following disclaimer
 *    in the documentation and/or other materials provided with the distribution.
 *  * Neither the name of the University of Illinois at Chicago nor
 *    the names of its contributors may be used to endorse or promote
 *    products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Direct questions, comments etc about SAGE to http://www.evl.uic.edu/cavern/forum/
 *
 *****************************************************************************/

/*
 *      img_seek, img_write, img_read, img_optseek -
 *
 *                              Paul Haeberli - 1984
 *
 */
#include        <stdio.h>
#include        <errno.h>
#include        <unistd.h>
#include        "image.h"

int img_seek( IMAGE *image, int y, int z )
{
    if(img_badrow(image,y,z)) {
        i_errhdlr("imglib: row number out of range\n");
        return EOF;
    }
    image->x = 0;
    image->y = y;
    image->z = z;
    if(ISVERBATIM(image->type)) {
        switch(image->dim) {
            case 1:
                return img_optseek(image, 512L);
            case 2:
                return img_optseek(image,512L+(y*image->xsize)*BPP(image->type));
            case 3:
                return img_optseek(image,
                    512L+(y*image->xsize+z*image->xsize*image->ysize)*
                                                        BPP(image->type));
            default:
                i_errhdlr("img_seek: wierd dim\n");
                break;
        }
    } else if(ISRLE(image->type)) {
        switch(image->dim) {
            case 1:
                return img_optseek(image, image->rowstart[0]);
            case 2:
                return img_optseek(image, image->rowstart[y]);
            case 3:
                return img_optseek(image, image->rowstart[y+z*image->ysize]);
            default:
                i_errhdlr("img_seek: wierd dim\n");
                break;
        }
    } else
        i_errhdlr("img_seek: wierd image type\n");
    return EOF;
}

int img_badrow( IMAGE *image, int y, int z )
{
    if(y>=image->ysize || z>=image->zsize)
        return 1;
    else
        return 0;
}

int img_write( IMAGE *image, char *buffer, long count )
{
    long retval;

    retval =  write(image->file,buffer,count);
    if(retval == count)
        image->offset += count;
    else
        image->offset = -1;
    return retval;
}

int img_read( IMAGE *image, char *buffer, long count)
{
    long retval;

    retval =  read(image->file,buffer,count);
    if(retval == count)
        image->offset += count;
    else
        image->offset = -1;
    return retval;
}

unsigned long img_optseek( IMAGE *image, unsigned long offset )
{
    if(image->offset != offset) {
       image->offset = offset;
       return lseek(image->file,offset,0);
   }
   return offset;
}