aboutsummaryrefslogtreecommitdiffstats
path: root/src/zix
diff options
context:
space:
mode:
Diffstat (limited to 'src/zix')
-rw-r--r--src/zix/ring.c222
-rw-r--r--src/zix/ring.h130
2 files changed, 352 insertions, 0 deletions
diff --git a/src/zix/ring.c b/src/zix/ring.c
new file mode 100644
index 0000000..3da4f7f
--- /dev/null
+++ b/src/zix/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 <stdint.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(__APPLE__)
+# include <libkern/OSAtomic.h>
+# define ZIX_FULL_BARRIER() OSMemoryBarrier()
+#elif defined(_WIN32)
+# include <windows.h>
+# define ZIX_FULL_BARRIER() MemoryBarrier()
+#elif (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
+# define ZIX_FULL_BARRIER() __sync_synchronize()
+#else
+# pragma message("warning: No memory barriers, possible SMP bugs")
+# define ZIX_FULL_BARRIER()
+#endif
+
+/* No support for any systems with separate read and write barriers */
+#define ZIX_READ_BARRIER() ZIX_FULL_BARRIER()
+#define ZIX_WRITE_BARRIER() ZIX_FULL_BARRIER()
+
+#include "zix/ring.h"
+
+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 >> 1;
+ size |= size >> 2;
+ size |= size >> 4;
+ size |= size >> 8;
+ size |= size >> 16;
+ 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;
+ } else {
+ 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;
+ } else if (r < w) {
+ return ((r - w + ring->size) & ring->size_mask) - 1;
+ } else {
+ 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;
+ } else {
+ 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;
+}
diff --git a/src/zix/ring.h b/src/zix/ring.h
new file mode 100644
index 0000000..f7f1893
--- /dev/null
+++ b/src/zix/ring.h
@@ -0,0 +1,130 @@
+/*
+ Copyright 2011-2014 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 `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);
+
+/**
+ @}
+ @}
+*/
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* ZIX_RING_H */
generated by cgit v1.2.1 (git 2.18.0) at 2024-11-15 00:57:11 +0000