binutils-gdb/gdb/dfp.c

385 lines
10 KiB
C

/* Decimal floating point support for GDB.
Copyright (C) 2007-2017 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "expression.h"
#include "gdbtypes.h"
#include "value.h"
#include "dfp.h"
/* The order of the following headers is important for making sure
decNumber structure is large enough to hold decimal128 digits. */
#include "dpd/decimal128.h"
#include "dpd/decimal64.h"
#include "dpd/decimal32.h"
/* In GDB, we are using an array of gdb_byte to represent decimal values.
They are stored in host byte order. This routine does the conversion if
the target byte order is different. */
static void
match_endianness (const gdb_byte *from, int len, enum bfd_endian byte_order,
gdb_byte *to)
{
int i;
#if WORDS_BIGENDIAN
#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_LITTLE
#else
#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_BIG
#endif
if (byte_order == OPPOSITE_BYTE_ORDER)
for (i = 0; i < len; i++)
to[i] = from[len - i - 1];
else
for (i = 0; i < len; i++)
to[i] = from[i];
return;
}
/* Helper function to get the appropriate libdecnumber context for each size
of decimal float. */
static void
set_decnumber_context (decContext *ctx, int len)
{
switch (len)
{
case 4:
decContextDefault (ctx, DEC_INIT_DECIMAL32);
break;
case 8:
decContextDefault (ctx, DEC_INIT_DECIMAL64);
break;
case 16:
decContextDefault (ctx, DEC_INIT_DECIMAL128);
break;
}
ctx->traps = 0;
}
/* Check for errors signaled in the decimal context structure. */
static void
decimal_check_errors (decContext *ctx)
{
/* An error here could be a division by zero, an overflow, an underflow or
an invalid operation (from the DEC_Errors constant in decContext.h).
Since GDB doesn't complain about division by zero, overflow or underflow
errors for binary floating, we won't complain about them for decimal
floating either. */
if (ctx->status & DEC_IEEE_854_Invalid_operation)
{
/* Leave only the error bits in the status flags. */
ctx->status &= DEC_IEEE_854_Invalid_operation;
error (_("Cannot perform operation: %s"),
decContextStatusToString (ctx));
}
}
/* Helper function to convert from libdecnumber's appropriate representation
for computation to each size of decimal float. */
static void
decimal_from_number (const decNumber *from, gdb_byte *to, int len)
{
decContext set;
set_decnumber_context (&set, len);
switch (len)
{
case 4:
decimal32FromNumber ((decimal32 *) to, from, &set);
break;
case 8:
decimal64FromNumber ((decimal64 *) to, from, &set);
break;
case 16:
decimal128FromNumber ((decimal128 *) to, from, &set);
break;
}
}
/* Helper function to convert each size of decimal float to libdecnumber's
appropriate representation for computation. */
static void
decimal_to_number (const gdb_byte *from, int len, decNumber *to)
{
switch (len)
{
case 4:
decimal32ToNumber ((decimal32 *) from, to);
break;
case 8:
decimal64ToNumber ((decimal64 *) from, to);
break;
case 16:
decimal128ToNumber ((decimal128 *) from, to);
break;
default:
error (_("Unknown decimal floating point type."));
break;
}
}
/* Convert decimal type to its string representation. LEN is the length
of the decimal type, 4 bytes for decimal32, 8 bytes for decimal64 and
16 bytes for decimal128. */
void
decimal_to_string (const gdb_byte *decbytes, int len,
enum bfd_endian byte_order, char *s)
{
gdb_byte dec[16];
match_endianness (decbytes, len, byte_order, dec);
switch (len)
{
case 4:
decimal32ToString ((decimal32 *) dec, s);
break;
case 8:
decimal64ToString ((decimal64 *) dec, s);
break;
case 16:
decimal128ToString ((decimal128 *) dec, s);
break;
default:
error (_("Unknown decimal floating point type."));
break;
}
}
/* Convert the string form of a decimal value to its decimal representation.
LEN is the length of the decimal type, 4 bytes for decimal32, 8 bytes for
decimal64 and 16 bytes for decimal128. */
int
decimal_from_string (gdb_byte *decbytes, int len, enum bfd_endian byte_order,
const char *string)
{
decContext set;
gdb_byte dec[16];
set_decnumber_context (&set, len);
switch (len)
{
case 4:
decimal32FromString ((decimal32 *) dec, string, &set);
break;
case 8:
decimal64FromString ((decimal64 *) dec, string, &set);
break;
case 16:
decimal128FromString ((decimal128 *) dec, string, &set);
break;
default:
error (_("Unknown decimal floating point type."));
break;
}
match_endianness (dec, len, byte_order, decbytes);
/* Check for errors in the DFP operation. */
decimal_check_errors (&set);
return 1;
}
/* Converts a value of an integral type to a decimal float of
specified LEN bytes. */
void
decimal_from_integral (struct value *from,
gdb_byte *to, int len, enum bfd_endian byte_order)
{
LONGEST l;
gdb_byte dec[16];
decNumber number;
struct type *type;
type = check_typedef (value_type (from));
if (TYPE_LENGTH (type) > 4)
/* libdecnumber can convert only 32-bit integers. */
error (_("Conversion of large integer to a "
"decimal floating type is not supported."));
l = value_as_long (from);
if (TYPE_UNSIGNED (type))
decNumberFromUInt32 (&number, (unsigned int) l);
else
decNumberFromInt32 (&number, (int) l);
decimal_from_number (&number, dec, len);
match_endianness (dec, len, byte_order, to);
}
/* Converts a value of a float type to a decimal float of
specified LEN bytes.
This is an ugly way to do the conversion, but libdecnumber does
not offer a direct way to do it. */
void
decimal_from_floating (struct value *from,
gdb_byte *to, int len, enum bfd_endian byte_order)
{
char *buffer;
buffer = xstrprintf ("%.30" DOUBLEST_PRINT_FORMAT, value_as_double (from));
decimal_from_string (to, len, byte_order, buffer);
xfree (buffer);
}
/* Converts a decimal float of LEN bytes to a double value. */
DOUBLEST
decimal_to_doublest (const gdb_byte *from, int len, enum bfd_endian byte_order)
{
char buffer[MAX_DECIMAL_STRING];
/* This is an ugly way to do the conversion, but libdecnumber does
not offer a direct way to do it. */
decimal_to_string (from, len, byte_order, buffer);
return strtod (buffer, NULL);
}
/* Perform operation OP with operands X and Y with sizes LEN_X and LEN_Y
and byte orders BYTE_ORDER_X and BYTE_ORDER_Y, and store value in
RESULT with size LEN_RESULT and byte order BYTE_ORDER_RESULT. */
void
decimal_binop (enum exp_opcode op,
const gdb_byte *x, int len_x, enum bfd_endian byte_order_x,
const gdb_byte *y, int len_y, enum bfd_endian byte_order_y,
gdb_byte *result, int len_result,
enum bfd_endian byte_order_result)
{
decContext set;
decNumber number1, number2, number3;
gdb_byte dec1[16], dec2[16], dec3[16];
match_endianness (x, len_x, byte_order_x, dec1);
match_endianness (y, len_y, byte_order_y, dec2);
decimal_to_number (dec1, len_x, &number1);
decimal_to_number (dec2, len_y, &number2);
set_decnumber_context (&set, len_result);
switch (op)
{
case BINOP_ADD:
decNumberAdd (&number3, &number1, &number2, &set);
break;
case BINOP_SUB:
decNumberSubtract (&number3, &number1, &number2, &set);
break;
case BINOP_MUL:
decNumberMultiply (&number3, &number1, &number2, &set);
break;
case BINOP_DIV:
decNumberDivide (&number3, &number1, &number2, &set);
break;
case BINOP_EXP:
decNumberPower (&number3, &number1, &number2, &set);
break;
default:
internal_error (__FILE__, __LINE__,
_("Unknown decimal floating point operation."));
break;
}
/* Check for errors in the DFP operation. */
decimal_check_errors (&set);
decimal_from_number (&number3, dec3, len_result);
match_endianness (dec3, len_result, byte_order_result, result);
}
/* Returns true if X (which is LEN bytes wide) is the number zero. */
int
decimal_is_zero (const gdb_byte *x, int len, enum bfd_endian byte_order)
{
decNumber number;
gdb_byte dec[16];
match_endianness (x, len, byte_order, dec);
decimal_to_number (dec, len, &number);
return decNumberIsZero (&number);
}
/* Compares two numbers numerically. If X is less than Y then the return value
will be -1. If they are equal, then the return value will be 0. If X is
greater than the Y then the return value will be 1. */
int
decimal_compare (const gdb_byte *x, int len_x, enum bfd_endian byte_order_x,
const gdb_byte *y, int len_y, enum bfd_endian byte_order_y)
{
decNumber number1, number2, result;
decContext set;
gdb_byte dec1[16], dec2[16];
int len_result;
match_endianness (x, len_x, byte_order_x, dec1);
match_endianness (y, len_y, byte_order_y, dec2);
decimal_to_number (dec1, len_x, &number1);
decimal_to_number (dec2, len_y, &number2);
/* Perform the comparison in the larger of the two sizes. */
len_result = len_x > len_y ? len_x : len_y;
set_decnumber_context (&set, len_result);
decNumberCompare (&result, &number1, &number2, &set);
/* Check for errors in the DFP operation. */
decimal_check_errors (&set);
if (decNumberIsNaN (&result))
error (_("Comparison with an invalid number (NaN)."));
else if (decNumberIsZero (&result))
return 0;
else if (decNumberIsNegative (&result))
return -1;
else
return 1;
}
/* Convert a decimal value from a decimal type with LEN_FROM bytes to a
decimal type with LEN_TO bytes. */
void
decimal_convert (const gdb_byte *from, int len_from,
enum bfd_endian byte_order_from, gdb_byte *to, int len_to,
enum bfd_endian byte_order_to)
{
decNumber number;
gdb_byte dec[16];
match_endianness (from, len_from, byte_order_from, dec);
decimal_to_number (dec, len_from, &number);
decimal_from_number (&number, dec, len_to);
match_endianness (dec, len_to, byte_order_to, to);
}