Add __ldtoa(), a wrapper around gdtoa() to make it look like dtoa().

In support of this, add some MD macros to assist in converting long
doubles to the format expected by gdtoa().

Reviewed by:	silence on standards@

1 files changed, 97 insertions, 0 deletions

diff --git a/lib/libc/gdtoa/_ldtoa.c b/lib/libc/gdtoa/_ldtoa.c
new file mode 100644
index 0000000..c81c09b
--- /dev/null
+++ b/lib/libc/gdtoa/_ldtoa.c
@@ -0,0 +1,97 @@
+/*-
+ * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <float.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <math.h>
+#include <stdlib.h>
+#include "fpmath.h"
+#include "gdtoaimp.h"
+
+/*
+ * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
+ * except that the floating point argument is passed by reference.
+ * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
+ * However, a long double could have a valid exponent of 9999, so we
+ * use INT_MAX in ldtoa() instead.
+ */
+char *
+__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
+    char **rve)
+{
+	static FPI fpi = {
+		LDBL_MANT_DIG,			/* nbits */
+		LDBL_MIN_EXP - LDBL_MANT_DIG,	/* emin */
+		LDBL_MAX_EXP - LDBL_MANT_DIG,	/* emax */
+		FPI_Round_near,	       		/* rounding */
+#ifdef Sudden_Underflow	/* unused, but correct anyway */
+		1
+#else
+		0
+#endif
+	};
+	int be, kind;
+	char *ret;
+	union IEEEl2bits u;
+	uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
+
+	u.e = *ld;
+	*sign = u.bits.sign;
+	be = u.bits.exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
+	LDBL_TO_ARRAY32(u, bits);
+
+	switch (fpclassify(u.e)) {
+	case FP_NORMAL:
+		kind = STRTOG_Normal;
+#ifdef	LDBL_IMPLICIT_NBIT
+		bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
+#endif /* LDBL_IMPLICIT_NBIT */
+		break;
+	case FP_ZERO:
+		kind = STRTOG_Zero;
+		break;
+	case FP_SUBNORMAL:
+		kind = STRTOG_Denormal;
+		break;
+	case FP_INFINITE:
+		kind = STRTOG_Infinite;
+		break;
+	case FP_NAN:
+		kind = STRTOG_NaN;
+		break;
+	default:
+		abort();
+	}
+
+	ret = gdtoa(&fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
+	if (*decpt == -32768)
+		*decpt = INT_MAX;
+	return ret;
+}