1. Converting reals
Can anyone write a Euphoria function to convert a
48 bit Pascal real to Euphoria atom?
Format is: msb..................................lsb
bit 1 = sign
bits 2..39 = f
bits 40..48 = e
The formula given is :
if 0 < e <= 255 then v = (-1)s * 2(e-129) * (1.f)
^ ^
the s and e-129 are superscripts.
Thanks,
Irv
2. Re: Converting reals
On Tue, 9 Feb 1999, Irv Mullins wrote:
] Can anyone write a Euphoria function to convert a
] 48 bit Pascal real to Euphoria atom?
]
] Format is: msb..................................lsb
] bit 1 = sign
] bits 2..39 = f
] bits 40..48 = e
]
] The formula given is :
] if 0 < e <= 255 then v = (-1)s * 2(e-129) * (1.f)
] ^ ^
] the s and e-129 are superscripts.
It might help if you told us how you've currently got it stored in
memory... It's too big for an integer...
On the fly coding...
00000000 00000000 00000000 00000000 00000000 00000000
sfffffff ffffffff ffffffff ffffffff ffffffff eeeeeeee
function two_to_the(integer n)
return power(2, n)
end function
function pascal48IEEE_to_atom(six_byte_integer ieee)
six_byte_integer index, index2
integer sign, number, mantissa
atom out
index = two_to_the(47)
sign = 1 - 2 * (and_bits(ieee, index)/index)
index2 = two_to_the(8)
index = (two_to_the(46)/index2 - 1) * index2
number = and_bits(ieee, index) / index2
index2 = index2 - 1
mantissa = and_bits(ieee, index2) - two_to_the(7) - 1
out = sign * number * two_to_the(mantissa)
end function
I may have misplaced a power of two by coding on the fly and not
testing but HTH,
Carl
--
Carl R White -- Final Year Computer Science at the University of Bradford
E-mail........: cyrek- at -bigfoot.com -- Remove hyphens. Ta :)
URL...........: http://www.bigfoot.com/~cyrek/
Uncrackable...: "19.6A.23.38.52.73.45 25.31.1C 3C.53.44.39.58"
