--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/spandsp/ima_adpcm.h	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,109 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * imaadpcm.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
+ *
+ * Based on a bit from here, a bit from there, eye of toad,
+ * ear of bat, etc - plus, of course, my own 2 cents.
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: ima_adpcm.h,v 1.12 2006/10/24 13:45:28 steveu Exp $
+ */
+
+/*! \file */
+
+#if !defined(_IMA_ADPCM_H_)
+#define _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
+{
+    IMA_ADPCM_DVI4 = 0,
+    IMA_ADPCM_VDVI = 1
+};
+
+/*!
+    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
+{
+    int variant;
+    int last;
+    int step_index;
+    uint16_t ima_byte;
+    int bits;
+} ima_adpcm_state_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*! Initialise an IMA ADPCM encode or decode context.
+    \param s The IMA ADPCM context
+    \param variant ???
+    \return A pointer to the IMA ADPCM context, or NULL for error. */
+ima_adpcm_state_t *ima_adpcm_init(ima_adpcm_state_t *s, int variant);
+
+/*! Free an IMA ADPCM encode or decode context.
+    \param s The IMA ADPCM context.
+    \return 0 for OK. */
+int ima_adpcm_release(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. */
+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
+    \param ima_bytes
+    \return The number of samples returned. */
+int ima_adpcm_decode(ima_adpcm_state_t *s,
+                     int16_t amp[],
+                     const uint8_t ima_data[],
+                     int ima_bytes);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/