1 files changed, 159 insertions, 0 deletions
diff --git a/lib/nghttp3_ringbuf.c b/lib/nghttp3_ringbuf.c
new file mode 100644
index 0000000..75ef7ad
--- /dev/null
+++ b/lib/nghttp3_ringbuf.c
@@ -0,0 +1,159 @@
+/*
+ * nghttp3
+ *
+ * Copyright (c) 2019 nghttp3 contributors
+ * 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 "nghttp3_ringbuf.h"
+
+#include <assert.h>
+#include <string.h>
+#ifdef WIN32
+#  include <intrin.h>
+#endif
+
+#include "nghttp3_macro.h"
+
+#if defined(_MSC_VER) && (defined(_M_ARM) || defined(_M_ARM64))
+unsigned int __popcnt(unsigned int x) {
+  unsigned int c = 0;
+  for (; x; ++c) {
+    x &= x - 1;
+  }
+  return c;
+}
+#endif
+
+int nghttp3_ringbuf_init(nghttp3_ringbuf *rb, size_t nmemb, size_t size,
+                         const nghttp3_mem *mem) {
+  if (nmemb) {
+#ifdef WIN32
+    assert(1 == __popcnt((unsigned int)nmemb));
+#else
+    assert(1 == __builtin_popcount((unsigned int)nmemb));
+#endif
+
+    rb->buf = nghttp3_mem_malloc(mem, nmemb * size);
+    if (rb->buf == NULL) {
+      return NGHTTP3_ERR_NOMEM;
+    }
+  } else {
+    rb->buf = NULL;
+  }
+
+  rb->mem = mem;
+  rb->nmemb = nmemb;
+  rb->size = size;
+  rb->first = 0;
+  rb->len = 0;
+
+  return 0;
+}
+
+void nghttp3_ringbuf_free(nghttp3_ringbuf *rb) {
+  if (rb == NULL) {
+    return;
+  }
+
+  nghttp3_mem_free(rb->mem, rb->buf);
+}
+
+void *nghttp3_ringbuf_push_front(nghttp3_ringbuf *rb) {
+  rb->first = (rb->first - 1) & (rb->nmemb - 1);
+  rb->len = nghttp3_min(rb->nmemb, rb->len + 1);
+
+  return (void *)&rb->buf[rb->first * rb->size];
+}
+
+void *nghttp3_ringbuf_push_back(nghttp3_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 nghttp3_ringbuf_pop_front(nghttp3_ringbuf *rb) {
+  rb->first = (rb->first + 1) & (rb->nmemb - 1);
+  --rb->len;
+}
+
+void nghttp3_ringbuf_pop_back(nghttp3_ringbuf *rb) {
+  assert(rb->len);
+  --rb->len;
+}
+
+void nghttp3_ringbuf_resize(nghttp3_ringbuf *rb, size_t len) {
+  assert(len <= rb->nmemb);
+  rb->len = len;
+}
+
+void *nghttp3_ringbuf_get(nghttp3_ringbuf *rb, size_t offset) {
+  assert(offset < rb->len);
+  offset = (rb->first + offset) & (rb->nmemb - 1);
+  return &rb->buf[offset * rb->size];
+}
+
+int nghttp3_ringbuf_full(nghttp3_ringbuf *rb) { return rb->len == rb->nmemb; }
+
+int nghttp3_ringbuf_reserve(nghttp3_ringbuf *rb, size_t nmemb) {
+  uint8_t *buf;
+
+  if (rb->nmemb >= nmemb) {
+    return 0;
+  }
+
+#ifdef WIN32
+  assert(1 == __popcnt((unsigned int)nmemb));
+#else
+  assert(1 == __builtin_popcount((unsigned int)nmemb));
+#endif
+
+  buf = nghttp3_mem_malloc(rb->mem, nmemb * rb->size);
+  if (buf == NULL) {
+    return NGHTTP3_ERR_NOMEM;
+  }
+
+  if (rb->buf != NULL) {
+    if (rb->first + rb->len <= rb->nmemb) {
+      memcpy(buf, rb->buf + rb->first * rb->size, rb->len * rb->size);
+      rb->first = 0;
+    } else {
+      memcpy(buf, rb->buf + rb->first * rb->size,
+             (rb->nmemb - rb->first) * rb->size);
+      memcpy(buf + (rb->nmemb - rb->first) * rb->size, rb->buf,
+             (rb->len - (rb->nmemb - rb->first)) * rb->size);
+      rb->first = 0;
+    }
+
+    nghttp3_mem_free(rb->mem, rb->buf);
+  }
+
+  rb->buf = buf;
+  rb->nmemb = nmemb;
+
+  return 0;
+}