Annotation of /sml/branches/SMLNJ/src/compiler/MiscUtil/bignums/ieeereal.sml

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Revision 221 - (view) (download)
Original Path: sml/trunk/src/compiler/MiscUtil/bignums/ieeereal.sml

1 :	monnier	221	(* Copyright 1989 by AT&T Bell Laboratories
2 :			*
3 :			*)
4 :			(* Support for IEEE floating-point constants
5 :			* Double precision format (for normalized numbers):
6 :			* Bias = 1023.
7 :			* Exponent = 11 bits.
8 :			* Range of exponent = [1..2046]
9 :			* Mantissa = 52 (+1) bits.
10 :			* Value = (-1)^s * 2^(e-1023) * 1.f
11 :			*)
12 :			structure IEEERealConst = RealConst(
13 :			struct
14 :			val significant = 53 (* 52 + redundant 1 bit *)
15 :			val minexp = ~1021 and maxexp = 1024
16 :			val itow = Word.fromInt
17 :			val wtoi = Word.toIntX
18 :
19 :			fun transreal (sign, frac, exp) =
20 :			if frac(0,1)=0
21 :			then if sign=0 then "\000\000\000\000\000\000\000\000"
22 :			else "\128\000\000\000\000\000\000\000"
23 :			else implode
24 :			[Char.chr(wtoi
25 :			(Word.orb(Word.<<(itow sign, 0w7),
26 :			Word.>>(itow(exp+1022), 0w4)))),
27 :			Char.chr(wtoi
28 :			(Word.andb(0w255,
29 :			Word.orb(Word.<<(itow(exp+1022), 0w4),
30 :			itow (frac(1,4)))))),
31 :			Char.chr(frac(5,8)),
32 :			Char.chr(frac(13,8)),
33 :			Char.chr(frac(21,8)),
34 :			Char.chr(frac(29,8)),
35 :			Char.chr(frac(37,8)),
36 :			Char.chr(frac(45,8))]
37 :
38 :			end)
39 :
40 :			(*
41 :			* $Log: ieeereal.sml,v $
42 :			* Revision 1.1 1998/10/28 18:22:32 jhr
43 :			* Moved from OldCGen.
44 :			*
45 :			* Revision 1.1.1.1 1998/04/08 18:39:49 george
46 :			* Version 110.5
47 :			*
48 :			*)

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