-/* origin: FreeBSD /usr/src/lib/msun/src/s_ceil.c */
-/*
- * ====================================================
- * 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.
- * ====================================================
- */
-/*
- * ceil(x)
- * Return x rounded toward -inf to integral value
- * Method:
- * Bit twiddling.
- * Exception:
- * Inexact flag raised if x not equal to ceil(x).
- */
-
#include "libm.h"
-static const double huge = 1.0e300;
+#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
+#define EPS DBL_EPSILON
+#elif FLT_EVAL_METHOD==2
+#define EPS LDBL_EPSILON
+#endif
+static const double_t toint = 1/EPS;
double ceil(double x)
{
- int32_t i0,i1,j0;
- uint32_t i,j;
+ union {double f; uint64_t i;} u = {x};
+ int e = u.i >> 52 & 0x7ff;
+ double_t y;
- EXTRACT_WORDS(i0, i1, x);
- // FIXME signed shift
- 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 = 0x80000000;
- i1=0;
- } else if ((i0|i1) != 0) {
- i0=0x3ff00000;
- i1=0;
- }
- }
- } else {
- i = (0x000fffff)>>j0;
- if (((i0&i)|i1) == 0) /* x is integral */
- return x;
- /* raise inexact flag */
- if (huge+x > 0.0) {
- if (i0 > 0)
- i0 += 0x00100000>>j0;
- i0 &= ~i;
- i1 = 0;
- }
- }
- } else if (j0 > 51) {
- if (j0 == 0x400) /* inf or NaN */
- return x+x;
- return x; /* x is integral */
- } else {
- i = (uint32_t)0xffffffff>>(j0-20);
- if ((i1&i) == 0)
- return x; /* x is integral */
- /* raise inexact flag */
- if (huge+x > 0.0) {
- if (i0 > 0) {
- if (j0 == 20)
- i0 += 1;
- else {
- j = i1 + (1<<(52-j0));
- if (j < i1) /* got a carry */
- i0 += 1;
- i1 = j;
- }
- }
- i1 &= ~i;
- }
+ if (e >= 0x3ff+52 || x == 0)
+ return x;
+ /* y = int(x) - x, where int(x) is an integer neighbor of x */
+ if (u.i >> 63)
+ y = x - toint + toint - x;
+ else
+ y = x + toint - toint - x;
+ /* special case because of non-nearest rounding modes */
+ if (e <= 0x3ff-1) {
+ FORCE_EVAL(y);
+ return u.i >> 63 ? -0.0 : 1;
}
- INSERT_WORDS(x, i0, i1);
- return x;
+ if (y < 0)
+ return x + y + 1;
+ return x + y;
}