//! K531: real SGI entry, then a hardware spurious IAR inside that IRQ vector.
//! The trigger is deliberately consumed before the second dispatcher read.
//! This models a withdrawn/consumed source, not an electrical hardware fault.
//! Special INTIDs never reach the acknowledged-source EOI helper.
use super::*;

static mut SEEN: u64 = 0;
static mut GICR: u64 = 0;

fn fail(reason: &str) -> usize {
    write_str("TURKOS/IRQ-EDGE-ERROR: ");
    write_line(reason);
    0
}

pub(super) fn handle(frame: *const irq::IrqContext, low: usize, top: usize, sp: usize) -> usize {
    if frame.is_null() {
        return fail("null frame");
    }
    let context = unsafe { &*frame };
    if frame as usize != top - size_of::<irq::IrqContext>()
        || !irq::handler_sp_in_stack(low, frame as usize, sp)
        || context.vector_slot != 5
        || context.spsr & 0x8f != 5
        || context.interrupted_sp & 15 != 0
        || context.x[20] != 0x5310
        || context.x[21] != 0x5311
        || context.q[0] != [0x5a5a_5a5a_5a5a_5a5a; 2]
        || context.q[31] != [0xa5a5_a5a5_a5a5_a5a5; 2]
        || unsafe { read_volatile(core::ptr::addr_of!(__irq_stack_guard)) } != IRQ_GUARD
        || unsafe { read_volatile(core::ptr::addr_of!(SEEN)) } != 0
    {
        return fail("vector/context");
    }
    let trigger: u64;
    unsafe { asm!("mrs {value}, ICC_IAR1_EL1", value = out(reg) trigger, options(nomem, nostack)) };
    if irq::classify_iar(trigger, 2) != irq::IarClass::Expected {
        return fail("SGI trigger");
    }
    let gicr = unsafe { GICR };
    unsafe {
        write_volatile((gicr + 0x10180) as *mut u32, 4);
        asm!("dsb sy", options(nostack));
        let mut ready = false;
        for _ in 0..1_000_000 {
            if read_volatile(gicr as *const u32) & 8 == 0 {
                ready = true;
                break;
            }
        }
        if !ready || read_volatile((gicr + 0x10100) as *const u32) & 4 != 0 {
            return fail("trigger source not masked");
        }
        // Exactly this acknowledged SGI, not either special value, is EOI'd.
        asm!("msr ICC_EOIR1_EL1, {value}", "isb", value = in(reg) trigger, options(nomem, nostack));
        let control: u64;
        asm!("mrs {value}, ICC_CTLR_EL1", value = out(reg) control, options(nomem, nostack));
        if control & 2 != 0 {
            asm!("msr ICC_DIR_EL1, {value}", "isb", value = in(reg) trigger, options(nomem, nostack));
        }
    }
    let special: u64;
    let again: u64;
    let priority_before: u64;
    let priority_after: u64;
    unsafe {
        asm!("mrs {priority}, ICC_RPR_EL1", "mrs {iar}, ICC_IAR1_EL1", priority = out(reg) priority_before, iar = out(reg) special, options(nomem, nostack));
        // The repeat hardware read witnesses the no-EOI path. No constant is
        // substituted for IAR, and no EOIR/DIR instruction is in this branch.
        asm!("mrs {iar}, ICC_IAR1_EL1", "mrs {priority}, ICC_RPR_EL1", iar = out(reg) again, priority = out(reg) priority_after, options(nomem, nostack));
    }
    if irq::classify_iar(special, 30) != irq::IarClass::Special(1023)
        || irq::classify_iar(again, 30) != irq::IarClass::Special(1023)
        || priority_before != priority_after
    {
        return fail("hardware special dispatch");
    }
    write_str("TURKOS/IRQ-SPURIOUS-VECTOR: SLOT=5 TRIGGER=0x");
    write_hex(trigger as usize);
    write_str(" SPECIAL=0x");
    write_hex(special as usize);
    write_str(" REPEAT=0x");
    write_hex(again as usize);
    write_line(" TRIGGER-EOI=1 SPECIAL-EOI=0 RPR=UNCHANGED");
    unsafe { write_volatile(core::ptr::addr_of_mut!(SEEN), 1) };
    1
}

pub(super) fn run(gicr: u64) -> ! {
    let mpidr: u64;
    unsafe { asm!("mrs {value}, MPIDR_EL1", value = out(reg) mpidr, options(nomem, nostack)) };
    let command = irq::sgi1r_for_mpidr(mpidr, 2).unwrap_or_else(|| park());
    unsafe {
        GICR = gicr;
        write_volatile(core::ptr::addr_of_mut!(__irq_stack_guard), IRQ_GUARD);
        #[cfg(feature = "irq-spurious-vector-guard-test")]
        write_volatile(core::ptr::addr_of_mut!(__irq_stack_guard), 0);
    }
    write_line("TURKOS/IRQ-SPURIOUS-VECTOR: ARMED REAL-SGI=2 CONSUME-THEN-SPECIAL");
    let seen: u64;
    let x20: u64;
    let x21: u64;
    let q0: u64;
    let q31: u64;
    unsafe {
        asm!(
            "movi v0.16b, #0x5a", "movi v31.16b, #0xa5",
            "msr ICC_SGI1R_EL1, {command}", "isb", "msr daifclr, #2",
            "2:", "ldr {seen}, [{pointer}]", "cbnz {seen}, 3f",
            "subs {budget}, {budget}, #1", "b.ne 2b",
            "3:", "msr daifset, #2", "isb",
            "umov {q0}, v0.d[0]", "umov {q31}, v31.d[0]",
            command = in(reg) command, pointer = in(reg) core::ptr::addr_of!(SEEN),
            budget = inout(reg) 10_000_000u64 => _, seen = out(reg) seen,
            inout("x20") 0x5310u64 => x20, inout("x21") 0x5311u64 => x21,
            q0 = lateout(reg) q0, q31 = lateout(reg) q31, out("v0") _, out("v31") _,
        );
    }
    if seen == 1
        && x20 == 0x5310
        && x21 == 0x5311
        && q0 == 0x5a5a_5a5a_5a5a_5a5a
        && q31 == 0xa5a5_a5a5_a5a5_a5a5
    {
        write_line("TURKOS/IRQ-SPURIOUS-RETURN: ERET GP-SIMD=RESTORED PASS");
    } else {
        fail("ERET witnesses/timeout");
    }
    park()
}