Port udiv to the `intrinsics!` macro
Alex Crichton
parent
7886ae275b
commit
d17042106f
274
src/int/udiv.rs
274
src/int/udiv.rs
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@ -1,141 +1,7 @@
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use core::intrinsics;
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use int::{Int, LargeInt};
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/// Returns `n / d`
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#[cfg(not(all(feature = "c", target_arch = "arm", not(target_os = "ios"), not(thumbv6m))))]
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#[cfg_attr(all(not(test), not(target_arch = "arm")), no_mangle)]
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#[cfg_attr(all(not(test), target_arch = "arm"), inline(always))]
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pub extern "C" fn __udivsi3(n: u32, d: u32) -> u32 {
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// Special cases
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if d == 0 {
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// NOTE This should be unreachable in safe Rust because the program will panic before
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// this intrinsic is called
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unsafe {
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intrinsics::abort()
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}
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}
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if n == 0 {
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return 0;
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}
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let mut sr = d.leading_zeros().wrapping_sub(n.leading_zeros());
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// d > n
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if sr > u32::bits() - 1 {
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return 0;
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}
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// d == 1
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if sr == u32::bits() - 1 {
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return n;
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}
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sr += 1;
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// 1 <= sr <= u32::bits() - 1
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let mut q = n << (u32::bits() - sr);
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let mut r = n >> sr;
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let mut carry = 0;
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for _ in 0..sr {
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// r:q = ((r:q) << 1) | carry
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r = (r << 1) | (q >> (u32::bits() - 1));
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q = (q << 1) | carry;
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// carry = 0;
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// if r > d {
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// r -= d;
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// carry = 1;
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// }
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let s = (d.wrapping_sub(r).wrapping_sub(1)) as i32 >> (u32::bits() - 1);
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carry = (s & 1) as u32;
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r -= d & s as u32;
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}
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(q << 1) | carry
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}
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/// Returns `n % d`
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#[cfg(not(all(feature = "c", target_arch = "arm", not(target_os = "ios"))))]
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn __umodsi3(n: u32, d: u32) -> u32 {
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#[cfg(all(feature = "c", target_arch = "arm", not(target_os = "ios")))]
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extern "C" {
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fn __udivsi3(n: u32, d: u32) -> u32;
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}
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let q = match () {
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#[cfg(all(feature = "c", target_arch = "arm", not(target_os = "ios")))]
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() => unsafe { __udivsi3(n, d) },
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#[cfg(not(all(feature = "c", target_arch = "arm", not(target_os = "ios"))))]
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() => __udivsi3(n, d),
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};
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n - q * d
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}
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/// Returns `n / d` and sets `*rem = n % d`
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#[cfg(not(all(feature = "c", target_arch = "arm", not(target_os = "ios"), not(thumbv6m))))]
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn __udivmodsi4(n: u32, d: u32, rem: Option<&mut u32>) -> u32 {
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#[cfg(all(feature = "c", target_arch = "arm", not(target_os = "ios"), not(thumbv6m)))]
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extern "C" {
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fn __udivsi3(n: u32, d: u32) -> u32;
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}
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let q = match () {
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#[cfg(all(feature = "c", target_arch = "arm", not(target_os = "ios"), not(thumbv6m)))]
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() => unsafe { __udivsi3(n, d) },
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#[cfg(not(all(feature = "c", target_arch = "arm", not(target_os = "ios"), not(thumbv6m))))]
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() => __udivsi3(n, d),
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};
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if let Some(rem) = rem {
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*rem = n - (q * d);
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}
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q
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}
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macro_rules! div_mod_intrinsics {
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($udiv_intr:ident, $umod_intr:ident : $ty:ty) => {
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div_mod_intrinsics!($udiv_intr, $umod_intr : $ty,
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__udivmoddi4);
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};
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($udiv_intr:ident, $umod_intr:ident : $ty:ty, $divmod_intr:expr) => {
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div_mod_intrinsics!($udiv_intr, $umod_intr : $ty,
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$divmod_intr, $ty, |i|{ i });
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};
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($udiv_intr:ident, $umod_intr:ident : $ty:ty, $divmod_intr:expr,
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$tyret:ty, $conv:expr) => {
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/// Returns `n / d`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn $udiv_intr(n: $ty, d: $ty) -> $tyret {
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let r = $divmod_intr(n, d, None);
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($conv)(r)
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}
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/// Returns `n % d`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn $umod_intr(a: $ty, b: $ty) -> $tyret {
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use core::mem;
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let mut rem = unsafe { mem::uninitialized() };
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$divmod_intr(a, b, Some(&mut rem));
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($conv)(rem)
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}
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}
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}
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#[cfg(not(all(feature = "c", target_arch = "x86")))]
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div_mod_intrinsics!(__udivdi3, __umoddi3: u64);
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#[cfg(not(all(windows, target_pointer_width="64")))]
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div_mod_intrinsics!(__udivti3, __umodti3: u128, u128_div_mod);
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#[cfg(all(windows, target_pointer_width="64"))]
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div_mod_intrinsics!(__udivti3, __umodti3: u128, u128_div_mod, ::U64x2, ::conv);
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macro_rules! udivmod_inner {
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($n:expr, $d:expr, $rem:expr, $ty:ty) => {{
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let (n, d, rem) = ($n, $d, $rem);
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@ -285,30 +151,120 @@ macro_rules! udivmod_inner {
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}}
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}
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/// Returns `n / d` and sets `*rem = n % d`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
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udivmod_inner!(n, d, rem, u64)
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}
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macro_rules! udivmodti4 {
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($tyret:ty, $conv:expr) => {
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/// Returns `n / d` and sets `*rem = n % d`
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#[cfg_attr(not(test), no_mangle)]
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pub extern "C" fn __udivmodti4(n: u128, d: u128, rem: Option<&mut u128>) -> $tyret {
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let r = u128_div_mod(n, d, rem);
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($conv)(r)
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intrinsics! {
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#[use_c_shim_if(all(target_arch = "arm",
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not(target_os = "ios"),
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not(thumbv6m)))]
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/// Returns `n / d`
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pub extern "C" fn __udivsi3(n: u32, d: u32) -> u32 {
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// Special cases
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if d == 0 {
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// NOTE This should be unreachable in safe Rust because the program will panic before
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// this intrinsic is called
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unsafe {
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intrinsics::abort()
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}
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}
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if n == 0 {
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return 0;
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}
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let mut sr = d.leading_zeros().wrapping_sub(n.leading_zeros());
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// d > n
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if sr > u32::bits() - 1 {
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return 0;
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}
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// d == 1
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if sr == u32::bits() - 1 {
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return n;
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}
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sr += 1;
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// 1 <= sr <= u32::bits() - 1
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let mut q = n << (u32::bits() - sr);
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let mut r = n >> sr;
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let mut carry = 0;
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for _ in 0..sr {
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// r:q = ((r:q) << 1) | carry
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r = (r << 1) | (q >> (u32::bits() - 1));
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q = (q << 1) | carry;
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// carry = 0;
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// if r > d {
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// r -= d;
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// carry = 1;
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// }
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let s = (d.wrapping_sub(r).wrapping_sub(1)) as i32 >> (u32::bits() - 1);
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carry = (s & 1) as u32;
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r -= d & s as u32;
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}
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(q << 1) | carry
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}
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#[use_c_shim_if(all(target_arch = "arm", not(target_os = "ios")))]
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/// Returns `n % d`
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pub extern "C" fn __umodsi3(n: u32, d: u32) -> u32 {
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let q = __udivsi3(n, d);
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n - q * d
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}
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#[use_c_shim_if(all(target_arch = "arm",
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not(target_os = "ios"),
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not(thumbv6m)))]
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/// Returns `n / d` and sets `*rem = n % d`
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pub extern "C" fn __udivmodsi4(n: u32, d: u32, rem: Option<&mut u32>) -> u32 {
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let q = __udivsi3(n, d);
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if let Some(rem) = rem {
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*rem = n - (q * d);
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}
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q
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}
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#[use_c_shim_if(target_arch = "x86")]
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/// Returns `n / d`
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pub extern "C" fn __udivdi3(n: u64, d: u64) -> u64 {
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__udivmoddi4(n, d, None)
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}
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#[use_c_shim_if(target_arch = "x86")]
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/// Returns `n % d`
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pub extern "C" fn __umoddi3(n: u64, d: u64) -> u64 {
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let mut rem = 0;
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__udivmoddi4(n, d, Some(&mut rem));
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rem
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}
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#[win64_128bit_abi_hack]
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/// Returns `n / d`
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pub extern "C" fn __udivti3(n: u128, d: u128) -> u128 {
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__udivmodti4(n, d, None)
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}
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#[win64_128bit_abi_hack]
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/// Returns `n % d`
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pub extern "C" fn __umodti3(n: u128, d: u128) -> u128 {
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let mut rem = 0;
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__udivmodti4(n, d, Some(&mut rem));
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rem
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}
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/// Returns `n / d` and sets `*rem = n % d`
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pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
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udivmod_inner!(n, d, rem, u64)
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}
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#[win64_128bit_abi_hack]
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/// Returns `n / d` and sets `*rem = n % d`
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pub extern "C" fn __udivmodti4(n: u128,
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d: u128,
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rem: Option<&mut u128>) -> u128 {
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udivmod_inner!(n, d, rem, u128)
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}
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}
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/// Returns `n / d` and sets `*rem = n % d`
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fn u128_div_mod(n: u128, d: u128, rem: Option<&mut u128>) -> u128 {
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udivmod_inner!(n, d, rem, u128)
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}
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#[cfg(all(windows, target_pointer_width="64"))]
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udivmodti4!(::U64x2, ::conv);
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#[cfg(not(all(windows, target_pointer_width="64")))]
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udivmodti4!(u128, |i|{ i });
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