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bladerf: Removed sign extension and masking of samples 

This is no longer required as of FPGA v0.0.1, and has been removed to
remove some unnecessary computation on samples.
This commit is contained in:
Jon Szymaniak 2014-01-11 21:46:01 -05:00 committed by Dimitri Stolnikov
parent 4a0d74f059
commit 03c387bcda
1 changed files with 17 additions and 10 deletions
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27
lib/bladerf/bladerf_source_c.cc
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@ -83,6 +83,7 @@ bladerf_source_c::bladerf_source_c (const std::string &args)
int ret;
size_t fifo_size;
std::string device_name;
struct bladerf_version fpga_version;
dict_t dict = params_to_dict(args);
@ -139,6 +140,19 @@ bladerf_source_c::bladerf_source_c (const std::string &args)
/* Set the range of VGA2 VGA2GAIN[4:0], not recommended to be used above 30dB */
_vga2_range = osmosdr::gain_range_t( 0, 60, 3 );
/* Warn user about using an old FPGA version, as we no longer strip off the
* markers that were pressent in the pre-v0.0.1 FPGA */
if (bladerf_fpga_version( _dev.get(), &fpga_version ) != 0) {
std::cerr << _pfx << "Failed to get FPGA version" << std::endl;
} else if ( fpga_version.major <= 0 &&
fpga_version.minor <= 0 &&
fpga_version.patch < 1 ) {
std::cerr << _pfx << "Warning: FPGA version v0.0.1 or later is required. "
<< "Using an earlier FPGA version will result in misinterpeted samples. "
<< std::endl;
}
}
/*
@ -186,6 +200,7 @@ void *bladerf_source_c::stream_task( void *samples, size_t num_samples )
size_t i, n_avail, to_copy;
int16_t *sample = (int16_t *)samples;
void *ret;
const float scaling = 1.0f / 2048.0f;
ret = _buffers[_buf_index];
_buf_index = (_buf_index + 1) % _num_buffers;
@ -196,17 +211,9 @@ void *bladerf_source_c::stream_task( void *samples, size_t num_samples )
to_copy = (n_avail < num_samples ? n_avail : num_samples);
for(i = 0; i < to_copy; i++ ) {
/* Mask valid bits only */
*(sample) &= 0xfff;
*(sample+1) &= 0xfff;
/* Sign extend the 12-bit IQ values, if needed */
if( (*sample) & 0x800 ) *(sample) |= 0xf000;
if( *(sample+1) & 0x800 ) *(sample+1) |= 0xf000;
/* Push sample to the fifo */
_fifo->push_back( gr_complex( *sample * (1.0f/2048.0f),
*(sample+1) * (1.0f/2048.0f) ) );
_fifo->push_back( gr_complex( *sample * scaling,
*(sample+1) * scaling) );
/* offset to the next I+Q sample */
sample += 2;