Moved --extract to its own utility

fdsextract now handles all extraction stuff.  This utility also has more
functionality.  There are options to extract a single side, a single
file on a single side, and an address range from a single file from a
single side.  Files and sides are 0-indexed.

Makefile

@@ -1,6 +1,7 @@
 
 CMDS= \
-	  bin/fdslist
+	  bin/fdslist \
+	  bin/fdsextract
 
 all: bin $(CMDS)
 

cmd/fdsextract.go

@@ -0,0 +1,155 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"strconv"
+
+	"github.com/alexflint/go-arg"
+
+	"git.zorchenhimer.com/zorchenhimer/go-fds"
+)
+
+type Arguments struct {
+	Input string `arg:"positional,required"`
+
+	// for getting a specific file
+	Side int `arg:"--side" default:"-1"`
+
+	FileNum int `arg:"--file-num" default:"-1"`
+	Range string `arg:"--range"`
+}
+
+func main() {
+	args := &Arguments{}
+	arg.MustParse(args)
+
+	err := run(args)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func run(args *Arguments) error {
+	rom, err := fds.ReadRomFile(args.Input)
+	if err != nil {
+		return err
+	}
+
+	outdir := strings.TrimSuffix(args.Input, filepath.Ext(args.Input))
+	err = os.MkdirAll(outdir, 0775)
+	if err != nil {
+		return err
+	}
+
+	if args.Side >= 0 && args.FileNum == -1 {
+		if args.Side >= len(rom.Sides) {
+			return fmt.Errorf("--side out of range")
+		}
+
+		num := 0
+		for _, s := range rom.Sides[:args.Side] {
+			num += len(s.Files)
+		}
+
+		side := rom.Sides[args.Side]
+		sideName := fmt.Sprintf("Side%d", side.Header.PhysicalSide)
+		for _, file := range side.Files {
+			fileName := filepath.Join(outdir, fmt.Sprintf("%03d_%s_%02d_%02X", num, sideName, file.Number, file.Id))
+			err := os.WriteFile(fileName, file.Data, 0664)
+			if err != nil {
+				return err
+			}
+			num++
+		}
+		return nil
+	} else if args.Side >= 0 && args.FileNum >= 0 {
+		if args.Side >= len(rom.Sides) {
+			return fmt.Errorf("--side out of range")
+		}
+
+		side := rom.Sides[args.Side]
+
+		if len(side.Files) <= args.FileNum {
+			return fmt.Errorf("--file-num out of range; %d", len(side.Files))
+		}
+
+		sideName := fmt.Sprintf("Side%d", side.Header.PhysicalSide)
+		file := side.Files[args.FileNum]
+
+		var start int
+		var end int
+		if args.Range != "" {
+			start, end, err = parseRange(args.Range)
+			if err != nil {
+				return err
+			}
+
+			fmt.Printf("start: %04X\nend: %04X\n", start, end)
+
+			start = start - int(file.Address)
+			end = end - int(file.Address)
+
+			fmt.Printf("start: %04X\nend: %04X\n", start, end)
+
+		} else {
+			start = 0
+			end = file.Size
+		}
+
+		fileName := filepath.Join(outdir, fmt.Sprintf("%03d_%s_%02d_%02X", args.FileNum, sideName, file.Number, file.Id))
+		fmt.Println("fileName:", fileName)
+		err := os.WriteFile(fileName, file.Data[start:end], 0664)
+		if err != nil {
+			return err
+		}
+		return nil
+
+	} else if args.Range != "" && (args.Side < 0 || args.FileNum < 0) {
+		return fmt.Errorf("--range cannot be given alone")
+	}
+
+	num := 0
+	for _, side := range rom.Sides {
+		sideName := fmt.Sprintf("Side%d", side.Header.PhysicalSide)
+		for _, file := range side.Files {
+			fileName := filepath.Join(outdir, fmt.Sprintf("%03d_%s_%02d_%02X", args.FileNum, sideName, file.Number, file.Id))
+			err := os.WriteFile(fileName, file.Data, 0664)
+			if err != nil {
+				return err
+			}
+			num++
+		}
+	}
+
+	return nil
+}
+
+// $6000-$5000
+func parseRange(input string) (int, int, error) {
+	splits := strings.Split(input, "-")
+	if len(splits) != 2 {
+		return 0, 0, fmt.Errorf("invalid range: %q", input)
+	}
+	fmt.Println("splits:", splits)
+
+	splits[0] = strings.Replace(splits[0], "$", "0x", 1)
+	splits[1] = strings.Replace(splits[1], "$", "0x", 1)
+
+	fmt.Println("splits:", splits)
+
+	start, err := strconv.ParseInt(splits[0], 0, 64)
+	if err != nil {
+		return 0, 0, fmt.Errorf("invalid range: %q", input)
+	}
+
+	end, err := strconv.ParseInt(splits[1], 0, 64)
+	if err != nil {
+		return 0, 0, fmt.Errorf("invalid range: %q", input)
+	}
+
+	return int(start), int(end), nil
+}