diff --git a/src/int/mod.rs b/src/int/mod.rs index 28c41907..2102e3a2 100644 --- a/src/int/mod.rs +++ b/src/int/mod.rs @@ -1,17 +1,5 @@ use core::ops; -macro_rules! hty { - ($ty:ty) => { - <$ty as LargeInt>::HighHalf - }; -} - -macro_rules! os_ty { - ($ty:ty) => { - <$ty as Int>::OtherSign - }; -} - pub mod addsub; pub mod mul; pub mod shift; diff --git a/src/int/sdiv.rs b/src/int/sdiv.rs index fd56f94e..62294281 100644 --- a/src/int/sdiv.rs +++ b/src/int/sdiv.rs @@ -1,62 +1,5 @@ -use int::Int; use super::specialized_div_rem::*; -trait Div: Int { - /// Returns `a / b` - fn div(self, other: Self) -> Self { - let s_a = self >> (Self::BITS - 1); - let s_b = other >> (Self::BITS - 1); - // NOTE it's OK to overflow here because of the `.unsigned()` below. - // This whole operation is computing the absolute value of the inputs - // So some overflow will happen when dealing with e.g. `i64::MIN` - // where the absolute value is `(-i64::MIN) as u64` - let a = (self ^ s_a).wrapping_sub(s_a); - let b = (other ^ s_b).wrapping_sub(s_b); - let s = s_a ^ s_b; - - let r = a.unsigned().aborting_div(b.unsigned()); - (Self::from_unsigned(r) ^ s) - s - } -} - -impl Div for i32 {} -impl Div for i64 {} -impl Div for i128 {} - -trait Mod: Int { - /// Returns `a % b` - fn mod_(self, other: Self) -> Self { - let s = other >> (Self::BITS - 1); - // NOTE(wrapping_sub) see comment in the `div` - let b = (other ^ s).wrapping_sub(s); - let s = self >> (Self::BITS - 1); - let a = (self ^ s).wrapping_sub(s); - - let r = a.unsigned().aborting_rem(b.unsigned()); - (Self::from_unsigned(r) ^ s) - s - } -} - -impl Mod for i32 {} -impl Mod for i64 {} -impl Mod for i128 {} - -trait Divmod: Int { - /// Returns `a / b` and sets `*rem = n % d` - fn divmod(self, other: Self, rem: &mut Self, div: F) -> Self - where - F: Fn(Self, Self) -> Self, - { - let r = div(self, other); - // NOTE won't overflow because it's using the result from the - // previous division - *rem = self - r.wrapping_mul(other); - r - } -} - -impl Divmod for i32 {} -impl Divmod for i64 {} // NOTE: there are aborts inside the specialized_div_rem functions if division by 0 // is encountered, however these should be unreachable and optimized away unless // uses of `std/core::intrinsics::unchecked_div/rem` do not have a 0 check in front diff --git a/src/int/udiv.rs b/src/int/udiv.rs index c2a666ba..198ad004 100644 --- a/src/int/udiv.rs +++ b/src/int/udiv.rs @@ -1,156 +1,5 @@ -use int::{Int, LargeInt}; use super::specialized_div_rem::*; -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 <$ty>::from(n.high() >> d.high().trailing_zeros()); - } - - sr = d.high().leading_zeros().wrapping_sub(n.high().leading_zeros()); - - // D > N - if sr > ::BITS - 2 { - if let Some(rem) = rem { - *rem = n; - } - return 0; - } - - sr += 1; - - // 1 <= sr <= ::BITS - 1 - q = n << (<$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 = <$ty>::from(n.low() & (d.low() - 1)); - } - - if d.low() == 1 { - return n; - } else { - let sr = d.low().trailing_zeros(); - return n >> sr; - }; - } - - sr = 1 + ::BITS + d.low().leading_zeros() - n.high().leading_zeros(); - - // 2 <= sr <= u64::BITS - 1 - q = n << (<$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 > ::BITS - 1 { - if let Some(rem) = rem { - *rem = n; - } - return 0; - } - - sr += 1; - - // 1 <= sr <= ::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 - }} -} // NOTE: there are aborts inside the specialized_div_rem functions if division by 0 // is encountered, however these should be unreachable and optimized away unless // uses of `std/core::intrinsics::unchecked_div/rem` do not have a 0 check in front