added ring_buffer

diff --git a/palacios/include/geekos/ring_buffer.h b/palacios/include/geekos/ring_buffer.h
new file mode 100644 (file)
index 0000000..2e14891
--- /dev/null
+++ b/palacios/include/geekos/ring_buffer.h
@@ -0,0 +1,31 @@
+#ifndef __RING_BUFFER_H__
+#define __RING_BUFFER_H__
+
+
+#include <geekos/ktypes.h>
+
+
+struct ring_buffer {
+  uchar_t * buf;
+  uint_t size;
+
+  uint_t start;
+  uint_t end;
+  uint_t current_len;
+
+};
+
+
+void init_ring_buffer(struct ring_buffer * ring, uint_t size);
+struct ring_buffer * create_ring_buffer(uint_t size);
+
+void free_ring_buffer(struct ring_buffer * ring);
+
+
+int rb_read(struct ring_buffer * ring, char * dst, uint_t len);
+int rb_write(struct ring_buffer * ring, char * src, uint_t len);
+int rb_data_len(struct ring_buffer * ring);
+int rb_capacity(struct ring_buffer * ring);
+
+
+#endif // ! __RING_BUFFER_H__

diff --git a/palacios/src/geekos/ring_buffer.c b/palacios/src/geekos/ring_buffer.c
new file mode 100644 (file)
index 0000000..0e2f9b1
--- /dev/null
+++ b/palacios/src/geekos/ring_buffer.c
@@ -0,0 +1,76 @@
+#include <geekos/ring_buffer.h>
+#include <geekos/malloc.h>
+#include <geekos/ktypes.h>
+
+
+
+void init_ring_buffer(struct ring_buffer * ring, uint_t size) {
+  ring->buf = Malloc(size);
+  ring->size = size;
+  
+  ring->start = 0;
+  ring->end = 0;
+  ring->current_len = 0;
+}
+
+
+struct ring_buffer * create_ring_buffer(uint_t size) {
+  struct ring_buffer * ring = (struct ring_buffer *)Malloc(sizeof(struct ring_buffer));
+
+  init_ring_buffer(ring, size);
+
+  return ring;
+}
+
+void free_ring_buffer(struct ring_buffer * ring) {
+  Free(ring->buf);
+  Free(ring);
+}
+
+
+
+
+
+static inline uchar_t * get_buf_ptr(struct ring_buffer * ring) {
+  return (uchar_t *)&(ring->buf + ring->start);
+}
+
+
+static inline int get_section_size(struct ring_buffer * ring) {
+  return ring->size - ring->start;
+}
+
+static inline int is_loop(struct ring_buffer * ring, uint_t len) {
+  if ((ring->start >= ring->end) && (ring->current_len > 0)) {
+    // end is past the end of the buffer
+    if (get_section_size(ring) < len) {
+      return 1;
+    }
+  }
+
+  return 0;
+}
+
+
+int rb_read(struct ring_buffer * ring, char * dst, uint_t len) {
+  int read_len = 0;
+  int ring_data_len = ring->current_len;
+
+  read_len = (len > ring_data_len) ? ring_data_len : len;
+
+  if (is_loop(ring, read_len)) {
+    int first_len = get_section_size(ring);
+
+    memcpy(dst, get_buf_ptr(ring), first_len);
+    read_len -= first_len;
+    ring->start = 0;
+
+    memcpy(dst + first_len, get_buf_ptr, read_len);
+
+  } else {
+    memcpy(dst, get_buf_ptr(ring), read_len);
+  }
+
+  return read_len;
+  
+}