// Kernel IRQL model. This file synchronizes per-CPU IRQL with APIC task priority.

#include <stdbool.h>
#include <kernel/ke_irql.h>
#include <kernel/ke_cpu.h>
#include <kernel/ke_hal.h>
#include <kernel/ke_debug.h>
#include <kernel/ke_apc.h>
#include <intrin.h>

__declspec(dllexport) const char* KeIrqlName(KIRQL irql) {
    switch (irql) {
        case PASSIVE_LEVEL:  return "PASSIVE_LEVEL";
        case APC_LEVEL:      return "APC_LEVEL";
        case DISPATCH_LEVEL: return "DISPATCH_LEVEL";
        case HIGH_LEVEL:     return "HIGH_LEVEL";
        default:
            if (irql >= DIRQL_BASE && irql < HIGH_LEVEL)
                return "DIRQL";
            return "INVALID_IRQL";
    }
}

// Returns current Irql.
__declspec(dllexport) KIRQL KeGetCurrentIrql(void) {
    return KeGetCurrentCpu()->CurrentIrql;
}

// IRQL classes 16-25 map to vectors 0x30-0xC0. The TPR masks the current
// class and all lower-priority external interrupts. HIGH_LEVEL masks all.
static uint8_t KiIrqlTaskPriority(KIRQL level) {
    if (level == HIGH_LEVEL) return 0xFFu;
    if (level >= 28u) return 0xF0u;
    if (level >= DIRQL_BASE) return (uint8_t)((level - DIRQL_BASE + 3u) << 4u);
    if (level >= DISPATCH_LEVEL) return 0x20u;
    if (level >= APC_LEVEL) return 0x10u;
    return 0u;
}

// Applies the priority before publishing a raised IRQL and after a lowered IRQL.
static void KiSetIrql(KCPU* cpu, KIRQL level, bool raising) {
    const HAL_API* hal = KeGetHal();
    if (raising && hal && hal->InterruptController.SetTaskPriority)
        hal->InterruptController.SetTaskPriority(KiIrqlTaskPriority(level));
    cpu->CurrentIrql = level;
    if (!raising && hal && hal->InterruptController.SetTaskPriority)
        hal->InterruptController.SetTaskPriority(KiIrqlTaskPriority(level));
}

__declspec(dllexport) KIRQL KeRaiseIrql(KIRQL newIrql) {
    KCPU* cpu = KeGetCurrentCpu();
    KIRQL oldIrql = cpu->CurrentIrql;

    if (newIrql > HIGH_LEVEL) {
        KePanic(KE_PANIC_CODE_IRQL, "KeRaiseIrql: invalid target IRQL %u\n", (unsigned)newIrql);
    }

    if (newIrql < oldIrql) {
        KePanic(KE_PANIC_CODE_IRQL, "KeRaiseIrql: attempted raise from %s(%u) down to %s(%u)\n",
                KeIrqlName(oldIrql), (unsigned)oldIrql,
                KeIrqlName(newIrql), (unsigned)newIrql);
    }

    KiSetIrql(cpu, newIrql, true);
    return oldIrql;
}

__declspec(dllexport) void KeLowerIrql(KIRQL oldIrql) {
    KCPU* cpu = KeGetCurrentCpu();
    KIRQL currentIrql = cpu->CurrentIrql;

    if (oldIrql > HIGH_LEVEL) {
        KePanic(KE_PANIC_CODE_IRQL, "KeLowerIrql: invalid target IRQL %u\n", (unsigned)oldIrql);
    }

    if (oldIrql > currentIrql) {
        KePanic(KE_PANIC_CODE_IRQL, "KeLowerIrql: attempted lower from %s(%u) up to %s(%u)\n",
                KeIrqlName(currentIrql), (unsigned)currentIrql,
                KeIrqlName(oldIrql), (unsigned)oldIrql);
    }

    KiSetIrql(cpu, oldIrql, false);

    if (oldIrql == PASSIVE_LEVEL && currentIrql != PASSIVE_LEVEL &&
        (__readeflags() & 0x200u) != 0 && cpu->InterruptDepth == 0)
        KiDeliverKernelApcs();
}

__declspec(dllexport) void KeAssertIrql(KIRQL expected) {
    KIRQL currentIrql = KeGetCurrentIrql();
    if (currentIrql != expected) {
        KePanic(KE_PANIC_CODE_IRQL, "IRQL assertion failed: expected %s(%u), current %s(%u)\n",
                KeIrqlName(expected), (unsigned)expected,
                KeIrqlName(currentIrql), (unsigned)currentIrql);
    }
}

__declspec(dllexport) void KeAssertIrqlAtOrBelow(KIRQL maxIrql) {
    KIRQL currentIrql = KeGetCurrentIrql();
    if (currentIrql > maxIrql) {
        KePanic(KE_PANIC_CODE_IRQL, "IRQL assertion failed: expected <= %s(%u), current %s(%u)\n",
                KeIrqlName(maxIrql), (unsigned)maxIrql,
                KeIrqlName(currentIrql), (unsigned)currentIrql);
    }
}

// Checks whether wait.
__declspec(dllexport) bool KeCanWait(void) {
    return KeGetCurrentIrql() == PASSIVE_LEVEL;
}