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Partially revert 482d98318f 

This partially reverts "Convert int_to_float! to a function".
master
est31 2017-09-29 02:19:40 +02:00
parent 789e8c159f
commit a20840262e
1 changed files with 66 additions and 70 deletions
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136
src/float/conv.rs
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@ -1,87 +1,83 @@
use float::Float;
use int::{Int, CastInto};
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;
}
macro_rules! int_to_float {
($i:expr, $ity:ty, $fty:ty) => ({
let i = $i;
if i == 0 {
return 0.0
}
let two = I::UnsignedInt::ONE + I::UnsignedInt::ONE;
let four = two + two;
let mant_dig = F::SIGNIFICAND_BITS + 1;
let exponent_bias = F::EXPONENT_BIAS;
let mant_dig = <$fty>::SIGNIFICAND_BITS + 1;
let exponent_bias = <$fty>::EXPONENT_BIAS;
let n = I::BITS;
let (s, a) = i.extract_sign();
let mut a = a;
let n = <$ity>::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 I::BITS < mant_dig {
return F::from_parts(s,
(e + exponent_bias).cast(),
a.cast() << (mant_dig - e - 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))
}
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 = 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
/* a is now rounded to mant_dig bits */
} else {
(a >> (sd - mant_dig_plus_two)) |
Int::from_bool((a & I::UnsignedInt::max_value()).wrapping_shl((n + mant_dig_plus_two) - sd) != Int::ZERO)
a.wrapping_shl(mant_dig - sd)
/* a is now rounded to mant_dig bits */
};
/* 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())
<$fty>::from_parts(s,
(e + exponent_bias) as <$fty as Float>::Int,
a as <$fty as Float>::Int)
})
}
intrinsics! {
#[arm_aeabi_alias = __aeabi_i2f]
pub extern "C" fn __floatsisf(i: i32) -> f32 {
int_to_float(i)
int_to_float!(i, i32, f32)
}
#[arm_aeabi_alias = __aeabi_i2d]
pub extern "C" fn __floatsidf(i: i32) -> f64 {
int_to_float(i)
int_to_float!(i, i32, f64)
}
#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
@ -92,28 +88,28 @@ intrinsics! {
if cfg!(target_arch = "x86_64") {
i as f64
} else {
int_to_float(i)
int_to_float!(i, i64, f64)
}
}
#[unadjusted_on_win64]
pub extern "C" fn __floattisf(i: i128) -> f32 {
int_to_float(i)
int_to_float!(i, i128, f32)
}
#[unadjusted_on_win64]
pub extern "C" fn __floattidf(i: i128) -> f64 {
int_to_float(i)
int_to_float!(i, i128, f64)
}
#[arm_aeabi_alias = __aeabi_ui2f]
pub extern "C" fn __floatunsisf(i: u32) -> f32 {
int_to_float(i)
int_to_float!(i, u32, f32)
}
#[arm_aeabi_alias = __aeabi_ui2d]
pub extern "C" fn __floatunsidf(i: u32) -> f64 {
int_to_float(i)
int_to_float!(i, u32, f64)
}
#[use_c_shim_if(all(not(target_env = "msvc"),
@ -121,17 +117,17 @@ 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)
int_to_float!(i, u64, f64)
}
#[unadjusted_on_win64]
pub extern "C" fn __floatuntisf(i: u128) -> f32 {
int_to_float(i)
int_to_float!(i, u128, f32)
}
#[unadjusted_on_win64]
pub extern "C" fn __floatuntidf(i: u128) -> f64 {
int_to_float(i)
int_to_float!(i, u128, f64)
}
}