Add support for preamble/trailer before starting real data transmission: this give...

[bertos.git] / bertos / net / afsk.c

diff --git a/bertos/net/afsk.c b/bertos/net/afsk.c
index d2291262858cefe7d7d68f3a395ac01b8a85792d..e516a3f32b854bf23d813ebcc70600afd1eca34d 100644 (file)
--- a/bertos/net/afsk.c
+++ b/bertos/net/afsk.c
@@ -164,6 +164,9 @@ static uint8_t hdlc_bit_idx;
 #define BIT_DIFFER(bitline1, bitline2) (((bitline1) ^ (bitline2)) & 0x01)
 #define EDGE_FOUND(bitline)            BIT_DIFFER((bitline), (bitline) >> 1)
 
+static uint16_t preamble_len;
+static uint16_t trailer_len;
+
 static void hdlc_parse(bool bit)
 {
        demod_bits <<= 1;
@@ -342,8 +345,10 @@ static void afsk_txStart(void)
                phase_acc = 0;
                stuff_cnt = 0;
                sending = true;
+               preamble_len = DIV_ROUND(CONFIG_AFSK_PREAMBLE_LEN * BITRATE, 8000);
                AFSK_DAC_IRQ_START();
        }
+       ATOMIC(trailer_len  = DIV_ROUND(CONFIG_AFSK_TRAILER_LEN  * BITRATE, 8000));
 }
 
 #define BIT_STUFF_LEN 5
@@ -358,7 +363,7 @@ DEFINE_AFSK_DAC_ISR()
                if (tx_bit == 0)
                {
                        /* We have just finished transimitting a char, get a new one. */
-                       if (fifo_isempty(&tx_fifo))
+                       if (fifo_isempty(&tx_fifo) && trailer_len == 0)
                        {
                                AFSK_DAC_IRQ_STOP();
                                sending = false;
@@ -375,7 +380,25 @@ DEFINE_AFSK_DAC_ISR()
                                        stuff_cnt = 0;
 
                                bit_stuff = true;
-                               curr_out = fifo_pop(&tx_fifo);
+
+                               /*
+                                * Handle preamble and trailer
+                                */
+                               if (preamble_len == 0)
+                               {
+                                       if (fifo_isempty(&tx_fifo))
+                                       {
+                                               trailer_len--;
+                                               curr_out = HDLC_FLAG;
+                                       }
+                                       else
+                                               curr_out = fifo_pop(&tx_fifo);
+                               }
+                               else
+                               {
+                                       preamble_len--;
+                                       curr_out = HDLC_FLAG;
+                               }
 
                                /* Handle char escape */
                                if (curr_out == AX25_ESC)