95 lines
2.8 KiB
Rust
95 lines
2.8 KiB
Rust
use int::{Int, LargeInt};
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trait Ashl: Int + LargeInt {
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/// Returns `a << b`, requires `b < $ty::bits()`
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fn ashl(self, offset: u32) -> Self
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where Self: LargeInt<HighHalf = <Self as LargeInt>::LowHalf>,
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{
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let half_bits = Self::bits() / 2;
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if offset & half_bits != 0 {
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Self::from_parts(Int::zero(), self.low() << (offset - half_bits))
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} else if offset == 0 {
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self
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} else {
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Self::from_parts(self.low() << offset,
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(self.high() << offset) |
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(self.low() >> (half_bits - offset)))
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}
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}
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}
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impl Ashl for u64 {}
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impl Ashl for u128 {}
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trait Ashr: Int + LargeInt {
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/// Returns arithmetic `a >> b`, requires `b < $ty::bits()`
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fn ashr(self, offset: u32) -> Self
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where Self: LargeInt<LowHalf = <<Self as LargeInt>::HighHalf as Int>::UnsignedInt>,
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{
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let half_bits = Self::bits() / 2;
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if offset & half_bits != 0 {
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Self::from_parts((self.high() >> (offset - half_bits)).unsigned(),
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self.high() >> (half_bits - 1))
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} else if offset == 0 {
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self
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} else {
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let high_unsigned = self.high().unsigned();
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Self::from_parts((high_unsigned << (half_bits - offset)) | (self.low() >> offset),
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self.high() >> offset)
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}
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}
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}
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impl Ashr for i64 {}
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impl Ashr for i128 {}
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trait Lshr: Int + LargeInt {
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/// Returns logical `a >> b`, requires `b < $ty::bits()`
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fn lshr(self, offset: u32) -> Self
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where Self: LargeInt<HighHalf = <Self as LargeInt>::LowHalf>,
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{
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let half_bits = Self::bits() / 2;
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if offset & half_bits != 0 {
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Self::from_parts(self.high() >> (offset - half_bits), Int::zero())
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} else if offset == 0 {
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self
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} else {
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Self::from_parts((self.high() << (half_bits - offset)) |
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(self.low() >> offset),
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self.high() >> offset)
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}
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}
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}
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impl Lshr for u64 {}
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impl Lshr for u128 {}
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intrinsics! {
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#[cfg(not(all(feature = "c", target_arch = "x86")))]
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pub extern "C" fn __ashldi3(a: u64, b: u32) -> u64 {
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a.ashl(b)
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}
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pub extern "C" fn __ashlti3(a: u128, b: u32) -> u128 {
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a.ashl(b)
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}
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#[cfg(not(all(feature = "c", target_arch = "x86")))]
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pub extern "C" fn __ashrdi3(a: i64, b: u32) -> i64 {
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a.ashr(b)
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}
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pub extern "C" fn __ashrti3(a: i128, b: u32) -> i128 {
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a.ashr(b)
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}
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#[cfg(not(all(feature = "c", target_arch = "x86")))]
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pub extern "C" fn __lshrdi3(a: u64, b: u32) -> u64 {
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a.lshr(b)
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}
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pub extern "C" fn __lshrti3(a: u128, b: u32) -> u128 {
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a.lshr(b)
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}
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}
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