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MySQL 5.1: mysql/src/5.1-dbg/libmysql_r/strtod.c File Reference

mysql/src/5.1-dbg/libmysql_r/strtod.c File Reference

#include "my_base.h"
#include "m_ctype.h"

Include dependency graph for strtod.c:


Defines
#define	MAX_DBL_EXP 308
#define	MAX_RESULT_FOR_MAX_EXP 1.79769313486232
Functions
double	my_strtod (const char str, char end_ptr, int error)
double	my_atof (const char *nptr)
Variables
static double	scaler10 []
static double	scaler1 []

Define Documentation

#define MAX_DBL_EXP 308

Definition at line 32 of file strtod.c.

#define MAX_RESULT_FOR_MAX_EXP 1.79769313486232

Definition at line 33 of file strtod.c.

Function Documentation

double my_atof ( const char * nptr )

Definition at line 198 of file strtod.c.

References error, and my_strtod().

00199 {
00200   int error;
00201   const char *end= nptr+65535;                  /* Should be enough */
00202   return (my_strtod(nptr, (char**) &end, &error));
00203 }

Here is the call graph for this function:

double my_strtod	(	const char *	str,
		char **	end_ptr,
		int *	error
	)

Definition at line 56 of file strtod.c.

References DBL_MAX, EOVERFLOW, isinf, MAX_DBL_EXP, MAX_RESULT_FOR_MAX_EXP, my_charset_latin1, my_isdigit, my_isspace, scaler1, and scaler10.

00057 {
00058   double result= 0.0;
00059   uint negative= 0, ndigits, dec_digits= 0, neg_exp= 0;
00060   int exp= 0, digits_after_dec_point= 0;
00061   const char *old_str, *end= *end_ptr, *start_of_number;
00062   char next_char;
00063   my_bool overflow=0;
00064 
00065   *error= 0;
00066   if (str >= end)
00067     goto done;
00068 
00069   while (my_isspace(&my_charset_latin1, *str))
00070   {
00071     if (++str == end)
00072       goto done;
00073   }
00074 
00075   start_of_number= str;
00076   if ((negative= (*str == '-')) || *str=='+')
00077   {
00078     if (++str == end)
00079       goto done;                                /* Could be changed to error */
00080   }
00081 
00082   /* Skip pre-zero for easier calculation of overflows */
00083   while (*str == '0')
00084   {
00085     if (++str == end)
00086       goto done;
00087     start_of_number= 0;                         /* Found digit */
00088   }
00089 
00090   old_str= str;
00091   while ((next_char= *str) >= '0' && next_char <= '9')
00092   {
00093     result= result*10.0 + (next_char - '0');
00094     if (++str == end)
00095     {
00096       next_char= 0;                             /* Found end of string */
00097       break;
00098     }
00099     start_of_number= 0;                         /* Found digit */
00100   }
00101   ndigits= (uint) (str-old_str);
00102 
00103   if (next_char == '.' && str < end-1)
00104   {
00105     /*
00106       Continue to add numbers after decimal point to the result, as if there
00107       was no decimal point. We will later (in the exponent handling) shift
00108       the number down with the required number of fractions.  We do it this
00109       way to be able to get maximum precision for numbers like 123.45E+02,
00110       which are normal for some ODBC applications.
00111     */
00112     old_str= ++str;
00113     while (my_isdigit(&my_charset_latin1, (next_char= *str)))
00114     {
00115       result= result*10.0 + (next_char - '0');
00116       digits_after_dec_point++;
00117       if (++str == end)
00118       {
00119         next_char= 0;
00120         break;
00121       }
00122     }
00123     /* If we found just '+.' or '.' then point at first character */
00124     if (!(dec_digits= (uint) (str-old_str)) && start_of_number)
00125       str= start_of_number;                     /* Point at '+' or '.' */
00126   }
00127   if ((next_char == 'e' || next_char == 'E') &&
00128       dec_digits + ndigits != 0 && str < end-1)
00129   {
00130     const char *old_str= str++;
00131 
00132     if ((neg_exp= (*str == '-')) || *str == '+')
00133       str++;
00134 
00135     if (str == end || !my_isdigit(&my_charset_latin1, *str))
00136       str= old_str;
00137     else
00138     {
00139       do
00140       {
00141         if (exp < 9999)                         /* prot. against exp overfl. */
00142           exp= exp*10 + (*str - '0');
00143         str++;
00144       } while (str < end && my_isdigit(&my_charset_latin1, *str));
00145     }
00146   }
00147   if ((exp= (neg_exp ? exp + digits_after_dec_point :
00148              exp - digits_after_dec_point)))
00149   {
00150     double scaler;
00151     if (exp < 0)
00152     {
00153       exp= -exp;
00154       neg_exp= 1;                               /* neg_exp was 0 before */
00155     }
00156     if (exp + ndigits >= MAX_DBL_EXP + 1 && result)
00157     {
00158       /*
00159         This is not 100 % as we actually will give an owerflow for
00160         17E307 but not for 1.7E308 but lets cut some corners to make life
00161         simpler
00162       */
00163       if (exp + ndigits > MAX_DBL_EXP + 1 ||
00164           result >= MAX_RESULT_FOR_MAX_EXP)
00165       {
00166         if (neg_exp)
00167           result= 0.0;
00168         else
00169           overflow= 1;
00170         goto done;
00171       }
00172     }
00173     scaler= 1.0;
00174     while (exp >= 100)
00175     {
00176       scaler*= 1.0e100;
00177       exp-= 100;
00178     }
00179     scaler*= scaler10[exp/10]*scaler1[exp%10];
00180     if (neg_exp)
00181       result/= scaler;
00182     else
00183       result*= scaler;
00184   }
00185 
00186 done:
00187   *end_ptr= (char*) str;                        /* end of number */
00188 
00189   if (overflow || isinf(result))
00190   {
00191     result= DBL_MAX;
00192     *error= EOVERFLOW;
00193   }
00194 
00195   return negative ? -result : result;
00196 }

Variable Documentation

double scaler1[] [static]

Initial value:

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

Definition at line 37 of file strtod.c.

double scaler10[] [static]

Initial value:

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

Definition at line 34 of file strtod.c.

Generated on Sat Sep 9 02:07:48 2006 for MySQL 5.1 by

1.4.7

The world's most popular open source database

mysql/src/5.1-dbg/libmysql_r/strtod.c File Reference

Defines

Functions

Variables

Define Documentation

Function Documentation

Variable Documentation