--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/ima_adpcm.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,117 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * ima_adpcm.c - Conversion routines between linear 16 bit PCM data and
+ *		         IMA/DVI/Intel ADPCM format.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2004 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Based on a bit from here, a bit from there, eye of toad,
+ * ear of bat, etc - plus, of course, my own 2 cents.
+ *
+ * $Id: ima_adpcm.h,v 1.25 2009/04/11 18:11:19 steveu Exp $
+ */
+
+/*! \file */
+
+#if !defined(_SPANDSP_IMA_ADPCM_H_)
+#define _SPANDSP_IMA_ADPCM_H_
+
+/*! \page ima_adpcm_page IMA/DVI/Intel ADPCM encoding and decoding
+\section ima_adpcm_page_sec_1 What does it do?
+IMA ADPCM offers a good balance of simplicity and quality at a rate of
+32kbps.
+
+\section ima_adpcm_page_sec_2 How does it work?
+
+\section ima_adpcm_page_sec_3 How do I use it?
+*/
+
+enum
+{
+    /*! IMA4 is the original IMA ADPCM variant */
+    IMA_ADPCM_IMA4 = 0,
+    /*! DVI4 is the IMA ADPCM variant defined in RFC3551 */
+    IMA_ADPCM_DVI4 = 1,
+    /*! VDVI is the variable bit rate IMA ADPCM variant defined in RFC3551 */
+    IMA_ADPCM_VDVI = 2
+};
+
+/*!
+    IMA (DVI/Intel) ADPCM conversion state descriptor. This defines the state of
+    a single working instance of the IMA ADPCM converter. This is used for
+    either linear to ADPCM or ADPCM to linear conversion.
+*/
+typedef struct ima_adpcm_state_s ima_adpcm_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! Initialise an IMA ADPCM encode or decode context.
+    \param s The IMA ADPCM context.
+    \param variant IMA_ADPCM_IMA4, IMA_ADPCM_DVI4, or IMA_ADPCM_VDVI.
+    \param chunk_size The size of a chunk, in samples. A chunk size of
+           zero sample samples means treat each encode or decode operation
+           as a chunk.
+    \return A pointer to the IMA ADPCM context, or NULL for error. */
+SPAN_DECLARE(ima_adpcm_state_t *) ima_adpcm_init(ima_adpcm_state_t *s,
+                                                 int variant,
+                                                 int chunk_size);
+
+/*! Release an IMA ADPCM encode or decode context.
+    \param s The IMA ADPCM context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) ima_adpcm_release(ima_adpcm_state_t *s);
+
+/*! Free an IMA ADPCM encode or decode context.
+    \param s The IMA ADPCM context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) ima_adpcm_free(ima_adpcm_state_t *s);
+
+/*! Encode a buffer of linear PCM data to IMA ADPCM.
+    \param s The IMA ADPCM context.
+    \param ima_data The IMA ADPCM data produced.
+    \param amp The audio sample buffer.
+    \param len The number of samples in the buffer.
+    \return The number of bytes of IMA ADPCM data produced. */
+SPAN_DECLARE(int) ima_adpcm_encode(ima_adpcm_state_t *s,
+                                   uint8_t ima_data[],
+                                   const int16_t amp[],
+                                   int len);
+
+/*! Decode a buffer of IMA ADPCM data to linear PCM.
+    \param s The IMA ADPCM context.
+    \param amp The audio sample buffer.
+    \param ima_data The IMA ADPCM data
+    \param ima_bytes The number of bytes of IMA ADPCM data
+    \return The number of samples returned. */
+SPAN_DECLARE(int) ima_adpcm_decode(ima_adpcm_state_t *s,
+                                   int16_t amp[],
+                                   const uint8_t ima_data[],
+                                   int ima_bytes);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/