| /* @(#)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. |
| * ==================================================== |
| */ |
| |
| /* |
| * floor(x) |
| * Return x rounded toward -inf to integral value |
| * Method: |
| * Bit twiddling. |
| */ |
| |
| #include <math.h> |
| #include <math_private.h> |
| #include <libm-alias-double.h> |
| |
| double |
| __floor (double x) |
| { |
| 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) |
| { |
| /* 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 (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 (i0 < 0) |
| { |
| if (j0 == 20) |
| i0 += 1; |
| else |
| { |
| j = i1 + (1 << (52 - j0)); |
| if (j < i1) |
| i0 += 1; /* got a carry */ |
| i1 = j; |
| } |
| } |
| i1 &= (~i); |
| } |
| INSERT_WORDS (x, i0, i1); |
| return x; |
| } |
| #ifndef __floor |
| libm_alias_double (__floor, floor) |
| #endif |
