[erlang-questions] Help! Do I need erl_driver_compat.h
Fri Nov 14 19:27:32 CET 2008
I'm trying to write a Linked-in driver.
My guru's have suggested starting with the stdio buffered FILE i/o
driver 'bfile' as a good skeleton.
I have two question.
Q1. File FILE_drv.c (conditionally) #includes <erl_driver_compat.h>,
but I can't find that file anywhere (on my machine, or using google;
almost a googlewhack).
Briefly, what is it for? Is it 'deprecated', defunct, or does it come
from some other contributed piece?
This is for Erlang-DTrace, so I don't expect to run on many OS's for a
while (Solaris/OpenSolaris, Mac OS X, BSD and VXworks for now), though
I would like the code to build without error, even if it is all null
functions, on Erlang/OTP platforms.
I prefer to avoid stuff that I can't use, and can't test.
So can I safely throw away the #include <erl_driver_compat.h> ?
Q2. Why is the output done using ErlDrvData.control, and not
I can see that it is well-organised if all I/O goes through the one
ErlDrvData.control function (and that is a good reason to me), but is
there a performance difference between the two approaches?
Thanks in Advance for any help advice,
PS. A tiny, irrelevant, point. In FILE_drv.c the macro symbol
USE_STDIO is defined **always**, and then used to *conditionally*
I can't find any definition of USE_STDIO in the Erlang source, or
anywhere under /usr, /bin or /etc on Mac OS X.
I am not using stdio, so I'll remove all of this, but I am curious, is
this necessary on some platform?
#ifdef USE_STDIO // Always #include <stdio.h>
# include <stdio.h> // as it will anyway?
#else // ----
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