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// SPDX-License-Identifier: Apache-2.0 OR MIT
/*
M68k
See "Atomic operation overview by architecture" for atomic operations in this architecture:
https://github.com/taiki-e/atomic-maybe-uninit/blob/HEAD/src/arch/README.md#m68k
Refs:
- M68000 FAMILY Programmer's Reference Manual
https://www.nxp.com/docs/en/reference-manual/M68000PRM.pdf
- M68060 User’s Manual
https://www.nxp.com/docs/en/data-sheet/MC68060UM.pdf
See tests/asm-test/asm/atomic-maybe-uninit for generated assembly.
*/
use core::{
arch::asm,
mem::{self, MaybeUninit},
sync::atomic::Ordering,
};
use crate::raw::{AtomicLoad, AtomicStore};
cfg_sel!({
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
{
use crate::{
raw::{AtomicCompareExchange, AtomicSwap},
utils::{MaybeUninit64, Pair},
};
delegate_size!(delegate_all);
}
#[cfg(else)]
{
delegate_size!(delegate_load_store);
}
});
// -----------------------------------------------------------------------------
// Register-width or smaller atomics
macro_rules! atomic {
($ty:ident, $suffix:tt) => {
#[cfg(not(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020")))]
delegate_signed!(delegate_load_store, $ty);
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
delegate_signed!(delegate_all, $ty);
impl AtomicLoad for $ty {
#[inline]
unsafe fn atomic_load(
src: *const MaybeUninit<Self>,
_order: Ordering,
) -> MaybeUninit<Self> {
let out: MaybeUninit<Self>;
// SAFETY: the caller must uphold the safety contract.
// MOVE has SeqCst semantics.
unsafe {
asm!(
concat!("move.", $suffix, " ({src}), {out}"), // atomic { out = *src }
src = in(reg_addr) ptr_reg!(src),
out = out(reg_data) out,
// Do not use `preserves_flags` because MOVE modifies N, Z, V, and C bits in the condition codes.
options(nostack),
);
}
out
}
}
impl AtomicStore for $ty {
#[inline]
unsafe fn atomic_store(
dst: *mut MaybeUninit<Self>,
val: MaybeUninit<Self>,
_order: Ordering,
) {
// SAFETY: the caller must uphold the safety contract.
// MOVE has SeqCst semantics.
unsafe {
asm!(
concat!("move.", $suffix, " {val}, ({dst})"), // atomic { *dst = val }
dst = in(reg_addr) ptr_reg!(dst),
val = in(reg_data) val,
// Do not use `preserves_flags` because MOVE modifies N, Z, V, and C bits in the condition codes.
options(nostack),
);
}
}
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicSwap for $ty {
#[inline]
unsafe fn atomic_swap(
dst: *mut MaybeUninit<Self>,
val: MaybeUninit<Self>,
_order: Ordering,
) -> MaybeUninit<Self> {
let mut out: MaybeUninit<Self>;
// SAFETY: the caller must uphold the safety contract.
// CAS2 has SeqCst semantics.
unsafe {
asm!(
concat!("move.", $suffix, " ({dst}), {out}"), // atomic { out = *dst }
"2:", // 'retry:
concat!("cas.", $suffix, " {out}, {val}, ({dst})"), // atomic { if *dst == out { cc.Z = 1; *dst = val } else { cc.Z = 0; out = *dst } }
"bne 2b", // if cc.Z == 0 { jump 'retry }
dst = in(reg_addr) ptr_reg!(dst),
val = in(reg_data) val,
out = out(reg_data) out,
// Do not use `preserves_flags` because MOVE and CAS modify N, Z, V, and C bits in the condition codes.
options(nostack),
);
}
out
}
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicCompareExchange for $ty {
#[inline]
unsafe fn atomic_compare_exchange(
dst: *mut MaybeUninit<Self>,
old: MaybeUninit<Self>,
new: MaybeUninit<Self>,
_success: Ordering,
_failure: Ordering,
) -> (MaybeUninit<Self>, bool) {
let out: MaybeUninit<Self>;
let r: u8;
// SAFETY: the caller must uphold the safety contract.
// CAS has SeqCst semantics.
unsafe {
asm!(
concat!("cas.", $suffix, " {out}, {new}, ({dst})"), // atomic { if *dst == out { cc.Z = 1; *dst = new } else { cc.Z = 0; out = *dst } }
"seq {r}", // r = if cc.Z { !0u8 } else { 0 }
dst = in(reg_addr) ptr_reg!(dst),
new = in(reg_data) new,
out = inout(reg_data) old => out,
r = lateout(reg_data) r,
// Do not use `preserves_flags` because CAS modifies N, Z, V, and C bits in the condition codes.
options(nostack),
);
debug_assert!(r == 0 || r == u8::MAX);
}
(out, r != 0)
}
}
};
}
atomic!(u8, "b");
atomic!(u16, "w");
atomic!(u32, "l");
// -----------------------------------------------------------------------------
// 64-bit atomics
//
// Use .2byte directive because CAS2 is not yet supported in LLVM (as of 21): https://godbolt.org/z/eWaT9Mbfe
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
delegate_signed!(delegate_all, u64);
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicLoad for u64 {
#[inline]
unsafe fn atomic_load(src: *const MaybeUninit<Self>, _order: Ordering) -> MaybeUninit<Self> {
let (out_hi, out_lo);
// SAFETY: the caller must uphold the safety contract.
// CAS2 has SeqCst semantics.
unsafe {
let src1 = src.cast::<u32>();
let src2 = src1.add(1);
asm!(
".2byte 0x0efc",
".2byte 0x8081",
".2byte 0x90c0",
// "cas2.l %d1:%d0, %d2:%d3, (%a0):(%a1)", // atomic { _out1 = *src1; _out2 = *src2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *src1 = new1; *src2 = new2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
in("a0") ptr_reg!(src1),
in("a1") ptr_reg!(src2),
in("d2") 0_u32, // new1
in("d3") 0_u32, // new2
inout("d1") 0_u32 => out_hi, // out1
inout("d0") 0_u32 => out_lo, // out2
// Do not use `preserves_flags` because CAS2 modifies N, Z, V, and C bits in the condition codes.
options(nostack),
);
// asm!(
// "cas2.l {out1}:{out2}, {new1}:{new2}, ({src1}):({src2})", // atomic { _out1 = *src1; _out2 = *src2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *src1 = new1; *src2 = new2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
// src1 = in(reg_addr) ptr_reg!(src1),
// src2 = in(reg_addr) ptr_reg!(src2),
// new1 = in(reg_data) 0_u32,
// new2 = in(reg_data) 0_u32,
// out1 = inout(reg_data) 0_u32 => out_hi,
// out2 = inout(reg_data) 0_u32 => out_lo,
// // Do not use `preserves_flags` because CAS2 modifies N, Z, V, and C bits in the condition codes.
// options(nostack),
// );
MaybeUninit64 { pair: Pair { hi: out_hi, lo: out_lo } }.whole
}
}
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicStore for u64 {
#[inline]
unsafe fn atomic_store(dst: *mut MaybeUninit<Self>, val: MaybeUninit<Self>, _order: Ordering) {
// SAFETY: the caller must uphold the safety contract.
// CAS2 has SeqCst semantics.
unsafe {
<Self as AtomicSwap>::atomic_swap(dst, val, Ordering::SeqCst);
}
}
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicSwap for u64 {
#[inline]
unsafe fn atomic_swap(
dst: *mut MaybeUninit<Self>,
val: MaybeUninit<Self>,
_order: Ordering,
) -> MaybeUninit<Self> {
let val = MaybeUninit64 { whole: val };
let (mut prev_lo, mut prev_hi);
// SAFETY: the caller must uphold the safety contract.
// CAS2 has SeqCst semantics.
unsafe {
let dst1 = dst.cast::<u32>();
let dst2 = dst1.add(1);
asm!(
"move.l (%a0), %d1", // atomic { out1 = *dst1 }
"move.l (%a1), %d0", // atomic { out2 = *dst2 }
"2:", // 'retry:
".2byte 0x0efc",
".2byte 0x8081",
".2byte 0x90c0",
// "cas2.l %d1:%d0, %d2:%d3, (%a0):(%a1)", // atomic { _out1 = *dst1; _out2 = *dst2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *dst1 = val1; *dst2 = val2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
"bne 2b", // if cc.Z == 0 { jump 'retry }
in("a0") ptr_reg!(dst1),
in("a1") ptr_reg!(dst2),
in("d2") val.pair.hi, // val1
in("d3") val.pair.lo, // val2
out("d1") prev_hi, // out1
out("d0") prev_lo, // out2
// Do not use `preserves_flags` because MOVE and CAS2 modify N, Z, V, and C bits in the condition codes.
options(nostack),
);
// asm!(
// "move.l ({dst1}), {out1}", // atomic { out1 = *dst1 }
// "move.l ({dst2}), {out2}", // atomic { out2 = *dst2 }
// "2:", // 'retry:
// "cas2.l {out1}:{out2}, {val1}:{val2}, ({dst1}):({dst2})", // atomic { _out1 = *dst1; _out2 = *dst2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *dst1 = val1; *dst2 = val2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
// "bne 2b", // if cc.Z == 0 { jump 'dst }
// dst1 = in(reg_addr) ptr_reg!(dst1),
// dst2 = in(reg_addr) ptr_reg!(dst2),
// val1 = in(reg_data) val.pair.hi,
// val2 = in(reg_data) val.pair.lo,
// out1 = out(reg_data) prev_hi,
// out2 = out(reg_data) prev_lo,
// // Do not use `preserves_flags` because MOVE and CAS2 modify N, Z, V, and C bits in the condition codes.
// options(nostack),
// );
MaybeUninit64 { pair: Pair { hi: prev_hi, lo: prev_lo } }.whole
}
}
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
impl AtomicCompareExchange for u64 {
#[inline]
unsafe fn atomic_compare_exchange(
dst: *mut MaybeUninit<Self>,
old: MaybeUninit<Self>,
new: MaybeUninit<Self>,
_success: Ordering,
_failure: Ordering,
) -> (MaybeUninit<Self>, bool) {
let old = MaybeUninit64 { whole: old };
let new = MaybeUninit64 { whole: new };
let (prev_hi, prev_lo);
let r: u8;
// SAFETY: the caller must uphold the safety contract.
// CAS2 has SeqCst semantics.
unsafe {
let dst1 = dst.cast::<u32>();
let dst2 = dst1.add(1);
asm!(
".2byte 0x0efc",
".2byte 0x8081",
".2byte 0x90c0",
// "cas2.l %d1:%d0, %d2:%d3, (%a0):(%a1)", // atomic { _out1 = *dst1; _out2 = *dst2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *dst1 = new1; *dst2 = new2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
"seq {r}", // r = if cc.Z { !0u8 } else { 0 }
in("a0") ptr_reg!(dst1),
in("a1") ptr_reg!(dst2),
in("d2") new.pair.hi, // new1
in("d3") new.pair.lo, // new2
inout("d1") old.pair.hi => prev_hi, // out1
inout("d0") old.pair.lo => prev_lo, // out2
r = lateout(reg_data) r,
// Do not use `preserves_flags` because CAS2 modifies N, Z, V, and C bits in the condition codes.
options(nostack),
);
// asm!(
// "cas2.l {out1}:{out2}, {new1}:{new2}, ({dst1}):({dst2})", // atomic { _out1 = *dst1; _out2 = *dst2; if _out1 == out1 && _out2 == out2 { cc.Z = 1; *dst1 = new1; *dst2 = new2 } else { cc.Z = 0 }; out1 = _out1; out2 = _out2 }
// "seq {r}", // r = if cc.Z { !0u8 } else { 0 }
// dst1 = in(reg_addr) ptr_reg!(dst1),
// dst2 = in(reg_addr) ptr_reg!(dst2),
// new1 = in(reg_data) new.pair.hi,
// new2 = in(reg_data) new.pair.lo,
// out1 = inout(reg_data) old.pair.hi => prev_hi,
// out2 = inout(reg_data) old.pair.lo => prev_lo,
// r = lateout(reg_data) r,
// // Do not use `preserves_flags` because CAS2 modifies N, Z, V, and C bits in the condition codes.
// options(nostack),
// );
debug_assert!(r == 0 || r == u8::MAX);
(MaybeUninit64 { pair: Pair { hi: prev_hi, lo: prev_lo } }.whole, r != 0)
}
}
}
// -----------------------------------------------------------------------------
// cfg macros
#[macro_export]
macro_rules! cfg_has_atomic_8 {
($($tt:tt)*) => { $($tt)* };
}
#[macro_export]
macro_rules! cfg_no_atomic_8 {
($($tt:tt)*) => {};
}
#[macro_export]
macro_rules! cfg_has_atomic_16 {
($($tt:tt)*) => { $($tt)* };
}
#[macro_export]
macro_rules! cfg_no_atomic_16 {
($($tt:tt)*) => {};
}
#[macro_export]
macro_rules! cfg_has_atomic_32 {
($($tt:tt)*) => { $($tt)* };
}
#[macro_export]
macro_rules! cfg_no_atomic_32 {
($($tt:tt)*) => {};
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
#[macro_export]
macro_rules! cfg_has_atomic_64 {
($($tt:tt)*) => { $($tt)* };
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
#[macro_export]
macro_rules! cfg_no_atomic_64 {
($($tt:tt)*) => {};
}
#[cfg(not(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020")))]
#[macro_export]
macro_rules! cfg_has_atomic_64 {
($($tt:tt)*) => {};
}
#[cfg(not(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020")))]
#[macro_export]
macro_rules! cfg_no_atomic_64 {
($($tt:tt)*) => { $($tt)* };
}
#[macro_export]
macro_rules! cfg_has_atomic_128 {
($($tt:tt)*) => {};
}
#[macro_export]
macro_rules! cfg_no_atomic_128 {
($($tt:tt)*) => { $($tt)* };
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
#[macro_export]
macro_rules! cfg_has_atomic_cas {
($($tt:tt)*) => { $($tt)* };
}
#[cfg(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020"))]
#[macro_export]
macro_rules! cfg_no_atomic_cas {
($($tt:tt)*) => {};
}
#[cfg(not(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020")))]
#[macro_export]
macro_rules! cfg_has_atomic_cas {
($($tt:tt)*) => {};
}
#[cfg(not(any(target_feature = "isa-68020", atomic_maybe_uninit_target_feature = "isa-68020")))]
#[macro_export]
macro_rules! cfg_no_atomic_cas {
($($tt:tt)*) => { $($tt)* };
}