// hal_apic.c - Local APIC + I/O APIC
#include <hal_apic.h>
#include <hal_api.h>
#include <stdint.h>

extern HAL_API gApi;

// ---- Local APIC ----
static volatile uint32_t* gLapic = (volatile uint32_t *)0;
#define LAPIC_REG(off)   (*(volatile uint32_t *)((uint8_t *)gLapic + (off)))
#define LAPIC_EOI        0x0B0
#define LAPIC_SPURIOUS   0x0F0
#define LAPIC_ENABLE     0x100   // bit in spurious vector register

// ---- I/O APIC ----
static volatile uint32_t* gIoapic = (volatile uint32_t *)0;
#define IOAPIC_IDX   0x00
#define IOAPIC_DATA  0x10

static uint32_t IoapicRead(uint8_t reg) {
    *(volatile uint32_t *)((uint8_t *)gIoapic + IOAPIC_IDX) = reg;
    return *(volatile uint32_t *)((uint8_t *)gIoapic + IOAPIC_DATA);
}
static void IoapicWrite(uint8_t reg, uint32_t val) {
    *(volatile uint32_t *)((uint8_t *)gIoapic + IOAPIC_IDX) = reg;
    *(volatile uint32_t *)((uint8_t *)gIoapic + IOAPIC_DATA) = val;
}

// IRQ n -> redirection table at register 0x10 + 2*n (low), 0x11 + 2*n (high).
#define IOREDTBL_LO(n)  (0x10 + 2*(n))
#define IOREDTBL_HI(n)  (0x11 + 2*(n))
// Interrupt vector base: IRQ 0 -> vector 0x20, IRQ 1 -> 0x21, ...
#define IRQ_VECTOR_BASE  0x20

void HalApicRouteIrq(uint8_t irq) {
    // Full initial setup of the redirection entry.
    // Sets the vector and clears the mask bit in one write.
    uint32_t vector = IRQ_VECTOR_BASE + irq;   // e.g. IRQ 1 -> vector 0x21
    IoapicWrite(IOREDTBL_LO(irq), vector);     // unmasked (bit 16 = 0), edge, fixed
    IoapicWrite(IOREDTBL_HI(irq), 0);          // deliver to LAPIC id 0
}

void HalApicMaskIrq(uint8_t irq) {
    uint32_t lo = IoapicRead(IOREDTBL_LO(irq));
    lo |= (1 << 16);
    IoapicWrite(IOREDTBL_LO(irq), lo);
}

void HalApicUnmaskIrq(uint8_t irq) {
    uint32_t lo = IoapicRead(IOREDTBL_LO(irq));
    lo &= ~(1 << 16);   // clear mask bit
    lo  =  (lo & ~0xFF) | (IRQ_VECTOR_BASE + irq);
    IoapicWrite(IOREDTBL_LO(irq), lo);
    IoapicWrite(IOREDTBL_HI(irq), 0);   // LAPIC id 0
}

void HalApicSendEoi(void) {
    LAPIC_REG(LAPIC_EOI) = 0;
}

void HalApicInitialize(uintptr_t lapicPhys, uintptr_t ioapicPhys) {
    gLapic  = (volatile uint32_t *)(gApi.PhysToVirt(lapicPhys));
    gIoapic = (volatile uint32_t *)(gApi.PhysToVirt(ioapicPhys));

    // Enable Local APIC, set spurious vector to 0xFF.
    LAPIC_REG(LAPIC_SPURIOUS) = LAPIC_ENABLE | 0xFF;

    // Mask all IOAPIC lines initially.
    uint32_t maxRedir = (IoapicRead(1) >> 16) & 0xFF;
    for (uint8_t i = 0; i <= maxRedir; i++) {
        IoapicWrite(IOREDTBL_LO(i), (1 << 16) | (IRQ_VECTOR_BASE + i));
        IoapicWrite(IOREDTBL_HI(i), 0);
    }
}