* added circular index buffer implementation

core/Jamfile

@@ -28,7 +28,7 @@
 SubDir TOP core ;
 
 Module core : kernel_init.c sched.c mutex.c msg.c queue.c 
-                clist.c thread.c bitarithm.c ;
+                clist.c thread.c bitarithm.c cib.c ;
 
 Module hwtimer : hwtimer.c : hwtimer_cpu ;
 

core/cib.c

@@ -0,0 +1,47 @@
+typedef struct cib {
+    unsigned int read_count;
+    unsigned int write_count;
+    unsigned int complement;
+} cib_t;
+
+void cib_init(cib_t *cib, unsigned int size) {
+    cib->read_count = 0;
+    cib->write_count = 0;
+    cib->complement = 0-size;
+}
+
+int cib_avail (cib_t *cib) {
+    return cib->write_count - cib->read_count;
+}
+
+int cib_get(cib_t *cib) {
+    int avail = cib_avail (cib);
+
+    if (avail > 0) {
+        return cib->read_count++ & ~cib->complement;
+    } 
+
+    return -1;
+}
+
+int cib_put(cib_t *cib) {
+    int avail = cib_avail (cib);
+
+    if ((int)(avail + cib->complement) < 0 ) {
+        return cib->write_count++ & ~(cib->complement);
+    }
+
+    return -1;
+}
+
+/*
+int main() {
+    cib_t cib;
+
+    cib_init(&cib, 0);
+
+    int res = cib_get(&cib);
+
+    printf("%i\n", res);
+}
+*/

core/include/cib.h

@@ -0,0 +1,15 @@
+#ifndef __CIB_H
+#define __CIB_H 
+
+typedef struct cib_t {
+    unsigned int read_count;
+    unsigned int write_count;
+    unsigned int complement;
+} cib_t;
+
+void cib_init(cib_t *cib, unsigned int size);
+int cib_get(cib_t *cib);
+int cib_put(cib_t *cib);
+int cib_avail(cib_t *cib);
+
+#endif /* __CIB_H */