X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?p=palacios.git;a=blobdiff_plain;f=geekos%2Fsrc%2Fgeekos%2Fring_buffer.c;fp=geekos%2Fsrc%2Fgeekos%2Fring_buffer.c;h=8f08dd3ce0253abea7e529a6b6dab548d70e60df;hp=0000000000000000000000000000000000000000;hb=ddc16b0737cf58f7aa90a69c6652cdf4090aec51;hpb=626595465a2c6987606a6bc697df65130ad8c2d3

diff --git a/geekos/src/geekos/ring_buffer.c b/geekos/src/geekos/ring_buffer.c
new file mode 100644
index 0000000..8f08dd3
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+++ b/geekos/src/geekos/ring_buffer.c
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+/*
+ * 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]);
+  }
+}