134122Sbostic /* 234122Sbostic * Copyright (c) 1985 Regents of the University of California. 334401Sbostic * All rights reserved. 434401Sbostic * 542657Sbostic * %sccs.include.redist.c% 634122Sbostic */ 724596Szliu 834122Sbostic #ifndef lint 9*56371Sbostic static char sccsid[] = "@(#)floor.c 5.8 (Berkeley) 10/01/92"; 1034122Sbostic #endif /* not lint */ 1134122Sbostic 1235679Sbostic #include "mathimpl.h" 1334401Sbostic 1435679Sbostic vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */ 1535679Sbostic 1635679Sbostic ic(L, 4503599627370496.0E0, 52, 1.0) /* 2**52 */ 1735679Sbostic 1835679Sbostic #ifdef vccast 1935679Sbostic #define L vccast(L) 2035679Sbostic #endif 2135679Sbostic 2224596Szliu /* 2334401Sbostic * floor(x) := the largest integer no larger than x; 2434401Sbostic * ceil(x) := -floor(-x), for all real x. 2534401Sbostic * 2634401Sbostic * Note: Inexact will be signaled if x is not an integer, as is 2734401Sbostic * customary for IEEE 754. No other signal can be emitted. 2824596Szliu */ 2924596Szliu double 3034401Sbostic floor(x) 3134401Sbostic double x; 3224596Szliu { 33*56371Sbostic volatile double y; 3424596Szliu 3534401Sbostic if ( 3634401Sbostic #if !defined(vax)&&!defined(tahoe) 3734401Sbostic x != x || /* NaN */ 3834401Sbostic #endif /* !defined(vax)&&!defined(tahoe) */ 3934401Sbostic x >= L) /* already an even integer */ 4034401Sbostic return x; 4134401Sbostic else if (x < (double)0) 4234401Sbostic return -ceil(-x); 4334401Sbostic else { /* now 0 <= x < L */ 4434401Sbostic y = L+x; /* destructive store must be forced */ 4534401Sbostic y -= L; /* an integer, and |x-y| < 1 */ 4634401Sbostic return x < y ? y-(double)1 : y; 4734401Sbostic } 4824596Szliu } 4924596Szliu 5024596Szliu double 5134401Sbostic ceil(x) 5234401Sbostic double x; 5324596Szliu { 54*56371Sbostic volatile double y; 5534401Sbostic 5634401Sbostic if ( 5734401Sbostic #if !defined(vax)&&!defined(tahoe) 5834401Sbostic x != x || /* NaN */ 5934401Sbostic #endif /* !defined(vax)&&!defined(tahoe) */ 6034401Sbostic x >= L) /* already an even integer */ 6134401Sbostic return x; 6234401Sbostic else if (x < (double)0) 6334401Sbostic return -floor(-x); 6434401Sbostic else { /* now 0 <= x < L */ 6534401Sbostic y = L+x; /* destructive store must be forced */ 6634401Sbostic y -= L; /* an integer, and |x-y| < 1 */ 6734401Sbostic return x > y ? y+(double)1 : y; 6834401Sbostic } 6924596Szliu } 7024596Szliu 71*56371Sbostic #ifndef ns32000 /* rint() is in ./NATIONAL/support.s */ 7224596Szliu /* 7324596Szliu * algorithm for rint(x) in pseudo-pascal form ... 7424596Szliu * 7524596Szliu * real rint(x): real x; 7624596Szliu * ... delivers integer nearest x in direction of prevailing rounding 7724596Szliu * ... mode 7824596Szliu * const L = (last consecutive integer)/2 7924596Szliu * = 2**55; for VAX D 8024596Szliu * = 2**52; for IEEE 754 Double 8124596Szliu * real s,t; 8224596Szliu * begin 8324596Szliu * if x != x then return x; ... NaN 8424596Szliu * if |x| >= L then return x; ... already an integer 8524596Szliu * s := copysign(L,x); 8624596Szliu * t := x + s; ... = (x+s) rounded to integer 8724596Szliu * return t - s 8824596Szliu * end; 8924596Szliu * 9024596Szliu * Note: Inexact will be signaled if x is not an integer, as is 9124596Szliu * customary for IEEE 754. No other signal can be emitted. 9224596Szliu */ 9324596Szliu double 9424596Szliu rint(x) 9524596Szliu double x; 9624596Szliu { 97*56371Sbostic double s; 98*56371Sbostic volatile double t; 9935679Sbostic const double one = 1.0; 10035679Sbostic 10131853Szliu #if !defined(vax)&&!defined(tahoe) 10224596Szliu if (x != x) /* NaN */ 10324596Szliu return (x); 10431853Szliu #endif /* !defined(vax)&&!defined(tahoe) */ 10524596Szliu if (copysign(x,one) >= L) /* already an integer */ 10624596Szliu return (x); 10724596Szliu s = copysign(L,x); 10824596Szliu t = x + s; /* x+s rounded to integer */ 10924596Szliu return (t - s); 11024596Szliu } 11131853Szliu #endif /* not national */ 112