first commit of the new libm!

[musl] / src / math / ceill.c

diff --git a/src/math/ceill.c b/src/math/ceill.c
new file mode 100644 (file)
index 0000000..b938cc7
--- /dev/null
+++ b/src/math/ceill.c
@@ -0,0 +1,103 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_ceill.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.
+ * ====================================================
+ */
+/*
+ * ceill(x)
+ * Return x rounded toward -inf to integral value
+ * Method:
+ *      Bit twiddling.
+ * Exception:
+ *      Inexact flag raised if x not equal to ceill(x).
+ */
+
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double ceill(long double x)
+{
+       return ceil(x);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+#ifdef LDBL_IMPLICIT_NBIT
+#define MANH_SIZE       (LDBL_MANH_SIZE + 1)
+#define INC_MANH(u, c)  do {                                    \
+       uint64_t o = u.bits.manh;                               \
+       u.bits.manh += (c);                                     \
+       if (u.bits.manh < o)                                    \
+               u.bits.exp++;                                   \
+} while (0)
+#else
+#define MANH_SIZE       LDBL_MANH_SIZE
+#define INC_MANH(u, c)  do {                                    \
+       uint64_t o = u.bits.manh;                               \
+       u.bits.manh += (c);                                     \
+       if (u.bits.manh < o) {                                  \
+               u.bits.exp++;                                   \
+               u.bits.manh |= 1llu << (LDBL_MANH_SIZE - 1);    \
+       }                                                       \
+} while (0)
+#endif
+
+static const long double huge = 1.0e300;
+
+long double
+ceill(long double x)
+{
+       union IEEEl2bits u = { .e = x };
+       int e = u.bits.exp - LDBL_MAX_EXP + 1;
+
+       if (e < MANH_SIZE - 1) {
+               if (e < 0) {
+                       /* raise inexact if x != 0 */
+                       if (huge + x > 0.0)
+                               if (u.bits.exp > 0 ||
+                                       (u.bits.manh | u.bits.manl) != 0)
+                                       u.e = u.bits.sign ? -0.0 : 1.0;
+               } else {
+                       uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
+                       if (((u.bits.manh & m) | u.bits.manl) == 0)
+                               return x;  /* x is integral */
+                       if (!u.bits.sign) {
+#ifdef LDBL_IMPLICIT_NBIT
+                               if (e == 0)
+                                       u.bits.exp++;
+                               else
+#endif
+                               INC_MANH(u, 1llu << (MANH_SIZE - e - 1));
+                       }
+                       /* raise inexact flag */
+                       if (huge + x > 0.0) {
+                               u.bits.manh &= ~m;
+                               u.bits.manl = 0;
+                       }
+               }
+       } else if (e < LDBL_MANT_DIG - 1) {
+               uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
+               if ((u.bits.manl & m) == 0)
+                       return x;  /* x is integral */
+               if (!u.bits.sign) {
+                       if (e == MANH_SIZE - 1)
+                               INC_MANH(u, 1);
+                       else {
+                               uint64_t o = u.bits.manl;
+                               u.bits.manl += 1llu << (LDBL_MANT_DIG - e - 1);
+                               if (u.bits.manl < o)    /* got a carry */
+                                       INC_MANH(u, 1);
+                       }
+               }
+               /* raise inexact flag */
+               if (huge + x > 0.0)
+                       u.bits.manl &= ~m;
+       }
+       return u.e;
+}
+#endif