69 lines
1.8 KiB
Nim
69 lines
1.8 KiB
Nim
type
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VGA_Colour {.pure.} = enum
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black = 0,
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blue = 1,
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green = 2,
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cyan = 3,
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red = 4,
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magenta = 5,
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brown = 6,
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lightGrey = 7,
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darkGrey = 8,
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lightBlue = 9,
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lightGreen = 10,
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lightCyan = 11,
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lightRed = 12,
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lightMagenta = 13,
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lightBrown = 14,
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white = 15
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proc vgaEntryColour(fg: VGA_Colour, bg: VGA_Colour): int =
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result = ord(fg) or (ord(bg) shl 4)
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proc vgaEntry(c: char, colour: uint8): uint16 =
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result = uint16(c) or (uint16(colour) shl 8)
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const
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vgaWidth = 80
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vgaHeight = 25
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terminalBufferBaseAddress = 0xB8000
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var
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terminalRow, terminalColumn = 0
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terminalColour: int
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proc terminalWriteAtPoint(writeChar: char, colour: int, xPos: int, yPos: int) =
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let index = terminalBufferBaseAddress + (yPos * vgaWidth + (xPos * 2))
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cast[ptr int8](index)[] = int8(writeChar) # Write directly to display memory
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cast[ptr int8](index+1)[] = int8(terminalColour)
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proc terminalInitialize() =
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terminalColour = vgaEntryColour(VGA_Colour.lightGreen, VGA_Colour.red)
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for y in 0..<vgaWidth:
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for x in 0..<vgaHeight:
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terminalWriteAtPoint(' ', terminalColour, x, y)
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proc setTerminalColour(newColour: int) =
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terminalColour = newColour
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proc terminalWriteChar(writeChar: char) =
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if(writeChar == '\L'):
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inc(terminalRow)
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if(terminalRow == vgaHeight): terminalRow = 0
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return
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terminalWriteAtPoint(writeChar, terminalColour, terminalColumn, terminalRow)
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inc(terminalColumn)
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if(terminalColumn == vgaWidth):
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terminalColumn = 0
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inc(terminalRow)
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if(terminalRow == vgaHeight): terminalRow = 0
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proc terminalWrite(data: string) =
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for character in data:
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terminalWriteChar(character)
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proc kernelMain() {.exportc: "kernel_main"}=
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terminalInitialize()
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terminalWrite("Hello World\LThis is Nim!")
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