forked from PoliEcho-holding-org/kern
48 lines
1.3 KiB
C
48 lines
1.3 KiB
C
#ifndef TIMER_H
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#define TIMER_H
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#include <stdint.h>
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#include <idt.h>
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#include <pic.h>
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#include <screen.h>
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#define CHANNEL_0 0x40 // Offset it by 1 or 2 for ch1 and ch2
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#define COMMAND 0x43
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#define INPUT_CLK 1193182
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static uint32_t* timerTicks = (uint32_t*)0x1000;
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__attribute__ ((interrupt))
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void timerHandler(intFrame_t* iframe) {
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*timerTicks += 1;
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// TODO: Improve the cursor rendering
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if (*timerTicks % 500 == 0) putcAt(' ', cursor.x, cursor.y);
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else if (*timerTicks % 250 == 0) putcAt(127, cursor.x, cursor.y);
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sendPicEOI(0);
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}
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void setPitPhase(uint8_t channel, uint8_t opMode, uint16_t hz) {
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if (channel > 2 || opMode > 7) { return; }
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__asm__ volatile ("cli");
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// Send command - bits 7-6 channel, 5-4 Access mode, 3-1 operating mode, 0 - Should be zero in x86
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outb(COMMAND, ((channel << 6) | (3 << 4) | (opMode << 1)));
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// Send frequency
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uint16_t freq = INPUT_CLK / hz; // I solved an equation to figure this out
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outb(CHANNEL_0 + channel, (uint8_t)freq);
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outb(CHANNEL_0 + channel, (uint8_t)(freq >> 8));
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__asm__ volatile ("sti");
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}
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void setupTimer() { // Sets up IRQ 0 - PIT
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idtSetGate(0x20, timerHandler, INT_GATE_FLAGS);
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unsetIrqMask(0);
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setPitPhase(0, 2, 1000); // Default setup: 1000Hz - 1 tick per 1ms
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}
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#endif
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