28 lines
661 B
C
28 lines
661 B
C
#include "pit.h"
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#include "io.h"
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#include "irq.h"
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#include "klibc.h"
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#include "thread.h"
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#include "time.h"
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int pitSetup(unsigned int freq)
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{
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unsigned int divisor = PIT_FREQ / freq;
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if (divisor > 65535)
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divisor = 0; // Used to represent 35536
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outb(PIT_CMD, 0x34); // chan 0; low then high; mode 2
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outb(PIT_CHAN_0, divisor & 0xFF);
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outb(PIT_CHAN_0, divisor >> 8u);
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return 0;
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}
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struct cpu_state *pitIrqHandler(struct cpu_state *prevCpu)
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{
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__atomic_add_fetch(&jiffies, 1, __ATOMIC_RELAXED);
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threadOnJieffiesTick();
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// Uncomment for non-preemptible kernel
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// return prevCpu;
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return threadSwitch(prevCpu);
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}
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