A modified version of compiler-builtins for zynq, with fast memcpy implementation adapted from newlib.
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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);