Some modem cleanups, and movement towards efficient fixed point modem

implementations for platforms with slow floating point

libs/spandsp/src/spandsp/private/v22bis.h

@@ -26,10 +26,10 @@
 #if !defined(_SPANDSP_PRIVATE_V22BIS_H_)
 #define _SPANDSP_PRIVATE_V22BIS_H_
 
-/*! The number of steps to the left and to the right of the target position in the equalizer buffer. */
-#define V22BIS_EQUALIZER_LEN        7
-/*! One less than a power of 2 >= (2*V22BIS_EQUALIZER_LEN + 1) */
-#define V22BIS_EQUALIZER_MASK       15
+/*! The length of the equalizer buffer */
+#define V22BIS_EQUALIZER_LEN        17
+/*! Samples before the target position in the equalizer buffer */
+#define V22BIS_EQUALIZER_PRE_LEN    8
 
 /*! The number of taps in the transmit pulse shaping filter */
 #define V22BIS_TX_FILTER_STEPS      9
@@ -139,24 +139,24 @@ struct v22bis_state_s
 
 #if defined(SPANDSP_USE_FIXED_POINTx)
         /*! \brief The scaling factor accessed by the AGC algorithm. */
-        float agc_scaling;
+        int16_t agc_scaling;
         /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
         int16_t rrc_filter[V22BIS_RX_FILTER_STEPS];
 
         /*! \brief The current delta factor for updating the equalizer coefficients. */
-        float eq_delta;
+        int16_t eq_delta;
         /*! \brief The adaptive equalizer coefficients. */
-        complexi_t eq_coeff[2*V22BIS_EQUALIZER_LEN + 1];
+        complexi16_t eq_coeff[V22BIS_EQUALIZER_LEN];
         /*! \brief The equalizer signal buffer. */
-        complexi_t eq_buf[V22BIS_EQUALIZER_MASK + 1];
+        complexi16_t eq_buf[V22BIS_EQUALIZER_LEN];
 
         /*! \brief A measure of how much mismatch there is between the real constellation,
                    and the decoded symbol positions. */
-        float training_error;
+        int32_t training_error;
         /*! \brief The proportional part of the carrier tracking filter. */
-        float carrier_track_p;
+        int32_t carrier_track_p;
         /*! \brief The integral part of the carrier tracking filter. */
-        float carrier_track_i;
+        int32_t carrier_track_i;
 #else
         /*! \brief The scaling factor accessed by the AGC algorithm. */
         float agc_scaling;
@@ -166,9 +166,9 @@ struct v22bis_state_s
         /*! \brief The current delta factor for updating the equalizer coefficients. */
         float eq_delta;
         /*! \brief The adaptive equalizer coefficients. */
-        complexf_t eq_coeff[2*V22BIS_EQUALIZER_LEN + 1];
+        complexf_t eq_coeff[V22BIS_EQUALIZER_LEN];
         /*! \brief The equalizer signal buffer. */
-        complexf_t eq_buf[V22BIS_EQUALIZER_MASK + 1];
+        complexf_t eq_buf[V22BIS_EQUALIZER_LEN];
 
         /*! \brief A measure of how much mismatch there is between the real constellation,
                    and the decoded symbol positions. */
@@ -202,7 +202,7 @@ struct v22bis_state_s
     /* Transmit section */
     struct
     {
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
         /*! \brief The guard tone level. */
         int16_t guard_tone_gain;
         /*! \brief The gain factor needed to achieve the specified output power. */

libs/spandsp/src/spandsp/private/v27ter_rx.h

@@ -76,22 +76,22 @@ struct v27ter_rx_state_s
     int16_t agc_scaling_save;
 
     /*! \brief The current delta factor for updating the equalizer coefficients. */
-    float eq_delta;
+    int16_t eq_delta;
     /*! \brief The adaptive equalizer coefficients. */
-    /*complexi16_t*/ complexf_t  eq_coeff[V27TER_EQUALIZER_LEN];
+    complexi16_t eq_coeff[V27TER_EQUALIZER_LEN];
     /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
-    /*complexi16_t*/ complexf_t  eq_coeff_save[V27TER_EQUALIZER_LEN];
+    complexi16_t eq_coeff_save[V27TER_EQUALIZER_LEN];
     /*! \brief The equalizer signal buffer. */
-    /*complexi16_t*/ complexf_t eq_buf[V27TER_EQUALIZER_LEN];
+    complexi16_t eq_buf[V27TER_EQUALIZER_LEN];
 
     /*! \brief A measure of how much mismatch there is between the real constellation,
                and the decoded symbol positions. */
-    float training_error;
+    int32_t training_error;
 
     /*! \brief The proportional part of the carrier tracking filter. */
-    float carrier_track_p;
+    int32_t carrier_track_p;
     /*! \brief The integral part of the carrier tracking filter. */
-    float carrier_track_i;
+    int32_t carrier_track_i;
     /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
     int16_t rrc_filter[V27TER_RX_FILTER_STEPS];
 #else

libs/spandsp/src/spandsp/private/v29rx.h

@@ -87,7 +87,7 @@ struct v29_rx_state_s
 
     /*! \brief A measure of how much mismatch there is between the real constellation,
                and the decoded symbol positions. */
-    float training_error;
+    int32_t training_error;
 
     /*! \brief The proportional part of the carrier tracking filter. */
     int32_t carrier_track_p;

libs/spandsp/src/spandsp/v27ter_rx.h

@@ -126,7 +126,7 @@ SPAN_DECLARE_NONSTD(int) v27ter_rx_fillin(v27ter_rx_state_t *s, int len);
     \brief Get a snapshot of the current equalizer coefficients.
     \param coeffs The vector of complex coefficients.
     \return The number of coefficients in the vector. */
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 SPAN_DECLARE(int) v27ter_rx_equalizer_state(v27ter_rx_state_t *s, complexi16_t **coeffs);
 #else
 SPAN_DECLARE(int) v27ter_rx_equalizer_state(v27ter_rx_state_t *s, complexf_t **coeffs);

libs/spandsp/src/spandsp/v29rx.h

@@ -118,7 +118,7 @@ scrambler register) cannot be trusted for the test. The receive modem,
 therefore, only tests that bits starting at bit 24 are really ones. 
 */
 
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 typedef void (*qam_report_handler_t)(void *user_data, const complexi16_t *constel, const complexi16_t *target, int symbol);
 #else
 typedef void (*qam_report_handler_t)(void *user_data, const complexf_t *constel, const complexf_t *target, int symbol);

libs/spandsp/src/v17tx.c

@@ -53,13 +53,19 @@
 #include "spandsp/dds.h"
 #include "spandsp/power_meter.h"
 
+#if defined(SPANDSP_USE_FIXED_POINT)
+#define SPANDSP_USE_FIXED_POINTx
+#endif
+
 #include "spandsp/v17tx.h"
 
 #include "spandsp/private/logging.h"
 #include "spandsp/private/v17tx.h"
 
 #if defined(SPANDSP_USE_FIXED_POINT)
-#define SPANDSP_USE_FIXED_POINTx
+#define FP_SCALE(x)     ((int16_t) x)
+#else
+#define FP_SCALE(x)     (x)
 #endif
 
 #include "v17_v32bis_tx_constellation_maps.h"
@@ -229,6 +235,11 @@ static __inline__ complexf_t getbaud(v17_tx_state_t *s)
     int i;
     int bit;
     int bits;
+#if defined(SPANDSP_USE_FIXED_POINT)
+    static const complexi16_t zero = {0, 0};
+#else
+    static const complexf_t zero = {0.0f, 0.0f};
+#endif
 
     if (s->in_training)
     {
@@ -251,11 +262,7 @@ static __inline__ complexf_t getbaud(v17_tx_state_t *s)
             {
                 /* The shutdown sequence is 32 bauds of all 1's, then 48 bauds
                    of silence */
-#if defined(SPANDSP_USE_FIXED_POINT)
-                return complex_seti16(0, 0);
-#else
-                return complex_setf(0.0f, 0.0f);
-#endif
+                return zero;
             }
             if (s->training_step == V17_TRAINING_SHUTDOWN_END)
             {

libs/spandsp/src/v22bis_tx.c

@@ -62,7 +62,7 @@
 #include "spandsp/private/logging.h"
 #include "spandsp/private/v22bis.h"
 
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 #define FP_SCALE    FP_Q_6_10
 #include "v22bis_tx_fixed_rrc.h"
 #else
@@ -248,7 +248,7 @@ static const int phase_steps[4] =
     1, 0, 2, 3
 };
 
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 const complexi16_t v22bis_constellation[16] =
 #else
 const complexf_t v22bis_constellation[16] =
@@ -314,7 +314,7 @@ static __inline__ int get_scrambled_bit(v22bis_state_t *s)
 }
 /*- End of function --------------------------------------------------------*/
 
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 static complexi16_t training_get(v22bis_state_t *s)
 #else
 static complexf_t training_get(v22bis_state_t *s)
@@ -417,13 +417,13 @@ static complexf_t training_get(v22bis_state_t *s)
 }
 /*- End of function --------------------------------------------------------*/
 
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
 static complexi16_t getbaud(v22bis_state_t *s)
 #else
 static complexf_t getbaud(v22bis_state_t *s)
 #endif
 {
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
     static const complexi16_t zero = {0, 0};
 #else
     static const complexf_t zero = {0.0f, 0.0f};
@@ -464,7 +464,7 @@ static complexf_t getbaud(v22bis_state_t *s)
 
 SPAN_DECLARE_NONSTD(int) v22bis_tx(v22bis_state_t *s, int16_t amp[], int len)
 {
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
     complexi16_t v;
     complexi32_t x;
     complexi32_t z;
@@ -490,7 +490,7 @@ SPAN_DECLARE_NONSTD(int) v22bis_tx(v22bis_state_t *s, int16_t amp[], int len)
             if (++s->tx.rrc_filter_step >= V22BIS_TX_FILTER_STEPS)
                 s->tx.rrc_filter_step = 0;
         }
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
         /* Root raised cosine pulse shaping at baseband */
         x.re = vec_circular_dot_prodi16(s->tx.rrc_filter_re, tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->tx.baud_phase], V22BIS_TX_FILTER_STEPS, s->tx.rrc_filter_step) >> 14;
         x.im = vec_circular_dot_prodi16(s->tx.rrc_filter_im, tx_pulseshaper[TX_PULSESHAPER_COEFF_SETS - 1 - s->tx.baud_phase], V22BIS_TX_FILTER_STEPS, s->tx.rrc_filter_step) >> 14;
@@ -551,7 +551,7 @@ SPAN_DECLARE(void) v22bis_tx_power(v22bis_state_t *s, float power)
     }
     sig_gain = 0.4490f*powf(10.0f, (sig_power - DBM0_MAX_POWER)/20.0f)*32768.0f/TX_PULSESHAPER_GAIN;
     guard_tone_gain = powf(10.0f, (guard_tone_power - DBM0_MAX_POWER)/20.0f)*32768.0f;
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
     s->tx.gain = (int16_t) sig_gain;
     s->tx.guard_tone_gain = (int16_t) guard_tone_gain;
 #else
@@ -563,7 +563,7 @@ SPAN_DECLARE(void) v22bis_tx_power(v22bis_state_t *s, float power)
 
 static int v22bis_tx_restart(v22bis_state_t *s)
 {
-#if defined(SPANDSP_USE_FIXED_POINTx)
+#if defined(SPANDSP_USE_FIXED_POINT)
     vec_zeroi16(s->tx.rrc_filter_re, sizeof(s->tx.rrc_filter_re)/sizeof(s->tx.rrc_filter_re[0]));
     vec_zeroi16(s->tx.rrc_filter_im, sizeof(s->tx.rrc_filter_im)/sizeof(s->tx.rrc_filter_im[0]));
 #else