1 files changed, 76 insertions, 0 deletions
diff --git a/xxx/lib/buffer/ringbuffer.c b/xxx/lib/buffer/ringbuffer.c
new file mode 100644
index 0000000..a121df1
--- /dev/null
+++ b/xxx/lib/buffer/ringbuffer.c
@@ -0,0 +1,76 @@
+// can handle one buffer for a start.
+// later make it reentrant and manage multiple buffers!
+// todo: syncing access to buffer.
+
+#define FOOLOS_MODULE_NAME "ringbuffer"
+
+#include "ringbuffer.h"
+#include "kernel/x86.h"
+#include "lib/logger/log.h"
+#include "kernel/spinlock.h"
+
+#define RINGBUFFER_SIZE 10
+static int size=RINGBUFFER_SIZE;
+static volatile int front=RINGBUFFER_SIZE-1;
+static volatile int back=RINGBUFFER_SIZE-1;
+static volatile char buf[RINGBUFFER_SIZE];
+
+static spinlock sl=9;
+
+bool ringbuffer_put(char c)
+{
+
+    x86_int_disable();
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"put wants lock");
+    lock_spin(sl);
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by put");
+
+    if((back-1+size)%size==front)
+    {
+	lock_release(sl);
+	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put");
+	x86_int_enable();
+	return false;
+    }
+
+    buf[back]=c;
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"put %d %d (%c)", back, front,c);
+    back--;
+    back+=size;
+    back%=size;
+
+    lock_release(sl);
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put");
+    x86_int_enable();
+    
+    return true;
+}
+
+bool ringbuffer_get(char *c)
+{
+    x86_int_disable();
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"get wants lock");
+    lock_spin(sl);
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by get");
+    if(front==back)
+    {
+	lock_release(sl);
+	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get");
+	x86_int_enable();
+	*c='_';
+	return false;
+    }
+
+    *c=buf[front];
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"get %d %d (%c)", back, front,*c);
+
+    front--;
+    front+=size;
+    front%=size;
+
+    lock_release(sl);
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get");
+    x86_int_enable();
+
+    return true;
+}