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fixed the nibblizer routine -- DOS 3.3 disks boot now!

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This commit is contained in:
Luigi Thirty 2017-08-06 03:21:49 -04:00
parent 37bb5990fd
commit 8bac7aace2
2 changed files with 32 additions and 33 deletions
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2
FruitMachine/AppleII/Peripherals/DiskII/DiskII.swift
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@ -77,7 +77,7 @@ class DiskII: NSObject, Peripheral {
var mediaPosition: Int = 0
var motorPhase: MotorPhase = .Phase0
var diskImage = DiskImage(diskPath: "/Users/luigi/apple2/master.dsk")
var diskImage = DiskImage(diskPath: "/Users/luigi/apple2/clean332sysmas.do")
init(slot: Int, romPath: String) {

63
FruitMachine/AppleII/Peripherals/DiskII/DiskImage.swift
View File

@ -8,6 +8,21 @@
import Cocoa
/* while I figure out this C code port */
prefix operator ++
postfix operator ++
// Increment
prefix func ++(x: inout Int) -> Int {
x += 1
return x
}
postfix func ++(x: inout Int) -> Int {
x += 1
return (x - 1)
}
protocol DiskImageFormat {
static var BYTES_PER_SECTOR: Int { get }
static var SECTORS_PER_TRACK: Int { get }
@ -174,42 +189,26 @@ class DiskImage: NSObject {
return writtenData
}
private func GetSwappedLowBits(byte: UInt8) -> UInt8 {
let b0 = byte & 0b00000001
let b1 = byte & 0b00000010
return UInt8((b0 << 1) | (b1 >> 1))
}
private func SixAndTwoPrenibblize(sector: [UInt8]) -> [UInt8] {
//Create a 342-byte buffer from a 256-byte sector.
//TODO: Where does the checksum byte fit? I broke the low bit encoding trying to figure that out, need to fix that.
var nibblized: [UInt8] = [UInt8](repeating: 0x00, count: 343)
for byte in 0x00..<0x55 {
//Create a nibblized 342-byte buffer from a 256-byte sector.
var nibblized: [UInt8] = [UInt8](repeating: 0x00, count: 342)
var secondaryShift = 0
for (i, byte) in (0x00 ..< 0x100).enumerated() {
nibblized[byte] = sector[byte] >> 2
let b0 = (sector[byte] & 0b00000001)
let b1 = (sector[byte] & 0b00000010)
let low = 0x00 | (b0 << 1 | b1 >> 1)
nibblized[0x156 - byte] |= low
let secondaryOffset = 0x100 + (0x55 - (i % 0x56))
nibblized[secondaryOffset] |= GetSwappedLowBits(byte: sector[byte]) << secondaryShift
if(secondaryOffset == 0x100) {
secondaryShift += 2
}
}
for (i, byte) in (0x55..<0xAA).enumerated() {
nibblized[byte] = sector[byte] >> 2
let b0 = (sector[byte] & 0b00000001)
let b1 = (sector[byte] & 0b00000010)
let low = 0x00 | (b0 << 1 | b1 >> 1)
nibblized[0x156 - i] |= (low << 2)
}
for (i, byte) in (0xAA..<0x100).enumerated() {
nibblized[byte] = sector[byte] >> 2
let b0 = (sector[byte] & 0b00000001)
let b1 = (sector[byte] & 0b00000010)
let low = 0x00 | (b0 << 1 | b1 >> 1)
//Now we have a full six bits.
let completeLow: UInt8 = nibblized[0x156 - i] | (low << 4)
nibblized[0x156 - i] |= completeLow
}
return nibblized
}