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- #include "lib9.h"
- #define NANEXP (2047<<20)
- #define NANMASK (2047<<20)
- #define NANSIGN (1<<31)
- double
- NaN(void)
- {
- union
- {
- double d;
- long x[2];
- } a;
- a.x[1] = NANEXP;
- a.x[0] = 1;
- return a.d;
- }
- int
- isNaN(double d)
- {
- union
- {
- double d;
- long x[2];
- } a;
- a.d = d;
- if((a.x[1] & NANMASK) != NANEXP)
- return 0;
- return !isInf(d, 0);
- }
- double
- Inf(int sign)
- {
- union
- {
- double d;
- long x[2];
- } a;
- a.x[1] = NANEXP;
- a.x[0] = 0;
- if(sign < 0)
- a.x[1] |= NANSIGN;
- return a.d;
- }
- int
- isInf(double d, int sign)
- {
- union
- {
- double d;
- long x[2];
- } a;
- a.d = d;
- if(a.x[0] != 0)
- return 0;
- if(a.x[1] == NANEXP)
- return sign >= 0;
- if(a.x[1] == (NANEXP|NANSIGN))
- return sign <= 0;
- return 0;
- }
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