[PATCH] Replace use of snprintf with strfrom in libm tests

["Gabriel F. T. Gomes" <gftg at linux dot vnet dot ibm dot com>]

In order to support float128 tests, the calls to snprintf, which does
not support the type __float128, are replaced with calls to
strfrom{f,d,l}.

2016-11-08  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>

	* math/libm-test.inc (fmt_ftostr): New function.
	(print_float): Use fmt_ftostr instead of FTOSTR.
	(check_float_internal): Likewise.
	* math/test-double.h (FTOSTR): Define to strfromd.
	* math/test-float.h (FTOSTR): Define to strfromf.
	* math/test-ldouble.h (FTOSTR): Define to strfroml.
	(PRINTF_EXPR): Remove length modifier ('L') from format string.
	(PRINTF_XEXPR): Likewise.
	(PRINTF_NEXPR): Likewise.
---
 math/libm-test.inc  | 39 +++++++++++++++++++++++++++++++--------
 math/test-double.h  |  2 +-
 math/test-float.h   |  2 +-
 math/test-ldouble.h |  8 ++++----
 4 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/math/libm-test.inc b/math/libm-test.inc
index e973a3f..500bbed 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -355,6 +355,29 @@ static FLOAT max_valid_error;
 #define TYPE_DECIMAL_DIG __CONCATX (PREFIX, _DECIMAL_DIG)
 #define TYPE_HEX_DIG ((MANT_DIG + 6) / 4)
 
+/* The definitions TYPE_DECIMAL_DIG and TYPE_HEX_DIG are used to select the
+   precision (i.e.: number of fractional digits) to be printed.  When using
+   snprintf, it is possible to pass the precision in an argument with "%.*".
+   On the other hand, strfrom does not accept such format string, thus the
+   precision must be coded in the format string itself.  */
+static int
+fmt_ftostr (char *dest, size_t size, const char *format,
+	    const char *conversion, int precision, FLOAT value)
+{
+  char new_format[64];
+  char *ptr_format;
+  int ret;
+
+  /* Generate the format string.  */
+  ptr_format = stpcpy(new_format, format);
+  ret = sprintf(ptr_format, "%d", precision);
+  ptr_format += ret;
+  ptr_format = stpcpy(ptr_format, conversion);
+
+  /* Call the float to string conversion function, e.g.: strfromd.  */
+  return FTOSTR(dest, size, new_format, value);
+}
+
 /* Compare KEY (a string, with the name of a function) with ULP (a
    pointer to a struct ulp_data structure), returning a value less
    than, equal to or greater than zero for use in bsearch.  */
@@ -437,8 +460,8 @@ print_float (FLOAT f)
   else
     {
       char fstrn[FSTR_MAX], fstrx[FSTR_MAX];
-      FTOSTR (fstrn, FSTR_MAX, "% .*" PRINTF_EXPR, TYPE_DECIMAL_DIG - 1, f);
-      FTOSTR (fstrx, FSTR_MAX, "% .*" PRINTF_XEXPR, TYPE_HEX_DIG - 1, f);
+      fmt_ftostr (fstrn, FSTR_MAX, "%.", PRINTF_EXPR, TYPE_DECIMAL_DIG - 1, f);
+      fmt_ftostr (fstrx, FSTR_MAX, "%.", PRINTF_XEXPR, TYPE_HEX_DIG - 1, f);
       printf ("%s  %s\n", fstrn, fstrx);
     }
 }
@@ -884,12 +907,12 @@ check_float_internal (const char *test_name, FLOAT computed, FLOAT expected,
 	{
 	  char dstrn[FSTR_MAX], dstrx[FSTR_MAX];
 	  char ustrn[FSTR_MAX], mustrn[FSTR_MAX];
-	  FTOSTR (dstrn, FSTR_MAX, "% .*" PRINTF_EXPR,
-		  TYPE_DECIMAL_DIG - 1, diff);
-	  FTOSTR (dstrx, FSTR_MAX, "% .*" PRINTF_XEXPR,
-		  TYPE_HEX_DIG - 1, diff);
-	  FTOSTR (ustrn, FSTR_MAX, "% .4" PRINTF_NEXPR, ulps);
-	  FTOSTR (mustrn, FSTR_MAX, "% .4" PRINTF_NEXPR, max_ulp);
+	  fmt_ftostr (dstrn, FSTR_MAX, "%.", PRINTF_EXPR,
+		      TYPE_DECIMAL_DIG - 1, diff);
+	  fmt_ftostr (dstrx, FSTR_MAX, "%.", PRINTF_XEXPR,
+		      TYPE_HEX_DIG - 1, diff);
+	  FTOSTR (ustrn, FSTR_MAX, "%.4" PRINTF_NEXPR, ulps);
+	  FTOSTR (mustrn, FSTR_MAX, "%.4" PRINTF_NEXPR, max_ulp);
 	  printf (" difference: %s  %s\n", dstrn, dstrx);
 	  printf (" ulp       : %s\n", ustrn);
 	  printf (" max.ulp   : %s\n", mustrn);
diff --git a/math/test-double.h b/math/test-double.h
index e172b8f..f8a57f9 100644
--- a/math/test-double.h
+++ b/math/test-double.h
@@ -26,5 +26,5 @@
 #define LIT(x) (x)
 #define TYPE_STR "double"
 #define LITM(x) x
-#define FTOSTR snprintf
+#define FTOSTR strfromd
 #define snan_value_MACRO SNAN
diff --git a/math/test-float.h b/math/test-float.h
index ea096c8..6690966 100644
--- a/math/test-float.h
+++ b/math/test-float.h
@@ -27,5 +27,5 @@
 #define LIT(x) (x ## f)
 /* Use the double variants of macro constants.  */
 #define LITM(x) x
-#define FTOSTR snprintf
+#define FTOSTR strfromf
 #define snan_value_MACRO SNANF
diff --git a/math/test-ldouble.h b/math/test-ldouble.h
index 62c9eb8..53c6bb3 100644
--- a/math/test-ldouble.h
+++ b/math/test-ldouble.h
@@ -18,13 +18,13 @@
 
 #define FUNC(function) function##l
 #define FLOAT long double
-#define PRINTF_EXPR "Le"
-#define PRINTF_XEXPR "La"
-#define PRINTF_NEXPR "Lf"
+#define PRINTF_EXPR "e"
+#define PRINTF_XEXPR "a"
+#define PRINTF_NEXPR "f"
 #define BUILD_COMPLEX(real, imag) (CMPLXL ((real), (imag)))
 #define PREFIX LDBL
 #define TYPE_STR "ldouble"
 #define LIT(x) (x ## L)
 #define LITM(x) x ## l
-#define FTOSTR snprintf
+#define FTOSTR strfroml
 #define snan_value_MACRO SNANL
-- 
2.4.11