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Improved comments on the hasHighPrecisionDouble() routine. No changes to

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the underlying code.

FossilOrigin-Name: 810c635ce063d873e969bf83339c654f6008e84ce8a61f0ffc61806e98d13dde
This commit is contained in:
drh
2023-09-13 20:35:04 +00:00
parent 5b5d4492f2
commit 23164c984e
3 changed files with 16 additions and 13 deletions
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12
src/main.c
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@@ -160,15 +160,21 @@ char *sqlite3_temp_directory = 0;
char *sqlite3_data_directory = 0;
/*
** Determine what the default bUseLongDouble value should be and set it.
** Determine whether or not high-precision (long double) floating point
** math works correctly on CPU currently running.
*/
static SQLITE_NOINLINE int hasHighPrecisionDouble(int rc){
if( sizeof(LONGDOUBLE_TYPE)<=8 ){
/* If the size of "long double" is not more than 8, then
** high-precision math is not possible. */
return 0;
}else{
/* Just because sizeof(long double)>8 does not mean that the underlying
** hardware actually supports high-precision floating point. Do a test
** to verify that it really does */
** hardware actually supports high-precision floating point. For example,
** clearing the 0x100 bit in the floating-point control word on Intel
** processors will make long double work like double, even though long
** double takes up more space. The only way to determine if long double
** actually works is to run an experiment. */
LONGDOUBLE_TYPE a, b, c;
rc++;
a = 1.0+rc*0.1;