izapple2/diskette16sector.go

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package apple2
/*
See:
"Beneath Apple DOS" https://fabiensanglard.net/fd_proxy/prince_of_persia/Beneath%20Apple%20DOS.pdf
https://github.com/TomHarte/CLK/wiki/Apple-GCR-disk-encoding
*/
type diskette16sector struct {
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nib *fileNib
position int
}
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func newDisquette16Sector(f *fileNib) *diskette16sector {
var d diskette16sector
d.nib = f
return &d
}
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func (d *diskette16sector) powerOn(cycle uint64) {
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// Not used
}
func (d *diskette16sector) powerOff(_ uint64) {
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// Not used
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}
func (d *diskette16sector) read(quarterTrack int, cycle uint64) uint8 {
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track := d.nib.track[quarterTrack/stepsPerTrack]
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value := track[d.position]
d.position = (d.position + 1) % nibBytesPerTrack
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//fmt.Printf("%v, %v, %v, %x\n", 0, 0, d.position, uint8(value))
return value
}
func (d *diskette16sector) write(quarterTrack int, value uint8, _ uint64) {
track := quarterTrack / stepsPerTrack
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d.nib.track[track][d.position] = value
d.position = (d.position + 1) % nibBytesPerTrack
}