| |
| /* @(#)s_floor.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| /* |
| FUNCTION |
| <<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling |
| INDEX |
| floor |
| INDEX |
| floorf |
| INDEX |
| ceil |
| INDEX |
| ceilf |
| |
| ANSI_SYNOPSIS |
| #include <math.h> |
| double floor(double <[x]>); |
| float floorf(float <[x]>); |
| double ceil(double <[x]>); |
| float ceilf(float <[x]>); |
| |
| TRAD_SYNOPSIS |
| #include <math.h> |
| double floor(<[x]>) |
| double <[x]>; |
| float floorf(<[x]>) |
| float <[x]>; |
| double ceil(<[x]>) |
| double <[x]>; |
| float ceilf(<[x]>) |
| float <[x]>; |
| |
| DESCRIPTION |
| <<floor>> and <<floorf>> find |
| @tex |
| $\lfloor x \rfloor$, |
| @end tex |
| the nearest integer less than or equal to <[x]>. |
| <<ceil>> and <<ceilf>> find |
| @tex |
| $\lceil x\rceil$, |
| @end tex |
| the nearest integer greater than or equal to <[x]>. |
| |
| RETURNS |
| <<floor>> and <<ceil>> return the integer result as a double. |
| <<floorf>> and <<ceilf>> return the integer result as a float. |
| |
| PORTABILITY |
| <<floor>> and <<ceil>> are ANSI. |
| <<floorf>> and <<ceilf>> are extensions. |
| |
| |
| */ |
| |
| /* |
| * floor(x) |
| * Return x rounded toward -inf to integral value |
| * Method: |
| * Bit twiddling. |
| * Exception: |
| * Inexact flag raised if x not equal to floor(x). |
| */ |
| |
| #include "fdlibm.h" |
| |
| #ifndef _DOUBLE_IS_32BITS |
| |
| #ifdef __STDC__ |
| static const double huge = 1.0e300; |
| #else |
| static double huge = 1.0e300; |
| #endif |
| |
| #ifdef __STDC__ |
| double floor(double x) |
| #else |
| double floor(x) |
| double x; |
| #endif |
| { |
| int32_t i0,i1,j0; |
| uint32_t i,j; |
| EXTRACT_WORDS(i0,i1,x); |
| j0 = ((i0>>20)&0x7ff)-0x3ff; |
| if(j0<20) { |
| if(j0<0) { /* raise inexact if x != 0 */ |
| if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
| if(i0>=0) {i0=i1=0;} |
| else if(((i0&0x7fffffff)|i1)!=0) |
| { i0=0xbff00000;i1=0;} |
| } |
| } else { |
| i = (0x000fffff)>>j0; |
| if(((i0&i)|i1)==0) return x; /* x is integral */ |
| if(huge+x>0.0) { /* raise inexact flag */ |
| if(i0<0) i0 += (0x00100000)>>j0; |
| i0 &= (~i); i1=0; |
| } |
| } |
| } else if (j0>51) { |
| if(j0==0x400) return x+x; /* inf or NaN */ |
| else return x; /* x is integral */ |
| } else { |
| i = ((uint32_t)(0xffffffff))>>(j0-20); |
| if((i1&i)==0) return x; /* x is integral */ |
| if(huge+x>0.0) { /* raise inexact flag */ |
| if(i0<0) { |
| if(j0==20) i0+=1; |
| else { |
| j = i1+(1<<(52-j0)); |
| if(j<(uint32_t)i1) i0 +=1 ; /* got a carry */ |
| i1=j; |
| } |
| } |
| i1 &= (~i); |
| } |
| } |
| INSERT_WORDS(x,i0,i1); |
| return x; |
| } |
| |
| #endif /* _DOUBLE_IS_32BITS */ |
