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Explain and clean up decimator scalars (#1422)

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Kyle Reed 2023-08-30 09:05:49 -07:00 • committed by GitHub
parent 4bc752b7a8
commit f46e20c977
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16 changed files with 51 additions and 73 deletions
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23
firmware/baseband/dsp_decimate.hpp
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@ -23,19 +23,26 @@
#define __DSP_DECIMATE_H__
#include <cstdint>
#include <algorithm>
#include <array>
#include <memory>
#include <algorithm>
#include "utility.hpp"
#include "dsp_types.hpp"
#include "simd.hpp"
#include "utility.hpp"
namespace dsp {
namespace decimate {
/* "Saturating" scalars used by decimators to scale either
* 8 or 16 bit complex values into 32 bit complex values.
* Some of the decimators accept a scale factor as part of
* configuration, which is then passed to scale_round_and_pack. */
// c8_to_c32_sat_scalar == 2^25. 2^25 * 2^7 (signed C8 Max) == 2^32.
constexpr int32_t c8_to_c32_sat_scalar = 0x2000000;
// c16_to_c32_sat_scalar == 2^17. 2^17 * 2^15 (signed C16 Max) == 2^32.
constexpr int32_t c16_to_c32_sat_scalar = 0x20000;
class Complex8DecimateBy2CIC3 {
public:
buffer_c16_t execute(
@ -100,7 +107,7 @@ class FIRC8xR16x24FS4Decim4 {
void configure(
const std::array<tap_t, taps_count>& taps,
const int32_t scale,
const int32_t scale = c8_to_c32_sat_scalar,
const Shift shift = Shift::Down);
buffer_c16_t execute(
@ -128,7 +135,7 @@ class FIRC8xR16x24FS4Decim8 {
void configure(
const std::array<tap_t, taps_count>& taps,
const int32_t scale,
const int32_t scale = c8_to_c32_sat_scalar,
const Shift shift = Shift::Down);
buffer_c16_t execute(
@ -151,7 +158,7 @@ class FIRC16xR16x16Decim2 {
void configure(
const std::array<tap_t, taps_count>& taps,
const int32_t scale);
const int32_t scale = c16_to_c32_sat_scalar);
buffer_c16_t execute(
const buffer_c16_t& src,
@ -173,7 +180,7 @@ class FIRC16xR16x32Decim8 {
void configure(
const std::array<tap_t, taps_count>& taps,
const int32_t scale);
const int32_t scale = c16_to_c32_sat_scalar);
buffer_c16_t execute(
const buffer_c16_t& src,