Target FP: Add conversion routines to target-float.{c,h}

This patch adds the following conversion routines:
 - target_float_to_longest
 - target_float_from_longest
 - target_float_from_ulongest
 - target_float_convert
which call the equivalent decimal_ routines to handle decimal FP,
and call helper routines that currently still go via DOUBLEST to
handle binary FP.

The target_float_convert routine not only handles BFP<->BFP and
DFP<->DFP conversions, but also BFP<->DFP, which are implemented
by converting to a string and back.

These helpers are used in particular to implement conversion
from and to FP in value_cast, without going through DOUBLEST there.
In order to implement this for the FP<-integer case, the
pack_long / pack_unsigned_long routines are extended to support
floating-point values as output (thereby allowing use of
value_from_[u]longest with a floating-point target type).

This latter change also allows simplification of value_one.

gdb/ChangeLog:
2017-11-06  Ulrich Weigand  <uweigand@de.ibm.com>

	* target-float.c (floatformat_to_longest): New function.
	(floatformat_from_longest, floatformat_from_ulongest): Likewise.
	(floatformat_convert): Likewise.
	(target_float_to_longest): Likewise.
	(target_float_from_longest, target_float_from_ulongest): Likewise.
	(target_float_convert): Likewise.
	* target-float.h (target_float_to_longest): Add prototype.
	(target_float_from_longest, target_float_from_ulongest): Likewise.
	(target_float_convert): Likewise.

	* value.c (unpack_long): Use target_float_to_longest.
	(pack_long): Allow FP types.  Use target_float_from_longest.
	(pack_unsigned_long): Likewise using target_float_from_ulongest.
	* valops.c: Include "target-float.h".  Do not include "dfp.h".
	(value_cast): Handle conversions to FP using target_float_convert,
	value_from_ulongest, and value_from_longest.
	(value_one): Use value_from_longest for FP types as well.

1 files changed, 12 insertions, 0 deletions

diff --git a/gdb/target-float.h b/gdb/target-float.h
index 317e98e..9ea1812 100644
--- a/gdb/target-float.h
+++ b/gdb/target-float.h
@@ -32,4 +32,16 @@ extern bool target_float_from_string (gdb_byte *addr,
 				      const struct type *type,
 				      const std::string &string);
 
+extern LONGEST target_float_to_longest (const gdb_byte *addr,
+					const struct type *type);
+extern void target_float_from_longest (gdb_byte *addr,
+				       const struct type *type,
+				       LONGEST val);
+extern void target_float_from_ulongest (gdb_byte *addr,
+					const struct type *type,
+					ULONGEST val);
+extern void target_float_convert (const gdb_byte *from,
+				  const struct type *from_type,
+				  gdb_byte *to, const struct type *to_type);
+
 #endif