= 目標 =
 * 以 gcc 編譯 spin_or_mutex.c
 * 編輯configure.ac makefile.am
== spin_or_mutex.c ==
{{{
#!c
//export LIBRARY_PATH=/usr/lib/i386-linux-gnu/
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <errno.h>
#include <sys/time.h>

#define LOOPS 10000000

#ifdef USE_SPINLOCK
pthread_spinlock_t spinlock;
#else
pthread_mutex_t mutex;
#endif

pid_t gettid() { return syscall( __NR_gettid ); }

char data[LOOPS];

void *consumer(void *ptr)
{
    int i = 0;

    printf("Consumer TID %lu\n", (unsigned long)gettid());

    while (1)
    {
#ifdef USE_SPINLOCK
        pthread_spin_lock(&spinlock);
#else
        pthread_mutex_lock(&mutex);
#endif

        if (i > LOOPS)
        {
#ifdef USE_SPINLOCK
            pthread_spin_unlock(&spinlock);
#else
            pthread_mutex_unlock(&mutex);
#endif
            break;
        }

	
	data[i] = 0;
	i++;

#ifdef USE_SPINLOCK
        pthread_spin_unlock(&spinlock);
#else
        pthread_mutex_unlock(&mutex);
#endif
    }

    return NULL;
}

int main()
{
    int i;
    pthread_t thr1, thr2;
    struct timeval tv1, tv2;

#ifdef USE_SPINLOCK
    pthread_spin_init(&spinlock, 0);
#else
    pthread_mutex_init(&mutex, NULL);
#endif

    // Creating the list content...
    for (i = 0; i < LOOPS; i++){
	data[i] = 1;	
    }
        

    // Measuring time before starting the threads...
    gettimeofday(&tv1, NULL);

    pthread_create(&thr1, NULL, consumer, NULL);
    pthread_create(&thr2, NULL, consumer, NULL);

    pthread_join(thr1, NULL);
    pthread_join(thr2, NULL);

    // Measuring time after threads finished...
    gettimeofday(&tv2, NULL);

    if (tv1.tv_usec > tv2.tv_usec)
    {
        tv2.tv_sec--;
        tv2.tv_usec += 1000000;
    }

    printf("Result - %ld.%ld\n", tv2.tv_sec - tv1.tv_sec,
        tv2.tv_usec - tv1.tv_usec);

#ifdef USE_SPINLOCK
    pthread_spin_destroy(&spinlock);
#else
    pthread_mutex_destroy(&mutex);
#endif

    return 0;
}

}}}

== 以 gcc 編譯 spin_or_mutex.c ==
=== 編輯Makefile ===

{{{
#!text
all:
        gcc spin_or_mutex.c -o spin_or_mutex

clean:
        rm -f spin_or_mutex
}}}

== 執行 ==
{{{
$ make
gcc spin_or_mutex.c -o spin_or_mutex
/tmp/ccTHYKpZ.o: In function `main':
spin_or_mutex.c:(.text+0xf2): undefined reference to `pthread_create'
spin_or_mutex.c:(.text+0x116): undefined reference to `pthread_create'
spin_or_mutex.c:(.text+0x12a): undefined reference to `pthread_join'
spin_or_mutex.c:(.text+0x13e): undefined reference to `pthread_join'
collect2: ld returned 1 exit status
make: *** [all] Error 1
}}}


=== 修改 Makefile ===
{{{
#!text
all:
        gcc -lpthread  spin_or_mutex.c -o spin_or_mutex

clean:
        rm -f spin_or_mutex

}}}

== 執行 ==
{{{
$ make
$ ./spin_or_mutex
}}}

 * Done!

== 編輯configure.ac makefile.am ==
== 執行 ==
{{{
$ autoscan 
$ mv configure.scan configure.ac
$ mv Makefile Makefile.in
$ autoconf 
$ autoheader 
$ ./configure 
$ make clean 
}}}

== 修改spin_or_mutex.c ==
{{{
#!c
#include "config.h"
// 以下略
}}}

== 新增Makefile.am ==
{{{
#!text
bin_PROGRAMS=spin_or_mutex
spin_or_mutex_SOURCES=spin_or_mutex.c
}}}
== 產生make檔 ==
{{{
$ aclocal
$ autoconf
$ automake
}}}
 * 修改error
{{{
#!text
AM_CONDITIONAL
AC_PROG_CC
AC_PROG_CXX 
AC_PROG_OBJC
AM_PROG_AS 
AM_PROG_GCJ 
AM_PROG_UPC
}}}

 * ./confifure
{{{
$ ./configure
$ make
make  all-am
make[1]: Entering directory `/home/shunfa/test/P1_Thomas'
source='spin_or_mutex.c' object='spin_or_mutex.o' libtool=no \
	DEPDIR=.deps depmode=none /bin/bash ./depcomp \
	gcc -DHAVE_CONFIG_H -I.     -g -O2 -c spin_or_mutex.c
gcc  -g -O2   -o spin_or_mutex spin_or_mutex.o  -lpthread 
spin_or_mutex.o: In function `_start':
(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crt1.o:(.text+0x0): first defined here
spin_or_mutex.o:(.rodata+0x0): multiple definition of `_fp_hw'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crt1.o:(.rodata+0x0): first defined here
spin_or_mutex.o: In function `_fini':
(.fini+0x0): multiple definition of `_fini'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crti.o:(.fini+0x0): first defined here
spin_or_mutex.o:(.rodata+0x4): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crt1.o:(.rodata.cst4+0x0): first defined here
spin_or_mutex.o: In function `__data_start':
(.data+0x0): multiple definition of `__data_start'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crt1.o:(.data+0x0): first defined here
spin_or_mutex.o: In function `__data_start':
(.data+0x4): multiple definition of `__dso_handle'
/usr/lib/gcc/i486-linux-gnu/4.4.5/crtbegin.o:(.data+0x0): first defined here
spin_or_mutex.o: In function `_init':
(.init+0x0): multiple definition of `_init'
/usr/lib/gcc/i486-linux-gnu/4.4.5/../../../../lib/crti.o:(.init+0x0): first defined here
/usr/lib/gcc/i486-linux-gnu/4.4.5/crtend.o:(.dtors+0x0): multiple definition of `__DTOR_END__'
spin_or_mutex.o:(.dtors+0x4): first defined here
collect2: ld returned 1 exit status
make[1]: *** [spin_or_mutex] Error 1
make[1]: Leaving directory `/home/shunfa/test/P1_Thomas'
make: *** [all] Error 2
}}}