ben-blinkenlights/ubb-vga/ppmimg.c

/*
 * ppmimg.c - Convert a PPM image
 *
 * Written 2011 by Werner Almesberger
 * Copyright 2011 Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>

#include "ppm.h"
#include "ubb-vga.h"


char *img_name;


static uint8_t pattern(int r, int g, int b)
{
	return (r ? R_VAL : 0) | (g ? G_VAL : 0) | (b ? B_VAL : 0);
}


static void convert(uint8_t *f, int xres, int yres, uint8_t *ppm)
{
	int x, y;
	uint8_t v, last = 0;

	for (y = 0; y != yres; y++)
		for (x = 0; x != xres; x++) {
			v = pattern(ppm[0] >= thres, ppm[1] >= thres,
			    ppm[2] >= thres);
			if (x & 1) {
				*f++ = last | v;
			} else {
				last = v << 4;
			}
			ppm += 3;
		}
}


void ppmimg(void *f, int xres, int yres)
{
	uint8_t *ppm;
	int xr = 0, yr = 0;

	ppm = load_ppm(img_name, &xr, &yr);
	if (xr != xres || yr != yres) {
		fprintf(stderr, "image is %dx%d, display is %dx%d\n",
		    xr, yr, xres, yres);
		exit(1);
	}
	convert(f, xres, yres, ppm);
	free(ppm);
}