99 lines
3.0 KiB
Rust
99 lines
3.0 KiB
Rust
use int::{Int, LargeInt};
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macro_rules! ashl {
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($intrinsic:ident: $ty:ty) => {
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/// Returns `a << b`, requires `b < $ty::bits()`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn $intrinsic(a: $ty, b: u32) -> $ty {
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let half_bits = <$ty>::bits() / 2;
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if b & half_bits != 0 {
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<$ty>::from_parts(0, a.low() << (b - half_bits))
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} else if b == 0 {
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a
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} else {
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<$ty>::from_parts(a.low() << b, (a.high() << b) | (a.low() >> (half_bits - b)))
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}
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}
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}
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}
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macro_rules! ashr {
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($intrinsic:ident: $ty:ty) => {
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/// Returns arithmetic `a >> b`, requires `b < $ty::bits()`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn $intrinsic(a: $ty, b: u32) -> $ty {
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let half_bits = <$ty>::bits() / 2;
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if b & half_bits != 0 {
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<$ty>::from_parts((a.high() >> (b - half_bits)) as <$ty as LargeInt>::LowHalf,
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a.high() >> (half_bits - 1))
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} else if b == 0 {
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a
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} else {
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let high_unsigned = a.high() as <$ty as LargeInt>::LowHalf;
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<$ty>::from_parts((high_unsigned << (half_bits - b)) | (a.low() >> b),
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a.high() >> b)
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}
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}
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}
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}
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macro_rules! lshr {
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($intrinsic:ident: $ty:ty) => {
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/// Returns logical `a >> b`, requires `b < $ty::bits()`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn $intrinsic(a: $ty, b: u32) -> $ty {
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let half_bits = <$ty>::bits() / 2;
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if b & half_bits != 0 {
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<$ty>::from_parts(a.high() >> (b - half_bits), 0)
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} else if b == 0 {
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a
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} else {
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<$ty>::from_parts((a.high() << (half_bits - b)) | (a.low() >> b), a.high() >> b)
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}
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}
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}
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}
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ashl!(__ashldi3: u64);
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ashr!(__ashrdi3: i64);
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lshr!(__lshrdi3: u64);
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#[cfg(test)]
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mod tests {
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use quickcheck::TestResult;
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use qc::{I64, U64};
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// NOTE We purposefully stick to `u32` for `b` here because we want "small" values (b < 64)
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quickcheck! {
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fn ashldi(a: U64, b: u32) -> TestResult {
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let a = a.0;
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if b >= 64 {
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TestResult::discard()
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} else {
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let r = super::__ashldi3(a, b);
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TestResult::from_bool(r == a << b)
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}
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}
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fn ashrdi(a: I64, b: u32) -> TestResult {
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let a = a.0;
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if b >= 64 {
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TestResult::discard()
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} else {
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let r = super::__ashrdi3(a, b);
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TestResult::from_bool(r == a >> b)
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}
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}
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fn lshrdi(a: U64, b: u32) -> TestResult {
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let a = a.0;
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if b >= 64 {
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TestResult::discard()
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} else {
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let r = super::__lshrdi3(a, b);
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TestResult::from_bool(r == a >> b)
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}
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}
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}
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}
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