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https://sourceware.org/git/binutils-gdb.git
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403 lines
10 KiB
C
403 lines
10 KiB
C
/* Decimal floating point support for GDB.
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Copyright 2007, 2008, 2009 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "expression.h"
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#include "gdbtypes.h"
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#include "value.h"
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#include "dfp.h"
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/* The order of the following headers is important for making sure
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decNumber structure is large enough to hold decimal128 digits. */
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#include "dpd/decimal128.h"
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#include "dpd/decimal64.h"
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#include "dpd/decimal32.h"
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/* In GDB, we are using an array of gdb_byte to represent decimal values.
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They are stored in host byte order. This routine does the conversion if
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the target byte order is different. */
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static void
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match_endianness (const gdb_byte *from, int len, gdb_byte *to)
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{
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int i;
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#if WORDS_BIGENDIAN
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#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_LITTLE
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#else
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#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_BIG
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#endif
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if (gdbarch_byte_order (current_gdbarch) == OPPOSITE_BYTE_ORDER)
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for (i = 0; i < len; i++)
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to[i] = from[len - i - 1];
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else
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for (i = 0; i < len; i++)
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to[i] = from[i];
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return;
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}
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/* Helper function to get the appropriate libdecnumber context for each size
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of decimal float. */
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static void
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set_decnumber_context (decContext *ctx, int len)
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{
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switch (len)
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{
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case 4:
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decContextDefault (ctx, DEC_INIT_DECIMAL32);
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break;
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case 8:
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decContextDefault (ctx, DEC_INIT_DECIMAL64);
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break;
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case 16:
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decContextDefault (ctx, DEC_INIT_DECIMAL128);
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break;
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}
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ctx->traps = 0;
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}
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/* Check for errors signaled in the decimal context structure. */
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static void
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decimal_check_errors (decContext *ctx)
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{
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/* An error here could be a division by zero, an overflow, an underflow or
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an invalid operation (from the DEC_Errors constant in decContext.h).
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Since GDB doesn't complain about division by zero, overflow or underflow
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errors for binary floating, we won't complain about them for decimal
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floating either. */
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if (ctx->status & DEC_IEEE_854_Invalid_operation)
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{
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/* Leave only the error bits in the status flags. */
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ctx->status &= DEC_IEEE_854_Invalid_operation;
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error (_("Cannot perform operation: %s"), decContextStatusToString (ctx));
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}
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}
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/* Helper function to convert from libdecnumber's appropriate representation
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for computation to each size of decimal float. */
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static void
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decimal_from_number (const decNumber *from, gdb_byte *to, int len)
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{
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decContext set;
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set_decnumber_context (&set, len);
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switch (len)
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{
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case 4:
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decimal32FromNumber ((decimal32 *) to, from, &set);
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break;
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case 8:
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decimal64FromNumber ((decimal64 *) to, from, &set);
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break;
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case 16:
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decimal128FromNumber ((decimal128 *) to, from, &set);
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break;
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}
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}
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/* Helper function to convert each size of decimal float to libdecnumber's
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appropriate representation for computation. */
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static void
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decimal_to_number (const gdb_byte *from, int len, decNumber *to)
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{
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switch (len)
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{
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case 4:
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decimal32ToNumber ((decimal32 *) from, to);
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break;
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case 8:
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decimal64ToNumber ((decimal64 *) from, to);
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break;
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case 16:
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decimal128ToNumber ((decimal128 *) from, to);
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break;
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default:
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error (_("Unknown decimal floating point type.\n"));
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break;
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}
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}
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/* Convert decimal type to its string representation. LEN is the length
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of the decimal type, 4 bytes for decimal32, 8 bytes for decimal64 and
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16 bytes for decimal128. */
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void
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decimal_to_string (const gdb_byte *decbytes, int len, char *s)
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{
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gdb_byte dec[16];
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match_endianness (decbytes, len, dec);
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switch (len)
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{
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case 4:
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decimal32ToString ((decimal32 *) dec, s);
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break;
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case 8:
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decimal64ToString ((decimal64 *) dec, s);
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break;
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case 16:
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decimal128ToString ((decimal128 *) dec, s);
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break;
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default:
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error (_("Unknown decimal floating point type."));
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break;
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}
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}
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/* Convert the string form of a decimal value to its decimal representation.
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LEN is the length of the decimal type, 4 bytes for decimal32, 8 bytes for
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decimal64 and 16 bytes for decimal128. */
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int
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decimal_from_string (gdb_byte *decbytes, int len, const char *string)
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{
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decContext set;
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gdb_byte dec[16];
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set_decnumber_context (&set, len);
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switch (len)
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{
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case 4:
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decimal32FromString ((decimal32 *) dec, string, &set);
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break;
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case 8:
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decimal64FromString ((decimal64 *) dec, string, &set);
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break;
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case 16:
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decimal128FromString ((decimal128 *) dec, string, &set);
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break;
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default:
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error (_("Unknown decimal floating point type."));
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break;
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}
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match_endianness (dec, len, decbytes);
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/* Check for errors in the DFP operation. */
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decimal_check_errors (&set);
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return 1;
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}
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/* Converts a value of an integral type to a decimal float of
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specified LEN bytes. */
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void
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decimal_from_integral (struct value *from, gdb_byte *to, int len)
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{
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LONGEST l;
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gdb_byte dec[16];
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decNumber number;
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struct type *type;
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type = check_typedef (value_type (from));
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if (TYPE_LENGTH (type) > 4)
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/* libdecnumber can convert only 32-bit integers. */
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error (_("Conversion of large integer to a decimal floating type is not supported."));
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l = value_as_long (from);
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if (TYPE_UNSIGNED (type))
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decNumberFromUInt32 (&number, (unsigned int) l);
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else
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decNumberFromInt32 (&number, (int) l);
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decimal_from_number (&number, dec, len);
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match_endianness (dec, len, to);
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}
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/* Converts a value of a float type to a decimal float of
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specified LEN bytes.
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This is an ugly way to do the conversion, but libdecnumber does
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not offer a direct way to do it. */
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void
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decimal_from_floating (struct value *from, gdb_byte *to, int len)
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{
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char *buffer;
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buffer = xstrprintf ("%.30" DOUBLEST_PRINT_FORMAT, value_as_double (from));
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decimal_from_string (to, len, buffer);
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xfree (buffer);
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}
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/* Converts a decimal float of LEN bytes to a double value. */
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DOUBLEST
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decimal_to_doublest (const gdb_byte *from, int len)
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{
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char buffer[MAX_DECIMAL_STRING];
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/* This is an ugly way to do the conversion, but libdecnumber does
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not offer a direct way to do it. */
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decimal_to_string (from, len, buffer);
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return strtod (buffer, NULL);
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}
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/* Check if operands have the same size and convert them to the
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biggest of the two if necessary. */
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static int
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promote_decimal (gdb_byte *x, int len_x, gdb_byte *y, int len_y)
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{
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int len_result;
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decNumber number;
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if (len_x < len_y)
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{
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decimal_to_number (x, len_x, &number);
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decimal_from_number (&number, x, len_y);
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len_result = len_y;
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}
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else if (len_x > len_y)
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{
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decimal_to_number (y, len_y, &number);
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decimal_from_number (&number, y, len_x);
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len_result = len_x;
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}
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else
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len_result = len_x;
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return len_result;
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}
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/* Perform operation OP with operands X and Y and store value in RESULT.
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If LEN_X and LEN_Y are not equal, RESULT will have the size of the biggest
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of the two, and LEN_RESULT will be set accordingly. */
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void
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decimal_binop (enum exp_opcode op, const gdb_byte *x, int len_x,
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const gdb_byte *y, int len_y, gdb_byte *result, int *len_result)
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{
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decContext set;
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decNumber number1, number2, number3;
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gdb_byte dec1[16], dec2[16], dec3[16];
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match_endianness (x, len_x, dec1);
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match_endianness (y, len_y, dec2);
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*len_result = promote_decimal (dec1, len_x, dec2, len_y);
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/* Both operands are of size *len_result from now on. */
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decimal_to_number (dec1, *len_result, &number1);
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decimal_to_number (dec2, *len_result, &number2);
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set_decnumber_context (&set, *len_result);
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switch (op)
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{
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case BINOP_ADD:
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decNumberAdd (&number3, &number1, &number2, &set);
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break;
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case BINOP_SUB:
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decNumberSubtract (&number3, &number1, &number2, &set);
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break;
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case BINOP_MUL:
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decNumberMultiply (&number3, &number1, &number2, &set);
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break;
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case BINOP_DIV:
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decNumberDivide (&number3, &number1, &number2, &set);
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break;
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case BINOP_EXP:
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decNumberPower (&number3, &number1, &number2, &set);
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break;
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default:
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internal_error (__FILE__, __LINE__,
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_("Unknown decimal floating point operation."));
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break;
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}
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/* Check for errors in the DFP operation. */
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decimal_check_errors (&set);
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decimal_from_number (&number3, dec3, *len_result);
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match_endianness (dec3, *len_result, result);
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}
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/* Returns true if X (which is LEN bytes wide) is the number zero. */
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int
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decimal_is_zero (const gdb_byte *x, int len)
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{
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decNumber number;
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gdb_byte dec[16];
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match_endianness (x, len, dec);
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decimal_to_number (dec, len, &number);
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return decNumberIsZero (&number);
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}
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/* Compares two numbers numerically. If X is less than Y then the return value
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will be -1. If they are equal, then the return value will be 0. If X is
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greater than the Y then the return value will be 1. */
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int
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decimal_compare (const gdb_byte *x, int len_x, const gdb_byte *y, int len_y)
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{
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decNumber number1, number2, result;
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decContext set;
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gdb_byte dec1[16], dec2[16];
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int len_result;
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match_endianness (x, len_x, dec1);
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match_endianness (y, len_y, dec2);
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len_result = promote_decimal (dec1, len_x, dec2, len_y);
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decimal_to_number (dec1, len_result, &number1);
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decimal_to_number (dec2, len_result, &number2);
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set_decnumber_context (&set, len_result);
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decNumberCompare (&result, &number1, &number2, &set);
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/* Check for errors in the DFP operation. */
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decimal_check_errors (&set);
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if (decNumberIsNaN (&result))
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error (_("Comparison with an invalid number (NaN)."));
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else if (decNumberIsZero (&result))
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return 0;
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else if (decNumberIsNegative (&result))
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return -1;
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else
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return 1;
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}
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/* Convert a decimal value from a decimal type with LEN_FROM bytes to a
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decimal type with LEN_TO bytes. */
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void
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decimal_convert (const gdb_byte *from, int len_from, gdb_byte *to,
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int len_to)
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{
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decNumber number;
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gdb_byte dec[16];
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match_endianness (from, len_from, dec);
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decimal_to_number (dec, len_from, &number);
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decimal_from_number (&number, dec, len_to);
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match_endianness (dec, len_to, to);
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}
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