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Speedup in SubcarrierResampler - use LUT

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Was previously computing the BOC sign, now we just look up.
This commit is contained in:
Cillian O'Driscoll
2015-12-02 16:07:11 +00:00
parent 2020d77dcc
commit 12d2386653
1 changed files with 12 additions and 2 deletions
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14
src/algorithms/libs/subcarrier_resampler.h
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@@ -58,8 +58,16 @@ public:
int num_samples,
std::vector< T * > resampled_subcarriers,
bool is_cosine_phased = false) = 0;
protected:
static const std::vector< T > d_subcarrier_table;
};
template< typename T >
const std::vector< T > SubcarrierResamplerInterface< T >::d_subcarrier_table =
{ static_cast< T >( 1.0 ), static_cast<T >( -1.0 ) };
/*!
* \brief Simple generic implementation of subcarrier resampling. Most accurate
* and most expensive
@@ -100,7 +108,8 @@ public:
for( int j = 0; j < num_samples; ++j )
{
int_phase = static_cast< int64_t >( tsubcarrier_halfcycles );
*curr_sample = static_cast< T >( 1.0 - 2.0 *( int_phase & 0x01 ) );
//*curr_sample = static_cast< T >( 1.0 - 2.0 *( int_phase & 0x01 ) );
*curr_sample = this->d_subcarrier_table[ int_phase & 0x01 ];
tsubcarrier_halfcycles += subcarrier_phase_step;
++curr_sample;
}
@@ -212,7 +221,8 @@ public:
for( int j = 0 ; j < num_samples; ++j )
{
*curr_sample = static_cast< T >( 1 - 2*( (subcarrier_phase_fxp>>FRAC_LEN) & 0x01 ) );
//*curr_sample = static_cast< T >( 1 - 2*( (subcarrier_phase_fxp>>FRAC_LEN) & 0x01 ) );
*curr_sample = this->d_subcarrier_table[ ( subcarrier_phase_fxp >> FRAC_LEN ) & 0x01 ];
subcarrier_phase_fxp += subcarrier_phase_step_fxp;
++curr_sample;
}