From a72eedc5b6733401638eb0d09f2ada5de553a4d8 Mon Sep 17 00:00:00 2001
From: Remzi Arpaci-Dusseau <remzi.arpacidusseau@gmail.com>
Date: Mon, 10 Sep 2018 10:34:11 -0500
Subject: [PATCH] Added common include for simple C programs, and threads-intro
 code

---
 include/common.h         | 21 +++++++++++++++++++++
 include/common_threads.h | 33 +++++++++++++++++++++++++++++++++
 threads-intro/Makefile   | 14 ++++++++++++++
 threads-intro/t0.c       | 28 ++++++++++++++++++++++++++++
 threads-intro/t1.c       | 40 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 136 insertions(+)
 create mode 100644 include/common.h
 create mode 100644 include/common_threads.h
 create mode 100644 threads-intro/Makefile
 create mode 100644 threads-intro/t0.c
 create mode 100644 threads-intro/t1.c

diff --git a/include/common.h b/include/common.h
new file mode 100644
index 0000000..1202765
--- /dev/null
+++ b/include/common.h
@@ -0,0 +1,21 @@
+#ifndef __common_h__
+#define __common_h__
+
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <assert.h>
+
+double GetTime() {
+    struct timeval t;
+    int rc = gettimeofday(&t, NULL);
+    assert(rc == 0);
+    return (double) t.tv_sec + (double) t.tv_usec/1e6;
+}
+
+void Spin(int howlong) {
+    double t = GetTime();
+    while ((GetTime() - t) < (double) howlong)
+	; // do nothing in loop
+}
+
+#endif // __common_h__
diff --git a/include/common_threads.h b/include/common_threads.h
new file mode 100644
index 0000000..a587122
--- /dev/null
+++ b/include/common_threads.h
@@ -0,0 +1,33 @@
+#ifndef __common_threads_h__
+#define __common_threads_h__
+
+#include <pthread.h>
+#include <assert.h>
+#include <sched.h>
+
+#ifdef __linux__
+#include <semaphore.h>
+#endif
+
+#define Pthread_create(thread, attr, start_routine, arg) assert(pthread_create(thread, attr, start_routine, arg) == 0);
+#define Pthread_join(thread, value_ptr)                  assert(pthread_join(thread, value_ptr) == 0);
+
+#define Pthread_mutex_lock(m)                            assert(pthread_mutex_lock(m) == 0);
+#define Pthread_mutex_unlock(m)                          assert(pthread_mutex_unlock(m) == 0);
+#define Pthread_cond_signal(cond)                        assert(pthread_cond_signal(cond) == 0);
+#define Pthread_cond_wait(cond, mutex)                   assert(pthread_cond_wait(cond, mutex) == 0);
+
+#define Mutex_init(m)                                    assert(pthread_mutex_init(m, NULL) == 0);
+#define Mutex_lock(m)                                    assert(pthread_mutex_lock(m) == 0);
+#define Mutex_unlock(m)                                  assert(pthread_mutex_unlock(m) == 0);
+#define Cond_init(cond)                                  assert(pthread_cond_init(cond, NULL) == 0);
+#define Cond_signal(cond)                                assert(pthread_cond_signal(cond) == 0);
+#define Cond_wait(cond, mutex)                           assert(pthread_cond_wait(cond, mutex) == 0);
+
+#ifdef __linux__
+#define Sem_init(sem, value)                             assert(sem_init(sem, 0, value) == 0);
+#define Sem_wait(sem)                                    assert(sem_wait(sem) == 0);
+#define Sem_post(sem)                                    assert(sem_post(sem) == 0);
+#endif // __linux__
+
+#endif // __common_threads_h__
diff --git a/threads-intro/Makefile b/threads-intro/Makefile
new file mode 100644
index 0000000..8bb94fa
--- /dev/null
+++ b/threads-intro/Makefile
@@ -0,0 +1,14 @@
+
+FLAGS = -Wall -pthread
+INCLUDES = ../include
+
+all: t0 t1
+
+clean:
+	rm -f t0 t1
+
+t0: t0.c
+	gcc -I $(INCLUDES) -o t0 t0.c $(FLAGS)
+
+t1: t1.c
+	gcc -I $(INCLUDES) -o t1 t1.c $(FLAGS)
diff --git a/threads-intro/t0.c b/threads-intro/t0.c
new file mode 100644
index 0000000..1d238a8
--- /dev/null
+++ b/threads-intro/t0.c
@@ -0,0 +1,28 @@
+#include "common.h"
+#include "common_threads.h"
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *mythread(void *arg) {
+    printf("%s\n", (char *) arg);
+    return NULL;
+}
+
+int main(int argc, char *argv[]) {                    
+    if (argc != 1) {
+	fprintf(stderr, "usage: main\n");
+	exit(1);
+    }
+
+    pthread_t p1, p2;
+    printf("main: begin\n");
+    Pthread_create(&p1, NULL, mythread, "A"); 
+    Pthread_create(&p2, NULL, mythread, "B");
+    // join waits for the threads to finish
+    Pthread_join(p1, NULL); 
+    Pthread_join(p2, NULL); 
+    printf("main: end\n");
+    return 0;
+}
+
diff --git a/threads-intro/t1.c b/threads-intro/t1.c
new file mode 100644
index 0000000..7dc2571
--- /dev/null
+++ b/threads-intro/t1.c
@@ -0,0 +1,40 @@
+#include "common.h"
+#include "common_threads.h"
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int max;
+volatile int counter = 0; // shared global variable
+
+void *mythread(void *arg) {
+    char *letter = arg;
+    int i; // stack (private per thread) 
+    printf("%s: begin [addr of i: %p]\n", letter, &i);
+    for (i = 0; i < max; i++) {
+	counter = counter + 1; // shared: only one
+    }
+    printf("%s: done\n", letter);
+    return NULL;
+}
+                                                                             
+int main(int argc, char *argv[]) {                    
+    if (argc != 2) {
+	fprintf(stderr, "usage: main-first <loopcount>\n");
+	exit(1);
+    }
+    max = atoi(argv[1]);
+
+    pthread_t p1, p2;
+    printf("main: begin [counter = %d] [%x]\n", counter, 
+	   (unsigned int) &counter);
+    Pthread_create(&p1, NULL, mythread, "A"); 
+    Pthread_create(&p2, NULL, mythread, "B");
+    // join waits for the threads to finish
+    Pthread_join(p1, NULL); 
+    Pthread_join(p2, NULL); 
+    printf("main: done\n [counter: %d]\n [should: %d]\n", 
+	   counter, max*2);
+    return 0;
+}
+