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Convert int_to_float! to a function

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This commit is contained in:
est31 2017-09-14 16:32:50 +02:00
parent ff63f7b80f
commit 482d98318f
2 changed files with 101 additions and 67 deletions
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136
src/float/conv.rs
View File

@ -1,83 +1,87 @@
use float::Float;
use int::{Int, CastInto};
macro_rules! int_to_float {
($i:expr, $ity:ty, $fty:ty) => ({
let i = $i;
if i == 0 {
return 0.0
}
fn int_to_float<I: Int, F: Float>(i: I) -> F where
F::Int: CastInto<u32>,
F::Int: CastInto<I>,
I::UnsignedInt: CastInto<F::Int>,
u32: CastInto<F::Int>,
{
if i == I::ZERO {
return F::ZERO;
}
let mant_dig = <$fty>::SIGNIFICAND_BITS + 1;
let exponent_bias = <$fty>::EXPONENT_BIAS;
let two = I::UnsignedInt::ONE + I::UnsignedInt::ONE;
let four = two + two;
let mant_dig = F::SIGNIFICAND_BITS + 1;
let exponent_bias = F::EXPONENT_BIAS;
let n = <$ity>::BITS;
let (s, a) = i.extract_sign();
let mut a = a;
let n = I::BITS;
let (s, a) = i.extract_sign();
let mut a = a;
// number of significant digits
let sd = n - a.leading_zeros();
// number of significant digits
let sd = n - a.leading_zeros();
// exponent
let mut e = sd - 1;
// exponent
let mut e = sd - 1;
if <$ity>::BITS < mant_dig {
return <$fty>::from_parts(s,
(e + exponent_bias) as <$fty as Float>::Int,
(a as <$fty as Float>::Int) << (mant_dig - e - 1))
}
if I::BITS < mant_dig {
return F::from_parts(s,
(e + exponent_bias).cast(),
a.cast() << (mant_dig - e - 1));
}
a = if sd > mant_dig {
/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
* 12345678901234567890123456
* 1 = msb 1 bit
* P = bit MANT_DIG-1 bits to the right of 1
* Q = bit MANT_DIG bits to the right of 1
* R = "or" of all bits to the right of Q
*/
let mant_dig_plus_one = mant_dig + 1;
let mant_dig_plus_two = mant_dig + 2;
a = if sd == mant_dig_plus_one {
a << 1
} else if sd == mant_dig_plus_two {
a
} else {
(a >> (sd - mant_dig_plus_two)) as <$ity as Int>::UnsignedInt |
((a & <$ity as Int>::UnsignedInt::max_value()).wrapping_shl((n + mant_dig_plus_two) - sd) != 0) as <$ity as Int>::UnsignedInt
};
/* finish: */
a |= ((a & 4) != 0) as <$ity as Int>::UnsignedInt; /* Or P into R */
a += 1; /* round - this step may add a significant bit */
a >>= 2; /* dump Q and R */
/* a is now rounded to mant_dig or mant_dig+1 bits */
if (a & (1 << mant_dig)) != 0 {
a >>= 1; e += 1;
}
a = if sd > mant_dig {
/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
* 12345678901234567890123456
* 1 = msb 1 bit
* P = bit MANT_DIG-1 bits to the right of 1
* Q = bit MANT_DIG bits to the right of 1
* R = "or" of all bits to the right of Q
*/
let mant_dig_plus_one = mant_dig + 1;
let mant_dig_plus_two = mant_dig + 2;
a = if sd == mant_dig_plus_one {
a << 1
} else if sd == mant_dig_plus_two {
a
/* a is now rounded to mant_dig bits */
} else {
a.wrapping_shl(mant_dig - sd)
/* a is now rounded to mant_dig bits */
(a >> (sd - mant_dig_plus_two)) |
Int::from_bool((a & I::UnsignedInt::max_value()).wrapping_shl((n + mant_dig_plus_two) - sd) != Int::ZERO)
};
<$fty>::from_parts(s,
(e + exponent_bias) as <$fty as Float>::Int,
a as <$fty as Float>::Int)
})
/* finish: */
a |= Int::from_bool((a & four) != I::UnsignedInt::ZERO); /* Or P into R */
a += Int::ONE; /* round - this step may add a significant bit */
a >>= 2; /* dump Q and R */
/* a is now rounded to mant_dig or mant_dig+1 bits */
if (a & (I::UnsignedInt::ONE << mant_dig)) != Int::ZERO {
a >>= 1; e += 1;
}
a
/* a is now rounded to mant_dig bits */
} else {
a.wrapping_shl(mant_dig - sd)
/* a is now rounded to mant_dig bits */
};
F::from_parts(s,
(e + exponent_bias).cast(),
a.cast())
}
intrinsics! {
#[arm_aeabi_alias = __aeabi_i2f]
pub extern "C" fn __floatsisf(i: i32) -> f32 {
int_to_float!(i, i32, f32)
int_to_float(i)
}
#[arm_aeabi_alias = __aeabi_i2d]
pub extern "C" fn __floatsidf(i: i32) -> f64 {
int_to_float!(i, i32, f64)
int_to_float(i)
}
#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
@ -88,28 +92,28 @@ intrinsics! {
if cfg!(target_arch = "x86_64") {
i as f64
} else {
int_to_float!(i, i64, f64)
int_to_float(i)
}
}
#[unadjusted_on_win64]
pub extern "C" fn __floattisf(i: i128) -> f32 {
int_to_float!(i, i128, f32)
int_to_float(i)
}
#[unadjusted_on_win64]
pub extern "C" fn __floattidf(i: i128) -> f64 {
int_to_float!(i, i128, f64)
int_to_float(i)
}
#[arm_aeabi_alias = __aeabi_ui2f]
pub extern "C" fn __floatunsisf(i: u32) -> f32 {
int_to_float!(i, u32, f32)
int_to_float(i)
}
#[arm_aeabi_alias = __aeabi_ui2d]
pub extern "C" fn __floatunsidf(i: u32) -> f64 {
int_to_float!(i, u32, f64)
int_to_float(i)
}
#[use_c_shim_if(all(not(target_env = "msvc"),
@ -117,17 +121,17 @@ intrinsics! {
all(not(windows), target_arch = "x86_64"))))]
#[arm_aeabi_alias = __aeabi_ul2d]
pub extern "C" fn __floatundidf(i: u64) -> f64 {
int_to_float!(i, u64, f64)
int_to_float(i)
}
#[unadjusted_on_win64]
pub extern "C" fn __floatuntisf(i: u128) -> f32 {
int_to_float!(i, u128, f32)
int_to_float(i)
}
#[unadjusted_on_win64]
pub extern "C" fn __floatuntidf(i: u128) -> f64 {
int_to_float!(i, u128, f64)
int_to_float(i)
}
}

32
src/int/mod.rs
View File

@ -23,6 +23,9 @@ pub trait Int:
PartialEq +
PartialOrd +
ops::AddAssign +
ops::BitAndAssign +
ops::BitOrAssign +
ops::ShrAssign<u32> +
ops::Add<Output = Self> +
ops::Sub<Output = Self> +
ops::Div<Output = Self> +
@ -31,7 +34,6 @@ pub trait Int:
ops::BitOr<Output = Self> +
ops::BitXor<Output = Self> +
ops::BitAnd<Output = Self> +
ops::BitAndAssign +
ops::Not<Output = Self> +
{
/// Type with the same width but other signedness
@ -60,14 +62,18 @@ pub trait Int:
fn unsigned(self) -> Self::UnsignedInt;
fn from_unsigned(unsigned: Self::UnsignedInt) -> Self;
fn from_bool(b: bool) -> Self;
// copied from primitive integers, but put in a trait
fn max_value() -> Self;
fn min_value() -> Self;
fn wrapping_add(self, other: Self) -> Self;
fn wrapping_mul(self, other: Self) -> Self;
fn wrapping_sub(self, other: Self) -> Self;
fn wrapping_shl(self, other: u32) -> Self;
fn aborting_div(self, other: Self) -> Self;
fn aborting_rem(self, other: Self) -> Self;
fn leading_zeros(self) -> u32;
}
fn unwrap<T>(t: Option<T>) -> T {
@ -100,6 +106,10 @@ macro_rules! int_impl {
me
}
fn from_bool(b: bool) -> Self {
b as $uty
}
fn max_value() -> Self {
<Self>::max_value()
}
@ -120,6 +130,10 @@ macro_rules! int_impl {
<Self>::wrapping_sub(self, other)
}
fn wrapping_shl(self, other: u32) -> Self {
<Self>::wrapping_shl(self, other)
}
fn aborting_div(self, other: Self) -> Self {
unwrap(<Self>::checked_div(self, other))
}
@ -127,6 +141,10 @@ macro_rules! int_impl {
fn aborting_rem(self, other: Self) -> Self {
unwrap(<Self>::checked_rem(self, other))
}
fn leading_zeros(self) -> u32 {
<Self>::leading_zeros(self)
}
}
impl Int for $ity {
@ -154,6 +172,10 @@ macro_rules! int_impl {
me as $ity
}
fn from_bool(b: bool) -> Self {
b as $ity
}
fn max_value() -> Self {
<Self>::max_value()
}
@ -174,6 +196,10 @@ macro_rules! int_impl {
<Self>::wrapping_sub(self, other)
}
fn wrapping_shl(self, other: u32) -> Self {
<Self>::wrapping_shl(self, other)
}
fn aborting_div(self, other: Self) -> Self {
unwrap(<Self>::checked_div(self, other))
}
@ -181,6 +207,10 @@ macro_rules! int_impl {
fn aborting_rem(self, other: Self) -> Self {
unwrap(<Self>::checked_rem(self, other))
}
fn leading_zeros(self) -> u32 {
<Self>::leading_zeros(self)
}
}
}
}