1b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 2b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project/* @(#)s_nextafter.c 1.3 95/01/18 */ 3b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project/* 4b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * ==================================================== 5b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 6b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * 7b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * Developed at SunSoft, a Sun Microsystems, Inc. business. 8b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * Permission to use, copy, modify, and distribute this 9b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * software is freely granted, provided that this notice 10b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * is preserved. 11b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * ==================================================== 12b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project */ 13b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 14b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project/* IEEE functions 15b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * nextafter(x,y) 16b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * return the next machine floating-point number of x in the 17b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * direction toward y. 18b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project * Special cases: 19b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project */ 20b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 21b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project#include "fdlibm.h" 22b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 23b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project#ifdef __STDC__ 24b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project double ieee_nextafter(double x, double y) 25b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project#else 26b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project double ieee_nextafter(x,y) 27b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project double x,y; 28b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project#endif 29b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project{ 30b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project int hx,hy,ix,iy; 31b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project unsigned lx,ly; 32b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 33b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project hx = __HI(x); /* high word of x */ 34b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project lx = __LO(x); /* low word of x */ 35b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project hy = __HI(y); /* high word of y */ 36b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project ly = __LO(y); /* low word of y */ 37b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project ix = hx&0x7fffffff; /* |x| */ 38b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project iy = hy&0x7fffffff; /* |y| */ 39b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project 40b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ 41b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ 42b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project return x+y; 43b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(x==y) return x; /* x=y, return x */ 44b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if((ix|lx)==0) { /* x == 0 */ 45b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project __HI(x) = hy&0x80000000; /* return +-minsubnormal */ 46b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project __LO(x) = 1; 47b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project y = x*x; 48b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(y==x) return y; else return x; /* raise underflow flag */ 49b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 50b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(hx>=0) { /* x > 0 */ 51b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ 52b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(lx==0) hx -= 1; 53b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project lx -= 1; 54b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } else { /* x < y, x += ulp */ 55b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project lx += 1; 56b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(lx==0) hx += 1; 57b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 58b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } else { /* x < 0 */ 59b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ 60b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(lx==0) hx -= 1; 61b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project lx -= 1; 62b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } else { /* x > y, x += ulp */ 63b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project lx += 1; 64b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(lx==0) hx += 1; 65b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 66b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 67b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project hy = hx&0x7ff00000; 68b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(hy>=0x7ff00000) return x+x; /* overflow */ 69b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(hy<0x00100000) { /* underflow */ 70b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project y = x*x; 71b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project if(y!=x) { /* raise underflow flag */ 72b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project __HI(y) = hx; __LO(y) = lx; 73b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project return y; 74b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 75b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project } 76b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project __HI(x) = hx; __LO(x) = lx; 77b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project return x; 78b07e1d9fd8d9e4e03698e0bd9bf77154c5390326The Android Open Source Project} 79