Function decimalMulFunc

lib-src/sqlite/shell.c:5043–5095

** SQL Function: decimal_mul(X, Y) ** ** Return the product of X and Y. ** ** All significant digits after the decimal point are retained. ** Trailing zeros after the decimal point are omitted as long as ** the number of digits after the decimal point is no less than ** either the number of digits in either input. */

** either the number of digits in either input.
*/
static void decimalMulFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  Decimal *pA = decimal_new(context, argv[0], 0, 0);
  Decimal *pB = decimal_new(context, argv[1], 0, 0);
  signed char *acc = 0;
  int i, j, k;
  int minFrac;
  UNUSED_PARAMETER(argc);
  if( pA==0 || pA->oom || pA->isNull
   || pB==0 || pB->oom || pB->isNull 
  ){
    goto mul_end;
  }
  acc = sqlite3_malloc64( pA->nDigit + pB->nDigit + 2 );
  if( acc==0 ){
    sqlite3_result_error_nomem(context);
    goto mul_end;
  }
  memset(acc, 0, pA->nDigit + pB->nDigit + 2);
  minFrac = pA->nFrac;
  if( pB->nFrac<minFrac ) minFrac = pB->nFrac;
  for(i=pA->nDigit-1; i>=0; i--){
    signed char f = pA->a[i];
    int carry = 0, x;
    for(j=pB->nDigit-1, k=i+j+3; j>=0; j--, k--){
      x = acc[k] + f*pB->a[j] + carry;
      acc[k] = x%10;
      carry = x/10;
    }
    x = acc[k] + carry;
    acc[k] = x%10;
    acc[k-1] += x/10;
  }
  sqlite3_free(pA->a);
  pA->a = acc;
  acc = 0;
  pA->nDigit += pB->nDigit + 2;
  pA->nFrac += pB->nFrac;
  pA->sign ^= pB->sign;
  while( pA->nFrac>minFrac && pA->a[pA->nDigit-1]==0 ){
    pA->nFrac--;
    pA->nDigit--;
  }
  decimal_result(context, pA);

mul_end:
  sqlite3_free(acc);
  decimal_free(pA);
  decimal_free(pB);
}

#ifdef _WIN32