Factor out hdlc context, add some documentation.

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

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;