Index: /pjproject/trunk/pjmedia/build/pjmedia.dsp
===================================================================
--- /pjproject/trunk/pjmedia/build/pjmedia.dsp	(revision 2097)
+++ /pjproject/trunk/pjmedia/build/pjmedia.dsp	(revision 2098)
@@ -298,4 +298,8 @@
 # Begin Source File
 
+SOURCE=..\include\pjmedia\circbuf.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\include\pjmedia\clock.h
 # End Source File
Index: /pjproject/trunk/pjmedia/build/pjmedia.vcproj
===================================================================
--- /pjproject/trunk/pjmedia/build/pjmedia.vcproj	(revision 2097)
+++ /pjproject/trunk/pjmedia/build/pjmedia.vcproj	(revision 2098)
@@ -1106,4 +1106,8 @@
 			</File>
 			<File
+				RelativePath="..\include\pjmedia\circbuf.h"
+				>
+			</File>
+			<File
 				RelativePath="..\include\pjmedia\clock.h"
 				>
Index: /pjproject/trunk/pjmedia/build/wince-evc4/pjmedia_wince.vcp
===================================================================
--- /pjproject/trunk/pjmedia/build/wince-evc4/pjmedia_wince.vcp	(revision 2097)
+++ /pjproject/trunk/pjmedia/build/wince-evc4/pjmedia_wince.vcp	(revision 2098)
@@ -28352,4 +28352,8 @@
 # Begin Source File
 
+SOURCE=..\..\include\pjmedia\circbuf.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\..\include\pjmedia\clock.h
 # End Source File
Index: /pjproject/trunk/pjmedia/include/pjmedia/circbuf.h
===================================================================
--- /pjproject/trunk/pjmedia/include/pjmedia/circbuf.h	(revision 2098)
+++ /pjproject/trunk/pjmedia/include/pjmedia/circbuf.h	(revision 2098)
@@ -0,0 +1,338 @@
+/* $Id$ */
+/* 
+ * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
+ */
+
+#ifndef pjmedia_circ_buf_H
+#define pjmedia_circ_buf_H
+
+/**
+ * @file circbuf.h
+ * @brief Circular Buffer.
+ */
+
+#include <pj/assert.h>
+#include <pj/errno.h>
+#include <pj/pool.h>
+
+/**
+ * @defgroup PJMED_CIRCBUF Circular Buffer
+ * @ingroup PJMEDIA_FRAME_OP
+ * @brief Circular buffer manages read and write contiguous audio samples in a 
+ * non-contiguous buffer as if the buffer were contiguous. This should give
+ * better performance than keeping contiguous samples in a contiguous buffer,
+ * since read/write operations will only update the pointers, instead of 
+ * shifting audio samples.
+ *
+ * @{
+ *
+ * This section describes PJMEDIA's implementation of circular buffer.
+ */
+
+/* Algorithm checkings, for development purpose only */
+#if 0
+#   define PJMEDIA_CIRC_BUF_CHECK(x) pj_assert(x)
+#else
+#   define PJMEDIA_CIRC_BUF_CHECK(x)
+#endif
+
+PJ_BEGIN_DECL
+
+/** 
+ * Circular buffer structure
+ */
+typedef struct pjmedia_circ_buf {
+    pj_int16_t	    *buf;	    /**< The buffer			*/
+    unsigned	     capacity;	    /**< Buffer capacity, in samples	*/
+
+    pj_int16_t	    *start;	    /**< Pointer to the first sample	*/
+    unsigned	     len;	    /**< Audio samples length, 
+					 in samples			*/
+} pjmedia_circ_buf;
+
+
+/**
+ * Create the circular buffer.
+ *
+ * @param pool		    Pool where the circular buffer will be allocated
+ *			    from.
+ * @param capacity	    Capacity of the buffer, in samples.
+ * @param p_cb		    Pointer to receive the circular buffer instance.
+ *
+ * @return		    PJ_SUCCESS if the circular buffer has been
+ *			    created successfully, otherwise the appropriate
+ *			    error will be returned.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_create(pj_pool_t *pool, 
+					       unsigned capacity, 
+					       pjmedia_circ_buf **p_cb)
+{
+    pjmedia_circ_buf *cbuf;
+
+    cbuf = PJ_POOL_ZALLOC_T(pool, pjmedia_circ_buf);
+    cbuf->buf = (pj_int16_t*) pj_pool_calloc(pool, capacity, 
+					     sizeof(pj_int16_t));
+    cbuf->capacity = capacity;
+    cbuf->start = cbuf->buf;
+    cbuf->len = 0;
+
+    *p_cb = cbuf;
+
+    return PJ_SUCCESS;
+}
+
+
+/**
+ * Reset the circular buffer.
+ *
+ * @param circbuf	    The circular buffer.
+ *
+ * @return		    PJ_SUCCESS when successful.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_reset(pjmedia_circ_buf *circbuf)
+{
+    circbuf->start = circbuf->buf;
+    circbuf->len = 0;
+
+    return PJ_SUCCESS;
+}
+
+
+/**
+ * Get the circular buffer length, it is number of samples buffered in the 
+ * circular buffer.
+ *
+ * @param circbuf	    The circular buffer.
+ *
+ * @return		    The buffer length.
+ */
+PJ_INLINE(unsigned) pjmedia_circ_buf_get_len(pjmedia_circ_buf *circbuf)
+{
+    return circbuf->len;
+}
+
+
+/**
+ * Set circular buffer length. This is useful when audio buffer is manually 
+ * manipulated by the user, e.g: shrinked, expanded.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param len		    The new buffer length.
+ */
+PJ_INLINE(void) pjmedia_circ_buf_set_len(pjmedia_circ_buf *circbuf,
+					 unsigned len)
+{
+    PJMEDIA_CIRC_BUF_CHECK(len <= circbuf->capacity);
+    circbuf->len = len;
+}
+
+
+/**
+ * Advance the read pointer of circular buffer. This function will discard
+ * the skipped samples while advancing the read pointer, thus reducing 
+ * the buffer length.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param count		    Distance from current read pointer, can only be
+ *			    possitive number, in samples.
+ *
+ * @return		    PJ_SUCCESS when successful, otherwise the appropriate 
+ *			    error will be returned.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_adv_read_ptr(pjmedia_circ_buf *circbuf, 
+						     unsigned count)
+{
+    if (count >= circbuf->len)
+	return pjmedia_circ_buf_reset(circbuf);
+
+    PJMEDIA_CIRC_BUF_CHECK(count <= circbuf->len);
+
+    circbuf->start += count;
+    if (circbuf->start >= circbuf->buf + circbuf->capacity) 
+	circbuf->start -= circbuf->capacity;
+    circbuf->len -= count;
+
+    return PJ_SUCCESS;
+}
+
+
+/**
+ * Advance the write pointer of circular buffer. Since write pointer is always
+ * pointing to a sample after the end of sample, so this function also means
+ * increasing the buffer length.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param count		    Distance from current write pointer, can only be
+ *			    possitive number, in samples.
+ *
+ * @return		    PJ_SUCCESS when successful, otherwise the appropriate 
+ *			    error will be returned.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_adv_write_ptr(pjmedia_circ_buf *circbuf,
+						      unsigned count)
+{
+    if (count + circbuf->len > circbuf->capacity)
+	return PJ_ETOOBIG;
+
+    circbuf->len += count;
+
+    return PJ_SUCCESS;
+}
+
+
+/**
+ * Get the real buffer addresses containing the audio samples.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param reg1		    Pointer to store the first buffer address.
+ * @param reg1_len	    Pointer to store the length of the first buffer, 
+ *			    in samples.
+ * @param reg2		    Pointer to store the second buffer address.
+ * @param reg2_len	    Pointer to store the length of the second buffer, 
+ *			    in samples.
+ */
+PJ_INLINE(void) pjmedia_circ_buf_get_read_regions(pjmedia_circ_buf *circbuf, 
+						  pj_int16_t **reg1, 
+						  unsigned *reg1_len, 
+						  pj_int16_t **reg2, 
+						  unsigned *reg2_len)
+{
+    *reg1 = circbuf->start;
+    *reg1_len = circbuf->len;
+    if (*reg1 + *reg1_len > circbuf->buf + circbuf->capacity) {
+	*reg1_len = circbuf->buf + circbuf->capacity - circbuf->start;
+	*reg2 = circbuf->buf;
+	*reg2_len = circbuf->len - *reg1_len;
+    } else {
+	*reg2 = NULL;
+	*reg2_len = 0;
+    }
+
+    PJMEDIA_CIRC_BUF_CHECK(*reg1_len != 0 || (*reg1_len == 0 && circbuf->len == 0));
+    PJMEDIA_CIRC_BUF_CHECK(*reg1_len + *reg2_len == circbuf->len);
+}
+
+
+/**
+ * Get the real buffer addresses that is empty or writeable.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param reg1		    Pointer to store the first buffer address.
+ * @param reg1_len	    Pointer to store the length of the first buffer, 
+ *			    in samples.
+ * @param reg2		    Pointer to store the second buffer address.
+ * @param reg2_len	    Pointer to store the length of the second buffer, 
+ *			    in samples.
+ */
+PJ_INLINE(void) pjmedia_circ_buf_get_write_regions(pjmedia_circ_buf *circbuf, 
+						   pj_int16_t **reg1, 
+						   unsigned *reg1_len, 
+						   pj_int16_t **reg2, 
+						   unsigned *reg2_len)
+{
+    *reg1 = circbuf->start + circbuf->len;
+    if (*reg1 >= circbuf->buf + circbuf->capacity)
+	*reg1 -= circbuf->capacity;
+    *reg1_len = circbuf->capacity - circbuf->len;
+    if (*reg1 + *reg1_len > circbuf->buf + circbuf->capacity) {
+	*reg1_len = circbuf->buf + circbuf->capacity - *reg1;
+	*reg2 = circbuf->buf;
+	*reg2_len = circbuf->start - circbuf->buf;
+    } else {
+	*reg2 = NULL;
+	*reg2_len = 0;
+    }
+
+    PJMEDIA_CIRC_BUF_CHECK(*reg1_len != 0 || (*reg1_len == 0 && circbuf->len == 0));
+    PJMEDIA_CIRC_BUF_CHECK(*reg1_len + *reg2_len == circbuf->capacity - circbuf->len);
+}
+
+
+/**
+ * Read audio samples from the circular buffer.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param data		    Buffer to store the read audio samples.
+ * @param count		    Number of samples being read.
+ *
+ * @return		    PJ_SUCCESS when successful, otherwise the appropriate 
+ *			    error will be returned.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_read(pjmedia_circ_buf *circbuf, 
+					     pj_int16_t *data, 
+					     unsigned count)
+{
+    pj_int16_t *reg1, *reg2;
+    unsigned reg1cnt, reg2cnt;
+
+    /* Data in the buffer is less than requested */
+    if (count > circbuf->len)
+	return PJ_ETOOBIG;
+
+    pjmedia_circ_buf_get_read_regions(circbuf, &reg1, &reg1cnt, 
+				      &reg2, &reg2cnt);
+    if (reg1cnt >= count) {
+	pjmedia_copy_samples(data, reg1, count);
+    } else {
+	pjmedia_copy_samples(data, reg1, reg1cnt);
+	pjmedia_copy_samples(data + reg1cnt, reg2, count - reg1cnt);
+    }
+
+    return pjmedia_circ_buf_adv_read_ptr(circbuf, count);
+}
+
+
+/**
+ * Write audio samples to the circular buffer.
+ *
+ * @param circbuf	    The circular buffer.
+ * @param data		    Audio samples to be written.
+ * @param count		    Number of samples being written.
+ *
+ * @return		    PJ_SUCCESS when successful, otherwise the appropriate 
+ *			    error will be returned.
+ */
+PJ_INLINE(pj_status_t) pjmedia_circ_buf_write(pjmedia_circ_buf *circbuf, 
+					      pj_int16_t *data, 
+					      unsigned count)
+{
+    pj_int16_t *reg1, *reg2;
+    unsigned reg1cnt, reg2cnt;
+
+    /* Data to write is larger than buffer can store */
+    if (count > circbuf->capacity - circbuf->len)
+	return PJ_ETOOBIG;
+
+    pjmedia_circ_buf_get_write_regions(circbuf, &reg1, &reg1cnt, 
+				       &reg2, &reg2cnt);
+    if (reg1cnt >= count) {
+	pjmedia_copy_samples(reg1, data, count);
+    } else {
+	pjmedia_copy_samples(reg1, data, reg1cnt);
+	pjmedia_copy_samples(reg2, data + reg1cnt, count - reg1cnt);
+    }
+
+    return pjmedia_circ_buf_adv_write_ptr(circbuf, count);
+}
+
+PJ_END_DECL
+
+/**
+ * @}
+ */
+
+#endif
