Add nextup and nextdown math functions

TS 18661 adds nextup and nextdown functions alongside nextafter to provide
support for float128 equivalent to it.  This patch adds nextupl, nextup,
nextupf, nextdownl, nextdown and nextdownf to libm before float128 support.

The nextup functions return the next representable value in the direction of
positive infinity and the nextdown functions return the next representable
value in the direction of negative infinity.  These are currently enabled
as GNU extensions.

8 files changed, 380 insertions, 1 deletions

diff --git a/sysdeps/ieee754/dbl-64/s_nextup.c b/sysdeps/ieee754/dbl-64/s_nextup.c
new file mode 100644
index 0000000..d2432b5
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/s_nextup.c
@@ -0,0 +1,58 @@
+/* Return the least floating-point number greater than X.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+
+/* Return the least floating-point number greater than X.  */
+double
+__nextup (double x)
+{
+  int32_t hx, ix;
+  u_int32_t lx;
+
+  EXTRACT_WORDS (hx, lx, x);
+  ix = hx & 0x7fffffff;
+
+  if (((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0))  /* x is nan.  */
+    return x + x;
+  if ((ix | lx) == 0)
+    return DBL_TRUE_MIN;
+  if (hx >= 0)
+    {				/* x > 0.  */
+      if (isinf (x))
+        return x;
+      lx += 1;
+      if (lx == 0)
+        hx += 1;
+    }
+  else
+    {				/* x < 0.  */
+      if (lx == 0)
+        hx -= 1;
+      lx -= 1;
+    }
+  INSERT_WORDS (x, hx, lx);
+  return x;
+}
+
+weak_alias (__nextup, nextup)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__nextup, __nextupl)
+weak_alias (__nextup, nextupl)
+#endif
diff --git a/sysdeps/ieee754/flt-32/s_nextupf.c b/sysdeps/ieee754/flt-32/s_nextupf.c
new file mode 100644
index 0000000..9f3398e
--- /dev/null
+++ b/sysdeps/ieee754/flt-32/s_nextupf.c
@@ -0,0 +1,46 @@
+/* Return the least floating-point number greater than X.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+
+/* Return the least floating-point number greater than X.  */
+float
+__nextupf (float x)
+{
+  int32_t hx, ix;
+
+  GET_FLOAT_WORD (hx, x);
+  ix = hx & 0x7fffffff;
+  if (ix == 0)
+    return FLT_TRUE_MIN;
+  if (ix > 0x7f800000)		/* x is nan.  */
+    return x + x;
+  if (hx >= 0)
+    {				/* x > 0.  */
+      if (isinf (x))
+        return x;
+      hx += 1;
+    }
+  else
+    hx -= 1;
+  SET_FLOAT_WORD (x, hx);
+  return x;
+}
+
+weak_alias (__nextupf, nextupf)
diff --git a/sysdeps/ieee754/ldbl-128/s_nextupl.c b/sysdeps/ieee754/ldbl-128/s_nextupl.c
new file mode 100644
index 0000000..3ee47d8
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128/s_nextupl.c
@@ -0,0 +1,56 @@
+/* Return the least floating-point number greater than X.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+
+/* Return the least floating-point number greater than X.  */
+long double
+__nextupl (long double x)
+{
+  int64_t hx, ix;
+  u_int64_t lx;
+
+  GET_LDOUBLE_WORDS64 (hx, lx, x);
+  ix = hx & 0x7fffffffffffffffLL;
+
+  /* x is nan.  */
+  if (((ix >= 0x7fff000000000000LL)
+       && ((ix - 0x7fff000000000000LL) | lx) != 0))
+    return x + x;
+  if ((ix | lx) == 0)
+    return LDBL_TRUE_MIN;
+  if (hx >= 0)
+    {				/* x > 0.  */
+      if (isinf (x))
+        return x;
+      lx++;
+      if (lx == 0)
+        hx++;
+    }
+  else
+    {				/* x < 0.  */
+      if (lx == 0)
+        hx--;
+      lx--;
+    }
+  SET_LDOUBLE_WORDS64 (x, hx, lx);
+  return x;
+}
+
+weak_alias (__nextupl, nextupl)
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nextupl.c b/sysdeps/ieee754/ldbl-128ibm/s_nextupl.c
new file mode 100644
index 0000000..2a4fae7
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm/s_nextupl.c
@@ -0,0 +1,78 @@
+/* Return the least floating-point number greater than X.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+#include <math_ldbl_opt.h>
+
+/* Return the least floating-point number greater than X.  */
+long double
+__nextupl (long double x)
+{
+  int64_t hx, ihx, lx;
+  double xhi, xlo, yhi;
+
+  ldbl_unpack (x, &xhi, &xlo);
+  EXTRACT_WORDS64 (hx, xhi);
+  EXTRACT_WORDS64 (lx, xlo);
+  ihx = hx & 0x7fffffffffffffffLL;
+
+  if (ihx > 0x7ff0000000000000LL)	/* x is nan.  */
+    return x + x;		/* Signal the nan.  */
+  if (ihx == 0)
+    return LDBL_TRUE_MIN;
+
+  long double u;
+  if ((hx == 0x7fefffffffffffffLL) && (lx == 0x7c8ffffffffffffeLL))
+    return INFINITY;
+  if ((uint64_t) hx >= 0xfff0000000000000ULL)
+    {
+      u = -0x1.fffffffffffff7ffffffffffff8p+1023L;
+      return u;
+    }
+  if (ihx <= 0x0360000000000000LL)
+    {				/* x <= LDBL_MIN.  */
+      x += LDBL_TRUE_MIN;
+      if (x == 0.0L)		/* Handle negative LDBL_TRUE_MIN case.  */
+        x = -0.0L;
+      return x;
+    }
+  /* If the high double is an exact power of two and the low
+     double is the opposite sign, then 1ulp is one less than
+     what we might determine from the high double.  Similarly
+     if X is an exact power of two, and negative, because
+     making it a little larger will result in the exponent
+     decreasing by one and normalisation of the mantissa.   */
+  if ((hx & 0x000fffffffffffffLL) == 0
+      && ((lx != 0 && lx != 0x8000000000000000LL && (hx ^ lx) < 0)
+          || ((lx == 0 || lx == 0x8000000000000000LL) && hx < 0)))
+    ihx -= 1LL << 52;
+  if (ihx < (106LL << 52))
+    {				/* ulp will denormal.  */
+      INSERT_WORDS64 (yhi, ihx & (0x7ffLL << 52));
+      u = yhi * 0x1p-105;
+    }
+  else
+    {
+      INSERT_WORDS64 (yhi, (ihx & (0x7ffLL << 52)) - (105LL << 52));
+      u = yhi;
+    }
+  return x + u;
+}
+
+weak_alias (__nextupl, nextupl)
diff --git a/sysdeps/ieee754/ldbl-96/s_nextupl.c b/sysdeps/ieee754/ldbl-96/s_nextupl.c
new file mode 100644
index 0000000..701842d
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-96/s_nextupl.c
@@ -0,0 +1,84 @@
+/* Return the least floating-point number greater than X.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+
+/* Return the least floating-point number greater than X.  */
+long double
+__nextupl (long double x)
+{
+  u_int32_t hx, ix;
+  u_int32_t lx;
+  int32_t esx;
+
+  GET_LDOUBLE_WORDS (esx, hx, lx, x);
+  ix = esx & 0x7fff;
+
+  if (((ix == 0x7fff) && (((hx & 0x7fffffff) | lx) != 0)))  /* x is nan.  */
+    return x + x;
+  if ((ix | hx | lx) == 0)
+    return LDBL_TRUE_MIN;
+  if (esx >= 0)
+    {				/* x > 0.  */
+      if (isinf (x))
+        return x;
+      lx += 1;
+      if (lx == 0)
+        {
+          hx += 1;
+#if LDBL_MIN_EXP == -16381
+          if (hx == 0 || (esx == 0 && hx == 0x80000000))
+#else
+          if (hx == 0)
+#endif
+          {
+            esx += 1;
+            hx |= 0x80000000;
+          }
+        }
+    }
+  else
+    {				/* x < 0.  */
+      if (lx == 0)
+        {
+#if LDBL_MIN_EXP == -16381
+          if (hx <= 0x80000000 && esx != 0xffff8000)
+            {
+              esx -= 1;
+              hx = hx - 1;
+              if ((esx & 0x7fff) > 0)
+                hx |= 0x80000000;
+            }
+          else
+            hx -= 1;
+#else
+          if (ix != 0 && hx == 0x80000000)
+            hx = 0;
+          if (hx == 0)
+            esx -= 1;
+          hx -= 1;
+#endif
+        }
+      lx -= 1;
+    }
+  SET_LDOUBLE_WORDS (x, esx, hx, lx);
+  return x;
+}
+
+weak_alias (__nextupl, nextupl)
diff --git a/sysdeps/ieee754/ldbl-opt/Makefile b/sysdeps/ieee754/ldbl-opt/Makefile
index 53091e4..af08209 100644
--- a/sysdeps/ieee754/ldbl-opt/Makefile
+++ b/sysdeps/ieee754/ldbl-opt/Makefile
@@ -40,7 +40,8 @@ libnldbl-calls = asprintf dprintf fprintf fscanf fwprintf fwscanf iovfscanf \
 		 isoc99_scanf isoc99_fscanf isoc99_sscanf \
 		 isoc99_vscanf isoc99_vfscanf isoc99_vsscanf \
 		 isoc99_wscanf isoc99_fwscanf isoc99_swscanf \
-		 isoc99_vwscanf isoc99_vfwscanf isoc99_vswscanf
+		 isoc99_vwscanf isoc99_vfwscanf isoc99_vswscanf \
+		 nextup nextdown
 libnldbl-routines = $(libnldbl-calls:%=nldbl-%)
 libnldbl-inhibit-o = $(object-suffixes)
 libnldbl-static-only-routines = $(libnldbl-routines)
@@ -120,8 +121,10 @@ CFLAGS-nldbl-modf.c = -fno-builtin-modfl
 CFLAGS-nldbl-nan.c = -fno-builtin-nanl
 CFLAGS-nldbl-nearbyint.c = -fno-builtin-nearbyintl
 CFLAGS-nldbl-nextafter.c = -fno-builtin-nextafterl
+CFLAGS-nldbl-nextdown.c = -fno-builtin-nextdownl
 CFLAGS-nldbl-nexttoward.c = -fno-builtin-nexttoward -fno-builtin-nexttowardl
 CFLAGS-nldbl-nexttowardf.c = -fno-builtin-nexttowardf
+CFLAGS-nldbl-nextup.c = -fno-builtin-nextupl
 CFLAGS-nldbl-pow.c = -fno-builtin-powl
 CFLAGS-nldbl-pow10.c = -fno-builtin-pow10l
 CFLAGS-nldbl-remainder.c = -fno-builtin-remainderl -fno-builtin-dreml
diff --git a/sysdeps/ieee754/ldbl-opt/nldbl-nextdown.c b/sysdeps/ieee754/ldbl-opt/nldbl-nextdown.c
new file mode 100644
index 0000000..3b0047c
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-opt/nldbl-nextdown.c
@@ -0,0 +1,27 @@
+/* Compatibility routine for IEEE double as long double for nextdown.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "nldbl-compat.h"
+
+/* Return the greatest floating-point number less than X.  */
+double
+attribute_hidden
+nextdownl (double x)
+{
+  return nextdown (x);
+}
diff --git a/sysdeps/ieee754/ldbl-opt/nldbl-nextup.c b/sysdeps/ieee754/ldbl-opt/nldbl-nextup.c
new file mode 100644
index 0000000..b557edf
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-opt/nldbl-nextup.c
@@ -0,0 +1,27 @@
+/* Compatibility routine for IEEE double as long double for nextup.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "nldbl-compat.h"
+
+/* Return the least floating-point number greater than X.  */
+double
+attribute_hidden
+nextupl (double x)
+{
+  return nextup (x);
+}