cameo: added KiCad Gerber input and path merging

- Makefile (OBJS): added gerber.o
- cameo.c (usage, main): new option -g to process input a KiCad Gerber
- gerber.h, gerber.c (gerber_read): parse Gerber files as generated by KiCad
- path.h, path.c (path_reverse_inplace, points_eq, attr_eq, path_connect):
  merge sets of paths with equal endpoints into single paths

cameo/gerber.c

@@ -0,0 +1,93 @@
+/*
+ * gerber.c - Gerber file input
+ *
+ * Written 2010 by Werner Almesberger
+ * Copyright 2010 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.
+ */
+
+/*
+ * Note: this is limited to the Gerber produced by KiCad for the PCB Edge
+ * layer. Furthermore, we ignore the tool diameter for now.
+ *
+ * The relevant details are nicely explained at
+ * http://www.pcbmilling.com/Examples of Gerber and Excellon Data Files.htm
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "path.h"
+#include "gerber.h"
+
+
+/* KiCad Gerber uses 0.1 mil units */
+
+#define	KU2MM(in)	((in)/10000.0*25.4)
+
+
+struct path *gerber_read(const char *name, double r_tool_default)
+{
+	FILE *file;
+	int lineno = 0;
+	char buf[1024];
+	struct path *paths = NULL, **anchor = &paths, *path = NULL;
+	int start_x = 0, start_y = 0;
+	int x, y, d;
+
+	file = name ? fopen(name, "r") : stdin;
+	if (!file) {
+		perror(name);
+		exit(1);
+	}
+
+	while (fgets(buf, sizeof(buf), file)) {
+		lineno++;
+		if (!strncmp(buf, "%FS", 3)) {
+			if (strcmp(buf, "%FSLAX34Y34*%\n")) {
+				fprintf(stderr,
+				    "unrecognized format %s\n", buf);
+				exit(1);
+			}
+			continue;
+		}
+		if (!strncmp(buf, "%MO", 3)) {
+			if (strcmp(buf, "%MOIN*%\n")) {
+				fprintf(stderr,
+				    "unrecognized mode %s\n", buf);
+				exit(1);
+			}
+			continue;
+		}
+		if (sscanf(buf, "X%dY%dD%d*\n", &x, &y, &d) != 3)
+			continue;
+		x = KU2MM(x);
+		y = KU2MM(y);
+		switch (d) {
+		case 1:
+			if (!path) {
+				path = path_new(r_tool_default);
+				*anchor = path;
+				anchor = &path->next;
+				path_add(path, start_x, start_y, 0);
+			}
+			path_add(path, x, y, 0);
+			break;
+		case 2:
+			path = NULL;
+			start_x = x;
+			start_y = y;
+			break;
+		default:
+			fprintf(stderr, "don't recognize D%d\n", d);
+			exit(1);
+		}
+	}
+	fclose(file);
+	return path_connect(paths);
+}