Separate source from headers

1 files changed, 222 insertions, 0 deletions

diff --git a/src/ring.c b/src/ring.c
new file mode 100644
index 0000000..0607a18
--- /dev/null
+++ b/src/ring.c
@@ -0,0 +1,222 @@
+/*
+  Copyright 2011 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "zix/ring.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef HAVE_MLOCK
+#  include <sys/mman.h>
+#  define ZIX_MLOCK(ptr, size) mlock((ptr), (size))
+#elif defined(_WIN32)
+#  include <windows.h>
+#  define ZIX_MLOCK(ptr, size) VirtualLock((ptr), (size))
+#else
+#  pragma message("warning: No memory locking, possible RT violations")
+#  define ZIX_MLOCK(ptr, size)
+#endif
+
+#if defined(_MSC_VER)
+#  include <windows.h>
+#  define ZIX_READ_BARRIER() MemoryBarrier()
+#  define ZIX_WRITE_BARRIER() MemoryBarrier()
+#elif defined(__GNUC__)
+#  define ZIX_READ_BARRIER() __atomic_thread_fence(__ATOMIC_ACQUIRE)
+#  define ZIX_WRITE_BARRIER() __atomic_thread_fence(__ATOMIC_RELEASE)
+#else
+#  pragma message("warning: No memory barriers, possible SMP bugs")
+#  define ZIX_READ_BARRIER()
+#  define ZIX_WRITE_BARRIER()
+#endif
+
+struct ZixRingImpl {
+  uint32_t write_head; ///< Read index into buf
+  uint32_t read_head;  ///< Write index into buf
+  uint32_t size;       ///< Size (capacity) in bytes
+  uint32_t size_mask;  ///< Mask for fast modulo
+  char*    buf;        ///< Contents
+};
+
+static inline uint32_t
+next_power_of_two(uint32_t size)
+{
+  // http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+  size--;
+  size |= size >> 1u;
+  size |= size >> 2u;
+  size |= size >> 4u;
+  size |= size >> 8u;
+  size |= size >> 16u;
+  size++;
+  return size;
+}
+
+ZixRing*
+zix_ring_new(uint32_t size)
+{
+  ZixRing* ring    = (ZixRing*)malloc(sizeof(ZixRing));
+  ring->write_head = 0;
+  ring->read_head  = 0;
+  ring->size       = next_power_of_two(size);
+  ring->size_mask  = ring->size - 1;
+  ring->buf        = (char*)malloc(ring->size);
+  return ring;
+}
+
+void
+zix_ring_free(ZixRing* ring)
+{
+  free(ring->buf);
+  free(ring);
+}
+
+void
+zix_ring_mlock(ZixRing* ring)
+{
+  ZIX_MLOCK(ring, sizeof(ZixRing));
+  ZIX_MLOCK(ring->buf, ring->size);
+}
+
+void
+zix_ring_reset(ZixRing* ring)
+{
+  ring->write_head = 0;
+  ring->read_head  = 0;
+}
+
+static inline uint32_t
+read_space_internal(const ZixRing* ring, uint32_t r, uint32_t w)
+{
+  if (r < w) {
+    return w - r;
+  }
+
+  return (w - r + ring->size) & ring->size_mask;
+}
+
+uint32_t
+zix_ring_read_space(const ZixRing* ring)
+{
+  return read_space_internal(ring, ring->read_head, ring->write_head);
+}
+
+static inline uint32_t
+write_space_internal(const ZixRing* ring, uint32_t r, uint32_t w)
+{
+  if (r == w) {
+    return ring->size - 1;
+  }
+
+  if (r < w) {
+    return ((r - w + ring->size) & ring->size_mask) - 1;
+  }
+
+  return (r - w) - 1;
+}
+
+uint32_t
+zix_ring_write_space(const ZixRing* ring)
+{
+  return write_space_internal(ring, ring->read_head, ring->write_head);
+}
+
+uint32_t
+zix_ring_capacity(const ZixRing* ring)
+{
+  return ring->size - 1;
+}
+
+static inline uint32_t
+peek_internal(const ZixRing* ring,
+              uint32_t       r,
+              uint32_t       w,
+              uint32_t       size,
+              void*          dst)
+{
+  if (read_space_internal(ring, r, w) < size) {
+    return 0;
+  }
+
+  if (r + size < ring->size) {
+    memcpy(dst, &ring->buf[r], size);
+  } else {
+    const uint32_t first_size = ring->size - r;
+    memcpy(dst, &ring->buf[r], first_size);
+    memcpy((char*)dst + first_size, &ring->buf[0], size - first_size);
+  }
+
+  return size;
+}
+
+uint32_t
+zix_ring_peek(ZixRing* ring, void* dst, uint32_t size)
+{
+  return peek_internal(ring, ring->read_head, ring->write_head, size, dst);
+}
+
+uint32_t
+zix_ring_read(ZixRing* ring, void* dst, uint32_t size)
+{
+  const uint32_t r = ring->read_head;
+  const uint32_t w = ring->write_head;
+
+  if (peek_internal(ring, r, w, size, dst)) {
+    ZIX_READ_BARRIER();
+    ring->read_head = (r + size) & ring->size_mask;
+    return size;
+  }
+
+  return 0;
+}
+
+uint32_t
+zix_ring_skip(ZixRing* ring, uint32_t size)
+{
+  const uint32_t r = ring->read_head;
+  const uint32_t w = ring->write_head;
+  if (read_space_internal(ring, r, w) < size) {
+    return 0;
+  }
+
+  ZIX_READ_BARRIER();
+  ring->read_head = (r + size) & ring->size_mask;
+  return size;
+}
+
+uint32_t
+zix_ring_write(ZixRing* ring, const void* src, uint32_t size)
+{
+  const uint32_t r = ring->read_head;
+  const uint32_t w = ring->write_head;
+  if (write_space_internal(ring, r, w) < size) {
+    return 0;
+  }
+
+  if (w + size <= ring->size) {
+    memcpy(&ring->buf[w], src, size);
+    ZIX_WRITE_BARRIER();
+    ring->write_head = (w + size) & ring->size_mask;
+  } else {
+    const uint32_t this_size = ring->size - w;
+    memcpy(&ring->buf[w], src, this_size);
+    memcpy(&ring->buf[0], (const char*)src + this_size, size - this_size);
+    ZIX_WRITE_BARRIER();
+    ring->write_head = size - this_size;
+  }
+
+  return size;
+}