ref: d0ab3a0dd8f6355b3603d0fb04043a9ae867639b
dir: /libkern/frexp-386.c/
#include <lib9.h> #define MASK 0x7ffL #define SHIFT 20 #define BIAS 1022L typedef union { double d; struct { long ls; long ms; }; } Cheat; double frexp(double d, int *ep) { Cheat x; if(d == 0) { *ep = 0; return 0; } x.d = d; *ep = ((x.ms >> SHIFT) & MASK) - BIAS; x.ms &= ~(MASK << SHIFT); x.ms |= BIAS << SHIFT; return x.d; } double ldexp(double d, int e) { Cheat x; if(d == 0) return 0; x.d = d; e += (x.ms >> SHIFT) & MASK; if(e <= 0) return 0; /* underflow */ if(e >= MASK){ /* overflow */ if(d < 0) return Inf(-1); return Inf(1); } x.ms &= ~(MASK << SHIFT); x.ms |= (long)e << SHIFT; return x.d; } double modf(double d, double *ip) { Cheat x; int e; if(d < 1) { if(d < 0) { x.d = modf(-d, ip); *ip = -*ip; return -x.d; } *ip = 0; return d; } x.d = d; e = ((x.ms >> SHIFT) & MASK) - BIAS; if(e <= SHIFT+1) { x.ms &= ~(0x1fffffL >> e); x.ls = 0; } else if(e <= SHIFT+33) x.ls &= ~(0x7fffffffL >> (e-SHIFT-2)); *ip = x.d; return d - x.d; }