Chloe M.
43 lines
718 B
C
43 lines
718 B
C
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: i8254 timer driver
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* Author: Chloe M.
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*/
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#include <machine/i8254.h>
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#include <machine/pio.h>
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USHORT
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MdPitGetCount(VOID)
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{
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UCHAR Low, High;
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MdOutb(I8254_COMMAND, 0x00);
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Low = MdInb(0x40);
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High = MdInb(0x40);
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return (High << 8) | Low;
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}
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VOID
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MdPitSetCount(USHORT Value)
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{
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MdOutb(I8254_COMMAND, 0x34);
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MdOutb(0x40, Value & 0xFF);
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MdOutb(0x40, (Value >> 8) & 0xFF);
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}
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VOID
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MdPitSetFrequency(UQUAD Frequency)
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{
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UQUAD Divisor;
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Divisor = I8254_DIVIDEND / Frequency;
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if ((I8254_DIVIDEND % Frequency) > (Frequency / 2)) {
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++Divisor;
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}
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MdPitSetCount(Divisor);
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}
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