diff options
Diffstat (limited to 'configure.in')
| -rw-r--r-- | configure.in | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/configure.in b/configure.in index 7afc0fd..c8bd31d 100644 --- a/configure.in +++ b/configure.in @@ -3094,6 +3094,69 @@ else fi dnl ---------------------------------------------------------------------- +dnl Set the flag to indicate that the machine can accurately convert +dnl 'long double' to '(unsigned) long long' values. (This flag should be set for +dnl all machines, except for Mac OS 10.4 and SGI IRIX64 6.5. When the bit sequence +dnl of long double is 0x4351ccf385ebc8a0bfcc2a3c..., the values of (unsigned)long long +dnl start to go wrong on these two machines. Adjusting it higher to +dnl 0x4351ccf385ebc8a0dfcc... or 0x4351ccf385ebc8a0ffcc... will make the converted +dnl values wildly wrong. This test detects this wrong behavior and disable the test. +dnl +AC_MSG_CHECKING([if correctly converting long double to (unsigned) long long values]) + +if test ${ac_cv_sizeof_long_double} = 0; then + hdf5_ldouble_to_llong_accurate=${hdf5_ldouble_to_llong_accurate=no} +else + AC_CACHE_VAL([hdf5_ldouble_to_llong_accurate], + [AC_TRY_RUN([ + int main(void) + { + long double ld = 20041683600089727.779961L; + long long ll; + unsigned long long ull; + unsigned char s[16]; + int ret = 0; + + if(sizeof(long double) == 16) { + /*make sure the long double type is the same as the failing type + *which has 16 bytes in size and 11 bits of exponent. If it is, + *the bit sequence should be like below. It's not + *a decent way to check but this info isn't available. */ + memcpy(s, &ld, 16); + if(s[0]==0x43 && s[1]==0x51 && s[2]==0xcc && s[3]==0xf3 && + s[4]==0x85 && s[5]==0xeb && s[6]==0xc8 && s[7]==0xa0 && + s[8]==0xbf && s[9]==0xcc && s[10]==0x2a && s[11]==0x3c) { + + /*slightly adjust the bit sequence (s[8]=0xdf). The converted + *values will go wild on Mac OS 10.4 and IRIX64 6.5.*/ + s[0]=0x43; s[1]=0x51; s[2]=0xcc; s[3]=0xf3; + s[4]=0x85; s[5]=0xeb; s[6]=0xc8; s[7]=0xa0; + s[8]=0xdf; s[9]=0xcc; s[10]=0x2a; s[11]=0x3c; + s[12]=0x3d; s[13]=0x85; s[14]=0x56; s[15]=0x20; + + memcpy(&ld, s, 16); + ll = (long long)ld; + ull = (unsigned long long)ld; + + if(ll != 20041683600089728 || ull != 20041683600089728) + ret = 1; + } + } + done: + exit(ret); + } + ], [hdf5_ldouble_to_llong_accurate=yes], [hdf5_ldouble_to_llong_accurate=no],)]) +fi + +if test ${hdf5_ldouble_to_llong_accurate} = "yes"; then + AC_DEFINE([LDOUBLE_TO_LLONG_ACCURATE], [1], + [Define if your system can convert long double to (unsigned) long long values correctly.]) + AC_MSG_RESULT([yes]) +else + AC_MSG_RESULT([no]) +fi + +dnl ---------------------------------------------------------------------- dnl Set some variables for general configuration information to be saved dnl and installed with the libraries. dnl |