--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/g726.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,122 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * g726.h - ITU G.726 codec.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2006 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.
+ *
+ * $Id: g726.h,v 1.26 2009/04/12 09:12:10 steveu Exp $
+ */
+
+/*! \file */
+
+#if !defined(_SPANDSP_G726_H_)
+#define _SPANDSP_G726_H_
+
+/*! \page g726_page G.726 encoding and decoding
+\section g726_page_sec_1 What does it do?
+
+The G.726 module is a bit exact implementation of the full ITU G.726 specification.
+It supports:
+    - 16 kbps, 24kbps, 32kbps, and 40kbps operation.
+    - Tandem adjustment, for interworking with A-law and u-law.
+    - Annex A support, for use in environments not using A-law or u-law.
+
+It passes the ITU tests.
+
+\section g726_page_sec_2 How does it work?
+???.
+*/
+
+enum
+{
+    G726_ENCODING_LINEAR = 0,   /* Interworking with 16 bit signed linear */
+    G726_ENCODING_ULAW,         /* Interworking with u-law */
+    G726_ENCODING_ALAW          /* Interworking with A-law */
+};
+
+enum
+{
+    G726_PACKING_NONE = 0,
+    G726_PACKING_LEFT = 1,
+    G726_PACKING_RIGHT = 2
+};
+
+/*!
+    G.726 state
+ */
+typedef struct g726_state_s g726_state_t;
+
+typedef int16_t (*g726_decoder_func_t)(g726_state_t *s, uint8_t code);
+
+typedef uint8_t (*g726_encoder_func_t)(g726_state_t *s, int16_t amp);
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! Initialise a G.726 encode or decode context.
+    \param s The G.726 context.
+    \param bit_rate The required bit rate for the ADPCM data.
+           The valid rates are 16000, 24000, 32000 and 40000.
+    \param ext_coding The coding used outside G.726.
+    \param packing One of the G.726_PACKING_xxx options.
+    \return A pointer to the G.726 context, or NULL for error. */
+SPAN_DECLARE(g726_state_t *) g726_init(g726_state_t *s, int bit_rate, int ext_coding, int packing);
+
+/*! Release a G.726 encode or decode context.
+    \param s The G.726 context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) g726_release(g726_state_t *s);
+
+/*! Free a G.726 encode or decode context.
+    \param s The G.726 context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) g726_free(g726_state_t *s);
+
+/*! Decode a buffer of G.726 ADPCM data to linear PCM, a-law or u-law.
+    \param s The G.726 context.
+    \param amp The audio sample buffer.
+    \param g726_data
+    \param g726_bytes
+    \return The number of samples returned. */
+SPAN_DECLARE(int) g726_decode(g726_state_t *s,
+                              int16_t amp[],
+                              const uint8_t g726_data[],
+                              int g726_bytes);
+
+/*! Encode a buffer of linear PCM data to G.726 ADPCM.
+    \param s The G.726 context.
+    \param g726_data The G.726 data produced.
+    \param amp The audio sample buffer.
+    \param len The number of samples in the buffer.
+    \return The number of bytes of G.726 data produced. */
+SPAN_DECLARE(int) g726_encode(g726_state_t *s,
+                              uint8_t g726_data[],
+                              const int16_t amp[],
+                              int len);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/