Commit fe3672d2 authored by unknown's avatar unknown
Browse files

Alternative decimal2double implementation using an algorithm 

more similar to my_strtod() (and maybe even a bit faster due
to less floating point divisions).

This should at least partially fix Bug #23260 for DECIMALs
with a moderate number of total digits.
parent f8920dd5

strings/decimal.c

+26 −8
Original line number Diff line number Diff line
@@ -138,6 +138,12 @@ static const dec1 frac_max[DIG_PER_DEC1-1]={ 
  900000000, 990000000, 999000000,

  999900000, 999990000, 999999000,

  999999900, 999999990 };

static double scaler10[]= {

  1.0, 1e10, 1e20, 1e30, 1e40, 1e50, 1e60, 1e70, 1e80, 1e90

};

static double scaler1[]= {

  1.0, 10.0, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9

};



#ifdef HAVE_purify

#define sanity(d) DBUG_ASSERT((d)->len > 0)
@@ -946,15 +952,27 @@ internal_str2dec(const char *from, decimal_t *to, char **end, my_bool fixed) 


int decimal2double(decimal_t *from, double *to)

{

  double x=0, t=DIG_BASE;

  int intg, frac;

  double result= 0.0;

  int i, exp= 0;

  dec1 *buf= from->buf;



  for (intg=from->intg; intg > 0; intg-=DIG_PER_DEC1)

    x=x*DIG_BASE + *buf++;

  for (frac=from->frac; frac > 0; frac-=DIG_PER_DEC1, t*=DIG_BASE)

    x+=*buf++/t;

  *to=from->sign ? -x : x;

  for (i= from->intg; i > 0;  i-= DIG_PER_DEC1)

    result= result * DIG_BASE + *buf++;



  for (i= from->frac; i > 0; i-= DIG_PER_DEC1) {

    result= result * DIG_BASE + *buf++;

    exp+= DIG_PER_DEC1;

  }



  DBUG_PRINT("info", ("interm.: %f %d %f", result, exp,

             scaler10[exp / 10] * scaler1[exp % 10]));



  result/= scaler10[exp / 10] * scaler1[exp % 10];



  *to= from->sign ? -result : result;



  DBUG_PRINT("info", ("result: %f (%lx)", *to, *to));



  return E_DEC_OK;

}