diff options
Diffstat (limited to 'src/util.c')
| -rw-r--r-- | src/util.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/src/util.c b/src/util.c index a4dbe8fda..75de4b3b3 100644 --- a/src/util.c +++ b/src/util.c @@ -321,6 +321,24 @@ int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){ } /* +** Compute 10 to the E-th power. Examples: E==1 results in 10. +** E==2 results in 100. E==50 results in 1.0e50. +** +** This routine only works for values of E between 1 and 341. +*/ +static LONGDOUBLE_TYPE sqlite3Pow10(int E){ + LONGDOUBLE_TYPE x = 10.0; + LONGDOUBLE_TYPE r = 1.0; + while(1){ + if( E & 1 ) r *= x; + E >>= 1; + if( E==0 ) break; + x *= x; + } + return r; +} + +/* ** The string z[] is an text representation of a real number. ** Convert this string to a double and write it into *pResult. ** @@ -475,11 +493,10 @@ do_atof_calc: if( e==0 ){ /*OPTIMIZATION-IF-TRUE*/ result = (double)s; }else{ - LONGDOUBLE_TYPE scale = 1.0; /* attempt to handle extremely small/large numbers better */ if( e>307 ){ /*OPTIMIZATION-IF-TRUE*/ if( e<342 ){ /*OPTIMIZATION-IF-TRUE*/ - while( e%308 ) { scale *= 1.0e+1; e -= 1; } + LONGDOUBLE_TYPE scale = sqlite3Pow10(e-308); if( esign<0 ){ result = s / scale; result /= 1.0e+308; @@ -499,10 +516,7 @@ do_atof_calc: } } }else{ - /* 1.0e+22 is the largest power of 10 than can be - ** represented exactly. */ - while( e%22 ) { scale *= 1.0e+1; e -= 1; } - while( e>0 ) { scale *= 1.0e+22; e -= 22; } + LONGDOUBLE_TYPE scale = sqlite3Pow10(e); if( esign<0 ){ result = s / scale; }else{ |