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Subject: Re: [OMPI users] LDBL_MANT_DIG declaration trouble
From: Ralph Castain (rhc_at_[hidden])
Date: 2013-04-12 10:20:09


It should have been defined in <float.h>. Is that include file not found? You might check to ensure it was defined there.

On Apr 12, 2013, at 7:09 AM, Ray Sheppard <rsheppar_at_[hidden]> wrote:

> Hi,
> I am sorry to bother everyone. I have had no trouble building 1.6.3 with the Intel compiler. Now I am having to repeat the exercise for GNU. In opal/util/arch.h (about line 260) is the function below. I am getting an error that LDBL_MANT_DIG is not declared. I can not seem to find where it is declared. Any hints would be appreciated. Thanks.
> Ray
>
>
> static inline int32_t opal_arch_ldisintel( void )
> {
> long double ld = 2.0;
> int i, j;
> uint32_t* pui = (uint32_t*)(void*)&ld;
>
> j = LDBL_MANT_DIG / 32;
> i = (LDBL_MANT_DIG % 32) - 1;
> if( opal_arch_isbigendian() ) { /* big endian */
> j = (sizeof(long double) / sizeof(unsigned int)) - j;
> if( i < 0 ) {
> i = 31;
> j = j+1;
> }
> } else {
> if( i < 0 ) {
> i = 31;
> j = j-1;
> }
> }
> return (pui[j] & (1 << i) ? 1 : 0);
> }
>
>
> Function is described:
> /* we must find which representation of long double is used
> * intel or sparc. Both of them represent the long doubles using a close to
> * IEEE representation (seeeeeee..emmm...m) where the mantissa look like
> * 1.????. For the intel representaion the 1 is explicit, and for the sparc
> * the first one is implicit. If we take the number 2.0 the exponent is 1
> * and the mantissa is 1.0 (the sign of course should be 0). So if we check
> * for the first one in the binary representation of the number, we will
> * find the bit from the exponent, so the next one should be the begining
> * of the mantissa. If it's 1 then we have an intel representaion, if not
> * we have a sparc one. QED
> */
>
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