// ke_irq.c - IRQ dispatch, kernel-side
#include <ke_irq.h>
#include <hal_api.h>

#define MAX_IRQS 24

static void (*gIrqHandlers[MAX_IRQS])(void);
static const HAL_API *gHal;

void KeIrqInitialize(const HAL_API *hal) {
    gHal = hal;
}

__declspec(dllexport) void KeIrqRegister(uint8_t irq, void (*handler)(void)) {
    if (irq >= MAX_IRQS || !handler) return;
    gIrqHandlers[irq] = handler;
    gHal->Intc.RouteIrq(irq);
}

void KeIrqDispatch(uint8_t irq) {
    // KeIrqDispatch sends EOI after the handler returns, but the handler switched context before returning.
    // The EOI call is still sitting on the idle thread's stack, waiting for that thread to be resumed.
    // The LAPIC sees ISR[0x20] still set. Its rule is: don't deliver another interrupt at the same or lower priority until EOI is written.
    // So the timer never fires again. The user process runs completely unpreempted until it calls SYS_EXIT_PROCESS, which calls KeYield, which cooperatively switches back
    // and only then does the idle thread resume, KeIrqDispatch finally sends its EOI, and the timer starts firing again.
    // To fix this we send EOI before calling the handler, not after.
    gHal->Intc.SendEoi();
    if (irq < MAX_IRQS && gIrqHandlers[irq])
        gIrqHandlers[irq]();
}