Refactor *cvt functions implementation (1/2)

This patch refactors the *cvt functions implementation in a way that
makes it easier to re-use them for implementing the IEEE long double on
powerpc64le.  By splitting the implementation per se in one file
(efgcvt-template.c) and the alias definitions in others (e.g. efgcvt.c),
the new code makes it easier to define new function names, such as
__qecvtieee128.

Tested that installed stripped binaries for all build-many-glibcs
targets remain identical before and after this patch.  Also tested for
powerpc64le and x86_64.

Reviewed-by: Paul E. Murphy <murphyp@linux.ibm.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/misc/efgcvt-dbl-macros.h b/misc/efgcvt-dbl-macros.h
new file mode 100644
index 0000000000..17e01e77e3
--- /dev/null
+++ b/misc/efgcvt-dbl-macros.h
@@ -0,0 +1,52 @@
+/* Macros for the implementation of *cvt functions, double version.
+   Copyright (C) 1995-2019 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <float.h>
+
+#define FLOAT_TYPE double
+#define FUNC_PREFIX
+#define FLOAT_FMT_FLAG
+#define FLOAT_NAME_EXT
+#define FLOAT_MIN_10_EXP DBL_MIN_10_EXP
+/* Actually we have to write (DBL_DIG + log10 (DBL_MAX_10_EXP)) but we
+   don't have log10 available in the preprocessor.  */
+#define MAXDIG (NDIGIT_MAX + 3)
+#define FCVT_MAXDIG (DBL_MAX_10_EXP + MAXDIG)
+#if DBL_MANT_DIG == 53
+# define NDIGIT_MAX 17
+#elif DBL_MANT_DIG == 24
+# define NDIGIT_MAX 9
+#elif DBL_MANT_DIG == 56
+# define NDIGIT_MAX 18
+#else
+/* See IEEE 854 5.6, table 2 for this formula.  Unfortunately we need a
+   compile time constant here, so we cannot use it.  */
+# error "NDIGIT_MAX must be precomputed"
+# define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
+#endif
+#if DBL_MIN_10_EXP == -37
+# define FLOAT_MIN_10_NORM	1.0e-37
+#elif DBL_MIN_10_EXP == -307
+# define FLOAT_MIN_10_NORM	1.0e-307
+#elif DBL_MIN_10_EXP == -4931
+# define FLOAT_MIN_10_NORM	1.0e-4931
+#else
+/* libc can't depend on libm.  */
+# error "FLOAT_MIN_10_NORM must be precomputed"
+# define FLOAT_MIN_10_NORM	exp10 (DBL_MIN_10_EXP)
+#endif