gonzui

    1: /*      $OpenBSD: s_lrint.c,v 1.7 2011/07/06 00:02:42 martynas Exp $ */
    2: /* $NetBSD: lrint.c,v 1.3 2004/10/13 15:18:32 drochner Exp $ */
    3: 
    4: /*-
    5:  * Copyright (c) 2004
    6:  *      Matthias Drochner. All rights reserved.
    7:  *
    8:  * Redistribution and use in source and binary forms, with or without
    9:  * modification, are permitted provided that the following conditions
   10:  * are met:
   11:  * 1. Redistributions of source code must retain the above copyright
   12:  *    notice, this list of conditions and the following disclaimer.
   13:  * 2. Redistributions in binary form must reproduce the above copyright
   14:  *    notice, this list of conditions and the following disclaimer in the
   15:  *    documentation and/or other materials provided with the distribution.
   16:  *
   17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27:  * SUCH DAMAGE.
   28:  */
   29: 
   30: /* LINTLIBRARY */
   31: 
   32: #include <sys/types.h>
   33: #include <sys/limits.h>
   34: #include <float.h>
   35: #include <math.h>
   36: #include <ieeefp.h>
   37: #include <machine/ieee.h>
   38: 
   39: #include "math_private.h"
   40: 
   41: #ifndef LRINTNAME
   42: #define LRINTNAME lrint
   43: #define RESTYPE long int
   44: #define RESTYPE_MIN LONG_MIN
   45: #define RESTYPE_MAX LONG_MAX
   46: #endif
   47: 
   48: #define RESTYPE_BITS (sizeof(RESTYPE) * 8)
   49: 
   50: static const double
   51: TWO52[2]={
   52:   4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
   53:  -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
   54: };
   55: 
   56: RESTYPE
   57: LRINTNAME(double x)
   58: {
   59:         u_int32_t i0, i1;
   60:         int e, s, shift;
   61:         RESTYPE res;
   62: 
   63:         GET_HIGH_WORD(i0, x);
   64:         e = i0 >> DBL_FRACHBITS;
   65:         s = e >> DBL_EXPBITS;
   66:         e = (e & 0x7ff) - DBL_EXP_BIAS;
   67: 
   68:         /* 1.0 x 2^31 (or 2^63) is already too large */
   69:         if (e >= (int)RESTYPE_BITS - 1)
   70:                 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
   71: 
   72:         /* >= 2^52 is already an exact integer */
   73:         if (e < DBL_FRACBITS) {
   74:                 volatile double t = x;        /* clip extra precision */
   75:                 /* round, using current direction */
   76:                 t += TWO52[s];
   77:                 t -= TWO52[s];
   78:                 x = t;
   79:         }
   80: 
   81:         EXTRACT_WORDS(i0, i1, x);
   82:         e = ((i0 >> DBL_FRACHBITS) & 0x7ff) - DBL_EXP_BIAS;
   83:         i0 &= 0xfffff;
   84:         i0 |= (1 << DBL_FRACHBITS);
   85: 
   86:         if (e < 0)
   87:                 return (0);
   88: 
   89:         shift = e - DBL_FRACBITS;
   90:         if (shift >=0)
   91:                 res = (shift < RESTYPE_BITS ? (RESTYPE)i1 << shift : 0);
   92:         else
   93:                 res = (shift > -RESTYPE_BITS ? (RESTYPE)i1 >> -shift : 0);
   94:         shift += 32;
   95:         if (shift >=0)
   96:                 res |= (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0);
   97:         else
   98:                 res |= (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0);
   99: 
  100:         return (s ? -res : res);
  101: }
  102: 
  103: #if     LDBL_MANT_DIG == 53
  104: #ifdef  lint
  105: /* PROTOLIB1 */
  106: long int lrintl(long double);
  107: #else   /* lint */
  108: __weak_alias(lrintl, lrint);
  109: #endif  /* lint */
  110: #endif  /* LDBL_MANT_DIG == 53 */