Implement real-time safe sample loading.

1 files changed, 136 insertions, 0 deletions

diff --git a/plugins/eg-sampler.lv2/zix/ring.h b/plugins/eg-sampler.lv2/zix/ring.h
new file mode 100644
index 0000000..ea673fe
--- /dev/null
+++ b/plugins/eg-sampler.lv2/zix/ring.h
@@ -0,0 +1,136 @@
+/*
+  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.
+*/
+
+#ifndef ZIX_RING_H
+#define ZIX_RING_H
+
+#include <stdint.h>
+
+#include "zix/common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   @addtogroup zix
+   @{
+   @name Ring
+   @{
+*/
+
+/**
+   A lock-free ring buffer.
+
+   Thread-safe with a single reader and single writer, and realtime safe
+   on both ends.
+*/
+typedef struct ZixRingImpl ZixRing;
+
+/**
+   Create a new ring.
+   @param size Size in bytes (note this may be rounded up).
+
+   At most @c size - 1 bytes may be stored in the ring at once.
+*/
+ZixRing*
+zix_ring_new(uint32_t size);
+
+/**
+   Destroy a ring.
+*/
+void
+zix_ring_free(ZixRing* ring);
+
+/**
+   Lock the ring data into physical memory.
+
+   This function is NOT thread safe or real-time safe, but it should be called
+   after zix_ring_new() to lock all ring memory to avoid page faults while
+   using the ring (i.e. this function MUST be called first in order for the
+   ring to be truly real-time safe).
+
+*/
+void
+zix_ring_mlock(ZixRing* ring);
+
+/**
+   Reset (empty) a ring.
+
+   This function is NOT thread-safe, it may only be called when there are no
+   readers or writers.
+*/
+void
+zix_ring_reset(ZixRing* ring);
+
+/**
+   Return the number of bytes of space available for reading.
+*/
+uint32_t
+zix_ring_read_space(const ZixRing* ring);
+
+/**
+   Return the number of bytes of space available for writing.
+*/
+uint32_t
+zix_ring_write_space(const ZixRing* ring);
+
+/**
+   Return the capacity (i.e. total write space when empty).
+*/
+uint32_t
+zix_ring_capacity(const ZixRing* ring);
+
+/**
+   Read from the ring without advancing the read head.
+*/
+uint32_t
+zix_ring_peek(ZixRing* ring, void* dst, uint32_t size);
+
+/**
+   Read from the ring and advance the read head.
+*/
+uint32_t
+zix_ring_read(ZixRing* ring, void* dst, uint32_t size);
+
+/**
+   Skip data in the ring (advance read head without reading).
+*/
+uint32_t
+zix_ring_skip(ZixRing* ring, uint32_t size);
+
+/**
+   Write data to the ring.
+*/
+uint32_t
+zix_ring_write(ZixRing* ring, const void* src, uint32_t size);
+
+/**
+   Return a pointer to the current position of the write head.
+*/
+void*
+zix_ring_write_head(ZixRing* ring);
+
+/**
+   @}
+   @}
+*/
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif  /* ZIX_RING_H */