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              | https://weharmony.github.io (国外)
    论坛 | http://bbs.weharmonyos.com
    文档中心 | http://open.weharmonyos.com
    参考手册 | http://doxygen.weharmonyos.com

zzz/demo/futex_demo.c

-/* futex_demo.c
-
-          Usage: futex_demo [nloops]
-                           (Default: 5)
-
-          Demonstrate the use of futexes in a program where parent and child
-          use a pair of futexes located inside a shared anonymous mapping to
-          synchronize access to a shared resource: the terminal. The two
-          processes each write 'num-loops' messages to the terminal and employ
-          a synchronization protocol that ensures that they alternate in
-          writing messages.
-       */
-       #define _GNU_SOURCE
-       #include <stdio.h>
-       #include <errno.h>
-       #include <stdatomic.h>
-       #include <stdint.h>
-       #include <stdlib.h>
-       #include <unistd.h>
-       #include <sys/wait.h>
-       #include <sys/mman.h>
-       #include <sys/syscall.h>
-       #include <linux/futex.h>
-       #include <sys/time.h>
-
-       #define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \
-                               } while (0)
-
-       static uint32_t *futex1, *futex2, *iaddr;
-
-       static int
-       futex(uint32_t *uaddr, int futex_op, uint32_t val,
-             const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
-       {
-           return syscall(SYS_futex, uaddr, futex_op, val,
-                          timeout, uaddr2, val3);
-       }
-
-       /* Acquire the futex pointed to by 'futexp': wait for its value to
-          become 1, and then set the value to 0. */
-
-       static void
-       fwait(uint32_t *futexp)
-       {
-           long s;
-
-           /* atomic_compare_exchange_strong(ptr, oldval, newval)
-              atomically performs the equivalent of:
-
-                  if (*ptr == *oldval)
-                      *ptr = newval;
-
-              It returns true if the test yielded true and *ptr was updated. */
-
-           while (1) {
-
-               /* Is the futex available? */
-               const uint32_t one = 1;
-               if (atomic_compare_exchange_strong(futexp, &one, 0))
-                   break;      /* Yes */
-
-               /* Futex is not available; wait. */
-
-               s = futex(futexp, FUTEX_WAIT, 0, NULL, NULL, 0);
-               if (s == -1 && errno != EAGAIN)
-                   errExit("futex-FUTEX_WAIT");
-           }
-       }
-
-       /* Release the futex pointed to by 'futexp': if the futex currently
-          has the value 0, set its value to 1 and the wake any futex waiters,
-          so that if the peer is blocked in fwait(), it can proceed. */
-
-       static void
-       fpost(uint32_t *futexp)
-       {
-           long s;
-
-           /* atomic_compare_exchange_strong() was described
-              in comments above. */
-
-           const uint32_t zero = 0;
-           if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
-               s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
-               if (s  == -1)
-                   errExit("futex-FUTEX_WAKE");
-           }
-       }
-
-       int
-       main(int argc, char *argv[])
-       {
-           pid_t childPid;
-           int nloops;
-
-           setbuf(stdout, NULL);
-
-           nloops = (argc > 1) ? atoi(argv[1]) : 5;
-
-           /* Create a shared anonymous mapping that will hold the futexes.
-              Since the futexes are being shared between processes, we
-              subsequently use the "shared" futex operations (i.e., not the
-              ones suffixed "_PRIVATE"). */
-
-           iaddr = mmap(NULL, sizeof(*iaddr) * 2, PROT_READ | PROT_WRITE,
-                       MAP_ANONYMOUS | MAP_SHARED, -1, 0);
-           if (iaddr == MAP_FAILED)
-               errExit("mmap");
-
-           futex1 = &iaddr[0];
-           futex2 = &iaddr[1];
-
-           *futex1 = 0;        /* State: unavailable */
-           *futex2 = 1;        /* State: available */
-
-           /* Create a child process that inherits the shared anonymous
-              mapping. */
-
-           childPid = fork();
-           if (childPid == -1)
-               errExit("fork");
-
-           if (childPid == 0) {        /* Child */
-               for (int j = 0; j < nloops; j++) {
-                   fwait(futex1);
-                   printf("Child  (%jd) %d\n", (intmax_t) getpid(), j);
-                   fpost(futex2);
-               }
-
-               exit(EXIT_SUCCESS);
-           }
-
-           /* Parent falls through to here. */
-
-           for (int j = 0; j < nloops; j++) {
-               fwait(futex2);
-               printf("Parent (%jd) %d\n", (intmax_t) getpid(), j);
-               fpost(futex1);
-           }
-
-           wait(NULL);
-
-           exit(EXIT_SUCCESS);
-       }
\ No newline at end of file

zzz/git/push.sh

 git add -A
-git commit -m  ' 补充链接脚本的注解
-    百图画鸿蒙 + 百文说内核 + 百万注源码  => 挖透鸿蒙内核源码
+git commit -m  ' bbs.weharmonyos.com 上线 
     鸿蒙研究站 | http://weharmonyos.com (国内) 
               | https://weharmony.github.io (国外)
-    oschina | https://my.oschina.net/weharmony
-    博客园 | https://www.cnblogs.com/weharmony/
-    知乎 | https://www.zhihu.com/people/weharmonyos
-    csdn | https://blog.csdn.net/kuangyufei
-    51cto | https://harmonyos.51cto.com/column/34
-    掘金 | https://juejin.cn/user/756888642000808
-    公众号 | 鸿蒙研究站 (weharmonyos)
+    论坛 | http://bbs.weharmonyos.com
+    文档中心 | http://open.weharmonyos.com
+    参考手册 | http://doxygen.weharmonyos.com
+    
 '
 
 git push  gitee_origin master

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-包括：内核实现、驱动框架、协议栈、应用框架、编译构建、运行时系统 等其他核心子系统。工程浩大，自不量力，然兴趣所至，义无反顾， 此念不息，坚如磐石。
-
-三百鸿蒙是指：
-对内核写一百篇博客
-对系统画一百张图
-对源码注释一百万汉字
-
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-
-百图画鸿蒙 + 百文说内核 + 百万注源码  => 挖透鸿蒙内核源码
-鸿蒙研究站 | http://weharmonyos.com (国内)
-		  | https://weharmony.github.io (国外)
-oschina | https://my.oschina.net/weharmony
-博客园 | https://www.cnblogs.com/weharmony/
-知乎 | https://www.zhihu.com/people/weharmonyos
-csdn | https://blog.csdn.net/kuangyufei
-51cto | https://harmonyos.51cto.com/column/34
-掘金 | https://juejin.cn/user/756888642000808
-公众号 | 鸿蒙研究站 (weharmonyos)