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Auto merge of #147 - rust-lang-nursery:conv, r=japaric

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Conversion from&to float<->integer

this is a rebased version of #139

cc @ithinuel
This commit is contained in:
bors 2017-04-08 15:20:35 +00:00
commit 28ac4908f8
7 changed files with 373 additions and 7 deletions
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14
compiler-rt/compiler-rt-cdylib/build.rs
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@ -62,6 +62,20 @@ fn main() {
"powisf2.c",
"subdf3.c",
"subsf3.c",
"floatsisf.c",
"floatsidf.c",
"floatdidf.c",
"floatunsisf.c",
"floatunsidf.c",
"floatundidf.c",
"fixsfsi.c",
"fixsfdi.c",
"fixdfsi.c",
"fixdfdi.c",
"fixunssfsi.c",
"fixunssfdi.c",
"fixunsdfsi.c",
"fixunsdfdi.c",
// 128 bit integers
"lshrti3.c",
"modti3.c",

28
compiler-rt/compiler-rt-cdylib/src/lib.rs
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@ -26,6 +26,20 @@ extern {
fn __powidf2();
fn __subsf3();
fn __subdf3();
fn __floatsisf();
fn __floatsidf();
fn __floatdidf();
fn __floatunsisf();
fn __floatunsidf();
fn __floatundidf();
fn __fixsfsi();
fn __fixsfdi();
fn __fixdfsi();
fn __fixdfdi();
fn __fixunssfsi();
fn __fixunssfdi();
fn __fixunsdfsi();
fn __fixunsdfdi();
}
macro_rules! declare {
@ -61,6 +75,20 @@ declare!(___powisf2, __powisf2);
declare!(___powidf2, __powidf2);
declare!(___subsf3, __subsf3);
declare!(___subdf3, __subdf3);
declare!(___floatsisf, __floatsisf);
declare!(___floatsidf, __floatsidf);
declare!(___floatdidf, __floatdidf);
declare!(___floatunsisf, __floatunsisf);
declare!(___floatunsidf, __floatunsidf);
declare!(___floatundidf, __floatundidf);
declare!(___fixsfsi, __fixsfsi);
declare!(___fixsfdi, __fixsfdi);
declare!(___fixdfsi, __fixdfsi);
declare!(___fixdfdi, __fixdfdi);
declare!(___fixunssfsi, __fixunssfsi);
declare!(___fixunssfdi, __fixunssfdi);
declare!(___fixunsdfsi, __fixunsdfsi);
declare!(___fixunsdfdi, __fixunsdfdi);
#[cfg(all(not(windows),
not(target_arch = "mips64"),

6
src/arm.rs Normal file → Executable file
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@ -112,6 +112,12 @@ pub extern "aapcs" fn __aeabi_uidiv(a: u32, b: u32) -> u32 {
::int::udiv::__udivsi3(a, b)
}
#[cfg(not(feature = "c"))]
#[cfg_attr(not(test), no_mangle)]
pub extern "C" fn __aeabi_ui2d(a: u32) -> f64 {
::float::conv::__floatunsidf(a)
}
// TODO: These aeabi_* functions should be defined as aliases
#[cfg(not(feature = "mem"))]
extern "C" {

266
src/float/conv.rs Executable file
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@ -0,0 +1,266 @@
use float::Float;
use int::Int;
macro_rules! fp_overflow {
(infinity, $fty:ty, $sign: expr) => {
return {
<$fty as Float>::from_parts(
$sign,
<$fty as Float>::exponent_max() as <$fty as Float>::Int,
0 as <$fty as Float>::Int)
}
}
}
macro_rules! fp_convert {
($intrinsic:ident: $ity:ty, $fty:ty) => {
pub extern "C" fn $intrinsic(i: $ity) -> $fty {
if i == 0 {
return 0.0
}
let mant_dig = <$fty>::significand_bits() + 1;
let exponent_bias = <$fty>::exponent_bias();
let n = <$ity>::bits();
let (s, a) = i.extract_sign();
let mut a = a;
// number of significant digits
let sd = n - a.leading_zeros();
// 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))
}
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.wrapping_shl(mant_dig - sd)
/* a is now rounded to mant_dig bits */
};
<$fty>::from_parts(s,
(e + exponent_bias) as <$fty as Float>::Int,
a as <$fty as Float>::Int)
}
}
}
fp_convert!(__floatsisf: i32, f32);
fp_convert!(__floatsidf: i32, f64);
fp_convert!(__floatdidf: i64, f64);
fp_convert!(__floatunsisf: u32, f32);
fp_convert!(__floatunsidf: u32, f64);
fp_convert!(__floatundidf: u64, f64);
#[derive(PartialEq, Debug)]
enum Sign {
Positive,
Negative
}
macro_rules! fp_fix {
($intrinsic:ident: $fty:ty, $ity:ty) => {
pub extern "C" fn $intrinsic(f: $fty) -> $ity {
let fixint_min = <$ity>::min_value();
let fixint_max = <$ity>::max_value();
let fixint_bits = <$ity>::bits() as usize;
let fixint_unsigned = fixint_min == 0;
let sign_bit = <$fty>::sign_mask();
let significand_bits = <$fty>::significand_bits() as usize;
let exponent_bias = <$fty>::exponent_bias() as usize;
//let exponent_max = <$fty>::exponent_max() as usize;
// Break a into sign, exponent, significand
let a_rep = <$fty>::repr(f);
let a_abs = a_rep & !sign_bit;
// this is used to work around -1 not being available for unsigned
let sign = if (a_rep & sign_bit) == 0 { Sign::Positive } else { Sign::Negative };
let mut exponent = (a_abs >> significand_bits) as usize;
let significand = (a_abs & <$fty>::significand_mask()) | <$fty>::implicit_bit();
// if < 1 or unsigned & negative
if exponent < exponent_bias ||
fixint_unsigned && sign == Sign::Negative {
return 0
}
exponent -= exponent_bias;
// If the value is infinity, saturate.
// If the value is too large for the integer type, 0.
if exponent >= (if fixint_unsigned {fixint_bits} else {fixint_bits -1}) {
return if sign == Sign::Positive {fixint_max} else {fixint_min}
}
// If 0 <= exponent < significand_bits, right shift to get the result.
// Otherwise, shift left.
// (sign - 1) will never overflow as negative signs are already returned as 0 for unsigned
let r = if exponent < significand_bits {
(significand >> (significand_bits - exponent)) as $ity
} else {
(significand as $ity) << (exponent - significand_bits)
};
if sign == Sign::Negative {
(!r).wrapping_add(1)
} else {
r
}
}
}
}
fp_fix!(__fixsfsi: f32, i32);
fp_fix!(__fixsfdi: f32, i64);
fp_fix!(__fixdfsi: f64, i32);
fp_fix!(__fixdfdi: f64, i64);
fp_fix!(__fixunssfsi: f32, u32);
fp_fix!(__fixunssfdi: f32, u64);
fp_fix!(__fixunsdfsi: f64, u32);
fp_fix!(__fixunsdfdi: f64, u64);
// NOTE(cfg) for some reason, on arm*-unknown-linux-gnueabihf, our implementation doesn't
// match the output of its gcc_s or compiler-rt counterpart. Until we investigate further, we'll
// just avoid testing against them on those targets. Do note that our implementation gives the
// correct answer; gcc_s and compiler-rt are incorrect in this case.
//
#[cfg(all(test, not(arm_linux)))]
mod tests {
use qc::{I32, U32, I64, U64, F32, F64};
check! {
fn __floatsisf(f: extern "C" fn(i32) -> f32,
a: I32)
-> Option<F32> {
Some(F32(f(a.0)))
}
fn __floatsidf(f: extern "C" fn(i32) -> f64,
a: I32)
-> Option<F64> {
Some(F64(f(a.0)))
}
fn __floatdidf(f: extern "C" fn(i64) -> f64,
a: I64)
-> Option<F64> {
Some(F64(f(a.0)))
}
fn __floatunsisf(f: extern "C" fn(u32) -> f32,
a: U32)
-> Option<F32> {
Some(F32(f(a.0)))
}
fn __floatunsidf(f: extern "C" fn(u32) -> f64,
a: U32)
-> Option<F64> {
Some(F64(f(a.0)))
}
fn __floatundidf(f: extern "C" fn(u64) -> f64,
a: U64)
-> Option<F64> {
Some(F64(f(a.0)))
}
fn __fixsfsi(f: extern "C" fn(f32) -> i32,
a: F32)
-> Option<I32> {
if (a.0 as f64) > (i32::max_value() as f64) ||
(a.0 as f64) < (i32::min_value() as f64) || a.0.is_nan() {
None
} else { Some(I32(f(a.0))) }
}
fn __fixsfdi(f: extern "C" fn(f32) -> i64,
a: F32)
-> Option<I64> {
if (a.0 as f64) > (i64::max_value() as f64) ||
(a.0 as f64) < (i64::min_value() as f64) || a.0.is_nan() {
None
} else { Some(I64(f(a.0))) }
}
fn __fixdfsi(f: extern "C" fn(f64) -> i32,
a: F64)
-> Option<I32> {
if a.0 > (i32::max_value() as f64) ||
a.0 < (i32::min_value() as f64) || a.0.is_nan() {
None
} else { Some(I32(f(a.0))) }
}
fn __fixdfdi(f: extern "C" fn(f64) -> i64,
a: F64)
-> Option<I64> {
if a.0 > (i64::max_value() as f64) ||
a.0 < (i64::min_value() as f64) || a.0.is_nan() {
None
} else { Some(I64(f(a.0))) }
}
fn __fixunssfsi(f: extern "C" fn(f32) -> u32,
a: F32)
-> Option<U32> {
if (a.0 as f64) > (u32::max_value() as f64) ||
(a.0 as f64) < (u32::min_value() as f64) || a.0.is_nan() {
None
} else { Some(U32(f(a.0))) }
}
fn __fixunssfdi(f: extern "C" fn(f32) -> u64,
a: F32)
-> Option<U64> {
if (a.0 as f64) > (u64::max_value() as f64) ||
(a.0 as f64) < (u64::min_value() as f64) || a.0.is_nan() {
None
} else { Some(U64(f(a.0))) }
}
fn __fixunsdfsi(f: extern "C" fn(f64) -> u32,
a: F64)
-> Option<U32> {
if a.0 > (u32::max_value() as f64) ||
a.0 < (u32::min_value() as f64) || a.0.is_nan() {
None
} else { Some(U32(f(a.0))) }
}
fn __fixunsdfdi(f: extern "C" fn(f64) -> u64,
a: F64)
-> Option<U64> {
if a.0 <= (u64::max_value() as f64) ||
a.0 >= (u64::min_value() as f64) || a.0.is_nan() {
None
} else { Some(U64(f(a.0))) }
}
}
}

20
src/float/mod.rs
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@ -1,5 +1,6 @@
use core::mem;
pub mod conv;
pub mod add;
pub mod pow;
pub mod sub;
@ -19,6 +20,15 @@ pub trait Float: Sized + Copy {
fn exponent_bits() -> u32 {
Self::bits() - Self::significand_bits() - 1
}
/// Returns the maximum value of the exponent
fn exponent_max() -> u32 {
(1 << Self::exponent_bits()) - 1
}
/// Returns the exponent bias value
fn exponent_bias() -> u32 {
Self::exponent_max() >> 1
}
/// Returns a mask for the sign bit
fn sign_mask() -> Self::Int;
@ -26,6 +36,9 @@ pub trait Float: Sized + Copy {
/// Returns a mask for the significand
fn significand_mask() -> Self::Int;
// Returns the implicit bit of the float format
fn implicit_bit() -> Self::Int;
/// Returns a mask for the exponent
fn exponent_mask() -> Self::Int;
@ -58,6 +71,9 @@ impl Float for f32 {
fn significand_bits() -> u32 {
23
}
fn implicit_bit() -> Self::Int {
1 << Self::significand_bits()
}
fn sign_mask() -> Self::Int {
1 << (Self::bits() - 1)
}
@ -100,6 +116,10 @@ impl Float for f64 {
fn significand_bits() -> u32 {
52
}
// Returns the implicit bit of the float format
fn implicit_bit() -> Self::Int {
1 << Self::significand_bits()
}
fn sign_mask() -> Self::Int {
1 << (Self::bits() - 1)
}

42
src/int/mod.rs Normal file → Executable file
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@ -19,23 +19,55 @@ pub mod udiv;
pub trait Int {
/// Type with the same width but other signedness
type OtherSign;
/// Unsigned version of Self
type UnsignedInt;
/// Returns the bitwidth of the int type
fn bits() -> u32;
/// Extracts the sign from self and returns a tuple.
///
/// # Examples
///
/// ```rust,ignore
/// let i = -25_i32;
/// let (sign, u) = i.extract_sign();
/// assert_eq!(sign, true);
/// assert_eq!(u, 25_u32);
/// ```
fn extract_sign(self) -> (bool, Self::UnsignedInt);
}
macro_rules! int_impl {
($ity:ty, $sty:ty, $bits:expr) => {
impl Int for $ity {
type OtherSign = $sty;
($ity:ty, $uty:ty, $bits:expr) => {
impl Int for $uty {
type OtherSign = $ity;
type UnsignedInt = $uty;
fn bits() -> u32 {
$bits
}
fn extract_sign(self) -> (bool, $uty) {
(false, self)
}
}
impl Int for $sty {
type OtherSign = $ity;
impl Int for $ity {
type OtherSign = $uty;
type UnsignedInt = $uty;
fn bits() -> u32 {
$bits
}
fn extract_sign(self) -> (bool, $uty) {
if self < 0 {
(true, !(self as $uty) + 1)
} else {
(false, self as $uty)
}
}
}
}
}

4
src/qc.rs
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@ -15,7 +15,7 @@ use float::Float;
// Generates values in the full range of the integer type
macro_rules! arbitrary {
($TY:ident : $ty:ident) => {
#[derive(Clone, Copy)]
#[derive(Clone, Copy, PartialEq)]
pub struct $TY(pub $ty);
impl Arbitrary for $TY {
@ -82,7 +82,7 @@ arbitrary!(U32: u32);
// intrinsics.
macro_rules! arbitrary_large {
($TY:ident : $ty:ident) => {
#[derive(Clone, Copy)]
#[derive(Clone, Copy, PartialEq)]
pub struct $TY(pub $ty);
impl Arbitrary for $TY {