--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/private/t31.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,199 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * private/t31.h - A T.31 compatible class 1 FAX modem interface.
+ *
+ * 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.
+ *
+ * $Id: t31.h,v 1.7 2009/02/12 12:38:39 steveu Exp $
+ */
+
+#if !defined(_SPANDSP_PRIVATE_T31_H_)
+#define _SPANDSP_PRIVATE_T31_H_
+
+/*!
+    Analogue FAX front end channel descriptor. This defines the state of a single working
+    instance of an analogue line FAX front end.
+*/
+typedef struct
+{
+    fax_modems_state_t modems;
+
+    /*! The transmit signal handler to be used when the current one has finished sending. */
+    span_tx_handler_t *next_tx_handler;
+    void *next_tx_user_data;
+
+    /*! \brief No of data bits in current_byte. */
+    int bit_no;
+    /*! \brief The current data byte in progress. */
+    int current_byte;
+
+    /*! \brief Rx power meter, used to detect silence. */
+    power_meter_t rx_power;
+    /*! \brief Last sample, used for an elementary HPF for the power meter. */
+    int16_t last_sample;
+    /*! \brief The current silence threshold. */
+    int32_t silence_threshold_power;
+
+    /*! \brief Samples of silence heard */
+    int silence_heard;
+} t31_audio_front_end_state_t;
+
+/*!
+    Analogue FAX front end channel descriptor. This defines the state of a single working
+    instance of an analogue line FAX front end.
+*/
+typedef struct
+{
+    /*! \brief Internet Aware FAX mode bit mask. */
+    int iaf;
+    /*! \brief Required time between T.38 transmissions, in ms. */
+    int ms_per_tx_chunk;
+    /*! \brief Bit fields controlling the way data is packed into chunked for transmission. */
+    int chunking_modes;
+
+    /*! \brief Core T.38 IFP support */
+    t38_core_state_t t38;
+
+    /*! \brief The current transmit step being timed */
+    int timed_step;
+
+    /*! \brief TRUE is there has been some T.38 data missed */
+    int rx_data_missing;
+
+    /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current
+               rate and the current specified packet interval. */
+    int octets_per_data_packet;
+
+    /*! \brief An HDLC context used when sending HDLC messages to the terminal port
+               (ECM mode support). */
+    hdlc_tx_state_t hdlc_tx_term;
+    /*! \brief An HDLC context used when receiving HDLC messages from the terminal port.
+               (ECM mode support). */
+    hdlc_rx_state_t hdlc_rx_term;
+
+    struct
+    {
+        uint8_t buf[T31_T38_MAX_HDLC_LEN];
+        int len;
+    } hdlc_rx;
+
+    struct
+    {
+        /*! \brief The number of extra bits in a fully stuffed version of the
+                   contents of the HDLC transmit buffer. This is needed to accurately
+                   estimate the playout time for this frame, through an analogue modem. */
+        int extra_bits;
+    } hdlc_tx;
+
+    /*! \brief TRUE if we are using ECM mode. This is used to select HDLC faking, necessary
+               with clunky class 1 modems. */
+    int ecm_mode;
+
+    /*! \brief Counter for trailing non-ECM bytes, used to flush out the far end's modem. */
+    int non_ecm_trailer_bytes;
+
+    /*! \brief The next queued tramsit indicator */
+    int next_tx_indicator;
+    /*! \brief The current T.38 data type being transmitted */
+    int current_tx_data_type;
+
+    /*! \brief The current operating mode of the receiver. */
+    int current_rx_type;
+    /*! \brief The current operating mode of the transmitter. */
+    int current_tx_type;
+
+    /*! \brief Current transmission bit rate. */
+    int tx_bit_rate;
+    /*! \brief A "sample" count, used to time events. */
+    int32_t samples;
+    /*! \brief The value for samples at the next transmission point. */
+    int32_t next_tx_samples;
+    /*! \brief The current receive timeout. */
+    int32_t timeout_rx_samples;
+} t31_t38_front_end_state_t;
+
+/*!
+    T.31 descriptor. This defines the working state for a single instance of
+    a T.31 FAX modem.
+*/
+struct t31_state_s
+{
+    at_state_t at_state;
+    t31_modem_control_handler_t *modem_control_handler;
+    void *modem_control_user_data;
+
+    t31_audio_front_end_state_t audio;
+    t31_t38_front_end_state_t t38_fe;
+    /*! TRUE if working in T.38 mode. */
+    int t38_mode;
+
+    /*! HDLC buffer, for composing an HDLC frame from the computer to the channel. */
+    struct
+    {
+        uint8_t buf[T31_MAX_HDLC_LEN];
+        int len;
+        int ptr;
+        /*! \brief TRUE when the end of HDLC data from the computer has been detected. */
+        int final;
+    } hdlc_tx;
+    /*! Buffer for data from the computer to the channel. */
+    struct
+    {
+        uint8_t data[T31_TX_BUF_LEN];
+        /*! \brief The number of bytes stored in transmit buffer. */
+        int in_bytes;
+        /*! \brief The number of bytes sent from the transmit buffer. */
+        int out_bytes;
+        /*! \brief TRUE if the flow of real data has started. */
+        int data_started;
+        /*! \brief TRUE if holding up further data into the buffer, for flow control. */
+        int holding;
+        /*! \brief TRUE when the end of non-ECM data from the computer has been detected. */
+        int final;
+    } tx;
+
+    /*! TRUE if DLE prefix just used */
+    int dled;
+
+	/*! \brief Samples of silence awaited, as specified in a "wait for silence" command */
+    int silence_awaited;
+
+    /*! \brief The current bit rate for the FAX fast message transfer modem. */
+    int bit_rate;
+    /*! \brief TRUE if a valid HDLC frame has been received in the current reception period. */
+    int rx_frame_received;
+
+    /*! \brief Samples elapsed in the current call */
+    int64_t call_samples;
+    int64_t dte_data_timeout;
+
+    /*! \brief The currently queued modem type. */
+    int modem;
+    /*! \brief TRUE when short training mode has been selected by the computer. */
+    int short_train;
+    queue_state_t *rx_queue;
+
+    /*! \brief Error and flow logging control */
+    logging_state_t logging;
+};
+
+#endif
+/*- End of file ------------------------------------------------------------*/