more hacking

Move plugin API to separate directory for now
Add ringbuffer and way to get ringbuffer from a port

spa/lib/ringbuffer.c

@@ -0,0 +1,185 @@
+/* Simple Plugin API
+ * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <spa/ringbuffer.h>
+
+/**
+ * spa_ringbuffer_init:
+ * @rbuf: a #SpaRingbuffer
+ * @data: pointer to data
+ * @size: size of @data
+ *
+ * Initialize a #SpaRingbuffer with @data and @size.
+ * When size is a power of 2, size_mask will be set with the mask to
+ * efficiently wrap around the indexes.
+ *
+ * Returns: #SPA_RESULT_OK on success
+ *          #SPA_RESULT_INVALID_ARGUMENTS when data or rbuf is %NULL
+ */
+SpaResult
+spa_ringbuffer_init (SpaRingbuffer *rbuf,
+                     uint8_t *data, size_t size)
+{
+  if (rbuf == NULL || data == NULL || size == 0)
+    return SPA_RESULT_INVALID_ARGUMENTS;
+
+  rbuf->data = data;
+  rbuf->size = size;
+  rbuf->readindex = 0;
+  rbuf->writeindex = 0;
+  if ((size & (size - 1)) == 0)
+    rbuf->size_mask = size - 1;
+  else
+    rbuf->size_mask = 0;
+
+  return SPA_RESULT_OK;
+}
+
+/**
+ * spa_ringbuffer_clear:
+ * @rbuf: a #SpaRingbuffer
+ *
+ * Clear @rbuf
+ *
+ * Returns: #SPA_RESULT_OK
+ */
+SpaResult
+spa_ringbuffer_clear (SpaRingbuffer *rbuf)
+{
+  rbuf->readindex = 0;
+  rbuf->writeindex = 0;
+  return SPA_RESULT_OK;
+}
+
+/**
+ * spa_ringbuffer_get_read_areas:
+ * @rbuf: a #SpaRingbuffer
+ * @areas: an array of #SpaRingbufferArea
+ *
+ * Fill @areas with pointers to read from. The total amount of
+ * bytes that can be read can be obtained by summing the areas len fields.
+ *
+ * Returns: #SPA_RESULT_OK
+ */
+SpaResult
+spa_ringbuffer_get_read_areas (SpaRingbuffer      *rbuf,
+                               SpaRingbufferArea   areas[2])
+{
+  size_t avail, end, w, r;
+
+  w = rbuf->writeindex;
+  r = rbuf->readindex;
+
+  if (w > r) {
+    avail = w - r;
+  } else {
+    avail = (w - r + rbuf->size);
+    avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
+  }
+  end = r + avail;
+  if (end > rbuf->size) {
+    areas[0].data = &rbuf->data[r];
+    areas[0].len = rbuf->size - r;
+    areas[1].data = rbuf->data;
+    areas[1].len = end - rbuf->size;
+  } else {
+    areas[0].data = &rbuf->data[r];
+    areas[0].len = avail;
+    areas[1].len = 0;
+  }
+  return SPA_RESULT_OK;
+}
+
+/**
+ * spa_ringbuffer_read_advance:
+ * @rbuf: a #SpaRingbuffer
+ * @len: number of bytes to advance
+ *
+ * Advance the read pointer by @len
+ *
+ * Returns: #SPA_RESULT_OK
+ */
+SpaResult
+spa_ringbuffer_read_advance (SpaRingbuffer      *rbuf,
+                             ssize_t             len)
+{
+  size_t tmp = rbuf->readindex + len;
+  rbuf->readindex = (rbuf->size_mask ? tmp & rbuf->size_mask : tmp % rbuf->size);
+  return SPA_RESULT_OK;
+}
+
+/**
+ * spa_ringbuffer_get_write_areas:
+ * @rbuf: a #SpaRingbuffer
+ * @areas: an array of #SpaRingbufferArea
+ *
+ * Fill @areas with pointers to write to. The total amount of
+ * bytes that can be written can be obtained by summing the areas len fields.
+ *
+ * Returns: #SPA_RESULT_OK
+ */
+SpaResult
+spa_ringbuffer_get_write_areas (SpaRingbuffer      *rbuf,
+                                SpaRingbufferArea   areas[2])
+{
+  size_t avail, end, w, r;
+
+  w = rbuf->writeindex;
+  r = rbuf->readindex;
+
+  if (w > r) {
+    avail = (r - w + rbuf->size);
+    avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
+    avail -= 1;
+  } else if (w < r) {
+    avail = r - w - 1;
+  } else {
+    avail = rbuf->size - 1;
+  }
+  end = w + avail;
+  if (end > rbuf->size) {
+    areas[0].data = &rbuf->data[w];
+    areas[0].len = rbuf->size - w;
+    areas[1].data = rbuf->data;
+    areas[1].len = end - rbuf->size;
+  } else {
+    areas[0].data = &rbuf->data[w];
+    areas[0].len = avail;
+    areas[1].len = 0;
+  }
+  return SPA_RESULT_OK;
+}
+
+/**
+ * spa_ringbuffer_write_advance:
+ * @rbuf: a #SpaRingbuffer
+ * @len: number of bytes to advance
+ *
+ * Advance the write pointer by @len
+ *
+ * Returns: #SPA_RESULT_OK
+ */
+SpaResult
+spa_ringbuffer_write_advance (SpaRingbuffer      *rbuf,
+                              ssize_t             len)
+{
+  size_t tmp = rbuf->writeindex + len;
+  rbuf->writeindex = (rbuf->size_mask ? tmp & rbuf->size_mask : tmp % rbuf->size);
+  return SPA_RESULT_OK;
+}