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Maybe fixed questionable code

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This commit is contained in:
Erin 2024-02-04 22:36:52 +01:00
parent 975ce8a9fe
commit fe9a0667b8
1 changed files with 17 additions and 34 deletions
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51
hbvm/src/float/aarch64.rs
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@ -9,13 +9,28 @@ macro_rules! fnsdef {
$vis fn $name(val: $from, mode: RoundingMode) -> $to { $vis fn $name(val: $from, mode: RoundingMode) -> $to {
let result: $to; let result: $to;
unsafe { unsafe {
set_rounding_mode(mode); if mode == RoundingMode::NearestEven {
return;
}
let fpcr: u64;
unsafe { asm!("mrs {}, fpcr", out(reg) fpcr) };
let fpcr_new = fpcr & !(0b11 << 22)
| (match mode {
RoundingMode::NearestEven => 0b00,
RoundingMode::Truncate => 0b11,
RoundingMode::Up => 0b01,
RoundingMode::Down => 0b10,
}) << 22;
unsafe { asm!("msr fpcr, {}", in(reg) fpcr_new) };
asm!( asm!(
$ins, $ins,
out($outreg) result, out($outreg) result,
in($inreg) val, in($inreg) val,
); );
default_rounding_mode(); unsafe { asm!("msr fpcr, {}", in(reg) fpcr) };
} }
result result
} }
@ -32,35 +47,3 @@ fnsdef! {
/// Convert [`f64`] to [`i64`] with chosen rounding mode /// Convert [`f64`] to [`i64`] with chosen rounding mode
pub fn f64toint[vreg -> reg](f64 -> i64): "fcvtzs {}, {:d}"; pub fn f64toint[vreg -> reg](f64 -> i64): "fcvtzs {}, {:d}";
} }
/// Set rounding mode
///
/// # Safety
/// - Do not call if rounding mode isn't [`RoundingMode::NearestEven`]
/// - Do not perform any Rust FP operations until reset using
/// [`default_rounding_mode`], you have to rely on inline assembly
#[inline(always)]
unsafe fn set_rounding_mode(mode: RoundingMode) {
if mode == RoundingMode::NearestEven {
return;
}
let fpcr: u64;
unsafe { asm!("mrs {}, fpcr", out(reg) fpcr) };
let fpcr = fpcr & !(0b11 << 22)
| (match mode {
RoundingMode::NearestEven => 0b00,
RoundingMode::Truncate => 0b11,
RoundingMode::Up => 0b01,
RoundingMode::Down => 0b10,
}) << 22;
unsafe { asm!("msr fpcr, {}", in(reg) fpcr) };
}
#[inline(always)]
unsafe fn default_rounding_mode() {
// I hope so much it gets optimised
set_rounding_mode(RoundingMode::NearestEven);
}