shithub: mc

ref: 1b564b2e25048bc2bb7e4f0a6cd4dd24938eeb95
dir: /lib/std/fltbits.myr/

pkg std =
	const flt64bits	: (flt : flt64 -> uint64)
	const flt32bits	: (flt : flt32 -> uint32)
	const flt64inf	: (-> flt64)
	const flt64nan	: (-> flt64)
	const flt32inf	: (-> flt32)
	const flt32nan	: (-> flt32)

	generic isnan		: (f : @a -> bool) ::floating @a
	const flt64frombits	: (bits : uint64 -> flt64)
	const flt32frombits	: (bits : uint32 -> flt32)
	const flt64explode	: (flt : flt64 -> (bool, uint64, int64))
	const flt32explode	: (flt : flt32 -> (bool, uint32, int32))
	const flt64assem	: (sign : bool, mant : uint64, exp : int64 -> flt64)
	const flt32assem	: (sign : bool, mant : uint32, exp : int32 -> flt32)
;;

const flt64bits	= {flt;	-> (&flt : uint64#)#}
const flt32bits	= {flt;	-> (&flt : uint32#)#}
const flt64frombits	= {bits;	-> (&bits : flt64#)#}
const flt32frombits	= {bits;	-> (&bits : flt32#)#}

const flt64explode = {flt
	var bits, isneg, mant, uexp, exp

	bits = flt64bits(flt)
	isneg = (bits >> 63) != 0 	/* msb is sign bit */
	uexp = (bits >> 52) & 0x7ff 	/* exp is in bits [52..63] */
	mant = bits & ((1ul << 52) - 1)	/* mant is in bits [..51] */

	/* add back the implicit bit if this is not a denormal */
	if uexp != 0
		mant |= 1ul << 52
		exp = (uexp : int64)
	else
		exp = 1
	;;
	/*
	   adjust for exponent bias. nb: because we are
	   treating the mantissa as m.0 instead of 0.m,
	   our exponent bias needs to be offset by the
	   size of m
	*/
	-> (isneg, mant, exp)
}

const flt32explode = {flt
	var bits, isneg, mant, uexp, exp

	bits = flt32bits(flt)
	isneg = (bits >> 31) != 0 	/* msb is sign bit */
	uexp = (bits >> 23) & 0xff	/* exp is in bits [23..30] */
	mant = bits & ((1 << 23) - 1)	/* mant is in bits [0..22] */

	/* add back the implicit bit if this is not a denormal */
	if uexp != 0
		mant |= 1 << 23
		exp = (uexp : int32)
	else
		exp = 1
	;;
	/*
	   adjust for exponent bias. nb: because we are
	   treating the mantissa as m.0 instead of 0.m,
	   our exponent bias needs to be offset by the
	   size of m
	*/
	-> (isneg, mant, exp)
}

const flt64assem = {sign, mant, exp
	var s, m, e

	s = (sign : uint64)
	e = (exp : uint64) & 0x7ff
	m = (mant : uint64) & ((1ul<<52) - 1)
	-> std.flt64frombits((s << 63) | (e << 52) | m)
}

const flt32assem = {sign, mant, exp
	var s, m, e

	s = (sign : uint32)
	e = (exp : uint32) & 0xff
	m = (mant : uint32) & ((1<<23) - 1)
	-> std.flt32frombits(s << 31 | e << 23 | m)

}

generic isnan = {f
	var b

	b = flt64bits((f : flt64))
	-> (b >> 52) & 0x7fful == 0x7fful && \
		b & ~(0xffful << 52) != 0
}

const flt64inf = {
	-> std.flt64frombits(0x7ff0000000000000ul)
}

const flt64nan = {
	-> std.flt64frombits(0x7ff8000000000000ul)
}

const flt32inf = {
	-> std.flt32frombits(0x7f800000)
}

const flt32nan = {
	-> std.flt32frombits(0x7fc00000)
}