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--- boundedbuffer [2007/09/20 01:25] – created franck
+++ boundedbuffer [2007/09/25 05:20] (current) – nshafiei
@@ Line 1: / Line 1: @@
 How do you implement a bounded FIFO buffer in C-Linda?
 Assume the buffer contains integers (to make life a little
-easier).  There are a number of producers and a number of
+ easier).  There are a number of producers and a number of
 consumer.  Assume that the functions consume and produce
 have already been defined.  Now consider the functions consumer
 and producer.
-<code c>
+ <code c>
 void consumer()
 {
@@ Line 61: / Line 61: @@
 How should get and put be completed?
+----
+A try for comment:
+<code c>
+void down_mutex()
+{
+  in("mutex", 1);
+  out("mutex", 0);
+}
+void up_mutex()
+{
+  in("mutex", 0);
+  out("mutex", 1);
+}
+int get()
+{
+  int i,j, data;
+  in("full");
+  down_mutex();
+  rd("size",?i);
+  in("head",?j);
+  in("buffer",j,?data);
+  j=(j+1)%i;
+  out("head",j);
+  up_mutex();
+  out("empty")
+  return data;
+}
+void put(int data)
+{
+  int i,j;
+  in("empty");
+  down_mutex();
+  rd("size",?i);
+  in("tail",?j)
+  out("buffer",j,?data);
+  j=(j+1)%i;
+  out("tail",j);
+  up_mutex();
+  out("full");
+  return;
+}
+void consumer()
+{
+  int data;
+  while (1)
+  {
+    data = get();
+    consume(data);
+  }
+}
+void producer()
+{
+  int data;
+  while (1)
+  {
+    data = produce();
+    put(data);
+  }
+}
+void real_main()
+{
+  #define Len 10
+  #define Run 5
+  for (int i =0 ; i<Len; i++)
+    out("empty");
+  out("head",1);
+  out("tail", 1);
+  out("size",len);
+  out("mutex",1);
+  for (int i =0 ; i<5; i++){
+    eval("consumer", consumer());
+    eval("producer", producer());
+}
+</code>
+variation of the same concept
+<code c>
+#define SEMAPHORE        "semaphore"
+#define PUT_COUNTER      "put"
+#define GET_COUNTER      "get"
+//---------------------- counter API ---------------------
+void counter_init(char * conterType) {
+	out(conterType,NULL);
+}
+int counter_next(char * conterType) {
+	int seq;
+	in(conterType,?seq);
+	out(conterType,++seq);
+	return seq;
+}
+//-------------------- semaphore API -----------------
+void semaphore_init (int counter) {
+	for (int i = 0; i < counter; i++ )
+		out(SEMAPHORE);
+}
+void semaphore_acquire() {
+	in(SEMAPHORE);
+}
+void semaphore_release() {
+	out(SEMAPHORE);
+}
+//-------------------------------------------------
+void put(int data) {
+	semaphore_acquire();
+	int seq_id = counter_next(PUT_COUNTER);
+	out(seq_id,data);
+}
+int get() {
+	int seq_id = counter_next(GET_COUNTER);
+	in(seq_id,?data);
+	semaphore_release();
+	return data;
+}
+void real_main()
+{
+   semaphore_init(BUFFER_SIZE);
+   counter_init(GET_COUNTER);
+   counter_init(PUT_COUNTER);
+   eval("consumer", consumer());
+   eval("producer", producer());
+}
+</code>
+Another variation.
+<code c>
+#define BUFFERSIZE 200
+int get()
+{
+  int i,j, data;
+  in("head",?i);
+  rd("tail",?j);
+  #wait when the buffer is empty
+  while (i==j) rd("tail",?j);
+  in("buffer",i,?data);
+  i=(i+1)%BUFFERSIZE;
+  out("head",i);
+  return data;
+}
+void put(int data)
+{
+  int i,j;
+  in("tail",?j);
+  rd("head",?i);
+  #wait when the buffer is full
+  while ( j-i==BUFFERSIZE-1 || i-j==1 ) rd("head",?i);
+  j=(j+1)%BUFFERSIZE;
+  out("buffer",j,data);
+  out("tail",j);
+}
+</code>
+Another Version
+<code c>
+#define SIZE 100
+Void Initialize()
+{
+ out("head", 0);
+ out("tail", 0);
+}
+int get()
+{
+  int head, tail, data;
+  in("head",?head);
+  rd("tail",?tail);
+  while(tail == head) rd("tail",?tail);
+  in("data",?data, head);
+  out("head",(head+1)%SIZE);
+  return data;
+}
+void put(int data)
+{
+  int head,tail;
+  in("tail",?tail);
+  rd("head",?head);
+  while( head == (tail+1)%SIZE ) rd("head",?head);
+  out("data",data, tail);
+  out("tail",(tail+1)%SIZE);
+}
+</code>
+<code c>
+// i1 and i2 are initialized to 0
+void put(int data)
+{
+      int i1, i2;
+      read("consumer", ?i2);
+      in("producer",?i1);
+      if(i1==size)i1=0;
+      while(i1+1==i2 || (i1+1==size && i2==0))
+         read("consumer",?i2);
+      out("data", data, i1);
+      out("producer", i1+1);
+}
+int get()
+{
+      int i2, data;
+      in("consumer",?i2);
+      if(i2==size)i2=0;
+      in("data",?data,i2);
+      out("consumer", i2+1);
+      return data;
+}
+</code>