reimplement buffering to make it more efficient

thanks to Hoernchen <la@tfc-server.de> for contributing a proof-of-concept implementation
gr3.6
Dimitri Stolnikov 11 years ago
parent 08b6f7ee0a
commit ba5e8e94b7
  1. 103
      lib/rtl_source_c.cc
  2. 10
      lib/rtl_source_c.h

@ -43,6 +43,8 @@
using namespace boost::assign;
#define BUF_SIZE (16 * 32 * 512)
/*
* Create a new instance of rtl_source_c and return
* a boost shared_ptr. This is effectively the public constructor.
@ -76,13 +78,19 @@ rtl_source_c::rtl_source_c (const std::string &args)
gr_make_io_signature (MIN_OUT, MAX_OUT, sizeof (gr_complex)))
{
int ret;
int dev_index = 0;
unsigned int dev_index = 0;
_buf_num = 32;
_buf = (unsigned short **) malloc(_buf_num * sizeof(unsigned short *));
_buf = boost::circular_buffer<unsigned short>(1024*1024);
for(unsigned int i = 0; i < _buf_num; ++i)
_buf[i] = (unsigned short *) malloc(BUF_SIZE);
_buf_head = _buf_used = _buf_offset = 0;
_samp_avail = BUF_SIZE;
// create a lookup table for gr_complex values
for (unsigned int i = 0; i <= 0xffff; i++)
{
for (unsigned int i = 0; i <= 0xffff; i++) {
#if 1 // little endian
_lut.push_back( gr_complex( (float(i & 0xff) - 127.5f) *(1.0f/128.0f),
(float(i >> 8) - 127.5f) * (1.0f/128.0f) ) );
@ -92,6 +100,9 @@ rtl_source_c::rtl_source_c (const std::string &args)
#endif
}
if ( dev_index >= rtlsdr_get_device_count() )
throw std::runtime_error("Device index out of bounds for rtlsdr.");
std::cerr << "Using device #" << dev_index << " "
<< "(" << rtlsdr_get_device_name(dev_index) << ")"
<< std::endl;
@ -125,6 +136,14 @@ rtl_source_c::~rtl_source_c ()
rtlsdr_close( _dev );
_dev = NULL;
}
for(unsigned int i = 0; i < _buf_num; ++i) {
if (_buf[i])
free(_buf[i]);
}
free(_buf);
_buf = NULL;
}
void rtl_source_c::_rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
@ -135,20 +154,22 @@ void rtl_source_c::_rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
void rtl_source_c::rtlsdr_callback(unsigned char *buf, uint32_t len)
{
unsigned short * sbuf = (unsigned short *)buf;
if (len != BUF_SIZE) {
printf("U(%d)\n", len); fflush(stdout);
return;
}
boost::mutex::scoped_lock lock( _buf_mutex );
{
boost::mutex::scoped_lock lock( _buf_mutex );
if (len % 2 != 0) {
printf("!!! len: %d\n", len); fflush(stdout);
}
int buf_tail = (_buf_head + _buf_used) % _buf_num;
memcpy(_buf[buf_tail], buf, len);
for (int i = 0; i < len/2; i++) {
if (!_buf.full()) {
_buf.push_back( sbuf[i] );
} else {
if (_buf_used == _buf_num) {
printf("O"); fflush(stdout);
break;
_buf_head = (_buf_head + 1) % _buf_num;
} else {
_buf_used++;
}
}
@ -162,7 +183,7 @@ void rtl_source_c::_rtlsdr_wait(rtl_source_c *obj)
void rtl_source_c::rtlsdr_wait()
{
int ret = rtlsdr_read_async( _dev, _rtlsdr_callback, (void *)this, 0, 0 );
int ret = rtlsdr_read_async( _dev, _rtlsdr_callback, (void *)this, 0, BUF_SIZE );
_running = false;
@ -176,29 +197,49 @@ int rtl_source_c::work( int noutput_items,
{
gr_complex *out = (gr_complex *)output_items[0];
{
boost::mutex::scoped_lock lock( _buf_mutex );
while (_buf_used < 3 && _running)
_buf_cond.wait( lock );
}
if (!_running)
return WORK_DONE;
int items_left = noutput_items;
while ( items_left )
{
{
boost::mutex::scoped_lock lock( _buf_mutex );
unsigned short *buf = _buf[_buf_head];
while( _buf.empty() ) {
_buf_cond.wait( lock );
}
}
if (noutput_items <= int(_samp_avail)) {
for (int i = 0; i <= noutput_items; ++i)
*out++ = _lut[ *(buf + _buf_offset + i) ];
// convert samples to gr_complex type by using the lookup table
*out++ = _lut[ _buf.front() ];
items_left--;
_buf_offset += noutput_items;
_samp_avail -= noutput_items;
return noutput_items;
} else {
for (int i = 0; i <= int(_samp_avail); ++i)
*out++ = _lut[ *(buf + _buf_offset + i) ];
{
boost::mutex::scoped_lock lock( _buf_mutex );
_buf.pop_front();
_buf_head = (_buf_head + 1) % _buf_num;
_buf_used--;
}
buf = _buf[_buf_head];
_buf_offset = 0;
int remaining = noutput_items - _samp_avail;
for (int i = 0; i <= remaining; ++i)
*out++ = _lut[ *(buf + _buf_offset + i) ];
_buf_offset = remaining;
_samp_avail = (BUF_SIZE/2) - remaining;
return noutput_items;
}
return noutput_items;
@ -213,9 +254,9 @@ osmosdr::meta_range_t rtl_source_c::get_sample_rates()
{
osmosdr::meta_range_t range;
range += osmosdr::range_t( 1024000 );
range += osmosdr::range_t( 2048000 );
range += osmosdr::range_t( 3200000 );
range += osmosdr::range_t( 1024000 ); // known to work
range += osmosdr::range_t( 2048000 ); // known to work
range += osmosdr::range_t( 3200000 ); // max rate, may work
// TODO: read from the librtlsdr as soon as the api is available

@ -25,8 +25,8 @@
#include <osmosdr_api.h>
#include <gr_sync_block.h>
#include <gruel/thread.h>
#include <boost/circular_buffer.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition_variable.hpp>
@ -117,10 +117,16 @@ private:
rtlsdr_dev_t *_dev;
gruel::thread _thread;
boost::circular_buffer<unsigned short> _buf;
unsigned short **_buf;
unsigned int _buf_num;
unsigned int _buf_head;
unsigned int _buf_used;
boost::mutex _buf_mutex;
boost::condition_variable _buf_cond;
bool _running;
unsigned int _buf_offset;
unsigned int _samp_avail;
};
#endif /* INCLUDED_RTLSDR_SOURCE_C_H */

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