c-dtoastr, c-ldtoastr: new modules

These modules provide the same functionality as the modules
dtoastr and ldtoastr except for the formatting taking place in the
C locale.

* MODULES.html.sh: Add c-dtoastr and c-ldtoastr.
* lib/c-dtoastr.c, lib/c-ldtoastr.c: New files.
* lib/ftoastr.c: Prefix exported functions when the macro C_LOCALE is
defined.  Use c_snprintf and c_strtod/c_strtold instead of
snprintf and strtod/strtold whhen the macro C_LOCALE is defined.
* lib/ftoastr.h: Add prototypes for c_dtoastr and c_ldtoastr.
* modules/c-dtoastr, modules/c-dtoastr-tests, modules/c-ldtoastr,
modules/c-ldtoastr-tests: New files.
* tests/test-c-dtoastr.c, tests/test-c-dtoastr.sh,
tests-c-ldtoastr.c tests-c-ldtoastr.sh: New files.

4 files changed, 29 insertions, 6 deletions

diff --git a/lib/c-dtoastr.c b/lib/c-dtoastr.c
new file mode 100644
index 0000000000..b57524fb14
--- /dev/null
+++ b/lib/c-dtoastr.c
@@ -0,0 +1,3 @@
+#define LENGTH 2
+#define C_LOCALE 1
+#include "ftoastr.c"
diff --git a/lib/c-ldtoastr.c b/lib/c-ldtoastr.c
new file mode 100644
index 0000000000..5446fc3e78
--- /dev/null
+++ b/lib/c-ldtoastr.c
@@ -0,0 +1,3 @@
+#define LENGTH 3
+#define C_LOCALE 1
+#include "ftoastr.c"
diff --git a/lib/ftoastr.c b/lib/ftoastr.c
index 7a7d4113c2..47a83152e3 100644
--- a/lib/ftoastr.c
+++ b/lib/ftoastr.c
@@ -33,20 +33,28 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#ifdef C_LOCALE
+# include "c-snprintf.h"
+# include "c-strtod.h"
+# define PREFIX(name) c_ ## name
+#else
+# define PREFIX(name) name
+#endif
+
 #if LENGTH == 3
 # define FLOAT long double
 # define FLOAT_DIG LDBL_DIG
 # define FLOAT_MIN LDBL_MIN
 # define FLOAT_PREC_BOUND _GL_LDBL_PREC_BOUND
-# define FTOASTR ldtoastr
+# define FTOASTR PREFIX (ldtoastr)
 # define PROMOTED_FLOAT long double
-# define STRTOF strtold
+# define STRTOF PREFIX (strtold)
 #elif LENGTH == 2
 # define FLOAT double
 # define FLOAT_DIG DBL_DIG
 # define FLOAT_MIN DBL_MIN
 # define FLOAT_PREC_BOUND _GL_DBL_PREC_BOUND
-# define FTOASTR dtoastr
+# define FTOASTR PREFIX (dtoastr)
 # define PROMOTED_FLOAT double
 #else
 # define LENGTH 1
@@ -54,7 +62,7 @@
 # define FLOAT_DIG FLT_DIG
 # define FLOAT_MIN FLT_MIN
 # define FLOAT_PREC_BOUND _GL_FLT_PREC_BOUND
-# define FTOASTR ftoastr
+# define FTOASTR PREFIX (ftoastr)
 # define PROMOTED_FLOAT double
 # if HAVE_STRTOF
 #  define STRTOF strtof
@@ -65,13 +73,16 @@
    may generate one or two extra digits, but that's better than not
    working at all.  */
 #ifndef STRTOF
-# define STRTOF strtod
+# define STRTOF PREFIX (strtod)
 #endif
 
 /* On hosts where it's not known that snprintf works, use sprintf to
    implement the subset needed here.  Typically BUFSIZE is big enough
    and there's little or no performance hit.  */
-#if ! GNULIB_SNPRINTF
+#ifdef C_LOCALE
+# undef snprintf
+# define snprintf c_snprintf
+#elif ! GNULIB_SNPRINTF
 # undef snprintf
 # define snprintf ftoastr_snprintf
 static int
diff --git a/lib/ftoastr.h b/lib/ftoastr.h
index 852e4000d2..78b569f3d9 100644
--- a/lib/ftoastr.h
+++ b/lib/ftoastr.h
@@ -49,6 +49,12 @@ int  ftoastr (char *buf, size_t bufsize, int flags, int width,       float x);
 int  dtoastr (char *buf, size_t bufsize, int flags, int width,      double x);
 int ldtoastr (char *buf, size_t bufsize, int flags, int width, long double x);
 
+/* The last two functions except that the formatting takes place in
+   the C locale.  */
+int  c_dtoastr (char *buf, size_t bufsize, int flags, int width,      double x);
+int c_ldtoastr (char *buf, size_t bufsize, int flags, int width, long double x);
+
+
 /* Flag values for ftoastr etc.  These can be ORed together.  */
 enum
   {