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/* Decimal floating point support for GDB.

   Copyright 2007, 2008 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, 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 (gdbarch_byte_order (current_gdbarch) == 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.\n"));

        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, char *s)

{

  gdb_byte dec[16];

  match_endianness (decbytes, len, 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, 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, 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)

{

  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, 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)

{

  char *buffer;

  int ret;

  ret = asprintf (&buffer, "%.30" DOUBLEST_PRINT_FORMAT,

                  value_as_double (from));

  if (ret < 0)

    error (_("Error in memory allocation for conversion to decimal float."));

  decimal_from_string (to, len, buffer);

  free (buffer);

}

/* Converts a decimal float of LEN bytes to a double value.  */

DOUBLEST

decimal_to_doublest (const gdb_byte *from, int len)

{

  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, buffer);

  return strtod (buffer, NULL);

}

/* Check if operands have the same size and convert them to the

   biggest of the two if necessary.  */

static int

promote_decimal (gdb_byte *x, int len_x, gdb_byte *y, int len_y)

{

  int len_result;

  decNumber number;

  if (len_x < len_y)

    {

      decimal_to_number (x, len_x, &number);

      decimal_from_number (&number, x, len_y);

      len_result = len_y;

    }

  else if (len_x > len_y)

    {

      decimal_to_number (y, len_y, &number);

      decimal_from_number (&number, y, len_x);

      len_result = len_x;

    }

  else

    len_result = len_x;

  return len_result;

}

/* Perform operation OP with operands X and Y and store value in RESULT.

   If LEN_X and LEN_Y are not equal, RESULT will have the size of the biggest

   of the two, and LEN_RESULT will be set accordingly.  */

void

decimal_binop (enum exp_opcode op, const gdb_byte *x, int len_x,

               const gdb_byte *y, int len_y, gdb_byte *result, int *len_result)

{

  decContext set;

  decNumber number1, number2, number3;

  gdb_byte dec1[16], dec2[16], dec3[16];

  match_endianness (x, len_x, dec1);

  match_endianness (y, len_y, dec2);

  *len_result = promote_decimal (dec1, len_x, dec2, len_y);

  /* Both operands are of size *len_result from now on.  */

  decimal_to_number (dec1, *len_result, &number1);

  decimal_to_number (dec2, *len_result, &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, result);

}

/* Returns true if X (which is LEN bytes wide) is the number zero.  */

int

decimal_is_zero (const gdb_byte *x, int len)

{

  decNumber number;

  gdb_byte dec[16];

  match_endianness (x, len, 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, const gdb_byte *y, int len_y)

{

  decNumber number1, number2, result;

  decContext set;

  gdb_byte dec1[16], dec2[16];

  int len_result;

  match_endianness (x, len_x, dec1);

  match_endianness (y, len_y, dec2);

  len_result = promote_decimal (dec1, len_x, dec2, len_y);

  decimal_to_number (dec1, len_result, &number1);

  decimal_to_number (dec2, len_result, &number2);

  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, gdb_byte *to,

                 int len_to)

{

  decNumber number;

  decimal_to_number (from, len_from, &number);

  decimal_from_number (&number, to, len_to);

}