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

ubb-vga/Makefile

@@ -3,7 +3,7 @@ CC=mipsel-linux-gcc
 
 CFLAGS=-Wall -g -O9 -march=mips32
 LDFLAGS=-lm
-OBJS=ubb-vga2.o grabfb.o tstimg.o
+OBJS=ubb-vga2.o grabfb.o tstimg.o ppm.o ppmimg.o
 
 .PHONY:		all asm sch clean spotless
 

ubb-vga/ppm.c

@@ -0,0 +1,97 @@
+/*
+ * 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;
+}

ubb-vga/ppm.h

@@ -0,0 +1,23 @@
+/*
+ * ppm.h - Load 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.
+ */
+
+
+#ifndef	PPM_H
+#define	PPM_H
+
+#include <stdint.h>
+
+
+uint8_t *load_ppm(const char *name, int *x, int *y);
+
+#endif /* !PPM_H */
+

ubb-vga/ppmimg.c

@@ -0,0 +1,63 @@
+/*
+ * 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))*0x11;
+}
+
+
+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);
+}

ubb-vga/ubb-vga.h

@@ -26,10 +26,20 @@
 void *map(off_t addr, size_t size);
 
 
+/* grabfb.c */
+
 extern uint8_t thres;
 
 void grabfb(void *f, int xres, int yres);
 
+/* tstimg.c */
+
 void tstimg(void *f, int xres, int yres);
 
+/* ppmimg.c */
+
+extern char *img_name;
+
+void ppmimg(void *f, int xres, int yres);
+
 #endif /* !UBB_VGA_H */

ubb-vga/ubb-vga2.c

@@ -410,9 +410,11 @@ static void session(void (*gen)(void *fb, int xres, int yres), int frames)
 static void usage(const char *name)
 {
 	fprintf(stderr,
-"usage: %s frames [threshold]\n\n"
-"  frames     number of frames to display\n"
-"  threshold  channel on/off threshold\n\n"
+"usage: %s [-l threshold] [-t] frames [file]\n\n"
+"  frames  number of frames to display\n"
+"  file    PPM file\n\n"
+"  -l threshold  channel on/off threshold\n"
+"  -t            generate a test image\n"
     , name);
 	exit(1);
 }
@@ -424,8 +426,11 @@ int main(int argc, char *const *argv)
 	int frames;
 	int c;
 
-	while ((c = getopt(argc, argv, "t")) != EOF)
+	while ((c = getopt(argc, argv, "l:t")) != EOF)
 		switch (c) {
+		case 'l':
+			thres = atoi(optarg);
+			break;
 		case 't':
 			gen = tstimg;
 			break;
@@ -435,7 +440,8 @@ int main(int argc, char *const *argv)
 
 	switch (argc-optind) {
 	case 2:
-		thres = atoi(argv[optind+1]);
+		img_name = argv[optind+1];
+		gen = ppmimg;
 		/* fall through */
 	case 1:
 		frames = atoi(argv[optind]);