1 files changed, 120 insertions, 0 deletions
diff --git a/lib/ngtcp2_ringbuf.c b/lib/ngtcp2_ringbuf.c
new file mode 100644
index 0000000..a6b3f73
--- /dev/null
+++ b/lib/ngtcp2_ringbuf.c
@@ -0,0 +1,120 @@
+/*
+ * ngtcp2
+ *
+ * Copyright (c) 2017 ngtcp2 contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "ngtcp2_ringbuf.h"
+
+#include <assert.h>
+#ifdef WIN32
+#  include <intrin.h>
+#endif
+
+#include "ngtcp2_macro.h"
+
+#if defined(_MSC_VER) && defined(_M_ARM64)
+unsigned int __popcnt(unsigned int x) {
+  unsigned int c = 0;
+  for (; x; ++c) {
+    x &= x - 1;
+  }
+  return c;
+}
+#endif
+
+int ngtcp2_ringbuf_init(ngtcp2_ringbuf *rb, size_t nmemb, size_t size,
+                        const ngtcp2_mem *mem) {
+  uint8_t *buf = ngtcp2_mem_malloc(mem, nmemb * size);
+  if (buf == NULL) {
+    return NGTCP2_ERR_NOMEM;
+  }
+
+  ngtcp2_ringbuf_buf_init(rb, nmemb, size, buf, mem);
+
+  return 0;
+}
+
+void ngtcp2_ringbuf_buf_init(ngtcp2_ringbuf *rb, size_t nmemb, size_t size,
+                             uint8_t *buf, const ngtcp2_mem *mem) {
+#ifdef WIN32
+  assert(1 == __popcnt((unsigned int)nmemb));
+#else
+  assert(1 == __builtin_popcount((unsigned int)nmemb));
+#endif
+
+  rb->buf = buf;
+  rb->mem = mem;
+  rb->nmemb = nmemb;
+  rb->size = size;
+  rb->first = 0;
+  rb->len = 0;
+}
+
+void ngtcp2_ringbuf_free(ngtcp2_ringbuf *rb) {
+  if (rb == NULL) {
+    return;
+  }
+
+  ngtcp2_mem_free(rb->mem, rb->buf);
+}
+
+void *ngtcp2_ringbuf_push_front(ngtcp2_ringbuf *rb) {
+  rb->first = (rb->first - 1) & (rb->nmemb - 1);
+  rb->len = ngtcp2_min(rb->nmemb, rb->len + 1);
+
+  return (void *)&rb->buf[rb->first * rb->size];
+}
+
+void *ngtcp2_ringbuf_push_back(ngtcp2_ringbuf *rb) {
+  size_t offset = (rb->first + rb->len) & (rb->nmemb - 1);
+
+  if (rb->len == rb->nmemb) {
+    rb->first = (rb->first + 1) & (rb->nmemb - 1);
+  } else {
+    ++rb->len;
+  }
+
+  return (void *)&rb->buf[offset * rb->size];
+}
+
+void ngtcp2_ringbuf_pop_front(ngtcp2_ringbuf *rb) {
+  rb->first = (rb->first + 1) & (rb->nmemb - 1);
+  --rb->len;
+}
+
+void ngtcp2_ringbuf_pop_back(ngtcp2_ringbuf *rb) {
+  assert(rb->len);
+  --rb->len;
+}
+
+void ngtcp2_ringbuf_resize(ngtcp2_ringbuf *rb, size_t len) {
+  assert(len <= rb->nmemb);
+  rb->len = len;
+}
+
+void *ngtcp2_ringbuf_get(ngtcp2_ringbuf *rb, size_t offset) {
+  assert(offset < rb->len);
+  offset = (rb->first + offset) & (rb->nmemb - 1);
+  return &rb->buf[offset * rb->size];
+}
+
+int ngtcp2_ringbuf_full(ngtcp2_ringbuf *rb) { return rb->len == rb->nmemb; }