/* MDB Tools - A library for reading MS Access database file

 * Copyright (C) 1998-1999  Brian Bruns

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include <stdio.h>

#include "mdbtools.h"

#define MAX_MONEY_PRECISION   20

#define MAX_NUMERIC_PRECISION 40

/* 

** these routines are copied from the freetds project which does something

** very similiar

*/

static int multiply_byte(unsigned char *product, int num, unsigned char *multiplier, size_t len);

static int do_carry(unsigned char *product, size_t len);

static char *array_to_string(unsigned char *array, size_t len, int unsigned scale, int neg);

/**

 * mdb_money_to_string

 * @mdb: Handle to open MDB database file

 * @start: Offset of the field within the current page

 *

 * Returns: the allocated string that has received the value.

 */

char *mdb_money_to_string(MdbHandle *mdb, int start)

{

  const int num_bytes=8, scale=4;

  int i;

  int neg=0;

  unsigned char multiplier[MAX_MONEY_PRECISION] = { 1 };

  unsigned char temp[MAX_MONEY_PRECISION];

  unsigned char product[MAX_MONEY_PRECISION] = { 0 };

  unsigned char bytes[num_bytes];

  memcpy(bytes, mdb->pg_buf + start, num_bytes);

  /* Perform two's complement for negative numbers */

  if (bytes[num_bytes-1] & 0x80) {

    neg = 1;

    for (i=0;i<num_bytes;i++) {

                       bytes[i] = ~bytes[i];

    }

    for (i=0; i<num_bytes; i++) {

                       bytes[i] ++;

                       if (bytes[i]!=0) break;

    }

  }

  for (i=0;i<num_bytes;i++) {

    /* product += multiplier * current byte */

               multiply_byte(product, bytes[i], multiplier, sizeof(multiplier));

    /* multiplier = multiplier * 256 */

               memcpy(temp, multiplier, sizeof(multiplier));

               memset(multiplier, 0, sizeof(multiplier));

    multiply_byte(multiplier, 256, temp, sizeof(multiplier));

  }

       return array_to_string(product, sizeof(product), scale, neg);

}

char *mdb_numeric_to_string(MdbHandle *mdb, int start, int scale, int prec) {

       const int num_bytes = 16;

       int i;

       int neg=0;

       unsigned char multiplier[MAX_NUMERIC_PRECISION] = { 1 };

       unsigned char temp[MAX_NUMERIC_PRECISION];

       unsigned char product[MAX_NUMERIC_PRECISION] = { 0 };

       unsigned char bytes[num_bytes];

       memcpy(bytes, mdb->pg_buf + start + 1, num_bytes);

       /* Negative bit is stored in first byte */

       if (mdb->pg_buf[start] & 0x80) neg = 1;

       for (i=0;i<num_bytes;i++) {

               /* product += multiplier * current byte */

               multiply_byte(product, bytes[12-4*(i/4)+i%4], multiplier, sizeof(multiplier));

               /* multiplier = multiplier * 256 */

               memcpy(temp, multiplier, sizeof(multiplier));

               memset(multiplier, 0, sizeof(multiplier));

               multiply_byte(multiplier, 256, temp, sizeof(multiplier));

       }

       return array_to_string(product, sizeof(product), prec, neg);

}

static int multiply_byte(unsigned char *product, int num, unsigned char *multiplier, size_t len)

{

  unsigned char number[3] = { num % 10, (num/10) % 10, (num/100) % 10 };

  unsigned int i, j;

  for (i=0;i<len;i++) {

    if (multiplier[i] == 0) continue;

    for (j=0;j<3 && i+j<len;j++) {

      if (number[j] == 0) continue;

      product[i+j] += multiplier[i]*number[j];

    }

    do_carry(product, len);

  }

  return 0;

}

static int do_carry(unsigned char *product, size_t len)

{

  unsigned int j;

       for (j=0;j<len-1;j++) {

    if (product[j]>9) {

      product[j+1]+=product[j]/10;

      product[j]%=10;

    }

  }

  if (product[j]>9) {

    product[j]%=10;

  }

  return 0;

}

static char *array_to_string(unsigned char *array, size_t len, unsigned int scale, int neg)

{

  char *s;

  unsigned int top, i, j=0;

       for (top=len;(top>0) && (top-1>scale) && !array[top-1];top--);

       /* allocate enough space for all digits + minus sign + decimal point + trailing NULL byte */

       s = g_malloc(len+3);

  if (neg)

    s[j++] = '-';

  if (top == 0) {

    s[j++] = '0';

  } else {

    for (i=top; i>0; i--) {

      if (i == scale) s[j++]='.';

      s[j++]=array[i-1]+'0';

    }

  }

  s[j]='\0';

  return s;

}