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ben-blinkenlights/ubb-vga/ppm.c
Werner Almesberger 080978ade0 ubb-vga2: added support for showing a PPM image
- Makefile (OBJS): added ppm.o and ppmimg.o
- ppm.h (load_ppm), ppm.c: PPM file loader, adapted from
  eda-tools/schhist/ppmdiff/ppmdiff.c
- ubb-vga.h (img_name, ppmimg), ppmimg.c: PPM image to frame buffer
  converter
- ubb-vga2.c (usage, main): the threshold is now set with the option -l
- ubb-vga2.c (usage, main): if a second argument is given, treat it as
  a PPM file
- ubb-vga2.c (usage): also documented option -t
2011-04-28 00:38:13 -03:00

98 lines
2.0 KiB
C

/*
* ppm.c - Load a PPM image
*
* Written 2010-2011 by Werner Almesberger
* Copyright 2010-2011 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 <string.h>
#include "ppm.h"
static char *fgets_comment(char *line, int n, FILE *file)
{
do {
if (!fgets(line, n, file))
return NULL;
}
while (*line == '#');
return line;
}
uint8_t *load_ppm(const char *name, int *x, int *y)
{
FILE *file;
char line[100];
int this_x, this_y, depth;
int n;
uint8_t *img;
file = fopen(name, "r");
if (!file) {
perror(name);
exit(1);
}
if (!fgets_comment(line, sizeof(line), file)) {
fprintf(stderr, "can't read file type\n");
exit(1);
}
if (strcmp(line, "P6\n")) {
fprintf(stderr, "file type must be P6, not %s", line);
exit(1);
}
if (!fgets_comment(line, sizeof(line), file)) {
fprintf(stderr, "can't read resolution\n");
exit(1);
}
if (sscanf(line, "%d %d", &this_x, &this_y) != 2) {
fprintf(stderr, "can't parse resolution: %s", line);
exit(1);
}
if (*x || *y) {
if (*x != this_x || *y != this_y) {
fprintf(stderr,
"resolution changed from %dx%d to %dx%d\n",
*x, *y, this_x, this_y);
exit(1);
}
} else {
*x = this_x;
*y = this_y;
}
if (!fgets_comment(line, sizeof(line), file)) {
fprintf(stderr, "can't read depth\n");
exit(1);
}
if (sscanf(line, "%d", &depth) != 1) {
fprintf(stderr, "can't parse depth: %s", line);
exit(1);
}
if (depth != 255) {
fprintf(stderr, "depth must be 255, not %d\n", depth);
exit(1);
}
n = *x**y*3;
img = malloc(n);
if (!img) {
perror("malloc");
exit(1);
}
if (fread(img, 1, n, file) != n) {
fprintf(stderr, "can't read %d bytes\n", n);
exit(1);
}
fclose(file);
return img;
}