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use int::{Int, LargeInt};
macro_rules! udivmod_inner {
($n:expr, $d:expr, $rem:expr, $ty:ty) => {{
let (n, d, rem) = ($n, $d, $rem);
// NOTE X is unknown, K != 0
if n.high() == 0 {
if d.high() == 0 {
// 0 X
// ---
// 0 X
if let Some(rem) = rem {
*rem = <$ty>::from(n.low().aborting_rem(d.low()));
}
return <$ty>::from(n.low().aborting_div(d.low()))
} else {
// 0 X
// ---
// K X
if let Some(rem) = rem {
*rem = n;
}
return 0;
};
}
let mut sr;
let mut q;
let mut r;
if d.low() == 0 {
if d.high() == 0 {
// K X
// ---
// 0 0
// NOTE This should be unreachable in safe Rust because the program will panic before
// this intrinsic is called
::abort();
}
if n.low() == 0 {
// K 0
// ---
// K 0
if let Some(rem) = rem {
*rem = <$ty>::from_parts(0, n.high().aborting_rem(d.high()));
}
return <$ty>::from(n.high().aborting_div(d.high()))
}
// K K
// ---
// K 0
if d.high().is_power_of_two() {
if let Some(rem) = rem {
*rem = <$ty>::from_parts(n.low(), n.high() & (d.high() - 1));
}
return <$ty>::from(n.high() >> d.high().trailing_zeros());
}
sr = d.high().leading_zeros().wrapping_sub(n.high().leading_zeros());
// D > N
if sr > <hty!($ty)>::BITS - 2 {
if let Some(rem) = rem {
*rem = n;
}
return 0;
}
sr += 1;
// 1 <= sr <= <hty!($ty)>::BITS - 1
q = n << (<$ty>::BITS - sr);
r = n >> sr;
} else if d.high() == 0 {
// K X
// ---
// 0 K
if d.low().is_power_of_two() {
if let Some(rem) = rem {
*rem = <$ty>::from(n.low() & (d.low() - 1));
}
if d.low() == 1 {
return n;
} else {
let sr = d.low().trailing_zeros();
return n >> sr;
};
}
sr = 1 + <hty!($ty)>::BITS + d.low().leading_zeros() - n.high().leading_zeros();
// 2 <= sr <= u64::BITS - 1
q = n << (<$ty>::BITS - sr);
r = n >> sr;
} else {
// K X
// ---
// K K
sr = d.high().leading_zeros().wrapping_sub(n.high().leading_zeros());
// D > N
if sr > <hty!($ty)>::BITS - 1 {
if let Some(rem) = rem {
*rem = n;
}
return 0;
}
sr += 1;
// 1 <= sr <= <hty!($ty)>::BITS
q = n << (<$ty>::BITS - sr);
r = n >> sr;
}
// Not a special case
// q and r are initialized with
// q = n << (u64::BITS - sr)
// r = n >> sr
// 1 <= sr <= u64::BITS - 1
let mut carry = 0;
// Don't use a range because they may generate references to memcpy in unoptimized code
let mut i = 0;
while i < sr {
i += 1;
// r:q = ((r:q) << 1) | carry
r = (r << 1) | (q >> (<$ty>::BITS - 1));
q = (q << 1) | carry as $ty;
// carry = 0
// if r >= d {
// r -= d;
// carry = 1;
// }
let s = (d.wrapping_sub(r).wrapping_sub(1)) as os_ty!($ty) >> (<$ty>::BITS - 1);
carry = (s & 1) as hty!($ty);
r -= d & s as $ty;
}
if let Some(rem) = rem {
*rem = r;
}
(q << 1) | carry as $ty
}}
}
intrinsics! {
#[maybe_use_optimized_c_shim]
#[arm_aeabi_alias = __aeabi_uidiv]
/// Returns `n / d`
pub extern "C" fn __udivsi3(n: u32, d: u32) -> u32 {
// Special cases
if d == 0 {
// NOTE This should be unreachable in safe Rust because the program will panic before
// this intrinsic is called
::abort();
}
if n == 0 {
return 0;
}
let mut sr = d.leading_zeros().wrapping_sub(n.leading_zeros());
// d > n
if sr > u32::BITS - 1 {
return 0;
}
// d == 1
if sr == u32::BITS - 1 {
return n;
}
sr += 1;
// 1 <= sr <= u32::BITS - 1
let mut q = n << (u32::BITS - sr);
let mut r = n >> sr;
let mut carry = 0;
// Don't use a range because they may generate references to memcpy in unoptimized code
let mut i = 0;
while i < sr {
i += 1;
// r:q = ((r:q) << 1) | carry
r = (r << 1) | (q >> (u32::BITS - 1));
q = (q << 1) | carry;
// carry = 0;
// if r > d {
// r -= d;
// carry = 1;
// }
let s = (d.wrapping_sub(r).wrapping_sub(1)) as i32 >> (u32::BITS - 1);
carry = (s & 1) as u32;
r -= d & s as u32;
}
(q << 1) | carry
}
#[maybe_use_optimized_c_shim]
/// Returns `n % d`
pub extern "C" fn __umodsi3(n: u32, d: u32) -> u32 {
let q = __udivsi3(n, d);
n - q * d
}
#[maybe_use_optimized_c_shim]
/// Returns `n / d` and sets `*rem = n % d`
pub extern "C" fn __udivmodsi4(n: u32, d: u32, rem: Option<&mut u32>) -> u32 {
let q = __udivsi3(n, d);
if let Some(rem) = rem {
*rem = n - (q * d);
}
q
}
#[maybe_use_optimized_c_shim]
/// Returns `n / d`
pub extern "C" fn __udivdi3(n: u64, d: u64) -> u64 {
__udivmoddi4(n, d, None)
}
#[maybe_use_optimized_c_shim]
/// Returns `n % d`
pub extern "C" fn __umoddi3(n: u64, d: u64) -> u64 {
let mut rem = 0;
__udivmoddi4(n, d, Some(&mut rem));
rem
}
#[win64_128bit_abi_hack]
/// Returns `n / d`
pub extern "C" fn __udivti3(n: u128, d: u128) -> u128 {
__udivmodti4(n, d, None)
}
#[win64_128bit_abi_hack]
/// Returns `n % d`
pub extern "C" fn __umodti3(n: u128, d: u128) -> u128 {
let mut rem = 0;
__udivmodti4(n, d, Some(&mut rem));
rem
}
/// Returns `n / d` and sets `*rem = n % d`
pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
udivmod_inner!(n, d, rem, u64)
}
#[win64_128bit_abi_hack]
/// Returns `n / d` and sets `*rem = n % d`
pub extern "C" fn __udivmodti4(n: u128,
d: u128,
rem: Option<&mut u128>) -> u128 {
udivmod_inner!(n, d, rem, u128)
}
}