first commit of the new libm!

[musl] / src / math / ceil.c

diff --git a/src/math/ceil.c b/src/math/ceil.c
new file mode 100644 (file)
index 0000000..c2ab4a5
--- /dev/null
+++ b/src/math/ceil.c
@@ -0,0 +1,83 @@
+/* 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;
+
+double ceil(double x)
+{
+       int32_t i0,i1,j0;
+       uint32_t i,j;
+
+       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;
+               }
+       }
+       INSERT_WORDS(x, i0, i1);
+       return x;
+}