forked from AbleOS/holey-bytes
idk
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8374dfe20a
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@ -30,9 +30,24 @@ macro_rules! fnsdef {
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$vis fn $name(val: $from, mode: RoundingMode) -> $to {
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let result: $to;
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unsafe {
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set_rounding_mode(mode);
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let mut mxcsr = 0_u32;
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'a: {
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asm!("stmxcsr {}", in(reg) &mut mxcsr);
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asm!(
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"ldmxcsr {}",
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in(reg) &(mxcsr & !arin::_MM_ROUND_MASK | match mode {
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RoundingMode::NearestEven => break 'a,
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RoundingMode::Truncate => arin::_MM_ROUND_TOWARD_ZERO,
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RoundingMode::Up => arin::_MM_ROUND_UP,
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RoundingMode::Down => arin::_MM_ROUND_DOWN,
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})
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);
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}
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op!($ins, val, result => $to);
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default_rounding_mode();
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// Set MXCSR to original value
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asm!("ldmxcsr {}", in(reg) &mxcsr);
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}
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result
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}
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@ -47,27 +62,3 @@ fnsdef! {
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/// Convert [`f64`] to [`i64`] with chosen rounding mode
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pub fn f64toint(f64 -> i64): "cvttsd2si";
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}
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/// Set rounding mode
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///
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/// # Safety
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/// - Do not call if rounding mode isn't [`RoundingMode::NearestEven`]
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/// - Do not perform any Rust FP operations until reset using
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/// [`default_rounding_mode`], you have to rely on inline assembly
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#[inline(always)]
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unsafe fn set_rounding_mode(mode: RoundingMode) {
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unsafe {
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arin::_MM_SET_ROUNDING_MODE(match mode {
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RoundingMode::NearestEven => return,
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RoundingMode::Truncate => arin::_MM_ROUND_TOWARD_ZERO,
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RoundingMode::Up => arin::_MM_ROUND_UP,
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RoundingMode::Down => arin::_MM_ROUND_DOWN,
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})
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}
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}
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#[inline(always)]
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fn default_rounding_mode() {
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// SAFETY: This is said to be the default mode, do not trust me.
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unsafe { arin::_MM_SET_ROUNDING_MODE(arin::_MM_ROUND_NEAREST) };
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}
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