for issue 45 CAS linked list

datastructs/Makefile

@@ -1,8 +1,8 @@
 # Mark some tasks phony to ensure proper building
-.PHONY: all clean rebuild test linkedlist hashtable ringbuffer
+.PHONY: all clean rebuild test linkedlist hashtable ringbuffer ll_atomic
 
 #List of dependency files needed for compilation
-all: linkedlist hashtable ringbuffer
+all: linkedlist hashtable ringbuffer ll_atomic
 
 rebuild: clean all
 
@@ -12,15 +12,20 @@ hashtable:
 linkedlist:
 	cd linkedlist && make
 
+ll_atomic:
+	cd ll_atomic && make
+
 ringbuffer:
 	cd ringbuffer && make
 
 test:
 	./linkedlist/test/test-list
+	./ll_atomic/test/test-list
 	./hashtable/test/test-hashtable
 	./ringbuffer/test/test-ringbuffer
 
 clean:
 	cd linkedlist && make clean
+	cd ll_atomic && make clean
 	cd hashtable && make clean
 	cd ringbuffer && make clean

datastructs/ll_atomic/Makefile

@@ -0,0 +1,21 @@
+#Use the gcc compiler
+CC = gcc
+CFLAGS = -std=c99 -pedantic -Wall
+#List of dependency files needed for compilation
+DEPS = ll_atomic.c
+LDFLAGS =
+OBJS = ll_atomic.o tests
+
+all: $(OBJS)
+
+rebuild: clean all
+
+linkedlist:
+	$(CC) $(CFLAGS) -c $(DEPS)
+
+tests:
+	cd test && make
+
+clean:
+	rm -f ll_atomic.o
+	cd test && make clean

datastructs/ll_atomic/ll_atomic.c

@@ -0,0 +1,96 @@
+#include "ll_atomic.h"
+
+void
+ll_init(struct list *ll)
+{
+        ll->dummy.next = &ll->dummy;
+        ll->dummy.prev = &ll->dummy;
+        ll->size = 0;
+}
+
+void
+ll_append(struct list *ll, struct ll_node *node)
+{
+        atomic_fetch_add(&ll->size, 1);
+
+        struct ll_node *temp = &ll->dummy;
+        struct ll_node *ptr = (struct ll_node *)node;
+        struct ll_node *tail;
+
+        ptr->next = temp;
+
+        while (1){
+                tail = temp->prev;
+                ptr->prev = tail;
+                if (atomic_compare_exchange_strong(&temp->prev, &tail, ptr)) {
+                        tail->next = ptr;
+                        break;
+                }
+        }
+}
+
+void
+ll_prepend(struct list *ll, struct ll_node *node)
+{
+        atomic_fetch_add(&ll->size, 1);
+
+        struct ll_node *temp = &ll->dummy;
+        struct ll_node *ptr = (struct ll_node *)node;
+        struct ll_node *head;
+
+        ptr->next = temp;
+
+        while (1){
+                head = temp->next;
+                ptr->next = head;
+                if (atomic_compare_exchange_strong(&temp->next, &head, ptr)) {
+                        head->prev = ptr;
+                        break;
+                }
+        }
+}
+
+struct ll_node *
+ll_first(struct list *ll)
+{
+        struct ll_node *dummy = &ll->dummy;
+        struct ll_node *ptr, *next, *dummy_next;
+
+        ptr = dummy->next;
+        if (ptr == dummy) return NULL;
+
+        while (1) {
+                next = ptr->next;
+                if (atomic_compare_exchange_strong(&next->prev, &ptr, dummy)) {
+                        dummy_next = dummy->next;
+                        atomic_compare_exchange_strong(&dummy->next, &dummy_next, next);
+                        break;
+                }
+        }
+
+        atomic_fetch_sub(&ll->size, 1);
+        return ptr;
+}
+
+struct ll_node *
+ll_last(struct list *ll)
+{
+        struct ll_node *dummy = &ll->dummy;
+        struct ll_node *ptr, *prev, *dummy_prev;
+
+        ptr = dummy->prev;
+
+        if(ptr == dummy) return NULL;
+
+        while (1) {
+                prev = ptr->prev;
+                if (atomic_compare_exchange_strong(&dummy->prev, &dummy_prev, prev)) {
+                        dummy_prev = dummy->prev;
+                        atomic_compare_exchange_strong(&dummy->prev, &dummy_prev, prev);
+                        break;
+                }
+        }
+
+        atomic_fetch_sub(&ll->size, 1);
+        return ptr;
+}

datastructs/ll_atomic/ll_atomic.h

@@ -0,0 +1,49 @@
+#ifndef LL_ATOMIC_
+#define LL_ATMOIC_
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <stdatomic.h>
+
+struct ll_node {
+        void *data;
+        struct ll_node * volatile next;
+        struct ll_node * volatile prev;
+
+};
+
+struct list {
+        struct ll_node dummy;
+        uint32_t size;
+};
+
+void
+ll_init(struct list *ll);
+
+struct ll_node *
+ll_init_node(void *value);
+
+static inline struct ll_node *
+ll_head(struct list *ll) { return ll->dummy.next; }
+
+static inline struct ll_node *
+ll_tail(struct list *ll) { return ll->dummy.prev; }
+
+int
+ll_size(void);
+
+void
+ll_append(struct list *ll, struct ll_node *node);
+
+void
+ll_prepend(struct list *ll, struct ll_node *node);
+
+struct ll_node *
+ll_first(struct list *ll);
+
+struct ll_node *
+ll_last(struct list *ll);
+
+#endif /*LL_ATOMIC*/

datastructs/ll_atomic/test/Makefile

@@ -0,0 +1,13 @@
+CC = gcc
+CFLAGS = -std=c99 -Wall -pedantic
+DEPS = ../ll_atomic.o
+OBJ = test-linkedlist
+
+all: linkedlist_test
+
+rebuild: clean all
+
+linkedlist_test:
+	$(CC) $(CFLAGS) test-ll.c -o $(OBJ) $(DEPS)
+clean:
+	rm -f $(OBJ)

datastructs/ll_atomic/test/test-ll.c

@@ -0,0 +1,23 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include "../ll_atomic.h"
+
+int
+main(void)
+{
+        struct list ll;
+        struct ll_node node, *wat;
+        node.data = (void *) 99;
+        printf("%d\n", *((int*)&node.data));
+        ll_init(&ll);
+        ll_append(&ll, &node);
+        wat = ll_last(&ll);
+        printf("%d\n", *((int*)&wat->data));
+        node.data = (void *) 100;
+        ll_prepend(&ll, &node);
+        wat = ll_first(&ll);
+        printf("%d\n", *((int*)&wat->data));
+
+        return 0;
+}