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/*

 * Copyright (c) 2006 Ondrej Palkovsky

 * 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <sys/types.h>

#include <errno.h>

#include "ppm.h"

static void skip_whitespace(unsigned char **data)

{

retry:

    while (**data == ' ' || **data == '\t' || **data == '\n' ||

        **data == '\r')

        (*data)++;

    if (**data == '#') {

        while (1) {

            if (**data == '\n' || **data == '\r')

                break;

            (*data)++;

        }

        goto retry;

    }

}

static void read_num(unsigned char **data, unsigned int *num)

{

    *num = 0;

    while (**data >= '0' && **data <= '9') {

        *num *= 10;

        *num += **data - '0';

        (*data)++;

    }

}

int ppm_get_data(unsigned char *data, size_t dtsz, unsigned int *width,

    unsigned int *height)

{

    /* Read magic */

    if (data[0] != 'P' || data[1] != '6')

        return EINVAL;

    data+=2;

    skip_whitespace(&data);

    read_num(&data, width);

    skip_whitespace(&data);

    read_num(&data,height);

    return 0;

}

/** Draw PPM pixmap

 *

 * @param data Pointer to PPM data

 * @param datasz Maximum data size

 * @param sx Coordinate of upper left corner

 * @param sy Coordinate of upper left corner

 * @param maxwidth Maximum allowed width for picture

 * @param maxheight Maximum allowed height for picture

 * @param putpixel Putpixel function used to print bitmap

 */

int ppm_draw(unsigned char *data, size_t datasz, unsigned int sx,

    unsigned int sy, unsigned int maxwidth, unsigned int maxheight,

    putpixel_cb_t putpixel, void *vport)

{

    unsigned int width, height;

    unsigned int maxcolor;

    unsigned int i;

    unsigned int color;

    unsigned int coef;

    /* Read magic */

    if ((data[0] != 'P') || (data[1] != '6'))

        return EINVAL;

    data += 2;

    skip_whitespace(&data);

    read_num(&data, &width);

    skip_whitespace(&data);

    read_num(&data, &height);

    skip_whitespace(&data);

    read_num(&data, &maxcolor);

    data++;

    if ((maxcolor == 0) || (maxcolor > 255) || (width * height > datasz))

        return EINVAL;

    coef = 255 / maxcolor;

    if (coef * maxcolor > 255)

        coef -= 1;

    for (i = 0; i < width * height; i++) {

        /* Crop picture if we don't fit into region */

        if (i % width > maxwidth || i / width > maxheight) {

            data += 3;

            continue;

        }

        color = ((data[0] * coef) << 16) + ((data[1] * coef) << 8) +

            data[2] * coef;

        (*putpixel)(vport, sx + (i % width), sy + (i / width), color);

        data += 3;

    }

    return 0;

}