add minmax

cmd/minmax/README

@@ -0,0 +1,3 @@
+minmax
+
+A quick tool to calculate minmax codes if needed for uLisp.

cmd/minmax/minmax.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strconv"
+)
+
+var kinds = map[string]int{
+	"sym": 0,
+	"tf":  1,
+	"fn":  2,
+	"sp":  3,
+}
+
+func dieIf(err error) {
+	if err == nil {
+		return
+	}
+	fmt.Fprintf(os.Stderr, "[!] %s\n", err)
+	os.Exit(1)
+}
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: minmax type min max\n")
+	fmt.Fprintf(os.Stderr, "    type is one of fn, sp, sym, tf\n")
+	os.Exit(1)
+}
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() != 3 {
+		usage()
+	}
+
+	kind, ok := kinds[flag.Arg(0)]
+	if !ok {
+		usage()
+	}
+
+	min, err := strconv.Atoi(flag.Arg(1))
+	dieIf(err)
+
+	max, err := strconv.Atoi(flag.Arg(2))
+	dieIf(err)
+
+	code := kind << 6
+	code += (min << 3)
+	code += max
+	fmt.Printf("%0o\n", code)
+}