Vector Optimized Library of Kernels 3.1.2
Architecture-tuned implementations of math kernels
 
Loading...
Searching...
No Matches
volk_32fc_s32f_power_spectrum_32f.h
Go to the documentation of this file.
1/* -*- c++ -*- */
2/*
3 * Copyright 2012, 2014 Free Software Foundation, Inc.
4 *
5 * This file is part of VOLK
6 *
7 * SPDX-License-Identifier: LGPL-3.0-or-later
8 */
9
40#ifndef INCLUDED_volk_32fc_s32f_power_spectrum_32f_a_H
41#define INCLUDED_volk_32fc_s32f_power_spectrum_32f_a_H
42
43#include <inttypes.h>
44#include <math.h>
45#include <stdio.h>
46
47#ifdef LV_HAVE_GENERIC
48
49static inline void
51 const lv_32fc_t* complexFFTInput,
52 const float normalizationFactor,
53 unsigned int num_points)
54{
55 // Calculate the Power of the complex point
56 const float normFactSq = 1.0 / (normalizationFactor * normalizationFactor);
57
58 // Calculate dBm
59 // 50 ohm load assumption
60 // 10 * log10 (v^2 / (2 * 50.0 * .001)) = 10 * log10( v^2 * 10)
61 // 75 ohm load assumption
62 // 10 * log10 (v^2 / (2 * 75.0 * .001)) = 10 * log10( v^2 * 15)
63
64 /*
65 * For generic reference, the code below is a volk-optimized
66 * approach that also leverages a faster log2 calculation
67 * to calculate the log10:
68 * n*log10(x) = n*log2(x)/log2(10) = (n/log2(10)) * log2(x)
69 *
70 * Generic code:
71 *
72 * const float real = *inputPtr++ * iNormalizationFactor;
73 * const float imag = *inputPtr++ * iNormalizationFactor;
74 * realFFTDataPointsPtr = 10.0*log10f(((real * real) + (imag * imag)) + 1e-20);
75 * realFFTDataPointsPtr++;
76 *
77 */
78
79 // Calc mag^2
80 volk_32fc_magnitude_squared_32f(logPowerOutput, complexFFTInput, num_points);
81
82 // Finish ((real * real) + (imag * imag)) calculation:
83 volk_32f_s32f_multiply_32f(logPowerOutput, logPowerOutput, normFactSq, num_points);
84
85 // The following calculates 10*log10(x) = 10*log2(x)/log2(10) = (10/log2(10))
86 // * log2(x)
87 volk_32f_log2_32f(logPowerOutput, logPowerOutput, num_points);
88 volk_32f_s32f_multiply_32f(
89 logPowerOutput, logPowerOutput, volk_log2to10factor, num_points);
90}
91#endif /* LV_HAVE_GENERIC */
92
93#ifdef LV_HAVE_NEON
94#include <arm_neon.h>
96
97static inline void
99 const lv_32fc_t* complexFFTInput,
100 const float normalizationFactor,
101 unsigned int num_points)
102{
103 float* logPowerOutputPtr = logPowerOutput;
104 const lv_32fc_t* complexFFTInputPtr = complexFFTInput;
105 const float iNormalizationFactor = 1.0 / normalizationFactor;
106 unsigned int number;
107 unsigned int quarter_points = num_points / 4;
108 float32x4x2_t fft_vec;
109 float32x4_t log_pwr_vec;
110 float32x4_t mag_squared_vec;
111
112 const float inv_ln10_10 = 4.34294481903f; // 10.0/ln(10.)
113
114 for (number = 0; number < quarter_points; number++) {
115 // Load
116 fft_vec = vld2q_f32((float*)complexFFTInputPtr);
117 // Prefetch next 4
118 __VOLK_PREFETCH(complexFFTInputPtr + 4);
119 // Normalize
120 fft_vec.val[0] = vmulq_n_f32(fft_vec.val[0], iNormalizationFactor);
121 fft_vec.val[1] = vmulq_n_f32(fft_vec.val[1], iNormalizationFactor);
122 mag_squared_vec = _vmagnitudesquaredq_f32(fft_vec);
123 log_pwr_vec = vmulq_n_f32(_vlogq_f32(mag_squared_vec), inv_ln10_10);
124 // Store
125 vst1q_f32(logPowerOutputPtr, log_pwr_vec);
126 // Move pointers ahead
127 complexFFTInputPtr += 4;
128 logPowerOutputPtr += 4;
129 }
130
131 // deal with the rest
132 for (number = quarter_points * 4; number < num_points; number++) {
133 const float real = lv_creal(*complexFFTInputPtr) * iNormalizationFactor;
134 const float imag = lv_cimag(*complexFFTInputPtr) * iNormalizationFactor;
135
136 *logPowerOutputPtr =
137 volk_log2to10factor * log2f_non_ieee(((real * real) + (imag * imag)));
138 complexFFTInputPtr++;
139 logPowerOutputPtr++;
140 }
141}
142
143#endif /* LV_HAVE_NEON */
144
145#endif /* INCLUDED_volk_32fc_s32f_power_spectrum_32f_a_H */
static void volk_32fc_s32f_power_spectrum_32f_generic(float *logPowerOutput, const lv_32fc_t *complexFFTInput, const float normalizationFactor, unsigned int num_points)
Definition volk_32fc_s32f_power_spectrum_32f.h:50
static void volk_32fc_s32f_power_spectrum_32f_neon(float *logPowerOutput, const lv_32fc_t *complexFFTInput, const float normalizationFactor, unsigned int num_points)
Definition volk_32fc_s32f_power_spectrum_32f.h:98
#define volk_log2to10factor
Definition volk_common.h:165
static float log2f_non_ieee(float f)
Definition volk_common.h:155
#define __VOLK_PREFETCH(addr)
Definition volk_common.h:68
#define lv_cimag(x)
Definition volk_complex.h:98
#define lv_creal(x)
Definition volk_complex.h:96
float complex lv_32fc_t
Definition volk_complex.h:74
static float32x4_t _vlogq_f32(float32x4_t x)
Definition volk_neon_intrinsics.h:143
static float32x4_t _vmagnitudesquaredq_f32(float32x4x2_t cmplxValue)
Definition volk_neon_intrinsics.h:73