Add (NOP) prodos factory and DiskBlockDevice

The prodos operator factory functions just return errors for now,
until Catalog is implemented.

lib/disk/dev.go

@@ -0,0 +1,67 @@
+// Copyright © 2017 Zellyn Hunter <zellyn@gmail.com>
+
+// dev.go contains logic for reading ".po" disk images.
+
+package disk
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+)
+
+// Dev represents a .po disk image.
+type Dev struct {
+	data   []byte // The actual data in the file
+	blocks uint16 // Number of blocks
+}
+
+var _ BlockDevice = (*Dev)(nil)
+
+// LoadDev loads a .po image from a file.
+func LoadDev(filename string) (Dev, error) {
+	bb, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return Dev{}, err
+	}
+	if len(bb)%512 != 0 {
+		return Dev{}, fmt.Errorf("expected file %q to contain a multiple of 512 bytes, but got %d", filename, len(bb))
+	}
+	return Dev{
+		data:   bb,
+		blocks: uint16(len(bb) / 512),
+	}, nil
+}
+
+// Empty creates a .po image that is all zeros.
+func EmptyDev(blocks uint16) Dev {
+	return Dev{
+		data:   make([]byte, 512*int(blocks)),
+		blocks: blocks,
+	}
+}
+
+// ReadBlock reads a single block from the device. It always returns
+// 512 byes.
+func (d Dev) ReadBlock(index uint16) (Block, error) {
+	var b Block
+	copy(b[:], d.data[int(index)*512:int(index+1)*512])
+	return b, nil
+}
+
+// WriteBlock writes a single block to a device. It expects exactly
+// 512 bytes.
+func (d Dev) WriteBlock(index uint16, data Block) error {
+	copy(d.data[int(index)*512:int(index+1)*512], data[:])
+	return nil
+}
+
+// Blocks returns the number of blocks in the device.
+func (d Dev) Blocks() uint16 {
+	return d.blocks
+}
+
+// Write writes the device contents to the given file.
+func (d Dev) Write(w io.Writer) (n int, err error) {
+	return w.Write(d.data)
+}

lib/disk/disk.go

@@ -166,15 +166,125 @@ func OpenDisk(filename string) (SectorDisk, error) {
 	return nil, fmt.Errorf("Unimplemented/unknown disk file extension %q", ext)
 }
 
+// OpenDev opens a device image by filename.
+func OpenDev(filename string) (BlockDevice, error) {
+	ext := strings.ToLower(path.Ext(filename))
+	switch ext {
+	case ".po":
+		return LoadDev(filename)
+	}
+	return nil, fmt.Errorf("Unimplemented/unknown device file extension %q", ext)
+}
+
 // Open opens a disk image by filename, returning an Operator.
 func Open(filename string) (Operator, error) {
 	sd, err := OpenDisk(filename)
-	if err != nil {
+	if err == nil {
-		return nil, err
+		var op Operator
+		op, err = OperatorForDisk(sd)
+		if err == nil {
+			return op, nil
 		}
-	op, err := OperatorForDisk(sd)
+	}
-	if err != nil {
+
-		return nil, err
+	dev, err2 := OpenDev(filename)
+	if err2 == nil {
+		var op Operator
+		op, err2 = OperatorForDevice(dev)
+		if err2 != nil {
+			return nil, err2
 		}
 		return op, nil
 	}
+
+	return nil, err
+}
+
+type DiskBlockDevice struct {
+	lsd    LogicalSectorDisk
+	blocks uint16
+}
+
+// BlockDeviceFromSectorDisk creates a ProDOS block device from a
+// SectorDisk. It reads maps ProDOS to physical sectors.
+func BlockDeviceFromSectorDisk(sd SectorDisk) (BlockDevice, error) {
+	lsd, err := NewMappedDisk(sd, ProDOSLogicalToPhysicalSectorMap)
+	if err != nil {
+		return nil, err
+	}
+
+	return DiskBlockDevice{
+		lsd:    lsd,
+		blocks: uint16(lsd.Tracks()) / 2 * uint16(lsd.Sectors()),
+	}, nil
+}
+
+// ReadBlock reads a single block from the device. It always returns
+// 512 byes.
+func (dbv DiskBlockDevice) ReadBlock(index uint16) (Block, error) {
+	var b Block
+	if index >= dbv.blocks {
+		return b, fmt.Errorf("device has %d blocks; tried to read block %d (index=%d)", dbv.blocks, index+1, index)
+	}
+	i := int(index) * 2
+	sectors := int(dbv.lsd.Sectors())
+
+	track0 := i / sectors
+	sector0 := i % sectors
+	sector1 := sector0 + 1
+	track1 := track0
+	if sector1 == sectors {
+		sector1 = 0
+		track1++
+	}
+
+	b0, err := dbv.lsd.ReadLogicalSector(byte(track0), byte(sector0))
+	if err != nil {
+		return b, fmt.Errorf("error reading first half of block %d (t:%d s:%d): %v", index, track0, sector0, err)
+	}
+	b1, err := dbv.lsd.ReadLogicalSector(byte(track1), byte(sector1))
+	if err != nil {
+		return b, fmt.Errorf("error reading second half of block %d (t:%d s:%d): %v", index, track1, sector1, err)
+	}
+	copy(b[:256], b0)
+	copy(b[256:], b1)
+	return b, nil
+}
+
+// WriteBlock writes a single block to a device. It expects exactly
+// 512 bytes.
+func (dbv DiskBlockDevice) WriteBlock(index uint16, data Block) error {
+	if index >= dbv.blocks {
+		return fmt.Errorf("device has %d blocks; tried to read block %d (index=%d)", dbv.blocks, index+1, index)
+	}
+	i := int(index) * 2
+	sectors := int(dbv.lsd.Sectors())
+
+	track0 := i / sectors
+	sector0 := i % sectors
+	sector1 := sector0 + 1
+	track1 := track0
+	if sector1 == sectors {
+		sector1 = 0
+		track1++
+	}
+
+	if err := dbv.lsd.WriteLogicalSector(byte(track0), byte(sector0), data[:256]); err != nil {
+		return fmt.Errorf("error writing first half of block %d (t:%d s:%d): %v", index, track0, sector0, err)
+	}
+	if err := dbv.lsd.WriteLogicalSector(byte(track1), byte(sector1), data[256:]); err != nil {
+		return fmt.Errorf("error writing second half of block %d (t:%d s:%d): %v", index, track1, sector1, err)
+	}
+
+	return nil
+}
+
+// Blocks returns the number of blocks on the device.
+func (dbv DiskBlockDevice) Blocks() uint16 {
+	return dbv.blocks
+}
+
+// Write writes the device contents to the given Writer.
+func (dbv DiskBlockDevice) Write(w io.Writer) (int, error) {
+	return dbv.lsd.Write(w)
+}

lib/disk/ops.go

@@ -91,3 +91,41 @@ func OperatorForDisk(sd SectorDisk) (Operator, error) {
 	sort.Strings(names)
 	return nil, fmt.Errorf("Cannot find a disk operator matching the given disk image (tried %s)", strings.Join(names, ", "))
 }
+
+// deviceOperatorFactory is the type of functions that accept a BlockDevice,
+// and may return an Operator interface to operate on it.
+type deviceOperatorFactory func(BlockDevice) (Operator, error)
+
+// deviceOperatorFactories is the map of currently-registered device
+// operator factories.
+var deviceOperatorFactories map[string]deviceOperatorFactory
+
+func init() {
+	deviceOperatorFactories = make(map[string]deviceOperatorFactory)
+}
+
+// RegisterDeviceOperatorFactory registers a device operator factory with
+// the given name: a function that accepts a BlockDevice, and may
+// return an Operator. It doesn't lock deviceOperatorFactories: it is
+// expected to be called only from package `init` functions.
+func RegisterDeviceOperatorFactory(name string, factory deviceOperatorFactory) {
+	deviceOperatorFactories[name] = factory
+}
+
+// OperatorForDevice returns an Operator for the given BlockDevice, if possible.
+func OperatorForDevice(sd BlockDevice) (Operator, error) {
+	if len(deviceOperatorFactories) == 0 {
+		return nil, errors.New("Cannot find an operator matching the given device image (none registered)")
+	}
+	for _, factory := range deviceOperatorFactories {
+		if operator, err := factory(sd); err == nil {
+			return operator, nil
+		}
+	}
+	names := make([]string, 0, len(deviceOperatorFactories))
+	for name := range deviceOperatorFactories {
+		names = append(names, `"`+name+`"`)
+	}
+	sort.Strings(names)
+	return nil, fmt.Errorf("Cannot find a device operator matching the given device image (tried %s)", strings.Join(names, ", "))
+}

lib/prodos/prodos.go

@@ -590,3 +590,29 @@ func (o operator) PutFile(fileInfo disk.FileInfo, overwrite bool) (existed bool,
 func (o operator) Write(w io.Writer) (int, error) {
 	return o.dev.Write(w)
 }
+
+// deviceOperatorFactory is the factory that returns prodos operators
+// given device images.
+func deviceOperatorFactory(bd disk.BlockDevice) (disk.Operator, error) {
+	op := operator{dev: bd}
+	_, err := op.Catalog("")
+	if err != nil {
+		return nil, fmt.Errorf("Cannot read catalog. Underlying error: %v", err)
+	}
+	return op, nil
+}
+
+// diskOperatorFactory is the factory that returns dos3 operators
+// given disk images.
+func diskOperatorFactory(sd disk.SectorDisk) (disk.Operator, error) {
+	bd, err := disk.BlockDeviceFromSectorDisk(sd)
+	if err != nil {
+		return nil, err
+	}
+	return deviceOperatorFactory(bd)
+}
+
+func init() {
+	disk.RegisterDeviceOperatorFactory(operatorName, deviceOperatorFactory)
+	disk.RegisterDiskOperatorFactory(operatorName, diskOperatorFactory)
+}

main.go

@@ -7,6 +7,7 @@ import (
 
 	// Import disk operator factories for DOS3 and Super-Mon
 	_ "github.com/zellyn/diskii/lib/dos3"
+	_ "github.com/zellyn/diskii/lib/prodos"
 	_ "github.com/zellyn/diskii/lib/supermon"
 )