This update brings the fax modem handling into line with the upstream code

libs/spandsp/src/fax.c

@@ -354,35 +354,22 @@ static void fax_set_rx_type(void *user_data, int type, int bit_rate, int short_t
     t->current_rx_type = type;
     t->rx_bit_rate = bit_rate;
     if (use_hdlc)
-    {
-        fax_modems_set_put_bit(t, (put_bit_func_t) hdlc_rx_put_bit, &t->hdlc_rx);
         hdlc_rx_init(&t->hdlc_rx, FALSE, TRUE, HDLC_FRAMING_OK_THRESHOLD, t30_hdlc_accept, &s->t30);
-    }
-    else
-    {
-        fax_modems_set_put_bit(t, (put_bit_func_t) t30_non_ecm_put_bit, &s->t30);
-    }
+
     switch (type)
     {
     case T30_MODEM_V21:
-        fsk_rx_init(&t->v21_rx, &preset_fsk_specs[FSK_V21CH2], FSK_FRAME_MODE_SYNC, (put_bit_func_t) hdlc_rx_put_bit, t->put_bit_user_data);
-        fsk_rx_signal_cutoff(&t->v21_rx, -45.5f);
+        fax_modems_start_slow_modem(t, FAX_MODEM_V21_RX);
         fax_modems_set_rx_handler(t, (span_rx_handler_t) &fsk_rx, &t->v21_rx, (span_rx_fillin_handler_t) &fsk_rx_fillin, &t->v21_rx);
         break;
+    case T30_MODEM_V17:
+        fax_modems_start_fast_modem(t, FAX_MODEM_V17_RX, bit_rate, short_train, use_hdlc);
+        break;
     case T30_MODEM_V27TER:
-        v27ter_rx_restart(&t->fast_modems.v27ter_rx, bit_rate, FALSE);
-        v27ter_rx_set_put_bit(&t->fast_modems.v27ter_rx, t->put_bit, t->put_bit_user_data);
-        fax_modems_set_rx_handler(t, &v27ter_v21_rx, s, &fax_modems_v27ter_v21_rx_fillin, t);
+        fax_modems_start_fast_modem(t, FAX_MODEM_V27TER_RX, bit_rate, short_train, use_hdlc);
         break;
     case T30_MODEM_V29:
-        v29_rx_restart(&t->fast_modems.v29_rx, bit_rate, FALSE);
-        v29_rx_set_put_bit(&t->fast_modems.v29_rx, t->put_bit, t->put_bit_user_data);
-        fax_modems_set_rx_handler(t, &v29_v21_rx, s, &fax_modems_v29_v21_rx_fillin, t);
-        break;
-    case T30_MODEM_V17:
-        v17_rx_restart(&t->fast_modems.v17_rx, bit_rate, short_train);
-        v17_rx_set_put_bit(&t->fast_modems.v17_rx, t->put_bit, t->put_bit_user_data);
-        fax_modems_set_rx_handler(t, &v17_v21_rx, s, &fax_modems_v17_v21_rx_fillin, t);
+        fax_modems_start_fast_modem(t, FAX_MODEM_V29_RX, bit_rate, short_train, use_hdlc);
         break;
     case T30_MODEM_DONE:
         span_log(&s->logging, SPAN_LOG_FLOW, "FAX exchange complete\n");
@@ -404,10 +391,6 @@ static void fax_set_tx_type(void *user_data, int type, int bit_rate, int short_t
     span_log(&s->logging, SPAN_LOG_FLOW, "Set tx type %d\n", type);
     if (t->current_tx_type == type)
         return;
-    if (use_hdlc)
-        fax_modems_set_get_bit(t, (get_bit_func_t) hdlc_tx_get_bit, &t->hdlc_tx);
-    else
-        fax_modems_set_get_bit(t, (get_bit_func_t) t30_non_ecm_get_bit, &s->t30);
     switch (type)
     {
     case T30_MODEM_PAUSE:
@@ -428,7 +411,7 @@ static void fax_set_tx_type(void *user_data, int type, int bit_rate, int short_t
         t->transmit = TRUE;
         break;
     case T30_MODEM_V21:
-        fsk_tx_init(&t->v21_tx, &preset_fsk_specs[FSK_V21CH2], t->get_bit, t->get_bit_user_data);
+        fax_modems_start_slow_modem(t, FAX_MODEM_V21_TX);
         /* The spec says 1s +-15% of preamble. So, the minimum is 32 octets. */
         fax_modems_hdlc_tx_flags(t, 32);
         /* Pause before switching from phase C, as per T.30 5.3.2.2. If we omit this, the receiver
@@ -444,8 +427,7 @@ static void fax_set_tx_type(void *user_data, int type, int bit_rate, int short_t
         silence_gen_alter(&t->silence_gen, ms_to_samples(75));
         /* For any fast modem, set 200ms of preamble flags */
         fax_modems_hdlc_tx_flags(t, bit_rate/(8*5));
-        v17_tx_restart(&t->fast_modems.v17_tx, bit_rate, t->use_tep, short_train);
-        v17_tx_set_get_bit(&t->fast_modems.v17_tx, t->get_bit, t->get_bit_user_data);
+        fax_modems_start_fast_modem(t, FAX_MODEM_V17_TX, bit_rate, short_train, use_hdlc);
         fax_modems_set_tx_handler(t, (span_tx_handler_t) &silence_gen, &t->silence_gen);
         fax_modems_set_next_tx_handler(t, (span_tx_handler_t) &v17_tx, &t->fast_modems.v17_tx);
         t->transmit = TRUE;
@@ -454,8 +436,7 @@ static void fax_set_tx_type(void *user_data, int type, int bit_rate, int short_t
         silence_gen_alter(&t->silence_gen, ms_to_samples(75));
         /* For any fast modem, set 200ms of preamble flags */
         fax_modems_hdlc_tx_flags(t, bit_rate/(8*5));
-        v27ter_tx_restart(&t->fast_modems.v27ter_tx, bit_rate, t->use_tep);
-        v27ter_tx_set_get_bit(&t->fast_modems.v27ter_tx, t->get_bit, t->get_bit_user_data);
+        fax_modems_start_fast_modem(t, FAX_MODEM_V27TER_TX, bit_rate, short_train, use_hdlc);
         fax_modems_set_tx_handler(t, (span_tx_handler_t) &silence_gen, &t->silence_gen);
         fax_modems_set_next_tx_handler(t, (span_tx_handler_t) &v27ter_tx, &t->fast_modems.v27ter_tx);
         t->transmit = TRUE;
@@ -464,8 +445,7 @@ static void fax_set_tx_type(void *user_data, int type, int bit_rate, int short_t
         silence_gen_alter(&t->silence_gen, ms_to_samples(75));
         /* For any fast modem, set 200ms of preamble flags */
         fax_modems_hdlc_tx_flags(t, bit_rate/(8*5));
-        v29_tx_restart(&t->fast_modems.v29_tx, bit_rate, t->use_tep);
-        v29_tx_set_get_bit(&t->fast_modems.v29_tx, t->get_bit, t->get_bit_user_data);
+        fax_modems_start_fast_modem(t, FAX_MODEM_V29_TX, bit_rate, short_train, use_hdlc);
         fax_modems_set_tx_handler(t, (span_tx_handler_t) &silence_gen, &t->silence_gen);
         fax_modems_set_next_tx_handler(t, (span_tx_handler_t) &v29_tx, &t->fast_modems.v29_tx);
         t->transmit = TRUE;

libs/spandsp/src/fax_modems.c

@@ -125,10 +125,10 @@ static void v17_rx_status_handler(void *user_data, int status)
         span_log(&s->logging, SPAN_LOG_FLOW, "Switching from V.17 + V.21 to V.17 (%.2fdBm0)\n", v17_rx_signal_power(&s->fast_modems.v17_rx));
         fax_modems_set_rx_handler(s, (span_rx_handler_t) &v17_rx, &s->fast_modems.v17_rx, (span_rx_fillin_handler_t) &v17_rx_fillin, &s->fast_modems.v17_rx);
         v17_rx_set_modem_status_handler(&s->fast_modems.v17_rx, NULL, s);
-        s->fast_modems.v17_rx.put_bit(s->fast_modems.v17_rx.put_bit_user_data, status);
         break;
     }
     /*endswitch*/
+    s->fast_modems.v17_rx.put_bit(s->fast_modems.v17_rx.put_bit_user_data, status);
 }
 /*- End of function --------------------------------------------------------*/
 
@@ -172,10 +172,10 @@ static void v27ter_rx_status_handler(void *user_data, int status)
         span_log(&s->logging, SPAN_LOG_FLOW, "Switching from V.27ter + V.21 to V.27ter (%.2fdBm0)\n", v27ter_rx_signal_power(&s->fast_modems.v27ter_rx));
         fax_modems_set_rx_handler(s, (span_rx_handler_t) &v27ter_rx, &s->fast_modems.v27ter_rx, (span_rx_fillin_handler_t) &v27ter_rx_fillin, &s->fast_modems.v27ter_rx);
         v27ter_rx_set_modem_status_handler(&s->fast_modems.v27ter_rx, NULL, s);
-        s->fast_modems.v27ter_rx.put_bit(s->fast_modems.v27ter_rx.put_bit_user_data, status);
         break;
     }
     /*endswitch*/
+    s->fast_modems.v27ter_rx.put_bit(s->fast_modems.v27ter_rx.put_bit_user_data, status);
 }
 /*- End of function --------------------------------------------------------*/
 
@@ -219,10 +219,10 @@ static void v29_rx_status_handler(void *user_data, int status)
         span_log(&s->logging, SPAN_LOG_FLOW, "Switching from V.29 + V.21 to V.29 (%.2fdBm0)\n", v29_rx_signal_power(&s->fast_modems.v29_rx));
         fax_modems_set_rx_handler(s, (span_rx_handler_t) &v29_rx, &s->fast_modems.v29_rx, (span_rx_fillin_handler_t) &v29_rx_fillin, &s->fast_modems.v29_rx);
         v29_rx_set_modem_status_handler(&s->fast_modems.v29_rx, NULL, s);
-        s->fast_modems.v29_rx.put_bit(s->fast_modems.v29_rx.put_bit_user_data, status);
         break;
     }
     /*endswitch*/
+    s->fast_modems.v29_rx.put_bit(s->fast_modems.v29_rx.put_bit_user_data, status);
 }
 /*- End of function --------------------------------------------------------*/
 
@@ -255,11 +255,6 @@ SPAN_DECLARE_NONSTD(int) fax_modems_v29_v21_rx_fillin(void *user_data, int len)
 }
 /*- End of function --------------------------------------------------------*/
 
-static void v21_rx_status_handler(void *user_data, int status)
-{
-}
-/*- End of function --------------------------------------------------------*/
-
 SPAN_DECLARE(void) fax_modems_start_slow_modem(fax_modems_state_t *s, int which)
 {
     switch (which)
@@ -393,25 +388,6 @@ SPAN_DECLARE(void) fax_modems_start_fast_modem(fax_modems_state_t *s, int which,
 }
 /*- End of function --------------------------------------------------------*/
 
-SPAN_DECLARE(void) fax_modems_start_rx_modem(fax_modems_state_t *s, int which)
-{
-    switch (which)
-    {
-    case FAX_MODEM_V17_RX:
-        v17_rx_set_modem_status_handler(&s->fast_modems.v17_rx, v17_rx_status_handler, s);
-        break;
-    case FAX_MODEM_V27TER_RX:
-        v27ter_rx_set_modem_status_handler(&s->fast_modems.v27ter_rx, v27ter_rx_status_handler, s);
-        break;
-    case FAX_MODEM_V29_RX:
-        v29_rx_set_modem_status_handler(&s->fast_modems.v29_rx, v29_rx_status_handler, s);
-        break;
-    }
-    /*endswitch*/
-    fsk_rx_set_modem_status_handler(&s->v21_rx, v21_rx_status_handler, s);
-}
-/*- End of function --------------------------------------------------------*/
-
 SPAN_DECLARE(void) fax_modems_set_put_bit(fax_modems_state_t *s, put_bit_func_t put_bit, void *user_data)
 {
     s->put_bit = put_bit;
@@ -432,9 +408,25 @@ SPAN_DECLARE(void) fax_modems_set_rx_handler(fax_modems_state_t *s,
                                              span_rx_fillin_handler_t rx_fillin_handler,
                                              void *rx_fillin_user_data)
 {
-    s->rx_handler = rx_handler;
+    if (s->deferred_rx_handler_updates)
+    {
+        /* Only update the actual handlers if they are not currently sidelined to dummy targets */
+        if (s->rx_handler != span_dummy_rx)
+            s->rx_handler = rx_handler;
+        /*endif*/
+        s->base_rx_handler = rx_handler;
+
+        if (s->rx_fillin_handler != span_dummy_rx_fillin)
+            s->rx_fillin_handler = rx_fillin_handler;
+        /*endif*/
+        s->base_rx_fillin_handler = rx_fillin_handler;
+    }
+    else
+    {
+        s->rx_handler = rx_handler;
+        s->rx_fillin_handler = rx_fillin_handler;
+    }
     s->rx_user_data = rx_user_data;
-    s->rx_fillin_handler = rx_fillin_handler;
     s->rx_fillin_user_data = rx_fillin_user_data;
 }
 /*- End of function --------------------------------------------------------*/
@@ -521,16 +513,9 @@ SPAN_DECLARE(fax_modems_state_t *) fax_modems_init(fax_modems_state_t *s,
     hdlc_rx_init(&s->hdlc_rx, FALSE, FALSE, HDLC_FRAMING_OK_THRESHOLD, fax_modems_hdlc_accept, s);
     hdlc_tx_init(&s->hdlc_tx, FALSE, 2, FALSE, hdlc_tx_underflow, user_data);
 
-    fsk_rx_init(&s->v21_rx, &preset_fsk_specs[FSK_V21CH2], FSK_FRAME_MODE_SYNC, (put_bit_func_t) hdlc_rx_put_bit, &s->hdlc_rx);
-    fsk_rx_signal_cutoff(&s->v21_rx, -39.09f);
+    fax_modems_start_slow_modem(s, FAX_MODEM_V21_RX);
     fsk_tx_init(&s->v21_tx, &preset_fsk_specs[FSK_V21CH2], (get_bit_func_t) hdlc_tx_get_bit, &s->hdlc_tx);
-    v17_rx_init(&s->fast_modems.v17_rx, 14400, non_ecm_put_bit, user_data);
-    v17_tx_init(&s->fast_modems.v17_tx, 14400, s->use_tep, non_ecm_get_bit, user_data);
-    v29_rx_init(&s->fast_modems.v29_rx, 9600, non_ecm_put_bit, user_data);
-    v29_rx_signal_cutoff(&s->fast_modems.v29_rx, -45.5f);
-    v29_tx_init(&s->fast_modems.v29_tx, 9600, s->use_tep, non_ecm_get_bit, user_data);
-    v27ter_rx_init(&s->fast_modems.v27ter_rx, 4800, non_ecm_put_bit, user_data);
-    v27ter_tx_init(&s->fast_modems.v27ter_tx, 4800, s->use_tep, non_ecm_get_bit, user_data);
+
     silence_gen_init(&s->silence_gen, 0);
 
     s->rx_signal_present = FALSE;

libs/spandsp/src/spandsp/fax_modems.h

@@ -69,8 +69,6 @@ SPAN_DECLARE_NONSTD(void) fax_modems_hdlc_tx_frame(void *user_data, const uint8_
 
 SPAN_DECLARE(void) fax_modems_hdlc_tx_flags(fax_modems_state_t *s, int flags);
 
-SPAN_DECLARE(void) fax_modems_start_rx_modem(fax_modems_state_t *s, int which);
-
 SPAN_DECLARE(void) fax_modems_start_fast_modem(fax_modems_state_t *s, int which, int bit_rate, int short_train, int hdlc_mode);
 
 SPAN_DECLARE(void) fax_modems_start_slow_modem(fax_modems_state_t *s, int which);

libs/spandsp/src/spandsp/private/fax_modems.h

@@ -52,7 +52,7 @@ struct fax_modems_state_s
     /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21
                messages. */
     fsk_rx_state_t v21_rx;
-    struct
+    union
     {
         /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps
                    12000bps or 14400bps */
@@ -113,6 +113,7 @@ struct fax_modems_state_s
     /*! \brief TRUE if an HDLC frame has been received correctly. */
     int rx_frame_received;
 
+    int deferred_rx_handler_updates;
     /*! \brief The current receive signal handler */
     span_rx_handler_t rx_handler;
     /*! \brief The current receive signal handler. Actual receiving hops between this