1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
Index: dietlibc-0.31/libm/ceil.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ dietlibc-0.31/libm/ceil.c 2009-02-01 02:54:28.533109301 +0100
@@ -0,0 +1,92 @@
+/* @(#)s_ceil.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.
+ * ====================================================
+ */
+
+/*
+ * 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 <math.h>
+
+typedef union {
+ double value;
+ struct {
+ unsigned int lsw;
+ unsigned int msw;
+ } parts;
+} ieee_double_shape_type;
+
+/* Get two 32 bit ints from a double. */
+
+#define EXTRACT_WORDS(ix0,ix1,d) \
+do { \
+ ieee_double_shape_type ew_u; \
+ ew_u.value = (d); \
+ (ix0) = ew_u.parts.msw; \
+ (ix1) = ew_u.parts.lsw; \
+} while (0)
+
+#define INSERT_WORDS(d,ix0,ix1) \
+do { \
+ ieee_double_shape_type iw_u; \
+ iw_u.parts.msw = (ix0); \
+ iw_u.parts.lsw = (ix1); \
+ (d) = iw_u.value; \
+} while (0)
+
+static const double huge = 1.0e300;
+
+double ceil(double x)
+{
+ int i0,i1,j0;
+ unsigned int 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=0x80000000;i1=0;}
+ else if((i0|i1)!=0) { i0=0x3ff00000;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 = ((unsigned int)(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<i1) i0+=1; /* got a carry */
+ i1 = j;
+ }
+ }
+ i1 &= (~i);
+ }
+ }
+ INSERT_WORDS(x,i0,i1);
+ return x;
+}
|
