working on character ROM generation

INSTALL.md

@@ -0,0 +1,3 @@
+brew install sdl sdl_image sdl_mixer sdl_ttf
+go get github.com/zellyn/Go-SDL/sdl --with-x11-driver
+go get github.com/zellyn/Go-SDL/sdl/audio

a2/charrom.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"io/ioutil"
+
+	"github.com/gonuts/commander"
+	"github.com/zellyn/goapple2/videoscan"
+)
+
+var cmdCharROM = &commander.Command{
+	Run:       runCharROM,
+	UsageLine: "charrom infile outfile",
+	Short:     "convert apple II character ROMs to text and back",
+	Long: `
+CharROM is a simple character ROM conversion utility.
+`,
+}
+
+var decompile bool
+var reverse bool
+
+func init() {
+	cmdCharROM.Flag.BoolVar(&decompile, "d", false, "decompile: convert from ROM to text.")
+	cmdCharROM.Flag.BoolVar(&reverse, "r", false, "reverse: put bits in opposite order.")
+}
+
+func runCharROM(cmd *commander.Command, args []string) error {
+	if len(args) != 2 {
+		cmd.Usage()
+		return nil
+	}
+
+	in, err := ioutil.ReadFile(args[0])
+	if err != nil {
+		panic("Cannot read file: " + args[0])
+	}
+
+	if decompile {
+		out := videoscan.BytesToText(in, reverse)
+		err := ioutil.WriteFile(args[1], out, 0644)
+		return err
+	}
+
+	out, err := videoscan.TextToBytes(in, reverse)
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(args[1], out, 0644)
+	return err
+}

a2/main.go

@@ -16,6 +16,7 @@ func init() {
 		Subcommands: []*commander.Command{
 			cmdDisasm,
 			cmdDiskConvert,
+			cmdCharROM,
 		},
 		Flag: *flag.NewFlagSet("a2", flag.ExitOnError),
 	}

videoscan/convert.go

@@ -0,0 +1,94 @@
+// convert.go contains routines to convert from character ROMs to text and back.
+package videoscan
+
+import (
+	"fmt"
+	"strings"
+)
+
+var chars = []rune{'.', '#'}
+
+func reverseByte(in byte) byte {
+	hi := in & 0x80
+	var out byte
+	for i := 0; i < 7; i++ {
+		out = out << 1
+		out = out | in&1
+		in = in >> 1
+	}
+	out |= hi
+	return out
+}
+
+func BytesToText(rom []byte, reverse bool) []byte {
+	result := []byte{}
+	for i, b := range rom {
+		if reverse {
+			b = reverseByte(b)
+		}
+		if i > 0 && i%8 == 0 {
+			result = append(result, '\n')
+		}
+		if b >= 0x80 {
+			result = append(result, 'i')
+		} else {
+			result = append(result, 'n')
+		}
+		result = append(result, ' ')
+		for i := 0; i < 7; i++ {
+			result = append(result, byte(chars[b&1]))
+			b = b >> 1
+		}
+		result = append(result, '\n')
+	}
+	return result
+}
+
+func TextToBytes(text []byte, reverse bool) ([]byte, error) {
+	result := []byte{}
+	lines := strings.Split(string(text), "\n")
+	for i, l := range lines {
+		l = strings.TrimSpace(l)
+		lines[i] = l
+		if i != 0 && i%9 == 8 {
+			if l != "" {
+				return nil, fmt.Errorf("line %d: expected empty line, got '%s'", i+1, l)
+			}
+			continue
+		}
+		if len(l) != 9 {
+			return nil, fmt.Errorf("line %d: expected 9 characters, got %d: '%s'", i+1, len(l), l)
+		}
+
+		var hi byte
+		switch l[0] {
+		case 'i':
+			hi = 0x80
+		case 'n':
+		default:
+			return nil, fmt.Errorf("line %d: should start with 'n' or 'i'; got '%s'", i+1, l[0])
+		}
+
+		if l[1] != ' ' {
+			return nil, fmt.Errorf("line %d: second char should be space; got '%s'", i+1, l[1])
+		}
+		var b byte
+		var bit byte = 1
+		for _, c := range l[2:] {
+			switch c {
+			case chars[0]: // do nothing
+			case chars[1]:
+				b |= bit
+			default:
+				return nil, fmt.Errorf("line %d: expected character: '%s'", i+1, c)
+			}
+			bit <<= 1
+		}
+		b |= hi
+		if reverse {
+			b = reverseByte(b)
+		}
+		result = append(result, b)
+	}
+	return result, nil
+}