372f9e9a11
It would be nice to do this in the assembly code, but we have to check if the feature is available before doing a CLAC, so I've put this in the C++ code for now.
81 lines
1.8 KiB
C++
81 lines
1.8 KiB
C++
#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Arch/i386/PIC.h>
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#include <Kernel/Arch/i386/PIT.h>
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#include <Kernel/IO.h>
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#include <Kernel/Scheduler.h>
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#define IRQ_TIMER 0
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extern "C" void timer_interrupt_entry();
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extern "C" void timer_interrupt_handler(RegisterDump);
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asm(
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".globl timer_interrupt_entry \n"
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"timer_interrupt_entry: \n"
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" pushl $0x0\n"
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" pusha\n"
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" pushl %ds\n"
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" pushl %es\n"
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" pushl %fs\n"
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" pushl %gs\n"
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" pushl %ss\n"
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" mov $0x10, %ax\n"
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" mov %ax, %ds\n"
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" mov %ax, %es\n"
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" cld\n"
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" call timer_interrupt_handler\n"
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" add $0x4, %esp\n"
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" popl %gs\n"
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" popl %fs\n"
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" popl %es\n"
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" popl %ds\n"
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" popa\n"
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" add $0x4, %esp\n"
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" iret\n");
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static u32 s_ticks_this_second;
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static u32 s_seconds_since_boot;
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void timer_interrupt_handler(RegisterDump regs)
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{
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clac();
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IRQHandlerScope scope(IRQ_TIMER);
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if (++s_ticks_this_second >= TICKS_PER_SECOND) {
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// FIXME: Synchronize with the RTC somehow to prevent drifting apart.
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++s_seconds_since_boot;
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s_ticks_this_second = 0;
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}
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Scheduler::timer_tick(regs);
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}
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namespace PIT {
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u32 ticks_this_second()
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{
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return s_ticks_this_second;
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}
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u32 seconds_since_boot()
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{
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return s_seconds_since_boot;
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}
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void initialize()
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{
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u16 timer_reload;
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IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
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timer_reload = (BASE_FREQUENCY / TICKS_PER_SECOND);
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kprintf("PIT: %u Hz, square wave (%x)\n", TICKS_PER_SECOND, timer_reload);
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IO::out8(TIMER0_CTL, LSB(timer_reload));
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IO::out8(TIMER0_CTL, MSB(timer_reload));
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register_interrupt_handler(IRQ_VECTOR_BASE + IRQ_TIMER, timer_interrupt_entry);
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PIC::enable(IRQ_TIMER);
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}
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}
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