rtl: add direct_samp as device parameter

This can be used to enable the direct sampling mode
of an rtlsdr stick, e.g.:

For input 1 (In-phase ADC):
rtl=0,direct_samp=1

For input 2 (Quadrature ADC):
rtl=0,direct_samp=2

Signed-off-by: Steve Markgraf <steve@steve-m.de>

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/rtl/rtl_source_c.cc b/lib/rtl/rtl_source_c.cc
index 0ca49af..9ca6d64 100644
--- a/lib/rtl/rtl_source_c.cc
+++ b/lib/rtl/rtl_source_c.cc
@@ -88,7 +88,7 @@ rtl_source_c::rtl_source_c (const std::string &args)
     _skipped(0)
 {
   int ret;
-  unsigned int dev_index = 0, rtl_freq = 0, tuner_freq = 0;
+  unsigned int dev_index = 0, rtl_freq = 0, tuner_freq = 0, direct_samp = 0;
 
   dict_t dict = params_to_dict(args);
 
@@ -101,6 +101,9 @@ rtl_source_c::rtl_source_c (const std::string &args)
   if (dict.count("tuner_xtal"))
     tuner_freq = (unsigned int)boost::lexical_cast< double >( dict["tuner_xtal"] );
 
+  if (dict.count("direct_samp"))
+    direct_samp = boost::lexical_cast< unsigned int >( dict["direct_samp"] );
+
   _buf_num = BUF_NUM;
   _buf_head = _buf_used = _buf_offset = 0;
   _samp_avail = BUF_SIZE / BYTES_PER_SAMPLE;
@@ -160,6 +163,12 @@ rtl_source_c::rtl_source_c (const std::string &args)
   if (ret < 0)
     throw std::runtime_error("Failed to set agc mode.");
 
+  if (direct_samp) {
+    ret = rtlsdr_set_direct_sampling(_dev, direct_samp);
+    if (ret < 0)
+      throw std::runtime_error("Failed to enable direct sampling mode.");
+  }
+
   ret = rtlsdr_reset_buffer( _dev );
   if (ret < 0)
     throw std::runtime_error("Failed to reset usb buffers.");