/* Floating point routines for GDB, the GNU debugger.
- Copyright 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
- 1997, 1998, 1999, 2000, 2001
- Free Software Foundation, Inc.
+
+ Copyright 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
+ 1996, 1997, 1998, 1999, 2000, 2001, 2003 Free Software Foundation,
+ Inc.
This file is part of GDB.
special_exponent = exponent == 0 || exponent == fmt->exp_nan;
-/* Don't bias NaNs. Use minimum exponent for denorms. For simplicity,
- we don't check for zero as the exponent doesn't matter. */
+ /* Don't bias NaNs. Use minimum exponent for denorms. For simplicity,
+ we don't check for zero as the exponent doesn't matter. Note the cast
+ to int; exp_bias is unsigned, so it's important to make sure the
+ operation is done in signed arithmetic. */
if (!special_exponent)
exponent -= fmt->exp_bias;
else if (exponent == 0)
{
mant_long <<= 1;
mant_long &= 0xffffffffL;
- mant_bits -= 1;
+ /* If we are processing the top 32 mantissa bits of a doublest
+ so as to convert to a float value with implied integer bit,
+ we will only be putting 31 of those 32 bits into the
+ final value due to the discarding of the top bit. In the
+ case of a small float value where the number of mantissa
+ bits is less than 32, discarding the top bit does not alter
+ the number of bits we will be adding to the result. */
+ if (mant_bits == 32)
+ mant_bits -= 1;
}
if (mant_bits < 32)
floatformat_is_negative (const struct floatformat *fmt, char *val)
{
unsigned char *uval = (unsigned char *) val;
-
+ gdb_assert (fmt != NULL);
return get_field (uval, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1);
}
unsigned int mant_bits, mant_off;
int mant_bits_left;
+ gdb_assert (fmt != NULL);
+
if (! fmt->exp_nan)
return 0;
char buf[9];
/* Make sure we have enough room to store the mantissa. */
+ gdb_assert (fmt != NULL);
gdb_assert (sizeof res > ((fmt->man_len + 7) / 8) * 2);
mant_off = fmt->man_start;
return res;
}
-
\f
/* Convert TO/FROM target to the hosts DOUBLEST floating-point format.
}
\f
-/* Extract/store a target floating-point number from byte-stream at
- ADDR to/from a DOUBLEST. The LEN is used to select between the
- pre-defined target type FLOAT, DOUBLE or LONG_DOUBLE. These
- functions are used when extract/store typed floating() find that
- the ``struct type'' did not include a FLOATFORMAT (e.g. some symbol
- table readers and XXX-language support modules). */
+/* Return a floating-point format for a floating-point variable of
+ length LEN. Return NULL, if no suitable floating-point format
+ could be found.
-DOUBLEST
-extract_floating (const void *addr, int len)
+ We need this functionality since information about the
+ floating-point format of a type is not always available to GDB; the
+ debug information typically only tells us the size of a
+ floating-point type.
+
+ FIXME: kettenis/2001-10-28: In many places, particularly in
+ target-dependent code, the format of floating-point types is known,
+ but not passed on by GDB. This should be fixed. */
+
+static const struct floatformat *
+floatformat_from_length (int len)
{
- DOUBLEST dretval;
if (len * TARGET_CHAR_BIT == TARGET_FLOAT_BIT)
- {
- floatformat_to_doublest (TARGET_FLOAT_FORMAT, addr, &dretval);
- }
+ return TARGET_FLOAT_FORMAT;
else if (len * TARGET_CHAR_BIT == TARGET_DOUBLE_BIT)
- {
- floatformat_to_doublest (TARGET_DOUBLE_FORMAT, addr, &dretval);
- }
+ return TARGET_DOUBLE_FORMAT;
else if (len * TARGET_CHAR_BIT == TARGET_LONG_DOUBLE_BIT)
- {
- floatformat_to_doublest (TARGET_LONG_DOUBLE_FORMAT, addr, &dretval);
- }
+ return TARGET_LONG_DOUBLE_FORMAT;
+ /* On i386 the 'long double' type takes 96 bits,
+ while the real number of used bits is only 80,
+ both in processor and in memory.
+ The code below accepts the real bit size. */
+ else if ((TARGET_LONG_DOUBLE_FORMAT != NULL)
+ && (len * TARGET_CHAR_BIT ==
+ TARGET_LONG_DOUBLE_FORMAT->totalsize))
+ return TARGET_LONG_DOUBLE_FORMAT;
+
+ return NULL;
+}
+
+const struct floatformat *
+floatformat_from_type (const struct type *type)
+{
+ gdb_assert (TYPE_CODE (type) == TYPE_CODE_FLT);
+ if (TYPE_FLOATFORMAT (type) != NULL)
+ return TYPE_FLOATFORMAT (type);
else
- {
- error ("Can't deal with a floating point number of %d bytes.", len);
- }
- return dretval;
+ return floatformat_from_length (TYPE_LENGTH (type));
}
-void
-store_floating (void *addr, int len, DOUBLEST val)
+/* If the host doesn't define NAN, use zero instead. */
+#ifndef NAN
+#define NAN 0.0
+#endif
+
+/* Extract a floating-point number of length LEN from a target-order
+ byte-stream at ADDR. Returns the value as type DOUBLEST. */
+
+static DOUBLEST
+extract_floating_by_length (const void *addr, int len)
{
- if (len * TARGET_CHAR_BIT == TARGET_FLOAT_BIT)
- {
- floatformat_from_doublest (TARGET_FLOAT_FORMAT, &val, addr);
- }
- else if (len * TARGET_CHAR_BIT == TARGET_DOUBLE_BIT)
- {
- floatformat_from_doublest (TARGET_DOUBLE_FORMAT, &val, addr);
- }
- else if (len * TARGET_CHAR_BIT == TARGET_LONG_DOUBLE_BIT)
+ const struct floatformat *fmt = floatformat_from_length (len);
+ DOUBLEST val;
+
+ if (fmt == NULL)
{
- floatformat_from_doublest (TARGET_LONG_DOUBLE_FORMAT, &val, addr);
+ warning ("Can't extract a floating-point number of %d bytes.", len);
+ return NAN;
}
- else
+
+ floatformat_to_doublest (fmt, addr, &val);
+ return val;
+}
+
+DOUBLEST
+deprecated_extract_floating (const void *addr, int len)
+{
+ return extract_floating_by_length (addr, len);
+}
+
+/* Store VAL as a floating-point number of length LEN to a
+ target-order byte-stream at ADDR. */
+
+static void
+store_floating_by_length (void *addr, int len, DOUBLEST val)
+{
+ const struct floatformat *fmt = floatformat_from_length (len);
+
+ if (fmt == NULL)
{
- error ("Can't deal with a floating point number of %d bytes.", len);
+ warning ("Can't store a floating-point number of %d bytes.", len);
+ memset (addr, 0, len);
+ return;
}
+
+ floatformat_from_doublest (fmt, &val, addr);
+}
+
+void
+deprecated_store_floating (void *addr, int len, DOUBLEST val)
+{
+ store_floating_by_length (addr, len, val);
}
-/* Extract/store a floating-point number of format TYPE from a
- target-ordered byte-stream at ADDR to/from an internal DOUBLEST
- accroding to its TYPE_FORMAT(). When GDB reads in debug
- information, it is sometimes only provided with the type name, its
- length and the fact that it is a float (TYPE_FORMAT() is not set).
- For such types, the old extract/store floating() functions are
- used. */
+/* Extract a floating-point number of type TYPE from a target-order
+ byte-stream at ADDR. Returns the value as type DOUBLEST. */
DOUBLEST
extract_typed_floating (const void *addr, const struct type *type)
{
DOUBLEST retval;
+
gdb_assert (TYPE_CODE (type) == TYPE_CODE_FLT);
+
if (TYPE_FLOATFORMAT (type) == NULL)
- retval = extract_floating (addr, TYPE_LENGTH (type));
- else
- floatformat_to_doublest (TYPE_FLOATFORMAT (type), addr, &retval);
+ /* Not all code remembers to set the FLOATFORMAT (language
+ specific code? stabs?) so handle that here as a special case. */
+ return extract_floating_by_length (addr, TYPE_LENGTH (type));
+
+ floatformat_to_doublest (TYPE_FLOATFORMAT (type), addr, &retval);
return retval;
}
+/* Store VAL as a floating-point number of type TYPE to a target-order
+ byte-stream at ADDR. */
+
void
store_typed_floating (void *addr, const struct type *type, DOUBLEST val)
{
gdb_assert (TYPE_CODE (type) == TYPE_CODE_FLT);
+
+ /* FIXME: kettenis/2001-10-28: It is debatable whether we should
+ zero out any remaining bytes in the target buffer when TYPE is
+ longer than the actual underlying floating-point format. Perhaps
+ we should store a fixed bitpattern in those remaining bytes,
+ instead of zero, or perhaps we shouldn't touch those remaining
+ bytes at all.
+
+ NOTE: cagney/2001-10-28: With the way things currently work, it
+ isn't a good idea to leave the end bits undefined. This is
+ because GDB writes out the entire sizeof(<floating>) bits of the
+ floating-point type even though the value might only be stored
+ in, and the target processor may only refer to, the first N <
+ TYPE_LENGTH (type) bits. If the end of the buffer wasn't
+ initialized, GDB would write undefined data to the target. An
+ errant program, refering to that undefined data, would then
+ become non-deterministic.
+
+ See also the function convert_typed_floating below. */
memset (addr, 0, TYPE_LENGTH (type));
+
if (TYPE_FLOATFORMAT (type) == NULL)
- store_floating (addr, TYPE_LENGTH (type), val);
+ /* Not all code remembers to set the FLOATFORMAT (language
+ specific code? stabs?) so handle that here as a special case. */
+ store_floating_by_length (addr, TYPE_LENGTH (type), val);
else
floatformat_from_doublest (TYPE_FLOATFORMAT (type), &val, addr);
}
+
+/* Convert a floating-point number of type FROM_TYPE from a
+ target-order byte-stream at FROM to a floating-point number of type
+ TO_TYPE, and store it to a target-order byte-stream at TO. */
+
+void
+convert_typed_floating (const void *from, const struct type *from_type,
+ void *to, const struct type *to_type)
+{
+ const struct floatformat *from_fmt = floatformat_from_type (from_type);
+ const struct floatformat *to_fmt = floatformat_from_type (to_type);
+
+ gdb_assert (TYPE_CODE (from_type) == TYPE_CODE_FLT);
+ gdb_assert (TYPE_CODE (to_type) == TYPE_CODE_FLT);
+
+ if (from_fmt == NULL || to_fmt == NULL)
+ {
+ /* If we don't know the floating-point format of FROM_TYPE or
+ TO_TYPE, there's not much we can do. We might make the
+ assumption that if the length of FROM_TYPE and TO_TYPE match,
+ their floating-point format would match too, but that
+ assumption might be wrong on targets that support
+ floating-point types that only differ in endianness for
+ example. So we warn instead, and zero out the target buffer. */
+ warning ("Can't convert floating-point number to desired type.");
+ memset (to, 0, TYPE_LENGTH (to_type));
+ }
+ else if (from_fmt == to_fmt)
+ {
+ /* We're in business. The floating-point format of FROM_TYPE
+ and TO_TYPE match. However, even though the floating-point
+ format matches, the length of the type might still be
+ different. Make sure we don't overrun any buffers. See
+ comment in store_typed_floating for a discussion about
+ zeroing out remaining bytes in the target buffer. */
+ memset (to, 0, TYPE_LENGTH (to_type));
+ memcpy (to, from, min (TYPE_LENGTH (from_type), TYPE_LENGTH (to_type)));
+ }
+ else
+ {
+ /* The floating-point types don't match. The best we can do
+ (aport from simulating the target FPU) is converting to the
+ widest floating-point type supported by the host, and then
+ again to the desired type. */
+ DOUBLEST d;
+
+ floatformat_to_doublest (from_fmt, from, &d);
+ floatformat_from_doublest (to_fmt, &d, to);
+ }
+}
projects / deliverable / binutils-gdb.git / blobdiff