51 lines
1.5 KiB
Swift
51 lines
1.5 KiB
Swift
//
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// VideoHelpers.swift
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// FruitMachine
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//
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// Created by Christopher Rohl on 8/2/17.
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// Copyright © 2017 Christopher Rohl. All rights reserved.
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//
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import Cocoa
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extension AppleIIBase {
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class VideoHelpers: NSObject {
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static func getPixelOffset(charCellX: Int, charCellY: Int) -> CGPoint {
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return CGPoint(x: charCellX * 7, y: charCellY * 8)
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}
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static func getPixelOffset(memoryOffset: Int) -> CGPoint {
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//Offset is between 0x000 and 0x3FF.
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//If offset & 0x28, second batch.
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//If offset & 0x50, third batch.
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//Else, first batch.
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var rowNumber = memoryOffset / 0x80
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let lowByte = memoryOffset & 0x0FF
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let cellX: Int
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if(0x28 ... 0x4F ~= lowByte || 0xA8 ... 0xCF ~= lowByte) {
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//Middle third.
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rowNumber += 8
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cellX = (lowByte & ~(0x80)) - 0x28
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}
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else if(0x50 ... 0x77 ~= lowByte || 0xD0 ... 0xF7 ~= lowByte) {
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//Bottom third.
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rowNumber += 16
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cellX = (lowByte & ~(0x80)) - 0x50
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}
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else if(0x78 ... 0x7F ~= lowByte || 0xF8 ... 0xFF ~= lowByte) {
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//Discard.
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return CGPoint(x: -1, y: -1)
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}
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else {
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//Top third.
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rowNumber += 0
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cellX = (lowByte & ~(0x80))
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}
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return getPixelOffset(charCellX: cellX, charCellY: rowNumber)
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}
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}
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}
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