// HAL ABI - The Contract between L0 (Zig) and L1 (Nim)
// This struct is the "contract" for future language integration

pub const HAL = extern struct {
    /// Write to console/serial
    console_write: *const fn ([*]const u8, usize) void,

    /// Allocate physical pages
    palloc: *const fn (usize) ?*anyopaque,

    /// Free physical pages
    pfree: *const fn (*anyopaque) void,

    /// Register interrupt handler
    irq_register: *const fn (u8, *const fn () void) void,

    /// Get current time in nanoseconds
    timer_now_ns: *const fn () u64,

    /// Halt the CPU
    halt: *const fn () noreturn,
};

/// Global HAL instance - initialized by boot code
pub var hal: HAL = undefined;

/// Initialize the HAL with platform-specific implementations
pub fn init(console: anytype, allocator: anytype) void {
    hal = HAL{
        .console_write = console.write,
        .palloc = allocator.alloc,
        .pfree = allocator.free,
        .irq_register = undefined, // TODO
        .timer_now_ns = undefined, // TODO
        .halt = halt_impl,
    };
}

fn halt_impl() noreturn {
    while (true) {
        asm volatile ("wfi");
    }
}

// =========================================================
// Exports for Nim FFI
// =========================================================

export fn rumpk_console_write(ptr: [*]const u8, len: usize) void {
    hal.console_write(ptr, len);
}

export fn rumpk_palloc(pages: usize) ?*anyopaque {
    return hal.palloc(pages);
}

export fn rumpk_pfree(ptr: *anyopaque) void {
    hal.pfree(ptr);
}

export fn rumpk_halt() noreturn {
    hal.halt();
}

var mock_ticks: u64 = 0;

export fn rumpk_timer_now_ns() u64 {
    // Phase 1 Mock: Incrementing counter to simulate time passage per call
    mock_ticks += 100000; // 100us per call
    return mock_ticks;
}