00001 /* 00002 $Id: noDVal.h 3433 2009-03-28 21:01:20Z leighsmith $ 00003 Defined In: The MusicKit 00004 00005 Description: 00006 This is used by the Music Kit to signal "no value" from functions and 00007 methods that return double. The value MK_NODVAL is a particular "NaN" 00008 ("not a number"). You cannot test its value directly. 00009 Instead, use MKIsNoDVal(). 00010 00011 Example: 00012 00013 double myFunction(int arg) 00014 { 00015 if (arg == 2) 00016 return MK_NODVAL; 00017 else return (double) arg * 2; 00018 } 00019 00020 main() 00021 { 00022 double d = myFunction(2); 00023 if (MKIsNoDVal(d)) 00024 printf("Illegal value.\n"); 00025 } 00026 00027 Original Author: David Jaffe 00028 00029 Copyright (c) 1988-1992, NeXT Computer, Inc. 00030 Portions Copyright (c) 1994 NeXT Computer, Inc. and reproduced under license from NeXT 00031 Portions Copyright (c) 1994 Stanford University 00032 Portions Copyright (c) 1999-2005 The MusicKit Project 00033 */ 00034 #ifndef __MK_noDVal_H___ 00035 #define __MK_noDVal_H___ 00036 00037 #ifndef _MK_NANHI 00038 #define _MK_NANHI 0x7ff80000 /* High bits of a particular non-signaling NaN */ 00039 #define _MK_NANLO 0x0 /* Low bits of a particular non-signaling NaN */ 00040 #endif 00041 00042 #ifndef MK_NODVAL 00043 00068 extern inline double MKGetNoDVal(void) 00069 { 00070 union {double d; int i[2];} u; 00071 u.i[0] = _MK_NANHI; 00072 u.i[1] = _MK_NANLO; 00073 return u.d; 00074 } 00075 00091 extern inline int MKIsNoDVal(double value) 00092 { 00093 union {double d; int i[2];} u; 00094 u.d = value; 00095 return (u.i[0] == _MK_NANHI); /* Don't bother to check low bits. */ 00096 } 00097 00108 #define MK_NODVAL MKGetNoDVal() /* For convenience */ 00109 00110 #endif 00111 00112 #endif
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