compiler-builtins-zynq/src/int/shift.rs

98 lines
2.9 KiB
Rust

use int::{Int, LargeInt};
trait Ashl: Int + LargeInt {
/// Returns `a << b`, requires `b < Self::BITS`
fn ashl(self, offset: u32) -> Self
where Self: LargeInt<HighHalf = <Self as LargeInt>::LowHalf>,
{
let half_bits = Self::BITS / 2;
if offset & half_bits != 0 {
Self::from_parts(Int::ZERO, self.low() << (offset - half_bits))
} else if offset == 0 {
self
} else {
Self::from_parts(self.low() << offset,
(self.high() << offset) |
(self.low() >> (half_bits - offset)))
}
}
}
impl Ashl for u64 {}
impl Ashl for u128 {}
trait Ashr: Int + LargeInt {
/// Returns arithmetic `a >> b`, requires `b < Self::BITS`
fn ashr(self, offset: u32) -> Self
where Self: LargeInt<LowHalf = <<Self as LargeInt>::HighHalf as Int>::UnsignedInt>,
{
let half_bits = Self::BITS / 2;
if offset & half_bits != 0 {
Self::from_parts((self.high() >> (offset - half_bits)).unsigned(),
self.high() >> (half_bits - 1))
} else if offset == 0 {
self
} else {
let high_unsigned = self.high().unsigned();
Self::from_parts((high_unsigned << (half_bits - offset)) | (self.low() >> offset),
self.high() >> offset)
}
}
}
impl Ashr for i64 {}
impl Ashr for i128 {}
trait Lshr: Int + LargeInt {
/// Returns logical `a >> b`, requires `b < Self::BITS`
fn lshr(self, offset: u32) -> Self
where Self: LargeInt<HighHalf = <Self as LargeInt>::LowHalf>,
{
let half_bits = Self::BITS / 2;
if offset & half_bits != 0 {
Self::from_parts(self.high() >> (offset - half_bits), Int::ZERO)
} else if offset == 0 {
self
} else {
Self::from_parts((self.high() << (half_bits - offset)) |
(self.low() >> offset),
self.high() >> offset)
}
}
}
impl Lshr for u64 {}
impl Lshr for u128 {}
intrinsics! {
#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
#[arm_aeabi_alias = __aeabi_llsl]
pub extern "C" fn __ashldi3(a: u64, b: u32) -> u64 {
a.ashl(b)
}
pub extern "C" fn __ashlti3(a: u128, b: u32) -> u128 {
a.ashl(b)
}
#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
#[arm_aeabi_alias = __aeabi_lasr]
pub extern "C" fn __ashrdi3(a: i64, b: u32) -> i64 {
a.ashr(b)
}
pub extern "C" fn __ashrti3(a: i128, b: u32) -> i128 {
a.ashr(b)
}
#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
#[arm_aeabi_alias = __aeabi_llsr]
pub extern "C" fn __lshrdi3(a: u64, b: u32) -> u64 {
a.lshr(b)
}
pub extern "C" fn __lshrti3(a: u128, b: u32) -> u128 {
a.lshr(b)
}
}