1 files changed, 95 insertions, 0 deletions
diff --git a/deg.c b/deg.c
new file mode 100644
index 0000000..8a480e3
--- /dev/null
+++ b/deg.c
@@ -0,0 +1,95 @@
+#include <u.h>
+#include <libc.h>
+
+typedef struct DMS DMS;
+struct DMS
+{
+	vlong	d;	/* degrees (°) */
+	vlong	m;	/* minutes (') */
+	double	s;	/* seconds (") */
+};
+
+#pragma varargck type "D" DMS
+int
+Dfmt(Fmt *f)
+{
+	DMS dms;
+
+	dms = va_arg(f->args, DMS);
+	if(dms.d < 0){
+		dms.m = -dms.m;
+		dms.s = -dms.s;
+	}
+	return fmtprint(f, "%lld°%lld'%g\"", dms.d, dms.m, dms.s);
+}
+
+DMS
+deg2dms(double deg)
+{
+	DMS dms;
+
+	dms.d = deg;
+	deg -= dms.d;
+	dms.m = deg = deg*60;
+	deg -= dms.m;
+	dms.s = deg*60;
+	return dms;
+}
+
+double
+dms2deg(DMS dms)
+{
+	return dms.d + dms.m/60.0 + dms.s/3600.0;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s deg\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	DMS dms;
+	Rune r;
+	char *s;
+	double degs;
+
+	fmtinstall('D', Dfmt);
+	ARGBEGIN{
+	default: usage();
+	}ARGEND;
+	if(argc != 1)
+		usage();
+	s = argv[0];
+	degs = strtod(s, &s);
+	if(*s != 0){
+		memset(&dms, 0, sizeof(DMS));
+		while(*s != 0){
+			s += chartorune(&r, s);
+			switch(r){
+			case L'°':
+				dms.d = degs;
+				degs = strtod(s, &s);
+				break;
+			case '\'':
+				dms.m = dms.d < 0? -degs: degs;
+				degs = strtod(s, &s);
+				break;
+			case '\"':
+				dms.s = dms.d < 0? -degs: degs;
+				break;
+			default:
+				sysfatal("unknown format");
+			}
+		}
+		degs = dms2deg(dms);
+		print("%g°\n", degs);
+	}else{
+		dms = deg2dms(degs);
+		print("%D\n", dms);
+	}
+	exits(0);
+}