Passing va_list as a function argument Topic is solved

[jmarple]

Hello everyone,

I have the following code which is trying to accept va_list as an argument:

foo.c:

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#include "foo.h"

void foo(va_list arg)
{
  // .. stuff here
}

foo.h:

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#include <stdarg.h>

void foo(va_list arg);

I get the following error when I build on xTimeComposer 14.20 on Ubuntu 15.10 64-bit

foo.h:##:##: error: parse error before "va_list"

When I declare the function prototype in the c file, it compiles fine. The error only occurs when I add the function prototype to the header file. Am I missing something really obvious here? Or perhaps a bug? Thanks in advanced.

[ers35]

I tried your exact code and it compiles without error with xTimeComposer 14.2.0 on Ubuntu 16.04.

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// foo.h
#include <stdarg.h>

void foo(va_list arg);

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// foo.c
// xcc -c -target=XCORE-200-EXPLORER foo.c

#include "foo.h"

void foo(va_list arg)
{
  // .. stuff here
}

Are you using the xTimeComposer GUI to compile? What happens if you use the command line as in the code above?

[jmarple]

I appreciate the fast response. I am using the GUI and when I ran your command, sure enough no compiler errors.

After some experimentation, I added a main method to an xc file:

foo.xc

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#include "foo.h"

int main()
{
  return 0;
}

And I run the following command.

xcc -c -target=XCORE-200-EXPLORER foo.xc -o foo.xe

I get the error listed below.

./foo.h:7:10: error: parse error before "va_list"
void foo(va_list arg);

Can that be replicated? Thanks in advanced.

EDIT: I did add header guards to foo.h but that shouldn't make a difference for this example.

[ers35]

XC is not 100% compatible with C syntax. Include stdio.h and use __VALIST instead.

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// xcc -c stdarg2.xc

#include <stdarg.h>
// #define __VALIST char*
#include <stdio.h>

void foo(__VALIST arg);

[jmarple]

Tricky! Got it working now, thanks for the help. Do you happen to know if these small differences between C and XC are documented anywhere?

[ers35]

I am not aware of a comprehensive document that covers all the differences. The XC 1.0 specification is still useful despite missing newer additions. The XMOS Programming Guide is more up to date.