1 files changed, 76 insertions, 0 deletions
diff --git a/CS3871/sync/writer.c b/CS3871/sync/writer.c
new file mode 100644
index 0000000..d38dd70
--- /dev/null
+++ b/CS3871/sync/writer.c
@@ -0,0 +1,76 @@
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/select.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+#include <sys/types.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#define NSEM 3
+
+char *mem;
+
+void quit(signum)
+int signum;
+{
+	shmdt(mem);
+	exit(1);
+}
+
+int main(argc, argv)
+int argc;
+char **argv;
+{
+	int shmid, semid, i, pid, id;
+	char *mem;
+	struct sembuf sb;
+
+	if (argc < 2) {
+		printf("usage: writer [id]\n");
+		exit(1);
+	}
+
+	id = atoi(argv[1]);
+
+
+	if ((shmid = shmget(52, 1<<14, IPC_CREAT | 0666)) == -1){
+		perror("shmget: shmget failed");
+		exit(1);
+	}
+
+	if ((mem = shmat(shmid, NULL, 0)) == (char *) -1) {
+		perror("shmat");
+		exit(1);
+	}
+printf("Wshmid: %x\n", shmid);
+
+	if ((semid = semget(shmid, NSEM, 0)) == -1) {
+		perror("Wsemget: ");
+		exit(1);
+	}
+
+	signal(SIGQUIT, quit);
+	
+	srand(time(NULL));
+
+	while (1) {
+		rand() % id;
+		
+		sb.sem_num = 0; sb.sem_op = -1; sb.sem_flg = 0;
+		semop(semid, &sb, 1);
+
+		for (i = 0; i < 1<<14; i++) {
+			mem[i]= 0x30 + id;
+		}
+		
+		sb.sem_op = 1;
+		semop(semid, &sb, 1);
+
+		sleep(rand() % ((id * 2) + 1));
+	}
+}