Factor out hdlc context, add some documentation.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@3061 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/bertos/net/afsk.c b/bertos/net/afsk.c
index a7273bdfd45789095091d6abe1fd5d9a1f92757c..4164fccd769272a2c6c1b5d8773eb04416d9726e 100644 (file)
--- a/bertos/net/afsk.c
+++ b/bertos/net/afsk.c
@@ -109,67 +109,67 @@ INLINE uint8_t sin_sample(uint16_t idx)
 #define EDGE_FOUND(bitline)            BIT_DIFFER((bitline), (bitline) >> 1)
 
 
-static void hdlc_parse(Afsk *af, bool bit)
+static void hdlc_parse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo)
 {
-       af->hdlc_demod_bits <<= 1;
-       af->hdlc_demod_bits |= bit ? 1 : 0;
+       hdlc->demod_bits <<= 1;
+       hdlc->demod_bits |= bit ? 1 : 0;
 
        /* HDLC Flag */
-       if (af->hdlc_demod_bits == HDLC_FLAG)
+       if (hdlc->demod_bits == HDLC_FLAG)
        {
-               if (!fifo_isfull(&af->rx_fifo))
+               if (!fifo_isfull(fifo))
                {
-                       fifo_push(&af->rx_fifo, HDLC_FLAG);
-                       af->hdlc_rxstart = true;
+                       fifo_push(fifo, HDLC_FLAG);
+                       hdlc->rxstart = true;
                }
                else
-                       af->hdlc_rxstart = false;
+                       hdlc->rxstart = false;
 
-               af->hdlc_currchar = 0;
-               af->hdlc_bit_idx = 0;
+               hdlc->currchar = 0;
+               hdlc->bit_idx = 0;
                return;
        }
 
        /* Reset */
-       if ((af->hdlc_demod_bits & HDLC_RESET) == HDLC_RESET)
+       if ((hdlc->demod_bits & HDLC_RESET) == HDLC_RESET)
        {
-               af->hdlc_rxstart = false;
+               hdlc->rxstart = false;
                return;
        }
 
-       if (!af->hdlc_rxstart)
+       if (!hdlc->rxstart)
                return;
 
        /* Stuffed bit */
-       if ((af->hdlc_demod_bits & 0x3f) == 0x3e)
+       if ((hdlc->demod_bits & 0x3f) == 0x3e)
                return;
 
-       if (af->hdlc_demod_bits & 0x01)
-               af->hdlc_currchar |= 0x80;
+       if (hdlc->demod_bits & 0x01)
+               hdlc->currchar |= 0x80;
 
-       if (++af->hdlc_bit_idx >= 8)
+       if (++hdlc->bit_idx >= 8)
        {
-               if ((af->hdlc_currchar == HDLC_FLAG
-                       || af->hdlc_currchar == HDLC_RESET
-                       || af->hdlc_currchar == AX25_ESC))
+               if ((hdlc->currchar == HDLC_FLAG
+                       || hdlc->currchar == HDLC_RESET
+                       || hdlc->currchar == AX25_ESC))
                {
-                       if (!fifo_isfull(&af->rx_fifo))
-                               fifo_push(&af->rx_fifo, AX25_ESC);
+                       if (!fifo_isfull(fifo))
+                               fifo_push(fifo, AX25_ESC);
                        else
-                               af->hdlc_rxstart = false;
+                               hdlc->rxstart = false;
                }
 
-               if (!fifo_isfull(&af->rx_fifo))
-                       fifo_push(&af->rx_fifo, af->hdlc_currchar);
+               if (!fifo_isfull(fifo))
+                       fifo_push(fifo, hdlc->currchar);
                else
-                       af->hdlc_rxstart = false;
+                       hdlc->rxstart = false;
 
-               af->hdlc_currchar = 0;
-               af->hdlc_bit_idx = 0;
+               hdlc->currchar = 0;
+               hdlc->bit_idx = 0;
                return;
        }
 
-       af->hdlc_currchar >>= 1;
+       hdlc->currchar >>= 1;
 }
 
 void afsk_adc_isr(Afsk *af, int8_t curr_sample)
@@ -267,7 +267,7 @@ void afsk_adc_isr(Afsk *af, int8_t curr_sample)
                 * NRZI coding: if 2 consecutive bits have the same value
                 * a 1 is received, otherwise it's a 0.
                 */
-               hdlc_parse(af, !EDGE_FOUND(af->found_bits));
+               hdlc_parse(&af->hdlc, !EDGE_FOUND(af->found_bits), &af->rx_fifo);
        }
 
 

diff --git a/bertos/net/afsk.h b/bertos/net/afsk.h
index 4ab20c5053391c2777c967316e7782033fb14618..902c5b9470944a6fbd136ab248ba7acfc7e608e9 100644 (file)
--- a/bertos/net/afsk.h
+++ b/bertos/net/afsk.h
@@ -58,12 +58,31 @@
 
 #define SAMPLEPERBIT (SAMPLERATE / BITRATE)
 
+/**
+ * HDLC (High-Level Data Link Control) context.
+ * Maybe to be moved in a separate HDLC module one day.
+ */
+typedef struct Hdlc
+{
+       uint8_t demod_bits; ///< Bitstream from the demodulator.
+       uint8_t bit_idx;    ///< Current received bit.
+       uint8_t currchar;   ///< Current received character.
+       bool rxstart;       ///< True if an HDLC_FLAG char has been found in the bitstream.
+} Hdlc;
 
+
+/**
+ * AFSK1200 modem context.
+ */
 typedef struct Afsk
 {
+       /** Base "class" */
        KFile fd;
 
+       /** ADC channel to be used by the demodulator */
        int adc_ch;
+
+       /** DAC channel to be used by the modulator */
        int dac_ch;
 
        /** Current sample of bit for output data. */
@@ -98,29 +117,60 @@ typedef struct Afsk
         */
        int8_t delay_buf[SAMPLEPERBIT / 2 + 1];
 
+       /** FIFO for received data */
        FIFOBuffer rx_fifo;
+
+       /** FIFO rx buffer */
        uint8_t rx_buf[CONFIG_AFSK_RX_BUFLEN];
 
+       /** FIFO for transmitted data */
        FIFOBuffer tx_fifo;
+
+       /** FIFO tx buffer */
        uint8_t tx_buf[CONFIG_AFSK_TX_BUFLEN];
 
+       /** IIR filter X cells, used to filter sampled data by the demodulator */
        int16_t iir_x[2];
+
+       /** IIR filter Y cells, used to filter sampled data by the demodulator */
        int16_t iir_y[2];
 
+       /**
+        * Bits sampled by the demodulator are here.
+        * Since ADC samplerate is higher than the bitrate, the bits here are
+        * SAMPLEPERBIT times the bitrate.
+        */
        uint8_t sampled_bits;
-       uint8_t found_bits;
+
+       /**
+        * Current phase, needed to know when the bitstream at ADC speed
+        * should be sampled.
+        */
        int8_t curr_phase;
 
-       /* True while modem sends data */
-       volatile bool sending;
+       /** Bits found by the demodulator at the correct bitrate speed. */
+       uint8_t found_bits;
 
+       /** True while modem sends data */
+       volatile bool sending;
 
-       bool hdlc_rxstart;
-       uint8_t hdlc_currchar;
-       uint8_t hdlc_bit_idx;
-       uint8_t hdlc_demod_bits;
+       /** Hdlc context */
+       Hdlc hdlc;
 
+       /**
+        * Preamble length.
+        * When the AFSK modem wants to send data, before sending the actual data,
+        * shifts out preamble_len HDLC_FLAG characters.
+        * This helps to synchronize the demodulator filters on the receiver side.
+        */
        uint16_t preamble_len;
+
+       /**
+        * Preamble length.
+        * After sending the actual data, the AFSK shifts out
+        * trailer_len HDLC_FLAG characters.
+        * This helps to synchronize the demodulator filters on the receiver side.
+        */
        uint16_t trailer_len;
 } Afsk;