hare

floats.ha (16109B)

---

 // SPDX-License-Identifier: MPL-2.0
 // (c) Hare authors <https://harelang.org>
 
 // Returns the binary representation of the given f64.
 export fn f64bits(n: f64) u64 = *(&n: *u64);
 
 // Returns the binary representation of the given f32.
 export fn f32bits(n: f32) u32 = *(&n: *u32);
 
 // Returns f64 with the given binary representation.
 export fn f64frombits(n: u64) f64 = *(&n: *f64);
 
 // Returns f32 with the given binary representation.
 export fn f32frombits(n: u32) f32 = *(&n: *f32);
 
 // The number of bits in the significand of the binary representation of f64.
 export def F64_MANTISSA_BITS = 52;
 
 // The number of bits in the exponent of the binary representation of f64.
 export def F64_EXPONENT_BITS = 11;
 
 // The bias of the exponent of the binary representation of f64. Subtract this
 // from the exponent in the binary representation to get the actual exponent.
 export def F64_EXPONENT_BIAS = 1023;
 
 // The number of bits in the significand of the binary representation of f32.
 export def F32_MANTISSA_BITS = 23;
 
 // The number of bits in the exponent of the binary representation of f32.
 export def F32_EXPONENT_BITS = 8;
 
 // The bias of the exponent of the binary representation of f32. Subtract this
 // from the exponent in the binary representation to get the actual exponent.
 export def F32_EXPONENT_BIAS = 127;
 
 // Mask with each bit of an f64's mantissa set.
 export def F64_MANTISSA_MASK: u64 = (1 << F64_MANTISSA_BITS) - 1;
 
 // Mask with each bit of an f64's exponent set.
 export def F64_EXPONENT_MASK: u64 = (1 << F64_EXPONENT_BITS) - 1;
 
 // Mask with each bit of an f32's mantissa set.
 export def F32_MANTISSA_MASK: u32 = (1 << F32_MANTISSA_BITS) - 1;
 
 // Mask with each bit of an f32's exponent set.
 export def F32_EXPONENT_MASK: u32 = (1 << F32_EXPONENT_BITS) - 1;
 
 // The largest representable f64 value which is less than Infinity.
 export def F64_MAX_NORMAL: f64 = 1.7976931348623157e+308;
 
 // The smallest representable normal f64 value.
 export def F64_MIN_NORMAL: f64 = 2.2250738585072014e-308;
 
 // The smallest (subnormal) f64 value greater than zero.
 export def F64_MIN_SUBNORMAL: f64 = 5.0e-324;
 
 // The difference between 1 and the smallest f64 representable value that is
 // greater than 1.
 export def F64_EPS: f64 = 2.22040000000000004884e-16;
 
 // The largest representable f32 value which is less than Infinity.
 export def F32_MAX_NORMAL: f32 = 3.4028234e+38;
 
 // The smallest representable normal f32 value.
 export def F32_MIN_NORMAL: f32 = 1.1754944e-38;
 
 // The smallest (subnormal) f32 value greater than zero.
 export def F32_MIN_SUBNORMAL: f32 = 1.0e-45;
 
 // The difference between 1 and the smallest f32 representable value that is
 // greater than 1.
 export def F32_EPS: f32 = 1.1920928955078125e-7;
 
 // The mask that gets an f64's sign.
 def F64_SIGN_MASK: u64 = 1u64 << 63;
 
 // The mask that sets all exponent bits to 0.
 // NOTE: Replace with the following expression once the lexer supports it
 // 0u64 & ~(F64_EXPONENT_MASK << F64_MANTISSA_BITS);
 def F64_EXP_REMOVAL_MASK: u64 =
 	0b1000000000001111111111111111111111111111111111111111111111111111;
 
 // The f64 that contains only an exponent that evaluates to zero.
 def F64_EXP_ZERO: u64 = ((F64_EXPONENT_BIAS: u64) - 1) << F64_MANTISSA_BITS;
 
 // The mask that gets an f32's sign.
 def F32_SIGN_MASK: u32 = 1u32 << 31;
 
 // The mask that sets all exponent bits to 0.
 // NOTE: Replace with the following expression once the lexer supports it
 // 0u32 & ~(F32_EXPONENT_MASK << F32_MANTISSA_BITS);
 def F32_EXP_REMOVAL_MASK: u32 = 0b10000000011111111111111111111111;
 
 // The f32 that contains only an exponent that evaluates to zero.
 def F32_EXP_ZERO: u32 =
 	((F32_EXPONENT_BIAS: u32) - 1) << (F32_MANTISSA_BITS: u32);
 
 // The bits that represent the number 1f64.
 def F64_ONE: u64 = 0x3FF0000000000000;
 
 // Contains information about the structure of a specific floating point number
 // type.
 export type floatinfo = struct {
 	// Bits in significand.
 	mantbits: u64,
 	// Bits in exponent.
 	expbits: u64,
 	// Bias of exponent.
 	expbias: int,
 	// Mask for mantissa.
 	mantmask: u64,
 	// Mask for exponent.
 	expmask: u64,
 };
 
 // A [[floatinfo]] structure defining the structure of the f64 type.
 export const f64info: floatinfo = floatinfo {
 	mantbits = 52,
 	expbits = 11,
 	expbias = 1023,
 	mantmask = (1 << 52) - 1,
 	expmask = (1 << 11) - 1,
 };
 
 // A [[floatinfo]] structure defining the structure of the f32 type.
 export const f32info: floatinfo = floatinfo {
 	mantbits = 23,
 	expbits = 8,
 	expbias = 127,
 	mantmask = (1 << 23) - 1,
 	expmask = (1 << 8) - 1,
 };
 
 // The floating point value representing Not a Number, i.e. an undefined or
 // unrepresentable value. You cannot test if a number is NaN by comparing to
 // this value; see [[isnan]] instead.
 export def NAN = 0.0 / 0.0;
 
 // The floating point value representing positive infinity. Use -[[INF]] for
 // negative infinity.
 export def INF = 1.0 / 0.0;
 
 // Returns true if the given floating-point number is NaN.
 export fn isnan(n: f64) bool = n != n;
 
 // Returns true if the given floating-point number is infinite.
 export fn isinf(n: f64) bool = {
 	const bits = f64bits(n);
 	const mant = bits & F64_MANTISSA_MASK;
 	const exp = bits >> F64_MANTISSA_BITS & F64_EXPONENT_MASK;
 	return exp == F64_EXPONENT_MASK && mant == 0;
 };
 
 @test fn isinf() void = {
 	assert(isinf(INF));
 	assert(isinf(-INF));
 	assert(!isinf(NAN));
 	assert(!isinf(1.23));
 	assert(!isinf(-1.23f32));
 };
 
 // Returns true if the given f64 is normal.
 export fn isnormalf64(n: f64) bool = {
 	const bits = f64bits(n);
 	const mant = bits & F64_MANTISSA_MASK;
 	const exp = bits >> F64_MANTISSA_BITS & F64_EXPONENT_MASK;
 	return exp != F64_EXPONENT_MASK && (exp > 0 || mant == 0);
 };
 
 // Returns true if the given f32 is normal.
 export fn isnormalf32(n: f32) bool = {
 	const bits = f32bits(n);
 	const mant = bits & F32_MANTISSA_MASK;
 	const exp = bits >> F32_MANTISSA_BITS & F32_EXPONENT_MASK;
 	return exp != F32_EXPONENT_MASK && (exp > 0 || mant == 0);
 };
 
 // Returns true if the given f64 is subnormal.
 export fn issubnormalf64(n: f64) bool = {
 	const bits = f64bits(n);
 	const mant = bits & F64_MANTISSA_MASK;
 	const exp = bits >> F64_MANTISSA_BITS & F64_EXPONENT_MASK;
 	return exp == 0 && mant != 0;
 };
 
 // Returns true if the given f32 is subnormal.
 export fn issubnormalf32(n: f32) bool = {
 	const bits = f32bits(n);
 	const mant = bits & F32_MANTISSA_MASK;
 	const exp = bits >> F32_MANTISSA_BITS & F32_EXPONENT_MASK;
 	return exp == 0 && mant != 0;
 };
 
 // Returns the absolute value of f64 n.
 export fn absf64(n: f64) f64 = {
 	if (isnan(n)) {
 		return n;
 	};
 	return f64frombits(f64bits(n) & ~F64_SIGN_MASK);
 };
 
 // Returns the absolute value of f32 n.
 export fn absf32(n: f32) f32 = {
 	if (isnan(n)) {
 		return n;
 	};
 	return f32frombits(f32bits(n) & ~F32_SIGN_MASK);
 };
 
 // Returns 1 if x is positive and -1 if x is negative. Note that zero is also
 // signed.
 export fn signf64(x: f64) i64 = {
 	if (f64bits(x) & F64_SIGN_MASK == 0) {
 		return 1i64;
 	} else {
 		return -1i64;
 	};
 };
 
 // Returns 1 if x is positive and -1 if x is negative. Note that zero is also
 // signed.
 export fn signf32(x: f32) i64 = {
 	if (f32bits(x) & F32_SIGN_MASK == 0) {
 		return 1i64;
 	} else {
 		return -1i64;
 	};
 };
 
 // Returns whether or not x is positive.
 export fn ispositivef64(x: f64) bool = signf64(x) == 1i64;
 
 // Returns whether or not x is positive.
 export fn ispositivef32(x: f32) bool = signf32(x) == 1i32;
 
 // Returns whether or not x is negative.
 export fn isnegativef64(x: f64) bool = signf64(x) == -1i64;
 
 // Returns whether or not x is negative.
 export fn isnegativef32(x: f32) bool = signf32(x) == -1i32;
 
 // Returns x, but with the sign of y.
 export fn copysignf64(x: f64, y: f64) f64 = {
 	return f64frombits((f64bits(x) & ~F64_SIGN_MASK) |
 		(f64bits(y) & F64_SIGN_MASK));
 };
 
 // Returns x, but with the sign of y.
 export fn copysignf32(x: f32, y: f32) f32 = {
 	return f32frombits((f32bits(x) & ~F32_SIGN_MASK) |
 		(f32bits(y) & F32_SIGN_MASK));
 };
 
 // Takes a potentially subnormal f64 n and returns a normal f64 normal_float
 // and an exponent exp such that n == normal_float * 2^{exp}.
 export fn normalizef64(n: f64) (f64, i64) = {
 	if (issubnormalf64(n)) {
 		const factor = 1i64 << (F64_MANTISSA_BITS: i64);
 		const normal_float = (n * (factor: f64));
 		return (normal_float, -(F64_MANTISSA_BITS: i64));
 	};
 	return (n, 0);
 };
 
 // Takes a potentially subnormal f32 n and returns a normal f32 normal_float
 // and an exponent exp such that n == normal_float * 2^{exp}.
 export fn normalizef32(n: f32) (f32, i64) = {
 	if (issubnormalf32(n)) {
 		const factor = 1i32 << (F32_MANTISSA_BITS: i32);
 		const normal_float = n * factor: f32;
 		return (normal_float, -(F32_MANTISSA_BITS: i64));
 	};
 	return (n, 0);
 };
 
 // Breaks a f64 down into its mantissa and exponent. The mantissa will be
 // between 0.5 and 1.
 export fn frexpf64(n: f64) (f64, i64) = {
 	if (isnan(n) || isinf(n) || n == 0f64) {
 		return (n, 0);
 	};
 	const normalized = normalizef64(n);
 	const normal_float = normalized.0;
 	const normalization_exp = normalized.1;
 	const bits = f64bits(normal_float);
 	const raw_exp: u64 = (bits >> F64_MANTISSA_BITS) & F64_EXPONENT_MASK;
 	const exp: i64 = normalization_exp +
 		(raw_exp: i64) - (F64_EXPONENT_BIAS: i64) + 1;
 	const mantissa: f64 =
 		f64frombits((bits & F64_EXP_REMOVAL_MASK) | F64_EXP_ZERO);
 	return (mantissa, exp);
 };
 
 // Breaks a f32 down into its mantissa and exponent. The mantissa will be
 // between 0.5 and 1.
 export fn frexpf32(n: f32) (f32, i64) = {
 	if (isnan(n) || isinf(n) || n == 0f32) {
 		return (n, 0);
 	};
 	const normalized = normalizef32(n);
 	const normal_float = normalized.0;
 	const normalization_exp = normalized.1;
 	const bits = f32bits(normal_float);
 	const raw_exp: u64 = (bits >> F32_MANTISSA_BITS)
 		& F32_EXPONENT_MASK: u32;
 	const exp: i64 = normalization_exp +
 		(raw_exp: i64) - (F32_EXPONENT_BIAS: i64) + 1;
 	const mantissa: f32 =
 		f32frombits((bits & F32_EXP_REMOVAL_MASK) | F32_EXP_ZERO);
 	return (mantissa, exp);
 };
 
 // Creates an f64 from a mantissa and an exponent.
 export fn ldexpf64(mantissa: f64, exp: i64) f64 = {
 	if (isnan(mantissa) || isinf(mantissa) || mantissa == 0f64) {
 		return mantissa;
 	};
 	const normalized = normalizef64(mantissa);
 	const normal_float = normalized.0;
 	const normalization_exp = normalized.1;
 	const bits = f64bits(normal_float);
 	const mantissa_exp =
 		(((bits >> F64_MANTISSA_BITS) & F64_EXPONENT_MASK): i64) -
 		(F64_EXPONENT_BIAS: i64);
 	let res_exp = exp + normalization_exp + mantissa_exp;
 	// Underflow
 	if (res_exp < -(F64_EXPONENT_BIAS: i64) - (F64_MANTISSA_BITS: i64)) {
 		return copysignf64(0f64, mantissa);
 	};
 	// Overflow
 	if (res_exp > (F64_EXPONENT_BIAS: i64)) {
 		if (mantissa < 0f64) {
 			return -INF;
 		} else {
 			return INF;
 		};
 	};
 	// Subnormal
 	let subnormal_factor = 1f64;
 	if (res_exp < -(F64_EXPONENT_BIAS: i64) + 1) {
 		res_exp += (F64_MANTISSA_BITS: i64) - 1;
 		subnormal_factor = 1f64 /
 			((1i64 << ((F64_MANTISSA_BITS: i64) - 1)): f64);
 	};
 	const res: u64 = (bits & F64_EXP_REMOVAL_MASK) |
 		(
 			((res_exp: u64) + F64_EXPONENT_BIAS)
 			<< F64_MANTISSA_BITS
 		);
 	return subnormal_factor * f64frombits(res);
 };
 
 // Creates an f32 from a mantissa and an exponent.
 export fn ldexpf32(mantissa: f32, exp: i64) f32 = {
 	if (isnan(mantissa) || isinf(mantissa) || mantissa == 0f32) {
 		return mantissa;
 	};
 	const normalized = normalizef32(mantissa);
 	const normal_float = normalized.0;
 	const normalization_exp = normalized.1;
 	const bits = f32bits(normal_float);
 	const mantissa_exp =
 		(((bits >> F32_MANTISSA_BITS) & F32_EXPONENT_MASK): i32) -
 		(F32_EXPONENT_BIAS: i32);
 	let res_exp = exp + normalization_exp + mantissa_exp;
 	// Underflow
 	if (res_exp < -(F32_EXPONENT_BIAS: i32) - (F32_MANTISSA_BITS: i32)) {
 		return copysignf32(0.0f32, mantissa);
 	};
 	// Overflow
 	if (res_exp > (F32_EXPONENT_BIAS: i32)) {
 		if (mantissa < 0.0f32) {
 			return -INF;
 		} else {
 			return INF;
 		};
 	};
 	// Subnormal
 	let subnormal_factor = 1.0f32;
 	if (res_exp < -(F32_EXPONENT_BIAS: i32) + 1) {
 		res_exp += (F32_MANTISSA_BITS: i32) - 1;
 		subnormal_factor = 1.0f32 /
 			((1i32 << ((F32_MANTISSA_BITS: i32) - 1)): f32);
 	};
 	const res: u32 = (bits & F32_EXP_REMOVAL_MASK) |
 		(
 			((res_exp: u32) + F32_EXPONENT_BIAS)
 			<< (F32_MANTISSA_BITS: u32)
 		);
 	return subnormal_factor * f32frombits(res);
 };
 
 // Returns the integer and fractional parts of an f64.
 export fn modfracf64(n: f64) (f64, f64) = {
 	if (n < 1f64) {
 		if (n < 0f64) {
 			let positive_parts = modfracf64(-n);
 			return (-positive_parts.0, -positive_parts.1);
 		};
 		if (n == 0f64) {
 			return (n, n);
 		};
 		return (0f64, n);
 	};
 	let bits = f64bits(n);
 	const exp = (((bits >> F64_MANTISSA_BITS) & F64_EXPONENT_MASK): i64) -
 		(F64_EXPONENT_BIAS: i64);
 	// For exponent exp, all integers can be represented with the top exp
 	// bits of the mantissa
 	const sign_and_exp_bits = 64u64 - (F64_EXPONENT_BITS: u64) - 1u64;
 	if (exp < (sign_and_exp_bits: i64)) {
 		const bits_to_shift = (((sign_and_exp_bits: i64) - exp): u64);
 		bits = bits & ~((1u64 << bits_to_shift) - 1);
 	};
 	const int_part = f64frombits(bits);
 	const frac_part = n - int_part;
 	return (int_part, frac_part);
 };
 
 // Returns the integer and fractional parts of an f32.
 export fn modfracf32(n: f32) (f32, f32) = {
 	if (n < 1.0f32) {
 		if (n < 0.0f32) {
 			let positive_parts = modfracf32(-n);
 			return (-positive_parts.0, -positive_parts.1);
 		};
 		if (n == 0.0f32) {
 			return (n, n);
 		};
 		return (0f32, n);
 	};
 	let bits = f32bits(n);
 	const exp = (((bits >> F32_MANTISSA_BITS) & F32_EXPONENT_MASK): i32) -
 		(F32_EXPONENT_BIAS: i32);
 	// For exponent exp, all integers can be represented with the top exp
 	// bits of the mantissa
 	const sign_and_exp_bits = 32u32 - (F32_EXPONENT_BITS: u32) - 1u32;
 	if (exp < (sign_and_exp_bits: i32)) {
 		const bits_to_shift = (((sign_and_exp_bits: i32) - exp): u32);
 		bits = bits & ~((1u32 << bits_to_shift) - 1);
 	};
 	const int_part = f32frombits(bits);
 	const frac_part = n - int_part;
 	return (int_part, frac_part);
 };
 
 // Returns the f32 that is closest to 'x' in direction of 'y'. Returns NaN
 // if either parameter is NaN. Returns 'x' if both parameters are same.
 export fn nextafterf32(x: f32, y: f32) f32 = {
 	if (isnan(x) || isnan(y)) {
 		return x + y;
 	};
 	let ux = f32bits(x);
 	let uy = f32bits(y);
 	if (ux == uy) {
 		return x;
 	};
 
 	let absx = ux & 0x7fffffff, absy = uy & 0x7fffffff;
 	if (absx == 0) {
 		if (absy == 0) {
 			return x;
 		};
 		ux = uy & 0x80000000 | 1;
 	} else if (absx > absy || (ux ^ uy) & 0x80000000 != 0) {
 		ux -= 1;
 	} else {
 		ux += 1;
 	};
 	// TODO handle over/underflow
 	return f32frombits(ux);
 };
 
 // Returns the f64 that is closest to 'x' in direction of 'y' Returns NaN
 // if either parameter is NaN. Returns 'x' if both parameters are same.
 export fn nextafterf64(x: f64, y: f64) f64 = {
 	if (isnan(x) || isnan(y)) {
 		return x + y;
 	};
 	let ux = f64bits(x);
 	let uy = f64bits(y);
 	if (ux == uy) {
 		return x;
 	};
 
 	let absx = ux & ~(1u64 << 63), absy = uy & ~(1u64 << 63);
 	if (absx == 0) {
 		if (absy == 0) {
 			return x;
 		};
 		ux = uy & (1u64 << 63) | 1u64;
 	} else if (absx > absy || (ux ^ uy) & (1u64 << 63) != 0) {
 		ux -= 1;
 	} else {
 		ux += 1;
 	};
 	// TODO handle over/underflow
 	return f64frombits(ux);
 };
 
 // Round a f32 to nearest integer value in floating point format
 fn nearbyintf32(x: f32) f32 = {
 	let n = f32bits(x);
 	let e = (n & F32_EXPONENT_MASK) >> F32_MANTISSA_BITS;
 	if (e >= F32_EXPONENT_BIAS + F32_MANTISSA_BITS) {
 		return x;
 	};
 	let s = n >> 31;
 	let y = if (s != 0)
 		x - 1.0 / F32_EPS + 1.0 / F32_EPS
 	else
 		x + 1.0 / F32_EPS - 1.0 / F32_EPS;
 
 	if (y == 0.0f32)
 		return if (s != 0) -0.0f32 else 0.0f32
 	else
 		return y;
 };
 
 // Round a f64 to nearest integer value in floating point format
 fn nearbyintf64(x: f64) f64 = {
 	let n = f64bits(x);
 	let e = (n & F64_EXPONENT_MASK) >> F64_MANTISSA_BITS;
 	if (e >= F64_EXPONENT_BIAS + F64_MANTISSA_BITS) {
 		return x;
 	};
 	let s = n >> 63;
 	let y = if (s != 0)
 		x - 1.0 / F64_EPS + 1.0 / F64_EPS
 	else
 		x + 1.0 / F64_EPS - 1.0 / F64_EPS;
 
 	if (y == 0.0f64)
 		return if (s != 0) -0.0f64 else 0.0f64
 	else
 		return y;
 };