bugfix and clarify API function rtlsdr_get_tuner_gain()

Signed-off-by: hayati ayguen <h_ayguen@web.de>

include/rtl-sdr.h

@@ -284,7 +284,7 @@ RTLSDR_API int rtlsdr_set_tuner_band_center(rtlsdr_dev_t *dev, int32_t if_band_c
 RTLSDR_API int rtlsdr_set_tuner_sideband(rtlsdr_dev_t *dev, int sideband);
 
 /*!
- * Get actual gain the device is configured to.
+ * Get actual (RF / HF) gain the device is configured to - excluding the IF gain.
  *
  * \param dev the device handle given by rtlsdr_open()
  * \return 0 on error, gain in tenths of a dB, 115 means 11.5 dB.

include/tuner_r82xx.h

@@ -145,6 +145,9 @@ int r82xx_standby(struct r82xx_priv *priv);
 int r82xx_init(struct r82xx_priv *priv);
 int r82xx_set_freq(struct r82xx_priv *priv, uint32_t freq);
 int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain, int extended_mode, int lna_gain, int mixer_gain, int vga_gain, int *rtl_vga_control);
+int r82xx_get_rf_gain(struct r82xx_priv *priv);
+int r82xx_get_if_gain(struct r82xx_priv *priv);
+
 int r82xx_set_if_mode(struct r82xx_priv *priv, int if_mode, int *rtl_vga_control);
 
 int r82xx_set_i2c_register(struct r82xx_priv *priv, unsigned i2c_register, unsigned data, unsigned mask);

src/librtlsdr.c

@@ -212,7 +212,7 @@ struct rtlsdr_dev {
 	int      tuner_if_freq;
 	int      tuner_sideband;
 	int corr; /* ppm */
-	int gain; /* tenth dB */
+	/* int gain; * tenth dB */
 	enum rtlsdr_ds_mode direct_sampling_mode;
 	uint32_t direct_sampling_threshold; /* Hz */
 	struct e4k_state e4k_s;
@@ -1589,11 +1589,6 @@ int rtlsdr_set_tuner_gain(rtlsdr_dev_t *dev, int gain)
 		rtlsdr_set_i2c_repeater(dev, 0);
 	}
 
-	if (!r)
-		dev->gain = gain;
-	else
-		dev->gain = 0;
-
 	return r;
 }
 
@@ -1610,11 +1605,6 @@ int rtlsdr_set_tuner_gain_ext(rtlsdr_dev_t *dev, int lna_gain, int mixer_gain, i
 		rtlsdr_set_i2c_repeater(dev, 0);
 	}
 
-	if (!r)
-		dev->gain = lna_gain + mixer_gain + vga_gain;
-	else
-		dev->gain = 0;
-
 	return r;
 }
 
@@ -1637,6 +1627,8 @@ int rtlsdr_set_tuner_if_mode(rtlsdr_dev_t *dev, int if_mode)
 
 int rtlsdr_get_tuner_gain(rtlsdr_dev_t *dev)
 {
+	int rf_gain = 0;
+
 	#ifdef _ENABLE_RPC
 	if (rtlsdr_rpc_is_enabled())
 	{
@@ -1647,7 +1639,11 @@ int rtlsdr_get_tuner_gain(rtlsdr_dev_t *dev)
 	if (!dev)
 		return 0;
 
-	return dev->gain;
+
+	if (dev->tuner_type == RTLSDR_TUNER_R820T)
+		rf_gain = r82xx_get_rf_gain(&dev->r82xx_p);
+
+	return rf_gain;
 }
 
 int rtlsdr_set_tuner_if_gain(rtlsdr_dev_t *dev, int stage, int gain)

src/tuner_r82xx.c

@@ -1083,6 +1083,37 @@ static int r82xx_get_if_gain_index(int gain)
 	return vga_index;
 }
 
+static int r82xx_get_lna_gain_from_index(int lna_index)
+{
+	int i, total_gain = 0;
+	if ( lna_index < 0 || lna_index > 15 )
+		return 0;
+	for ( i = 0; i <= lna_index; ++i )
+		total_gain += r82xx_lna_gain_steps[i];
+	return total_gain;
+}
+
+static int r82xx_get_mixer_gain_from_index(int mixer_index)
+{
+	int i, total_gain = 0;
+	if ( mixer_index < 0 || mixer_index > 15 )
+		return 0;
+	for ( i = 0; i <= mixer_index; ++i )
+		total_gain += r82xx_mixer_gain_steps[i];
+	return total_gain;
+}
+
+static int r82xx_get_vga_gain_from_index(int vga_index)
+{
+	int i, total_gain = VGA_BASE_GAIN;
+	if ( vga_index < 0 || vga_index > 15 )
+		return 0;
+	for ( i = 0; i <= vga_index; ++i )
+		total_gain += r82xx_vga_gain_steps[i];
+	return total_gain;
+}
+
+
 /* set HF gain (LNA/Mixer) and pass through for IF gain (VGA) */
 int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain,
   int extended_mode, int lna_gain_idx, int mixer_gain_idx, int vga_gain_idx, int *rtl_vga_control)
@@ -1153,6 +1184,22 @@ int r82xx_set_gain(struct r82xx_priv *priv, int set_manual_gain, int gain,
 	return rc;
 }
 
+int r82xx_get_rf_gain(struct r82xx_priv *priv)
+{
+	int lna_gain = r82xx_get_lna_gain_from_index(priv->last_LNA_value);
+	int mix_gain = r82xx_get_mixer_gain_from_index(priv->last_Mixer_value);
+	int gain = lna_gain + mix_gain;
+	return gain;
+}
+
+
+int r82xx_get_if_gain(struct r82xx_priv *priv)
+{
+	int vga_gain = r82xx_get_vga_gain_from_index(priv->last_VGA_value);
+	return vga_gain;
+}
+
+
 /* set IF gain (VGA) */
 int r82xx_set_if_mode(struct r82xx_priv *priv, int if_mode, int *rtl_vga_control)
 {