Question

I’m trying to “implement” a cross-platform mutex following the instructions here:

And here is my code:

#ifndef __SIMPLEAV_CORE_UTIL_SAMUTEX_H_DEFINED__
#define __SIMPLEAV_CORE_UTIL_SAMUTEX_H_DEFINED__

/*
 * A simple cross-platform (currently only on linux and win) mutex.
 *
 * usage:
 * SAMutex mutex;
 * SAMutex_init(&mutex);
 * SAMutex_lock(&mutex);
 * SAMutex_unlock(&mutex);
 * SAMutex_destroy(&mutex);
 *
 * all functions return 0 on success, -1 on error.
*/

#if defined(LINUX)
     #include <pthread.h>
     //typedef pthread_mutex_t SAMutex;
     #define SAMutex pthread_mutex_t
#elif defined(WINDOWS)
     #include <windows.h>
     #include <process.h>
     //typedef HANDLE SAMutex;
     #define SAMutex HANDLE
#endif

int SAMutex_init(SAMutex *);
int SAMutex_lock(SAMutex *);
int SAMutex_unlock(SAMutex *);
int SAMutex_destroy(SAMutex *);

#endif

but what I got after running gcc was:

~/git/SimpleAV/build $ make
[ 20%] Building C object CMakeFiles/player2.dir/player2.c.o
In file included from /home/wecing/git/SimpleAV/include/SimpleAV/core/core.h:4,
                 from /home/wecing/git/SimpleAV/include/SimpleAV/SDL/api.h:5,
                 from /home/wecing/git/SimpleAV/player2.c:4:
/home/wecing/git/SimpleAV/include/SimpleAV/core/util/SAMutex.h:28: error: expected ‘)’ before ‘*’ token
/home/wecing/git/SimpleAV/include/SimpleAV/core/util/SAMutex.h:29: error: expected ‘)’ before ‘*’ token
/home/wecing/git/SimpleAV/include/SimpleAV/core/util/SAMutex.h:30: error: expected ‘)’ before ‘*’ token
/home/wecing/git/SimpleAV/include/SimpleAV/core/util/SAMutex.h:31: error: expected ‘)’ before ‘*’ token
In file included from /home/wecing/git/SimpleAV/include/SimpleAV/SDL/api.h:5,
                 from /home/wecing/git/SimpleAV/player2.c:4:
/home/wecing/git/SimpleAV/include/SimpleAV/core/core.h:28: error: expected specifier-qualifier-list before ‘SAMutex’
make[2]: *** [CMakeFiles/player2.dir/player2.c.o] Error 1
make[1]: *** [CMakeFiles/player2.dir/all] Error 2
make: *** [all] Error 2

by the way, on linux, pthread_mutex_t is defined as:

typedef union
{
  struct __pthread_mutex_s
  {
    int __lock;
    unsigned int __count;
    int __owner;
#if __WORDSIZE == 64
    unsigned int __nusers;
#endif
    /* KIND must stay at this position in the structure to maintain
       binary compatibility.  */
    int __kind;
#if __WORDSIZE == 64
    int __spins;
    __pthread_list_t __list;
# define __PTHREAD_MUTEX_HAVE_PREV  1
#else
    unsigned int __nusers;
    __extension__ union
    {
      int __spins;
      __pthread_slist_t __list;
    };
#endif
  } __data;
  char __size[__SIZEOF_PTHREAD_MUTEX_T];
  long int __align;
} pthread_mutex_t;

What did I do wrong?

Answer 1

have you defined LINUX or WINDOWS define in your Makefile?

---

try

gcc -dM -E - < /dev/null

this prints all the predefined macros.

and here the windows macros.