1 #include <lib9.h> 2 3 #define MASK 0x7ffL 4 #define SHIFT 20 5 #define BIAS 1022L 6 7 typedef union 8 { 9 double d; 10 struct 11 { 12 long ms; 13 long ls; 14 }; 15 } Cheat; 16 17 double 18 frexp(double d, int *ep) 19 { 20 Cheat x; 21 22 if(d == 0) { 23 *ep = 0; 24 return 0; 25 } 26 x.d = d; 27 *ep = ((x.ms >> SHIFT) & MASK) - BIAS; 28 x.ms &= ~(MASK << SHIFT); 29 x.ms |= BIAS << SHIFT; 30 return x.d; 31 } 32 33 double 34 ldexp(double d, int e) 35 { 36 Cheat x; 37 38 if(d == 0) 39 return 0; 40 x.d = d; 41 e += (x.ms >> SHIFT) & MASK; 42 if(e <= 0) 43 return 0; /* underflow */ 44 if(e >= MASK){ /* overflow */ 45 if(d < 0) 46 return Inf(-1); 47 return Inf(1); 48 } 49 x.ms &= ~(MASK << SHIFT); 50 x.ms |= (long)e << SHIFT; 51 return x.d; 52 } 53 54 double 55 modf(double d, double *ip) 56 { 57 Cheat x; 58 int e; 59 60 if(d < 1) { 61 if(d < 0) { 62 x.d = modf(-d, ip); 63 *ip = -*ip; 64 return -x.d; 65 } 66 *ip = 0; 67 return d; 68 } 69 x.d = d; 70 e = ((x.ms >> SHIFT) & MASK) - BIAS; 71 if(e <= SHIFT+1) { 72 x.ms &= ~(0x1fffffL >> e); 73 x.ls = 0; 74 } else 75 if(e <= SHIFT+33) 76 x.ls &= ~(0x7fffffffL >> (e-SHIFT-2)); 77 *ip = x.d; 78 return d - x.d; 79 } 80