Merge pull request #3 from tjboldt/refactor

Change to reader/writer instead of file

README.md

@@ -151,4 +151,4 @@ ProDOS-Utilities -d ../Apple2-IO-RPi/RaspberryPi/Apple2-IO-RPi.hdv -c get -o Upd
 1060  NEXT PG
 1900  PRINT 
 2000  PRINT "Firmware Update Complete"
-```
+```

main.go

@@ -1,3 +1,11 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides a command line utility to read, write and delete
+// files and directories on a ProDOS drive image as well as format
+// new volumes
+
 package main
 
 import (
@@ -101,7 +109,7 @@ func main() {
 			fmt.Printf("Failed to open input file %s: %s", inFileName, err)
 			os.Exit(1)
 		}
-		err = prodos.WriteFile(file, pathName, fileType, auxType, inFile)
+		err = prodos.WriteFile(file, file, pathName, fileType, auxType, inFile)
 		if err != nil {
 			fmt.Printf("Failed to write file %s: %s", pathName, err)
 		}
@@ -136,7 +144,7 @@ func main() {
 			return
 		}
 		defer file.Close()
-		prodos.CreateVolume(file, volumeName, volumeSize)
+		prodos.CreateVolume(file, file, volumeName, volumeSize)
 	case "rm":
 		file, err := os.OpenFile(fileName, os.O_RDWR, 0755)
 		if err != nil {
@@ -144,7 +152,7 @@ func main() {
 			os.Exit(1)
 		}
 		defer file.Close()
-		prodos.DeleteFile(file, pathName)
+		prodos.DeleteFile(file, file, pathName)
 	default:
 		fmt.Printf("Invalid command: %s\n\n", command)
 		flag.PrintDefaults()

prodos/basic.go

@@ -1,3 +1,9 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides conversion between BASIC and text
+
 package prodos
 
 import (
@@ -115,6 +121,7 @@ var tokens = map[byte]string{
 	0xEA: "MID$",
 }
 
+// ConvertBasicToText converts AppleSoft BASIC to text
 func ConvertBasicToText(basic []byte) string {
 	var builder strings.Builder
 

prodos/bitmap.go

@@ -1,11 +1,19 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides access to volum bitmap on
+// a ProDOS drive image
+
 package prodos
 
 import (
-	"os"
+	"io"
 )
 
-func ReadVolumeBitmap(file *os.File) []byte {
+// ReadVolumeBitmap reads the volume bitmap from a ProDOS image
-	headerBlock := ReadBlock(file, 2)
+func ReadVolumeBitmap(reader io.ReaderAt) []byte {
+	headerBlock := ReadBlock(reader, 2)
 
 	volumeHeader := parseVolumeHeader(headerBlock)
 
@@ -23,7 +31,7 @@ func ReadVolumeBitmap(file *os.File) []byte {
 	}
 
 	for i := 0; i < totalBitmapBlocks; i++ {
-		bitmapBlock := ReadBlock(file, i+volumeHeader.BitmapStartBlock)
+		bitmapBlock := ReadBlock(reader, i+volumeHeader.BitmapStartBlock)
 
 		for j := 0; j < 512 && i*512+j < totalBitmapBytes; j++ {
 			bitmap[i*512+j] = bitmapBlock[j]
@@ -33,13 +41,25 @@ func ReadVolumeBitmap(file *os.File) []byte {
 	return bitmap
 }
 
-func writeVolumeBitmap(file *os.File, bitmap []byte) {
+// GetFreeBlockCount gets the number of free blocks on a ProDOS image
-	headerBlock := ReadBlock(file, 2)
+func GetFreeBlockCount(volumeBitmap []byte, totalBlocks int) int {
+	freeBlockCount := 0
+
+	for i := 0; i < totalBlocks; i++ {
+		if checkFreeBlockInVolumeBitmap(volumeBitmap, i) {
+			freeBlockCount++
+		}
+	}
+	return freeBlockCount
+}
+
+func writeVolumeBitmap(writer io.WriterAt, reader io.ReaderAt, bitmap []byte) {
+	headerBlock := ReadBlock(reader, 2)
 
 	volumeHeader := parseVolumeHeader(headerBlock)
 
 	for i := 0; i < len(bitmap)/512; i++ {
-		WriteBlock(file, volumeHeader.BitmapStartBlock+i, bitmap[i*512:i*512+512])
+		WriteBlock(writer, volumeHeader.BitmapStartBlock+i, bitmap[i*512:i*512+512])
 	}
 }
 
@@ -101,17 +121,6 @@ func findFreeBlocks(volumeBitmap []byte, numberOfBlocks int) []int {
 	return nil
 }
 
-func GetFreeBlockCount(volumeBitmap []byte, totalBlocks int) int {
-	freeBlockCount := 0
-
-	for i := 0; i < totalBlocks; i++ {
-		if checkFreeBlockInVolumeBitmap(volumeBitmap, i) {
-			freeBlockCount++
-		}
-	}
-	return freeBlockCount
-}
-
 func markBlockInVolumeBitmap(volumeBitmap []byte, blockNumber int) {
 	bitToChange := blockNumber % 8
 	byteToChange := blockNumber / 8

prodos/block.go

@@ -1,22 +1,26 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides access to read and write
+// blocks on a ProDOS drive image
+
 package prodos
 
 import (
-	"os"
+	"io"
 )
 
-func ReadBlock(file *os.File, block int) []byte {
+// ReadBlock reads a block from a ProDOS volume into a byte array
+func ReadBlock(reader io.ReaderAt, block int) []byte {
 	buffer := make([]byte, 512)
 
-	file.ReadAt(buffer, int64(block)*512)
+	reader.ReadAt(buffer, int64(block)*512)
 
 	return buffer
 }
 
-func WriteBlock(file *os.File, block int, buffer []byte) {
+// WriteBlock writes a block to a ProDOS volume from a byte array
-	WriteBlockNoSync(file, block, buffer)
+func WriteBlock(writer io.WriterAt, block int, buffer []byte) {
-	file.Sync()
+	writer.WriteAt(buffer, int64(block)*512)
-}
-
-func WriteBlockNoSync(file *os.File, block int, buffer []byte) {
-	file.WriteAt(buffer, int64(block)*512)
 }

prodos/directory.go

@@ -1,13 +1,21 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides access to read, write, delete
+// fand parse directories on a ProDOS drive image
+
 package prodos
 
 import (
 	"errors"
 	"fmt"
-	"os"
+	"io"
 	"strings"
 	"time"
 )
 
+// VolumeHeader from ProDOS
 type VolumeHeader struct {
 	VolumeName       string
 	CreationTime     time.Time
@@ -21,6 +29,7 @@ type VolumeHeader struct {
 	Version          int
 }
 
+// DirectoryHeader from ProDOS
 type DirectoryHeader struct {
 	Name            string
 	ActiveFileCount int
@@ -38,6 +47,7 @@ const (
 	StorageDirectory = 13
 )
 
+// FileEntry from ProDOS
 type FileEntry struct {
 	StorageType     int
 	FileName        string
@@ -56,8 +66,10 @@ type FileEntry struct {
 	DirectoryOffset int
 }
 
-func ReadDirectory(file *os.File, path string) (VolumeHeader, DirectoryHeader, []FileEntry) {
+// ReadDirectory reads the directory information from a specified path
-	buffer := ReadBlock(file, 2)
+// on a ProDOS image
+func ReadDirectory(reader io.ReaderAt, path string) (VolumeHeader, DirectoryHeader, []FileEntry) {
+	buffer := ReadBlock(reader, 2)
 
 	volumeHeader := parseVolumeHeader(buffer)
 
@@ -68,16 +80,16 @@ func ReadDirectory(file *os.File, path string) (VolumeHeader, DirectoryHeader, [
 	path = strings.ToUpper(path)
 	paths := strings.Split(path, "/")
 
-	directoryHeader, fileEntries := getFileEntriesInDirectory(file, 2, 1, paths)
+	directoryHeader, fileEntries := getFileEntriesInDirectory(reader, 2, 1, paths)
 
 	return volumeHeader, directoryHeader, fileEntries
 }
 
-func getFreeFileEntryInDirectory(file *os.File, directory string) (FileEntry, error) {
+func getFreeFileEntryInDirectory(reader io.ReaderAt, directory string) (FileEntry, error) {
-	_, directoryHeader, _ := ReadDirectory(file, directory)
+	_, directoryHeader, _ := ReadDirectory(reader, directory)
 	//DumpDirectoryHeader(directoryHeader)
 	blockNumber := directoryHeader.StartingBlock
-	buffer := ReadBlock(file, blockNumber)
+	buffer := ReadBlock(reader, blockNumber)
 
 	entryOffset := 43 // start at offset after header
 	entryNumber := 2  // header is essentially the first entry so start at 2
@@ -91,7 +103,7 @@ func getFreeFileEntryInDirectory(file *os.File, directory string) (FileEntry, er
 				return FileEntry{}, errors.New("No free file entries found")
 			}
 			// else read the next block in the directory
-			buffer = ReadBlock(file, blockNumber)
+			buffer = ReadBlock(reader, blockNumber)
 			entryOffset = 4
 			entryNumber = 1
 		}
@@ -109,8 +121,8 @@ func getFreeFileEntryInDirectory(file *os.File, directory string) (FileEntry, er
 	}
 }
 
-func getFileEntriesInDirectory(file *os.File, blockNumber int, currentPath int, paths []string) (DirectoryHeader, []FileEntry) {
+func getFileEntriesInDirectory(reader io.ReaderAt, blockNumber int, currentPath int, paths []string) (DirectoryHeader, []FileEntry) {
-	buffer := ReadBlock(file, blockNumber)
+	buffer := ReadBlock(reader, blockNumber)
 
 	directoryHeader := parseDirectoryHeader(buffer, blockNumber)
 
@@ -135,7 +147,7 @@ func getFileEntriesInDirectory(file *os.File, blockNumber int, currentPath int,
 			if blockNumber == 0 {
 				return DirectoryHeader{}, nil
 			}
-			buffer = ReadBlock(file, nextBlock)
+			buffer = ReadBlock(reader, nextBlock)
 			nextBlock = int(buffer[2]) + int(buffer[3])*256
 		}
 		fileEntry := parseFileEntry(buffer[entryOffset:entryOffset+40], blockNumber, entryOffset)
@@ -147,7 +159,7 @@ func getFileEntriesInDirectory(file *os.File, blockNumber int, currentPath int,
 			if matchedDirectory {
 				fileEntries[activeEntries] = fileEntry
 			} else if !matchedDirectory && fileEntry.FileType == 15 && paths[currentPath+1] == fileEntry.FileName {
-				return getFileEntriesInDirectory(file, fileEntry.KeyPointer, currentPath+1, paths)
+				return getFileEntriesInDirectory(reader, fileEntry.KeyPointer, currentPath+1, paths)
 			}
 			activeEntries++
 		}
@@ -194,7 +206,7 @@ func parseFileEntry(buffer []byte, blockNumber int, entryOffset int) FileEntry {
 	return fileEntry
 }
 
-func writeFileEntry(file *os.File, fileEntry FileEntry) {
+func writeFileEntry(writer io.WriterAt, fileEntry FileEntry) {
 	buffer := make([]byte, 39)
 	buffer[0] = byte(fileEntry.StorageType)<<4 + byte(len(fileEntry.FileName))
 	for i := 0; i < len(fileEntry.FileName); i++ {
@@ -224,7 +236,7 @@ func writeFileEntry(file *os.File, fileEntry FileEntry) {
 	buffer[0x25] = byte(fileEntry.HeaderPointer & 0x00FF)
 	buffer[0x26] = byte(fileEntry.HeaderPointer >> 8)
 
-	_, err := file.WriteAt(buffer, int64(fileEntry.DirectoryBlock*512+fileEntry.DirectoryOffset))
+	_, err := writer.WriteAt(buffer, int64(fileEntry.DirectoryBlock*512+fileEntry.DirectoryOffset))
 	if err != nil {
 
 	}
@@ -280,8 +292,8 @@ func parseDirectoryHeader(buffer []byte, blockNumber int) DirectoryHeader {
 	return directoryEntry
 }
 
-func writeDirectoryHeader(file *os.File, directoryHeader DirectoryHeader) {
+func writeDirectoryHeader(writer io.WriterAt, reader io.ReaderAt, directoryHeader DirectoryHeader) {
-	buffer := ReadBlock(file, directoryHeader.StartingBlock)
+	buffer := ReadBlock(reader, directoryHeader.StartingBlock)
 	buffer[0x00] = byte(directoryHeader.PreviousBlock & 0x00FF)
 	buffer[0x01] = byte(directoryHeader.PreviousBlock >> 8)
 	buffer[0x02] = byte(directoryHeader.NextBlock & 0x00FF)
@@ -292,5 +304,5 @@ func writeDirectoryHeader(file *os.File, directoryHeader DirectoryHeader) {
 	}
 	buffer[0x25] = byte(directoryHeader.ActiveFileCount & 0x00FF)
 	buffer[0x26] = byte(directoryHeader.ActiveFileCount >> 8)
-	WriteBlock(file, directoryHeader.StartingBlock, buffer)
+	WriteBlock(writer, directoryHeader.StartingBlock, buffer)
 }

prodos/doc.go

@@ -0,0 +1,11 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+/*
+  Package prodos provides access to read/write/delete/list files and
+  directories on a ProDOS order drive images.
+
+*/
+
+package prodos

prodos/file.go

@@ -1,19 +1,27 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides access to read, write and delete
+// files on a ProDOS drive image
+
 package prodos
 
 import (
 	"errors"
-	"os"
+	"io"
 	"strings"
 	"time"
 )
 
-func LoadFile(file *os.File, path string) ([]byte, error) {
+// LoadFile loads in a file from a ProDOS volume into a byte array
-	fileEntry, err := getFileEntry(file, path)
+func LoadFile(reader io.ReaderAt, path string) ([]byte, error) {
+	fileEntry, err := getFileEntry(reader, path)
 	if err != nil {
 		return nil, err
 	}
 
-	blockList, err := getDataBlocklist(file, fileEntry)
+	blockList, err := getDataBlocklist(reader, fileEntry)
 	if err != nil {
 		return nil, err
 	}
@@ -21,7 +29,7 @@ func LoadFile(file *os.File, path string) ([]byte, error) {
 	buffer := make([]byte, fileEntry.EndOfFile)
 
 	for i := 0; i < len(blockList); i++ {
-		block := ReadBlock(file, blockList[i])
+		block := ReadBlock(reader, blockList[i])
 		for j := 0; j < 512 && i*512+j < fileEntry.EndOfFile; j++ {
 			buffer[i*512+j] = block[j]
 		}
@@ -30,36 +38,37 @@ func LoadFile(file *os.File, path string) ([]byte, error) {
 	return buffer, nil
 }
 
-func WriteFile(file *os.File, path string, fileType int, auxType int, buffer []byte) error {
+// WriteFile writes a file to a ProDOS volume from a byte array
+func WriteFile(writer io.WriterAt, reader io.ReaderAt, path string, fileType int, auxType int, buffer []byte) error {
 	directory, fileName := GetDirectoryAndFileNameFromPath(path)
 
-	existingFileEntry, _ := getFileEntry(file, path)
+	existingFileEntry, _ := getFileEntry(reader, path)
 	if existingFileEntry.StorageType != StorageDeleted {
-		DeleteFile(file, path)
+		DeleteFile(writer, reader, path)
 	}
 
 	// get list of blocks to write file to
-	blockList := createBlockList(file, len(buffer))
+	blockList := createBlockList(reader, len(buffer))
 
 	// seedling file
 	if len(buffer) <= 0x200 {
-		WriteBlock(file, blockList[0], buffer)
+		WriteBlock(writer, blockList[0], buffer)
 	}
 
 	// sapling file needs index block
 	if len(buffer) > 0x200 && len(buffer) <= 0x20000 {
-		writeSaplingFile(file, buffer, blockList)
+		writeSaplingFile(writer, buffer, blockList)
 	}
 
 	// TODO: add tree file
 	if len(buffer) > 0x20000 {
-		return errors.New("Files > 128KB not supported yet.")
+		return errors.New("files > 128KB not supported yet")
 	}
 
-	updateVolumeBitmap(file, blockList)
+	updateVolumeBitmap(writer, reader, blockList)
 
 	// add file entry to directory
-	fileEntry, err := getFreeFileEntryInDirectory(file, directory)
+	fileEntry, err := getFreeFileEntryInDirectory(reader, directory)
 	if err != nil {
 		return err
 	}
@@ -80,59 +89,20 @@ func WriteFile(file *os.File, path string, fileType int, auxType int, buffer []b
 		fileEntry.StorageType = StorageTree
 	}
 
-	writeFileEntry(file, fileEntry)
+	writeFileEntry(writer, fileEntry)
 
 	// increment file count
-	directoryHeaderBlock := ReadBlock(file, fileEntry.HeaderPointer)
+	directoryHeaderBlock := ReadBlock(reader, fileEntry.HeaderPointer)
 	directoryHeader := parseDirectoryHeader(directoryHeaderBlock, fileEntry.HeaderPointer)
 	directoryHeader.ActiveFileCount++
-	writeDirectoryHeader(file, directoryHeader)
+	writeDirectoryHeader(writer, reader, directoryHeader)
 
 	return nil
 }
 
-func updateVolumeBitmap(file *os.File, blockList []int) {
+// DeleteFile deletes a file from a ProDOS volume
-	volumeBitmap := ReadVolumeBitmap(file)
+func DeleteFile(writer io.WriterAt, reader io.ReaderAt, path string) error {
-	for i := 0; i < len(blockList); i++ {
+	fileEntry, err := getFileEntry(reader, path)
-		markBlockInVolumeBitmap(volumeBitmap, blockList[i])
-	}
-	writeVolumeBitmap(file, volumeBitmap)
-}
-
-func writeSaplingFile(file *os.File, buffer []byte, blockList []int) {
-	// write index block with pointers to data blocks
-	indexBuffer := make([]byte, 512)
-	for i := 0; i < 256; i++ {
-		if i < len(blockList)-1 {
-			indexBuffer[i] = byte(blockList[i+1] & 0x00FF)
-			indexBuffer[i+256] = byte(blockList[i+1] >> 8)
-		}
-	}
-	WriteBlock(file, blockList[0], indexBuffer)
-
-	// write all data blocks
-	blockBuffer := make([]byte, 512)
-	blockPointer := 0
-	blockIndexNumber := 1
-	for i := 0; i < len(buffer); i++ {
-		blockBuffer[blockPointer] = buffer[i]
-		if blockPointer == 511 {
-			WriteBlock(file, blockList[blockIndexNumber], blockBuffer)
-			blockPointer = 0
-			blockIndexNumber++
-		} else if i == len(buffer)-1 {
-			for j := blockPointer; j < 512; j++ {
-				blockBuffer[j] = 0
-			}
-			WriteBlock(file, blockList[blockIndexNumber], blockBuffer)
-		} else {
-			blockPointer++
-		}
-	}
-}
-
-func DeleteFile(file *os.File, path string) error {
-	fileEntry, err := getFileEntry(file, path)
 	if err != nil {
 		return errors.New("File not found")
 	}
@@ -144,31 +114,32 @@ func DeleteFile(file *os.File, path string) error {
 	}
 
 	// free the blocks
-	blocks, err := getBlocklist(file, fileEntry)
+	blocks, err := getBlocklist(reader, fileEntry)
 	if err != nil {
 		return err
 	}
-	volumeBitmap := ReadVolumeBitmap(file)
+	volumeBitmap := ReadVolumeBitmap(reader)
 	for i := 0; i < len(blocks); i++ {
 		freeBlockInVolumeBitmap(volumeBitmap, blocks[i])
 	}
-	writeVolumeBitmap(file, volumeBitmap)
+	writeVolumeBitmap(writer, reader, volumeBitmap)
 
 	// decrement the directory entry count
-	directoryBlock := ReadBlock(file, fileEntry.HeaderPointer)
+	directoryBlock := ReadBlock(reader, fileEntry.HeaderPointer)
 	directoryHeader := parseDirectoryHeader(directoryBlock, fileEntry.HeaderPointer)
 
 	directoryHeader.ActiveFileCount--
-	writeDirectoryHeader(file, directoryHeader)
+	writeDirectoryHeader(writer, reader, directoryHeader)
 
 	// zero out directory entry
 	fileEntry.StorageType = 0
 	fileEntry.FileName = ""
-	writeFileEntry(file, fileEntry)
+	writeFileEntry(writer, fileEntry)
 
 	return nil
 }
 
+// GetDirectoryAndFileNameFromPath gets the directory and filename from a path
 func GetDirectoryAndFileNameFromPath(path string) (string, string) {
 	path = strings.ToUpper(path)
 	paths := strings.Split(path, "/")
@@ -186,8 +157,48 @@ func GetDirectoryAndFileNameFromPath(path string) (string, string) {
 	return directory, fileName
 }
 
+func updateVolumeBitmap(writer io.WriterAt, reader io.ReaderAt, blockList []int) {
+	volumeBitmap := ReadVolumeBitmap(reader)
+	for i := 0; i < len(blockList); i++ {
+		markBlockInVolumeBitmap(volumeBitmap, blockList[i])
+	}
+	writeVolumeBitmap(writer, reader, volumeBitmap)
+}
+
+func writeSaplingFile(writer io.WriterAt, buffer []byte, blockList []int) {
+	// write index block with pointers to data blocks
+	indexBuffer := make([]byte, 512)
+	for i := 0; i < 256; i++ {
+		if i < len(blockList)-1 {
+			indexBuffer[i] = byte(blockList[i+1] & 0x00FF)
+			indexBuffer[i+256] = byte(blockList[i+1] >> 8)
+		}
+	}
+	WriteBlock(writer, blockList[0], indexBuffer)
+
+	// write all data blocks
+	blockBuffer := make([]byte, 512)
+	blockPointer := 0
+	blockIndexNumber := 1
+	for i := 0; i < len(buffer); i++ {
+		blockBuffer[blockPointer] = buffer[i]
+		if blockPointer == 511 {
+			WriteBlock(writer, blockList[blockIndexNumber], blockBuffer)
+			blockPointer = 0
+			blockIndexNumber++
+		} else if i == len(buffer)-1 {
+			for j := blockPointer; j < 512; j++ {
+				blockBuffer[j] = 0
+			}
+			WriteBlock(writer, blockList[blockIndexNumber], blockBuffer)
+		} else {
+			blockPointer++
+		}
+	}
+}
+
 // Returns all blocks, including index blocks
-func getBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
+func getBlocklist(reader io.ReaderAt, fileEntry FileEntry) ([]int, error) {
 	blocks := make([]int, fileEntry.BlocksUsed)
 
 	switch fileEntry.StorageType {
@@ -195,17 +206,17 @@ func getBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
 		blocks[0] = fileEntry.KeyPointer
 		return blocks, nil
 	case StorageSapling:
-		index := ReadBlock(file, fileEntry.KeyPointer)
+		index := ReadBlock(reader, fileEntry.KeyPointer)
 		blocks[0] = fileEntry.KeyPointer
 		for i := 0; i < fileEntry.BlocksUsed-1; i++ {
 			blocks[i+1] = int(index[i]) + int(index[i+256])*256
 		}
 		return blocks, nil
 	case StorageTree:
-		masterIndex := ReadBlock(file, fileEntry.KeyPointer)
+		masterIndex := ReadBlock(reader, fileEntry.KeyPointer)
 		blocks[0] = fileEntry.KeyPointer
 		for i := 0; i < 128; i++ {
-			index := ReadBlock(file, int(masterIndex[i])+int(masterIndex[i+256])*256)
+			index := ReadBlock(reader, int(masterIndex[i])+int(masterIndex[i+256])*256)
 			for j := 0; j < 256 && i*256+j < fileEntry.BlocksUsed; j++ {
 				if (int(index[j]) + int(index[j+256])*256) == 0 {
 					return blocks, nil
@@ -215,10 +226,10 @@ func getBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
 		}
 	}
 
-	return nil, errors.New("Unsupported file storage type")
+	return nil, errors.New("unsupported file storage type")
 }
 
-func getDataBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
+func getDataBlocklist(reader io.ReaderAt, fileEntry FileEntry) ([]int, error) {
 	switch fileEntry.StorageType {
 	case StorageSeedling:
 		blocks := make([]int, 1)
@@ -226,7 +237,7 @@ func getDataBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
 		return blocks, nil
 	case StorageSapling:
 		blocks := make([]int, fileEntry.BlocksUsed-1)
-		index := ReadBlock(file, fileEntry.KeyPointer)
+		index := ReadBlock(reader, fileEntry.KeyPointer)
 		for i := 0; i < fileEntry.BlocksUsed-1; i++ {
 			blocks[i] = int(index[i]) + int(index[i+256])*256
 		}
@@ -236,7 +247,7 @@ func getDataBlocklist(file *os.File, fileEntry FileEntry) ([]int, error) {
 	return nil, errors.New("Unsupported file storage type")
 }
 
-func createBlockList(file *os.File, fileSize int) []int {
+func createBlockList(reader io.ReaderAt, fileSize int) []int {
 	numberOfBlocks := fileSize / 512
 	if fileSize%512 > 0 {
 		numberOfBlocks++
@@ -254,15 +265,15 @@ func createBlockList(file *os.File, fileSize int) []int {
 			numberOfBlocks++
 		}
 	}
-	volumeBitmap := ReadVolumeBitmap(file)
+	volumeBitmap := ReadVolumeBitmap(reader)
 	blockList := findFreeBlocks(volumeBitmap, numberOfBlocks)
 
 	return blockList
 }
 
-func getFileEntry(file *os.File, path string) (FileEntry, error) {
+func getFileEntry(reader io.ReaderAt, path string) (FileEntry, error) {
 	directory, fileName := GetDirectoryAndFileNameFromPath(path)
-	_, _, fileEntries := ReadDirectory(file, directory)
+	_, _, fileEntries := ReadDirectory(reader, directory)
 
 	if fileEntries == nil || len(fileEntries) == 0 {
 		return FileEntry{}, errors.New("File entry not found")

prodos/format.go

@@ -1,13 +1,21 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides access to format a ProDOS drive image
+
 package prodos
 
 import (
 	"fmt"
-	"os"
+	"io"
 	"strings"
 	"time"
 )
 
-func CreateVolume(file *os.File, volumeName string, numberOfBlocks int) {
+// CreateVolume formats a new ProDOS volume including boot block,
+// volume bitmap and empty directory
+func CreateVolume(writer io.WriterAt, reader io.ReaderAt, volumeName string, numberOfBlocks int) {
 	if numberOfBlocks > 65535 || numberOfBlocks < 64 {
 		return
 	}
@@ -20,7 +28,7 @@ func CreateVolume(file *os.File, volumeName string, numberOfBlocks int) {
 
 	blankBlock := make([]byte, 512)
 	for i := 0; i < numberOfBlocks; i++ {
-		WriteBlockNoSync(file, i, blankBlock)
+		WriteBlock(writer, i, blankBlock)
 	}
 
 	volumeHeader := [43]byte{}
@@ -55,11 +63,10 @@ func CreateVolume(file *os.File, volumeName string, numberOfBlocks int) {
 	volumeHeader[0x29] = byte(numberOfBlocks & 0xFF)
 	volumeHeader[0x2A] = byte(numberOfBlocks >> 8)
 
-	file.WriteAt(volumeHeader[:], 1024)
+	writer.WriteAt(volumeHeader[:], 1024)
-	file.Sync()
 
 	// boot block 0
-	WriteBlock(file, 0, getBootBlock())
+	WriteBlock(writer, 0, getBootBlock())
 
 	// pointers to volume directory blocks
 	for i := 2; i < 6; i++ {
@@ -76,12 +83,12 @@ func CreateVolume(file *os.File, volumeName string, numberOfBlocks int) {
 			pointers[2] = byte(i + 1)
 		}
 		pointers[3] = 0x00
-		file.WriteAt(pointers, int64(i*512))
+		writer.WriteAt(pointers, int64(i*512))
 	}
 
 	// volume bit map starting at block 6
 	volumeBitmap := createVolumeBitmap(numberOfBlocks)
-	writeVolumeBitmap(file, volumeBitmap)
+	writeVolumeBitmap(writer, reader, volumeBitmap)
 }
 
 func getBootBlock() []byte {

prodos/format_test.go

@@ -2,7 +2,6 @@ package prodos
 
 import (
 	"fmt"
-	"os"
 	"testing"
 )
 
@@ -20,17 +19,9 @@ func TestCreateVolume(t *testing.T) {
 	for _, tt := range tests {
 		testname := fmt.Sprintf("%d", tt.blocks)
 		t.Run(testname, func(t *testing.T) {
-			fileName := os.TempDir() + "/test-volume.hdv"
+			file := NewMemoryFile(0x2000000)
-			defer os.Remove(fileName)
-			file, err := os.Create(fileName)
-			if err != nil {
-				t.Errorf("failed to create file: %s\n", err)
-				return
-			}
 
-			defer file.Close()
+			CreateVolume(file, file, tt.wantVolumeName, tt.blocks)
-
-			CreateVolume(file, tt.wantVolumeName, tt.blocks)
 
 			volumeHeader, _, fileEntries := ReadDirectory(file, "")
 			if volumeHeader.VolumeName != tt.wantVolumeName {

prodos/memfile.go

@@ -0,0 +1,26 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides a file in memory
+
+package prodos
+
+type MemoryFile struct {
+	data []byte
+	size int
+}
+
+func NewMemoryFile(size int) *MemoryFile {
+	return &MemoryFile{make([]byte, size), size}
+}
+
+func (memoryFile *MemoryFile) WriteAt(data []byte, offset int64) (int, error) {
+	copy(memoryFile.data[int(offset):], data)
+	return len(data), nil
+}
+
+func (memoryFile *MemoryFile) ReadAt(data []byte, offset int64) (int, error) {
+	copy(data, memoryFile.data[int(offset):])
+	return len(data), nil
+}

prodos/text.go

@@ -1,3 +1,10 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides text dumps for directories
+// and blocks
+
 package prodos
 
 import (
@@ -6,6 +13,7 @@ import (
 	"time"
 )
 
+// TimeToString displays the date and time in ProDOS format
 func TimeToString(printTime time.Time) string {
 	return fmt.Sprintf("%04d-%s-%02d %02d:%02d",
 		printTime.Year(),
@@ -16,6 +24,7 @@ func TimeToString(printTime time.Time) string {
 	)
 }
 
+// FileTypeToString display the file type as a string
 func FileTypeToString(fileType int) string {
 	switch fileType {
 	case 1:
@@ -78,6 +87,7 @@ func FileTypeToString(fileType int) string {
 	*/
 }
 
+// DumpFileEntry dumps the file entry values as text
 func DumpFileEntry(fileEntry FileEntry) {
 	fmt.Printf("FileName: %s\n", fileEntry.FileName)
 	fmt.Printf("Creation time: %d-%s-%d %02d:%02d\n", fileEntry.CreationTime.Year(), fileEntry.CreationTime.Month(), fileEntry.CreationTime.Day(), fileEntry.CreationTime.Hour(), fileEntry.CreationTime.Minute())
@@ -92,6 +102,7 @@ func DumpFileEntry(fileEntry FileEntry) {
 	fmt.Printf("\n")
 }
 
+// DumpVolumeHeader dumps the volume header values as text
 func DumpVolumeHeader(volumeHeader VolumeHeader) {
 	fmt.Printf("Next block: %d\n", volumeHeader.NextBlock)
 	fmt.Printf("Volume name: %s\n", volumeHeader.VolumeName)
@@ -105,6 +116,7 @@ func DumpVolumeHeader(volumeHeader VolumeHeader) {
 	fmt.Printf("Total blocks: %d\n", volumeHeader.TotalBlocks)
 }
 
+// DumpDirectoryHeader dumps the directory header as text
 func DumpDirectoryHeader(directoryHeader DirectoryHeader) {
 	fmt.Printf("Name: %s\n", directoryHeader.Name)
 	fmt.Printf("File count: %d\n", directoryHeader.ActiveFileCount)
@@ -113,6 +125,7 @@ func DumpDirectoryHeader(directoryHeader DirectoryHeader) {
 	fmt.Printf("Next block: %04X\n", directoryHeader.NextBlock)
 }
 
+// DumpBlock dumps the block as hexadecimal and text
 func DumpBlock(buffer []byte) {
 	for i := 0; i < len(buffer); i += 16 {
 		fmt.Printf("%04X: ", i)
@@ -131,6 +144,7 @@ func DumpBlock(buffer []byte) {
 	}
 }
 
+// DumpDirectory displays the directory similar to ProDOS catalog
 func DumpDirectory(blocksFree int, totalBlocks int, path string, fileEntries []FileEntry) {
 	fmt.Printf("%s\n\n", path)
 	fmt.Printf("NAME          TYPE BLOCKS  MODIFIED          CREATED           ENDFILE  SUBTYPE\n\n")

prodos/time.go

@@ -1,24 +1,29 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides conversion to and from ProDOS time format
+
 package prodos
 
 import (
 	"time"
 )
 
-/*  49041 ($BF91)     49040 ($BF90)
+// DateTimeToProDOS converts Time to ProDOS date time
-
+//   49041 ($BF91)     49040 ($BF90)
-        7 6 5 4 3 2 1 0   7 6 5 4 3 2 1 0
+//
-       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
+//           7 6 5 4 3 2 1 0   7 6 5 4 3 2 1 0
-DATE:  |    year     |  month  |   day   |
+//          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
-       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
+//   DATE:  |    year     |  month  |   day   |
-
+//          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
-        7 6 5 4 3 2 1 0   7 6 5 4 3 2 1 0
+//
-       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
+//   49043 ($BF93)     49042 ($BF92)
-TIME:  |    hour       | |    minute     |
+//
-       +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
+//           7 6 5 4 3 2 1 0   7 6 5 4 3 2 1 0
-
+//          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
-       49043 ($BF93)     49042 ($BF92)
+//   TIME:  |    hour       | |    minute     |
-*/
+//          +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
-
 func DateTimeToProDOS(dateTime time.Time) []byte {
 	year := dateTime.Year() % 100
 	month := dateTime.Month()
@@ -35,6 +40,7 @@ func DateTimeToProDOS(dateTime time.Time) []byte {
 	return buffer
 }
 
+// DateTimeToProDOS converts Time from ProDOS date time
 func DateTimeFromProDOS(buffer []byte) time.Time {
 	if buffer[0] == 0 &&
 		buffer[1] == 0 &&

readme.go

@@ -1,3 +1,9 @@
+// Copyright Terence J. Boldt (c)2021-2022
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+// This file provides readme for command line utility
+
 package main
 
 import "fmt"
@@ -8,7 +14,7 @@ func printReadme() {
 	fmt.Println(`
 MIT License
 
-Copyright (c) 2021 Terence Boldt
+Copyright (c)2021-2022 Terence Boldt
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal