Re: Calling conventions (particularly 32-bit ARM)

scott@slp53.sl.home (Scott Lurndal) writes:

mitchalsup@aol.com (MitchAlsup1) writes:

On Mon, 13 Jan 2025 18:02:10 +0000, Thomas Koenig wrote:
>

MitchAlsup1 <mitchalsup@aol.com> schrieb:
>

errno is an atrocity all by itself; single handedly preventing
direct use of SIN(), COS(), TAN(), ATAN(), exp(), ln(), pow()
as instructions.

>
Fortunately, the C standard does not require errno to be set
for these functions.  Apple, for example, does not do so.

>
Nor will I.

>
POSIX does, however, require errno to be set conditionally
based on an application global variable 'math_errhandling'.

math_errhandling is specified by ISO C, starting with the 1999 edition
of the standard.

The value of math_errhandling is determined by the implementation, not
by the application.  "The value of math_errhandling is constant for the
duration of the program."  (A compiler could provide an option to set
the value; I don't know whether any do so.)

https://www.iso-9899.info/n1570.html#7.12

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */