mirror of https://github.com/zellyn/diskii.git
74 lines
1.6 KiB
Go
74 lines
1.6 KiB
Go
// Copyright © 2017 Zellyn Hunter <zellyn@gmail.com>
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// dev.go contains logic for reading ".po" disk images.
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package disk
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import (
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"fmt"
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"io"
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"io/ioutil"
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)
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// A ProDOS block.
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type Block [256]byte
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// Dev represents a .po disk image.
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type Dev struct {
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data []byte // The actual data in the file
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blocks uint16 // Number of blocks
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}
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// LoadDev loads a .po image from a file.
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func LoadDev(filename string) (Dev, error) {
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bb, err := ioutil.ReadFile(filename)
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if err != nil {
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return Dev{}, err
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}
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if len(bb)%512 != 0 {
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return Dev{}, fmt.Errorf("expected file %q to contain a multiple of 512 bytes, but got %d", filename, len(bb))
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}
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return Dev{
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data: bb,
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blocks: uint16(len(bb) / 512),
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}, nil
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}
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// Empty creates a .po image that is all zeros.
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func EmptyDev(blocks uint16) Dev {
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return Dev{
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data: make([]byte, 512*int(blocks)),
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blocks: blocks,
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}
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}
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// ReadBlock reads a single block from the device. It always returns
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// 512 byes.
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func (d Dev) ReadBlock(index uint16) (Block, error) {
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var b Block
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copy(b[:], d.data[int(index)*512:int(index+1)*512])
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return b, nil
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}
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// WriteBlock writes a single block to a device. It expects exactly
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// 512 bytes.
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func (d Dev) WriteBlock(index uint16, data Block) error {
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copy(d.data[int(index)*512:int(index+1)*512], data[:])
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return nil
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}
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// Blocks returns the number of blocks in the device.
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func (d Dev) Blocks() uint16 {
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return d.blocks
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}
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// Order returns the order of blocks on the device.
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func (d Dev) Order() string {
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return "prodos"
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}
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// Write writes the device contents to the given file.
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func (d Dev) Write(w io.Writer) (n int, err error) {
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return w.Write(d.data)
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}
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