cae-tools/cameo/gerber.c

/*
 * gerber.c - Gerber file input
 *
 * Written 2010, 2013, 2015, 2017 by Werner Almesberger
 * Copyright 2010, 2013, 2015, 2017 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 <math.h>

#include "path.h"
#include "gerber.h"


static double scale; /* KiCad Gerber units */

#define	KU2MM(in)	((in)/scale)


/*
 * @@@ Very crude implementation of G03. Tested with only one example in
 * KiCad.
 *
 * Command definition from:
 * http://www.rulabinsky.com/cavd/text/chapa.html
 */

static void arc(struct path *path, const char *buf, double ax, double ay)
{
	int xi, yi, cxi, cyi;
	double bx, by, cx, cy;
	double r, a, b, t;
	double x, y;

	if (sscanf(buf, "G03X%dY%dI%dJ%dD01*\n", &xi, &yi, &cxi, &cyi) != 4)
		return;
	bx = KU2MM(xi);
	by = KU2MM(yi);
	cx = KU2MM(cxi);
	cy = KU2MM(cyi);
	r = hypot(cx, cy);
	cx += ax;
	cy += ay;
	a = atan2(ay-cy, ax-cx);
	b = atan2(by-cy, bx-cx);
	if (a > b)
		b += 2*M_PI;
//fprintf(stderr, "@(%g,%g) (%g,%g)-(%g-%g) %g %g\n",
//  cx, cy, ax, ay, bx, by, a/M_PI*180, b/M_PI*180);
	for (t = a; t <= b; t += M_PI/180) {	/* @@@ 1 deg increment */
		x = cx+r*cos(t);
		y = cy+r*sin(t);
		path_add(path, x, y, 0);
	}
	path_add(path, bx, by, 0);
}


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;
	double start_x = 0, start_y = 0;
	int xi, yi, d;
	double x, y;

	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")) {
				scale = 10 * 1000;
			} else if (!strcmp(buf, "%FSLAX46Y46*%\n")) {
				scale = 1000 * 1000;
			} else {
				fprintf(stderr,
				    "unrecognized format %s\n", buf);
				exit(1);
			}
			continue;
		}
		/* @@@ we assume that %MO follows %FS */
		if (!strncmp(buf, "%MO", 3)) {
			if (!strcmp(buf, "%MOIN*%\n")) {
				scale /= 25.4;
			} else if (strcmp(buf, "%MOMM*%\n")) {
				fprintf(stderr,
				    "unrecognized mode %s\n", buf);
				exit(1);
			}
			continue;
		}
		if (!strncmp(buf, "G03", 3)) {
			if (path)
				abort();
			path = path_new(r_tool_default, name);
			*anchor = path;
			anchor = &path->next;
			arc(path, buf, start_x, start_y);
			continue;
		}
		if (sscanf(buf, "X%dY%dD%d*\n", &xi, &yi, &d) != 3)
			continue;
		x = KU2MM(xi);
		y = KU2MM(yi);
		switch (d) {
		case 1:
			if (!path) {
				path = path_new(r_tool_default, name);
				*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);
}


static int gerber_do_write(FILE *file, const struct path *paths)
{
	const struct path *path;
	const struct point *p;

	fprintf(file,
"G04 Generated by cameo*\n"
"%%MOMM*%%\n"			// dimensions are in mm
"%%FSLAX33Y33*%%\n"		// no leading zeroes; absolute; 3 digits int,
				// 3 digits fractional
"G01*\n"			// linear interpolation
"%%ADD10C,0.01*%%\n"		// aperture D10, 10 um circle
"D10*\n");			// select D10

	for (path = paths; path; path = path->next)
		for (p = path->first; p; p = p->next)
			fprintf(file, "X%.0fY%.0fD0%u*\n",
			    p->x * 1000.0, p->y * 1000.0,
			    p == path->first ? 2 : 1);

	fprintf(file, "M02**\n");// end of file

	if (file == stdout) {
		if (fflush(file) == EOF)
			return 0;
	} else {
		if (fclose(file) < 0)
			return 0;
	}
	return 1;
}


void gerber_write(const char *name, const struct path *paths)
{
	FILE *file;

	file = name ? fopen(name, "w") : stdout;
	if (!file) {
		perror(name);
		exit(1);
	}
	if (!gerber_do_write(file, paths)) {
		perror(name ? name : "(stdout)");
		exit(1);
	}
}