--- /dev/null
+/*
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National
+ * Science Foundation and the Department of Energy.
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico. You can find out more at
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu>
+ * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org>
+ * All rights reserved.
+ *
+ * Author: Jack Lange <jarusl@cs.northwestern.edu>
+ *
+ * This is free software. You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+
+#include <geekos/ring_buffer.h>
+#include <geekos/malloc.h>
+#include <geekos/ktypes.h>
+#include <geekos/debug.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_read_ptr(struct ring_buffer * ring) {
+ return (uchar_t *)(ring->buf + ring->start);
+}
+
+static inline uchar_t * get_write_ptr(struct ring_buffer * ring) {
+ return (uchar_t *)(ring->buf + ring->end);
+}
+
+
+static inline int get_read_section_size(struct ring_buffer * ring) {
+ return ring->size - ring->start;
+}
+
+static inline int get_write_section_size(struct ring_buffer * ring) {
+ return ring->size - ring->end;
+}
+
+static inline int is_read_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_read_section_size(ring) < len) {
+ return 1;
+ }
+ }
+ return 0;
+}
+
+
+static inline int is_write_loop(struct ring_buffer * ring, uint_t len) {
+ if ((ring->end >= ring->start) && (ring->current_len < ring->size)) {
+ // end is past the end of the buffer
+ if (get_write_section_size(ring) < len) {
+ return 1;
+ }
+ }
+ return 0;
+}
+
+
+int rb_data_len(struct ring_buffer * ring) {
+ return ring->current_len;
+}
+
+int rb_capacity(struct ring_buffer * ring) {
+ return ring->size;
+}
+
+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_read_loop(ring, read_len)) {
+ int section_len = get_read_section_size(ring);
+
+ memcpy(dst, get_read_ptr(ring), section_len);
+ memcpy(dst + section_len, ring->buf, read_len - section_len);
+
+ ring->start = read_len - section_len;
+ } else {
+ memcpy(dst, get_read_ptr(ring), read_len);
+
+ ring->start += read_len;
+ }
+
+ ring->current_len -= read_len;
+
+ return read_len;
+}
+
+
+
+
+int rb_peek(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_read_loop(ring, read_len)) {
+ int section_len = get_read_section_size(ring);
+
+ memcpy(dst, get_read_ptr(ring), section_len);
+ memcpy(dst + section_len, ring->buf, read_len - section_len);
+ } else {
+ memcpy(dst, get_read_ptr(ring), read_len);
+ }
+
+ return read_len;
+}
+
+
+int rb_delete(struct ring_buffer * ring, uint_t len) {
+ int del_len = 0;
+ int ring_data_len = ring->current_len;
+
+ del_len = (len > ring_data_len) ? ring_data_len : len;
+
+ if (is_read_loop(ring, del_len)) {
+ int section_len = get_read_section_size(ring);
+ ring->start = del_len - section_len;
+ } else {
+ ring->start += del_len;
+ }
+
+ ring->current_len -= del_len;
+ return del_len;
+}
+
+
+int rb_write(struct ring_buffer * ring, char * src, uint_t len) {
+ int write_len = 0;
+ int ring_avail_space = ring->size - ring->current_len;
+
+ write_len = (len > ring_avail_space) ? ring_avail_space : len;
+
+
+ if (is_write_loop(ring, write_len)) {
+ int section_len = get_write_section_size(ring);
+
+ memcpy(get_write_ptr(ring), src, section_len);
+ ring->end = 0;
+
+ memcpy(get_write_ptr(ring), src + section_len, write_len - section_len);
+
+ ring->end += write_len - section_len;
+ } else {
+ memcpy(get_write_ptr(ring), src, write_len);
+
+ ring->end += write_len;
+ }
+
+ ring->current_len += write_len;
+
+ return write_len;
+}
+
+
+void print_ring_buffer(struct ring_buffer * ring) {
+ int ctr = 0;
+
+ for (ctr = 0; ctr < ring->current_len; ctr++) {
+ int index = (ctr + ring->start) % ring->size;
+
+ PrintBoth("Entry %d (index=%d): %c\n", ctr, index, ring->buf[index]);
+ }
+}
