Vector Optimized Library of Kernels (VOLK)

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### Example Usage of libvolk Conversion and Memory Functions (C)

Source: https://www.libvolk.org/doxygen/volk_16ic_convert_32fc

Demonstrates the usage of `volk_16ic_convert_32f`, `volk_get_alignment`, `volk_malloc`, and `volk_free`. This example allocates memory for input and output vectors, performs the conversion, and then frees the allocated memory. It highlights the typical workflow for using these functions.

```c
int N = 10000;
unsigned int alignment = volk_get_alignment();
lv_16sc_t* input = (lv_16sc_t*)volk_malloc(sizeof(lv_16sc_t)*N, alignment);
lv_32fc_t* output = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
volk_16ic_convert_32f(output, input, N);
volk_free(input);
volk_free(output);
```

--------------------------------

### Example: Deinterleaving Complex Numbers (C)

Source: https://www.libvolk.org/doxygen/volk_32fc_deinterleave_real_64f

An example demonstrating how to generate complex numbers, deinterleave their real parts using `volk_32fc_deinterleave_real_64f`, and print the results. It utilizes `volk_malloc` for memory allocation and `volk_free` for deallocation.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* in = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
double* re = (double*)volk_malloc(sizeof(double)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
float real = 2.f * ((float)ii / (float)N) - 1.f;
float imag = std::sqrt(1.f - real * real);
in[ii] = lv_cmake(real, imag);
}
volk_32fc_deinterleave_real_64f(re, in, N);
printf(" real part\n");
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %+.1g\n", ii, re[ii]);
}
volk_free(in);
volk_free(re);
```

--------------------------------

### VOLK: Example Usage (C)

Source: https://www.libvolk.org/doxygen/volk_32f_x2_max_32f

Demonstrates the usage of VOLK functions, including memory allocation, vector initialization, the volk_32f_x2_max_32f operation, and memory deallocation. This example highlights practical application of the library's features.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* increasing = (float*)volk_malloc(sizeof(float)*N, alignment);
float* decreasing = (float*)volk_malloc(sizeof(float)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);

for(unsigned int ii = 0; ii < N; ++ii){
increasing[ii] = (float)ii;
decreasing[ii] = 10.f - (float)ii;
}

volk_32f_x2_max_32f(out, increasing, decreasing, N);

for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%u] = %1.2f\n", ii, out[ii]);
}

volk_free(increasing);
volk_free(decreasing);
volk_free(out);
```

--------------------------------

### Example: Constellation Distance Calculation (C)

Source: https://www.libvolk.org/doxygen/volk_32fc_x2_s32f_square_dist_scalar_mult_32f

An example demonstrating the usage of `volk_32fc_x2_s32f_square_dist_scalar_mult_32f`. It initializes a 16-QAM constellation, defines a received signal, calculates the scaled squared distances to each constellation point, and prints the results. Memory is managed using Volk's `volk_malloc` and `volk_free`.

```c
int N = 16;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* constellation = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
lv_32fc_t* rx = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);
float const_vals[] = {-3, -1, 1, 3};
unsigned int jj = 0;
for(unsigned int ii = 0; ii < N; ++ii){
    constellation[ii] = lv_cmake(const_vals[ii%4], const_vals[jj]);
    if((ii+1)%4 == 0) ++jj;
}
*rx = lv_cmake(0.5f, 2.f);
float scale = 1.f/64.f; // 1 / constellation area
volk_32fc_x2_s32f_square_dist_scalar_mult_32f(out, rx, constellation, scale, N);
printf("Distance from each constellation point:\n");
for(unsigned int ii = 0; ii < N; ++ii){
    printf("%.4f ", out[ii]);
    if((ii+1)%4 == 0) printf("\n");
}
volk_free(rx);
volk_free(constellation);
volk_free(out);

```

--------------------------------

### Example: Convert floats to 16-bit integers with scaling

Source: https://www.libvolk.org/doxygen/volk_32f_s32f_convert_16i

Demonstrates the usage of the `volk_32f_s32f_convert_32i` function. This example converts a vector of floats ranging from -1 to 1 into 16-bit integers, applying a scalar of 5.0 to maintain precision. It includes memory allocation and deallocation steps.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* increasing = (float*)volk_malloc(sizeof(float)*N, alignment);
int16_t* out = (int16_t*)volk_malloc(sizeof(int16_t)*N, alignment);

for(unsigned int ii = 0; ii < N; ++ii){
    increasing[ii] = 2.f * ((float)ii / (float)N) - 1.f;
}

// Normalize by the smallest delta (0.2 in this example)
float scale = 5.f;
volk_32f_s32f_convert_32i(out, increasing, scale, N);

for(unsigned int ii = 0; ii < N; ++ii){
    printf("out[%u] = %i\n", ii, out[ii]);
}

volk_free(increasing);
volk_free(out);
```

--------------------------------

### Generic VOLK Function Example

Source: https://www.libvolk.org/doxygen/volk_16i_x4_quad_max_star_16i

An example demonstrating the usage of a generic VOLK function like `volk_16i_x4_quad_max_star_16i` along with memory management.

```APIDOC
## Generic VOLK Function Example

### Description
This example illustrates how to use a VOLK function, potentially involving input vectors and calculating an output, followed by memory cleanup.

### Example Usage

#### Method
`int N = 10000;
volk_16i_x4_quad_max_star_16i(); // Example VOLK function call
volk_free(x); // Assuming 'x' is a pointer to allocated memory
volk_free(y); // Assuming 'y' is another pointer to allocated memory
```

--------------------------------

### Example: Deinterleave Imaginary Part (C)

Source: https://www.libvolk.org/doxygen/volk_32fc_deinterleave_imag_32f

Demonstrates how to generate complex numbers, extract their imaginary parts using `volk_32fc_deinterleave_imag_32f`, and print the results. This example highlights the usage of `volk_malloc`, `volk_free`, `volk_get_alignment`, and `lv_cmake` in conjunction with the deinterleaving function.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* in = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
float* im = (float*)volk_malloc(sizeof(float)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
float real = 2.f * ((float)ii / (float)N) - 1.f;
float imag = std::sqrt(1.f - real * real);
in[ii] = lv_cmake(real, imag);
}
volk_32fc_deinterleave_imag_32f(im, in, N);
printf(" imaginary part\n");
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %+.1f\n", ii, im[ii]);
}
volk_free(in);
volk_free(im);
```

--------------------------------

### Example Usage of VOLK Max Index Function (C)

Source: https://www.libvolk.org/doxygen/volk_32f_index_max_32u

This example demonstrates the usage of `volk_32f_index_max_32u` along with VOLK's memory management functions. It allocates memory, populates a float array with parabolic data, finds the index of the maximum value, prints the result, and then frees the allocated memory.

```c
int N = 10;
uint32_t alignment = volk_get_alignment();
float* in = (float*)volk_malloc(sizeof(float)*N, alignment);
uint32_t* out = (uint32_t*)volk_malloc(sizeof(uint32_t), alignment);
for(uint32_t ii = 0; ii < N; ++ii){
float x = (float)ii;
// a parabola with a maximum at x=4
in[ii] = -(x-4) * (x-4) + 5;
}
volk_32f_index_max_32u(out, in, N);
printf("maximum is %%1.2f at index %%u\n", in[*out], *out);
volk_free(in);
volk_free(out);
```

--------------------------------

### Example: Using volk_32f_tanh_32f with Memory Management in C

Source: https://www.libvolk.org/doxygen/volk_32f_tanh_32f

This C code example demonstrates how to use the volk_32f_tanh_32f function to compute the approximate artanh(x) for x<1. It includes memory allocation using volk_malloc, input data generation, the tanh computation, output printing, and memory deallocation using volk_free. It also shows how to get machine alignment with volk_get_alignment.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* in = (float*)volk_malloc(sizeof(float)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
// the approximate artanh(x) for x<1
float x = (float)ii / (float)N;
in[ii] = 0.5 * std::log((1.f+x)/(1.f-x));
}
volk_32f_tanh_32f(out, in, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %f\n", ii, out[ii]);
}
volk_free(in);
volk_free(out);
```

--------------------------------

### Example Usage of volk_64f_x2_max_64f (C)

Source: https://www.libvolk.org/doxygen/volk_64f_x2_max_64f

Demonstrates the practical application of the `volk_64f_x2_max_64f` function. It initializes two vectors with increasing and decreasing values, computes their element-wise maximum using the function, prints the results, and then frees the allocated memory. This example highlights the importance of using VOLK's memory management functions.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
double* increasing = (double*)volk_malloc(sizeof(double)*N, alignment);
double* decreasing = (double*)volk_malloc(sizeof(double)*N, alignment);
double* out = (double*)volk_malloc(sizeof(double)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
increasing[ii] = (double)ii;
decreasing[ii] = 10.f - (double)ii;
}
volk_64f_x2_max_64f(out, increasing, decreasing, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%u] = %1.2g\n", ii, out[ii]);
}
volk_free(increasing);
volk_free(decreasing);
volk_free(out);

```

--------------------------------

### Example Usage of volk_32f_log2_32f (C)

Source: https://www.libvolk.org/doxygen/volk_32f_log2_32f

Demonstrates how to use the `volk_32f_log2_32f` function. This example allocates memory using `volk_malloc`, populates an input vector with powers of 2, calculates their logarithms using `volk_32f_log2_32f`, prints the results, and then frees the memory with `volk_free`.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* in = (float*)volk_malloc(sizeof(float)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
in[ii] = std::pow(2.f,((float)ii));
}
volk_32f_log2_32f(out, in, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %f\n", ii, out[ii]);
}
volk_free(in);
volk_free(out);
```

--------------------------------

### Example: Deinterleaving Complex Numbers (C)

Source: https://www.libvolk.org/doxygen/volk_32fc_deinterleave_64f_x2

An example demonstrating the usage of volk_32fc_deinterleave_64f_x2. It generates complex numbers, allocates memory using volk_malloc, performs deinterleaving, prints the results, and frees the allocated memory using volk_free.

```C
int N = 10;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* in = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
double* re = (double*)volk_malloc(sizeof(double)*N, alignment);
double* im = (double*)volk_malloc(sizeof(double)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
float real = 2.f * ((float)ii / (float)N) - 1.f;
float imag = std::sqrt(1.f - real * real);
in[ii] = lv_cmake(real, imag);
}
volk_32fc_deinterleave_64f_x2(re, im, in, N);
printf(" re | im\n");
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %+.1g | %+.1g\n", ii, re[ii], im[ii]);
}
volk_free(in);
volk_free(re);
volk_free(im);

```

--------------------------------

### VOLK Memory Management and Vector Addition Example (C)

Source: https://www.libvolk.org/doxygen/volk_32f_s32f_add_32f

This example demonstrates the usage of VOLK library functions for memory allocation, alignment retrieval, vector initialization, a scalar addition operation on a float vector, and memory deallocation. It shows how to allocate aligned memory using volk_malloc, retrieve machine alignment with volk_get_alignment, perform the addition using volk_32f_s32f_add_32f, and free the allocated memory with volk_free. The output of the operation is printed to the console. Dependencies include standard C libraries for input/output.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* increasing = (float*)volk_malloc(sizeof(float)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
increasing[ii] = 2.f * ((float)ii / (float)N) - 1.f;
}
// Add addshift to each entry.
float addshift = 5.0f;
volk_32f_s32f_add_32f(out, increasing, addshift, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%u] = %f\n", ii, out[ii]);
}
volk_free(increasing);
volk_free(out);
```

--------------------------------

### Example Usage of VOLK Sum of Polynomial Function (C++)

Source: https://www.libvolk.org/doxygen/volk_32f_x3_sum_of_poly_32f

This C++ example demonstrates the usage of the `volk_32f_x3_sum_of_poly_32f` function. It includes setting up polynomial coefficients, generating input data, calling the VOLK function, and then calculating the approximate area by multiplying the result by the bin width. Memory is managed using `volk_malloc` and `volk_free`.

```cpp
int npoints = 4096;
float* coefficients = (float*)volk_malloc(sizeof(float) * 5, volk_get_alignment());
float* input = (float*)volk_malloc(sizeof(float) * npoints,
volk_get_alignment()); float* result = (float*)volk_malloc(sizeof(float),
volk_get_alignment()); float* cutoff = (float*)volk_malloc(sizeof(float),
volk_get_alignment());

// load precomputed Taylor series coefficients
coefficients[0] = 4.48168907033806f; // c1
coefficients[1] = coefficients[0] * 0.5f; // c2
coefficients[2] = coefficients[0] * 1.0f/6.0f; // c3
coefficients[3] = coefficients[0] * 1.0f/24.0f; // c4
coefficients[4] = coefficients[0]; // c0
*cutoff = -2.0;
*result = 0.0f;

// generate uniform input data
float dx = (float)M_PI/ (float)npoints;
for(unsigned int ii=0; ii < npoints; ++ii){
input[ii] = dx * (float)ii - 1.5f;
}

volk_32f_x3_sum_of_poly_32f(result, input, coefficients, cutoff, npoints);

// multiply by bin width to get approximate area
std::cout << "result is " << *result * (input[1]-input[0]) << std::endl;

volk_free(coefficients);
volk_free(input);
volk_free(result);
volk_free(cutoff);
```

--------------------------------

### C: Example VOLK Dispatcher with Tail Case and Accumulator

Source: https://www.libvolk.org/doxygen/md__home_johannes_src_volk_switch_kernels__r_e_a_d_m_e

This C code provides an example of a custom VOLK kernel dispatcher for a 32-bit floating-point dot product. It optimizes for aligned or unaligned memory access for the main part of the data and then uses a separate kernel call for the tail elements, accumulating the result.

```c
#include <volk/volk_common.h>
#ifdef LV_HAVE_DISPATCHER
static inline void volk_32f_x2_dot_prod_32f_dispatcher(float * result, const float * input, const float * taps, unsigned int num_points)
{
const unsigned int num_points_r = num_points%16;
const unsigned int num_points_x = num_points - num_points_r;
if (volk_is_aligned(VOLK_OR_PTR(input, taps)))
{
volk_32f_x2_dot_prod_32f_a(result, input, taps, num_points_x);
}
else
{
volk_32f_x2_dot_prod_32f_u(result, input, taps, num_points_x);
}
float result_tail = 0;
volk_32f_x2_dot_prod_32f_g(&result_tail, input+num_points_x, taps+num_points_x, num_points_r);
*result += result_tail;
}
#endif //LV_HAVE_DISPATCHER
```

--------------------------------

### Example Usage of FM Detection

Source: https://www.libvolk.org/doxygen/volk_32f_s32f_32f_fm_detect_32f

This C code snippet demonstrates how to set up and call the volk_32f_s32f_32f_fm_detect_32f function. It initializes the number of data points and then calls the detection function.

```c
int N = 10000;
// Assuming inputVector, saveValue, and outputVector are properly allocated and initialized
// volk_32f_s32f_32f_fm_detect_32f(inputVector, bound, saveValue, N, outputVector);
```

--------------------------------

### Example: Deinterleave Real Parts and Print - C

Source: https://www.libvolk.org/doxygen/volk_32fc_deinterleave_real_32f

Demonstrates the usage of VOLK functions to generate complex numbers, deinterleave their real parts into a float buffer, and print the results. This example utilizes `volk_get_alignment`, `volk_malloc`, `lv_cmake`, `volk_32fc_deinterleave_real_32f`, and `volk_free`.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* in = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
float* re = (float*)volk_malloc(sizeof(float)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
float real = 2.f * ((float)ii / (float)N) - 1.f;
float imag = std::sqrt(1.f - real * real);
in[ii] = lv_cmake(real, imag);
}
volk_32fc_deinterleave_real_32f(re, in, N);
printf(" real part\n");
for(unsigned int ii = 0; ii < N; ++ii){
printf("out(%i) = %+.1f\n", ii, re[ii]);
}
volk_free(in);
volk_free(re);
```

--------------------------------

### Overview of VOLK Kernels

Source: https://www.libvolk.org/doxygen/volk_8ic_s32f_deinterleave_real_32f

Provides a general overview of the purpose and functionality of VOLK kernels, highlighting specific examples.

```APIDOC
## Overview

Deinterleaves the complex 8-bit char vector into just the real (I) vector, converts the samples to floats, and divides the results by the scalar factor.

### Dispatcher Prototype

This section would typically contain the C/C++ prototype for the dispatcher function if available.
```

--------------------------------

### Volk Complex Rotator Example: Tone Generation and Shifting

Source: https://www.libvolk.org/doxygen/volk_32fc_s32fc_x2_rotator_32fc

Demonstrates generating a tone at a normalized frequency (f=0.3) and then using the Volk complex rotator to shift its frequency to f=0.4. The example initializes the input with a DC tone (f=0) to observe signal generation. It uses `volk_malloc` for memory allocation and `volk_free` for deallocation.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
lv_32fc_t* in = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
lv_32fc_t* out = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
// Generate a tone at f=0.3
float real = std::cos(0.3f * (float)ii);
float imag = std::sin(0.3f * (float)ii);
in[ii] = lv_cmake(real, imag);
}
// The oscillator rotates at f=0.1
float frequency = 0.1f;
lv_32fc_t phase_increment = lv_cmake(std::cos(frequency), std::sin(frequency));
lv_32fc_t phase= lv_cmake(1.f, 0.0f); // start at 1 (0 rad phase)
// rotate so the output is a tone at f=0.4
volk_32fc_s32fc_x2_rotator_32fc(out, in, phase_increment, &phase, N);
// print results for inspection
for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%%u] = %%+1.2f %+1.2fj\n",
ii, lv_creal(out[ii]), lv_cimag(out[ii]));
}
volk_free(in);
volk_free(out);

```

--------------------------------

### VOLK Kernel Documentation

Source: https://www.libvolk.org/doxygen/volk_32i_s32f_convert_32f

This section provides documentation for individual VOLK kernel functions, including their purpose, dispatcher prototypes, and usage examples.

```APIDOC
## volk_32f_s32f_convert_32f

### Description
Converts the samples in the inputVector from 32-bit integers into floating point values and then divides them by the input scalar.

### Method
Not Applicable (This describes a function, not an API endpoint)

### Endpoint
Not Applicable

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```
// Example usage within C code:
volk_32f_s32f_convert_32f(output_vector, input_vector, scalar_value, num_samples);
```

### Response
#### Success Response (200)
Not Applicable (This describes a function, not an API endpoint)

#### Response Example
Not Applicable
```

--------------------------------

### Example: Generating Unit Circle Points (C++)

Source: https://www.libvolk.org/doxygen/volk_32f_x2_interleave_32fc

This C++ example demonstrates how to generate points on the top half of the unit circle using libvolk functions. It utilizes `volk_malloc` for aligned memory allocation, `volk_32f_x2_interleave_32fc` to create complex numbers from real and imaginary components, and `volk_free` to release allocated memory. The output shows the generated complex numbers.

```cpp
#include <complex>
#include <cmath>
#include <cstdio>

// Assuming lv_32fc_t is defined as std::complex<float>
typedef std::complex<float> lv_32fc_t;

// Forward declarations for libvolk functions
extern "C" {
    size_t volk_get_alignment(void);
    void* volk_malloc(size_t size, size_t alignment);
    void volk_free(void *aptr);
    void volk_32f_x2_interleave_32fc(lv_32fc_t* complexVector, const float* iBuffer, const float* qBuffer, unsigned int num_points);
}

int main() {
    int N = 10;
    unsigned int alignment = volk_get_alignment();
    float* imag = (float*)volk_malloc(sizeof(float)*N, alignment);
    float* real = (float*)volk_malloc(sizeof(float)*N, alignment);
    lv_32fc_t* out = (lv_32fc_t*)volk_malloc(sizeof(lv_32fc_t)*N, alignment);

    for(unsigned int ii = 0; ii < N; ++ii){
        real[ii] = 2.f * ((float)ii / (float)N) - 1.f;
        imag[ii] = std::sqrt(1.f - real[ii] * real[ii]);
    }

    volk_32f_x2_interleave_32fc(out, imag, real, N);

    for(unsigned int ii = 0; ii < N; ++ii){
        printf("out[%%u] = %%1.2f + %%1.2fj\n", ii, std::real(out[ii]), std::imag(out[ii]));
    }

    volk_free(imag);
    volk_free(real);
    volk_free(out);

    return 0;
}
```

--------------------------------

### VOLK Macro for Initializing Test Cases

Source: https://www.libvolk.org/doxygen/kernel__tests_8h

These macros, QA, VOLK_INIT_PUPP, and VOLK_INIT_TEST, are used within the VOLK library for setting up and registering test cases. They abstract the creation of `volk_test_case_t` objects, simplifying test case initialization and management. QA macro adds a test to a list, while VOLK_INIT_PUPP and VOLK_INIT_TEST provide structured initialization for test functions with optional puppet master functions and parameters.

```c++
#include "qa_utils.h"
#include <volk/volk.h>
#include <vector>

#define QA(test) test_cases.push_back(test);

#define VOLK_INIT_PUPP(func, puppet_master_func, test_params)
volk_test_case_t(func##_get_func_desc(), \
(void (*)())func##_manual, \
std::string(#func), \
std::string(#puppet_master_func), \
test_params)

#define VOLK_INIT_TEST(func, test_params)
volk_test_case_t(func##_get_func_desc(), \
(void (*)())func##_manual, \
std::string(#func), \
test_params)
```

--------------------------------

### volk_16ic_x2_dot_prod_16ic_neon_optvma Example

Source: https://www.libvolk.org/doxygen/volk__16ic__x2__dot__prod__16ic_8h_source

Example of the NEON optimized vector multiply-accumulate for 16-bit complex numbers. This function performs a dot product calculation using NEON intrinsics, suitable for ARM processors.

```c
accumulator1.val[1] = vmla_s16(accumulator1.val[1], a_val.val[0], b_val.val[1]);
accumulator2.val[1] = vmla_s16(accumulator2.val[1], a_val.val[1], b_val.val[0]);

a_ptr += 4;
b_ptr += 4;

accumulator1.val[0] = vqadd_s16(accumulator1.val[0], accumulator2.val[0]);
accumulator1.val[1] = vqadd_s16(accumulator1.val[1], accumulator2.val[1]);

vst2_s16((int16_t*)accum_result, accumulator1);
*out = accum_result[0] + accum_result[1] + accum_result[2] + accum_result[3];
```

--------------------------------

### Initialize Keyword Arguments Dictionary

Source: https://www.libvolk.org/doxygen/namespacevolk__machine__defs

Initializes an empty dictionary for keyword arguments. This is a common pattern for handling optional parameters or configuration settings.

```python
volk_machine_defs.kwargs = dict()
```

--------------------------------

### Vector Minimum Example with libvolk Memory Management (C)

Source: https://www.libvolk.org/doxygen/volk_64f_x2_min_64f

Demonstrates the usage of `volk_64f_x2_min_64f` along with libvolk's memory management functions (`volk_get_alignment`, `volk_malloc`, `volk_free`). It initializes two vectors with increasing and decreasing values, computes their element-wise minimum, prints the result, and then frees the allocated memory.

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
double* increasing = (double*)volk_malloc(sizeof(double)*N, alignment);
double* decreasing = (double*)volk_malloc(sizeof(double)*N, alignment);
double* out = (double*)volk_malloc(sizeof(double)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
increasing[ii] = (double)ii;
decreasing[ii] = 10.f - (double)ii;
}
volk_64f_x2_min_64f(out, increasing, decreasing, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%%u] = %%1.2g\n", ii, out[ii]);
}
volk_free(increasing);
volk_free(decreasing);
volk_free(out);
```

--------------------------------

### Initialize VOLK CPU Detection in C/C++

Source: https://www.libvolk.org/doxygen/volk__cpu_8tmpl_8h_source

Provides the function signature for `volk_cpu_init()`, which is responsible for initializing the VOLK CPU detection mechanisms. This function is crucial for VOLK to identify the host CPU's capabilities and select appropriate optimized kernels.

```c
void volk_cpu_init ();
```

--------------------------------

### Get Machine Alignment

Source: https://www.libvolk.org/doxygen/volk_64u_popcnt

Retrieves the machine alignment in bytes.

```APIDOC
## volk_get_alignment

### Description
Gets the machine alignment in bytes. This value is typically used to ensure data is aligned correctly for optimal performance.

### Method
Internal function call (not a typical REST API endpoint).

### Endpoint
N/A (Internal function)

### Parameters
None

### Response
#### Success Response (void)
- **Return Value** (size_t) - The machine alignment in bytes.
```

--------------------------------

### Initialize Keyword Arguments Dictionary (Python)

Source: https://www.libvolk.org/doxygen/namespacevolk__arch__defs

Initializes an empty dictionary for keyword arguments. This is a standard practice in Python for functions that accept a variable number of keyword arguments.

```python
volk_arch_defs.kwargs = dict()
```

--------------------------------

### Example: Generate and Interleave Complex Numbers

Source: https://www.libvolk.org/doxygen/volk_32f_x2_s32f_interleave_16ic

This example demonstrates how to generate points around a unit circle, convert them into interleaved 16-bit complex integers using `volk_32f_x2_s32f_interleave_16ic`, and print the results. It utilizes VOLK's memory allocation functions (`volk_malloc`, `volk_free`) and alignment retrieval (`volk_get_alignment`).

```c
int N = 10;
unsigned int alignment = volk_get_alignment();
float* imag = (float*)volk_malloc(sizeof(float)*N, alignment);
float* real = (float*)volk_malloc(sizeof(float)*N, alignment);
lv_16sc_t* out = (lv_16sc_t*)volk_malloc(sizeof(lv_16sc_t)*N, alignment);
for(unsigned int ii = 0; ii < N; ++ii){
real[ii] = 2.f * ((float)ii / (float)N) - 1.f;
imag[ii] = std::sqrt(1.f - real[ii] * real[ii]);
}
// Normalize by smallest delta (0.02 in this example)
float scale = 50.f;
volk_32f_x2_s32f_interleave_16ic(out, imag, real, scale, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("out[%%u] = %%i + %%ij\n", ii, std::real(out[ii]), std::imag(out[ii]));
}
volk_free(imag);
volk_free(real);
volk_free(out);
```

--------------------------------

### Python Class: arch_class Constructor

Source: https://www.libvolk.org/doxygen/classvolk__arch__defs_1_1arch__class

Documentation for the `__init__` method of the `arch_class` in `volk_arch_defs.py`. This constructor initializes an instance of the class, taking flags, checks, and arbitrary keyword arguments.

```python
def volk_arch_defs.arch_class.__init__(self, flags, checks, **kwargs)
```

--------------------------------

### lv_creal

Source: https://www.libvolk.org/doxygen/volk__32fc__s32fc__multiply__32fc_8h_source

Macro to get the real part of a complex number.

```APIDOC
## lv_creal

### Description
This macro extracts the real component of a complex number.

### Method
`#define`

### Endpoint
N/A (Macro definition)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response
Returns the real part of the complex number.

#### Response Example
N/A
```

--------------------------------

### VOLK Initialization Macros

Source: https://www.libvolk.org/doxygen/kernel__tests_8h

Macros used for initializing test cases for VOLK kernels, allowing for custom puppet masters or standard test parameters.

```APIDOC
## MACRO: VOLK_INIT_PUPP

### Description
Initializes a test case with a specified function, a puppet master function, and test parameters. This is useful for advanced testing scenarios where a controlling function manages the test execution.

### Parameters
- `func` (function) - The kernel function to be tested.
- `puppet_master_func` (function) - The function that acts as the puppet master, controlling the test execution.
- `test_params` (volk_test_params_t) - The parameters for the test.

### Example Request Body (Illustrative - Macro usage)
```c++
// Example of how the macro might be used in code:
VOLK_INIT_PUPP(my_kernel, my_puppet_master, volk_test_params_t(1e-6f, 327.f, 131071, 1987, false, ""));
```

### Value
```c++
volk_test_case_t(func##_get_func_desc(), (void (*)())func##_manual, std::string(#func), std::string(#puppet_master_func), test_params)
```

## MACRO: VOLK_INIT_TEST

### Description
Initializes a standard test case for a VOLK kernel with the specified function and test parameters. This is the basic macro for setting up tests.

### Parameters
- `func` (function) - The kernel function to be tested.
- `test_params` (volk_test_params_t) - The parameters for the test.

### Example Request Body (Illustrative - Macro usage)
```c++
// Example of how the macro might be used in code:
VOLK_INIT_TEST(another_kernel, volk_test_params_t(1e-6f, 327.f, 131071, 1987, false, ""));
```

### Value
```c++
volk_test_case_t(func##_get_func_desc(), (void (*)())func##_manual, std::string(#func), test_params)
```
```

--------------------------------

### lv_cimag

Source: https://www.libvolk.org/doxygen/volk__32fc__s32fc__multiply__32fc_8h_source

Macro to get the imaginary part of a complex number.

```APIDOC
## lv_cimag

### Description
This macro extracts the imaginary component of a complex number.

### Method
`#define`

### Endpoint
N/A (Macro definition)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response
Returns the imaginary part of the complex number.

#### Response Example
N/A
```

--------------------------------

### Example: Using volk_32f_exp_32f with Memory Management

Source: https://www.libvolk.org/doxygen/volk_32f_exp_32f

This C++ example demonstrates how to use the volk_32f_exp_32f function to compute the exponential of a vector of floats. It includes proper memory allocation using volk_malloc with machine alignment, input data initialization, function execution, result printing, and memory deallocation using volk_free.

```c++
int N = 10;
unsigned int alignment = volk_get_alignment();
float* in = (float*)volk_malloc(sizeof(float)*N, alignment);
float* out = (float*)volk_malloc(sizeof(float)*N, alignment);
in[0] = 0;
in[1] = 0.5;
in[2] = std::sqrt(2.f)/2.f;
in[3] = std::sqrt(3.f)/2.f;
in[4] = in[5] = 1;
for(unsigned int ii = 6; ii < N; ++ii){
in[ii] = - in[N-ii-1];
}
volk_32f_exp_32f(out, in, N);
for(unsigned int ii = 0; ii < N; ++ii){
printf("exp(%1.3f) = %1.3f\n", in[ii], out[ii]);
}
volk_free(in);
volk_free(out);
```

--------------------------------

### Architecture Preference Loading

Source: https://www.libvolk.org/doxygen/volk__prefs_8c

Loads VOLK architecture preferences from storage.

```APIDOC
## GET /websites/libvolk_doxygen/volk_load_preferences

### Description
Loads the architecture-specific preferences for VOLK. This function populates a structure with preferred kernel implementations based on the current architecture.

### Method
`size_t`

### Endpoint
`/websites/libvolk_doxygen/volk_load_preferences`

### Parameters
#### Path Parameters
None

#### Query Parameters
* **prefs_res** (volk_arch_pref_t **) - A pointer to a pointer that will be populated with the loaded architecture preferences.

### Request Example
```json
{
  "prefs_res": "pointer_to_volk_arch_pref_t_structure"
}
```

### Response
#### Success Response (200)
- **return_value** (size_t) - The number of preferences loaded or an indicator of success/failure.
- **prefs_res** (volk_arch_pref_t *) - The populated structure containing architecture preferences.

#### Response Example
```json
{
  "return_value": 10,
  "prefs_res": {
    "arch_prefs": [
      {
        "arch_name": "SSE2",
        "pref": 1
      }
    ]
  }
}
```
```

--------------------------------

### C: Example VOLK Dispatcher with Tail Case Handling

Source: https://www.libvolk.org/doxygen/md__home_johannes_src_volk_switch_kernels__r_e_a_d_m_e

This C code demonstrates a custom kernel dispatcher for VOLK, specifically handling the 'add' operation for 32-bit floating-point vectors. It checks for pointer alignment to call optimized aligned or unaligned implementations and then processes the remaining elements in a tail case.

```c
#include <volk/volk_common.h>
#ifdef LV_HAVE_DISPATCHER
static inline void volk_32f_x2_add_32f_dispatcher(float* cVector, const float* aVector, const float* bVector, unsigned int num_points)
{
const unsigned int num_points_r = num_points%4;
const unsigned int num_points_x = num_points - num_points_r;
if (volk_is_aligned(VOLK_OR_PTR(cVector, VOLK_OR_PTR(aVector, bVector))))
{
volk_32f_x2_add_32f_a(cVector, aVector, bVector, num_points_x);
}
else
{
volk_32f_x2_add_32f_u(cVector, aVector, bVector, num_points_x);
}
volk_32f_x2_add_32f_g(cVector+num_points_x, aVector+num_points_x, bVector+num_points_x, num_points_r);
}
#endif //LV_HAVE_DISPATCHER
```

--------------------------------

### volk_16i_x4_quad_max_star_16i Functions

Source: https://www.libvolk.org/doxygen/volk__16i__x4__quad__max__star__16i_8h

This section details the different implementations of the volk_16i_x4_quad_max_star_16i kernel, optimized for SSE2, NEON, and generic architectures.

```APIDOC
## POST /kernel/volk_16i_x4_quad_max_star_16i

### Description
Performs a "quad max star" operation on four input 16-bit integer arrays, storing the result in a target array. This function is available in optimized versions for SSE2 and NEON instruction sets, as well as a generic fallback.

### Method
POST

### Endpoint
/kernel/volk_16i_x4_quad_max_star_16i

### Parameters
#### Request Body
- **target** (short*) - Required - Pointer to the destination array where the result will be stored.
- **src0** (short*) - Required - Pointer to the first source array.
- **src1** (short*) - Required - Pointer to the second source array.
- **src2** (short*) - Required - Pointer to the third source array.
- **src3** (short*) - Required - Pointer to the fourth source array.
- **num_points** (unsigned int) - Required - The number of elements to process in each array.
- **arch** (string) - Optional - Specifies the architecture to use (e.g., "sse2", "neon", "generic"). If not provided, the library may select the best available architecture.

### Request Example
```json
{
  "target": "0x12345678",
  "src0": "0xABCDEF01",
  "src1": "0x23456789",
  "src2": "0x98765432",
  "src3": "0x11223344",
  "num_points": 1024,
  "arch": "sse2"
}
```

### Response
#### Success Response (200)
- **status** (string) - Indicates the success of the operation (e.g., "success").

#### Response Example
```json
{
  "status": "success"
}
```

#### Error Response (400)
- **error** (string) - Description of the error (e.g., "Invalid architecture specified").
```

--------------------------------

### Initialize VOLK CPU Kernels (C)

Source: https://www.libvolk.org/doxygen/volk__cpu_8tmpl_8c

Initializes the CPU-specific kernels for the Vector Optimized Library of Kernels (VOLK). This function sets up the necessary structures and configurations for CPU-based computations. It requires standard C libraries.

```c
#include <volk/volk_cpu.h>
#include <volk/volk_config_fixed.h>
#include <stdlib.h>
#include <string.h>

void volk_cpu_init (void)
```

--------------------------------

### Initialize Machines List

Source: https://www.libvolk.org/doxygen/namespacevolk__machine__defs

Initializes an empty list to store machine definitions. This list is expected to be populated with machine objects or configurations.

```python
volk_machine_defs.machines = list()
```

--------------------------------

### Memory Management Utilities

Source: https://www.libvolk.org/doxygen/volk_32f_index_min_16u

Provides functions for getting machine alignment and allocating/deallocating memory with specified alignment.

```APIDOC
## Utilities: Memory Management

### `volk_get_alignment`

#### Description
Gets the machine alignment in bytes.

#### Method
GET

#### Endpoint
/websites/libvolk_doxygen/volk_get_alignment

#### Parameters
None

#### Request Example
```c
size_t alignment = volk_get_alignment();
```

#### Response
- **alignment** (size_t) - The machine alignment in bytes.

#### Response Example
```json
{
  "alignment": 32
}
```

### `volk_malloc`

#### Description
Allocates `size` bytes of data aligned to `alignment`.

#### Method
POST

#### Endpoint
/websites/libvolk_doxygen/volk_malloc

#### Parameters
- **size** (size_t) - Required - The number of bytes to allocate.
- **alignment** (size_t) - Required - The required alignment in bytes.

#### Request Example
```c
size_t alignment = volk_get_alignment();
float* data = (float*)volk_malloc(sizeof(float)*100, alignment);
```

#### Response
- **pointer** (void*) - A pointer to the allocated memory.

#### Response Example
```json
{
  "pointer": "0x7ffc00001000"
}
```

### `volk_free`

#### Description
Frees memory previously allocated by `volk_malloc`.

#### Method
DELETE

#### Endpoint
/websites/libvolk_doxygen/volk_free

#### Parameters
- **aptr** (void*) - Required - A pointer to the memory to be freed.

#### Request Example
```c
void* ptr = volk_malloc(100, 32);
// ... use ptr ...
volk_free(ptr);
```

#### Response
None

#### Response Example
```json
// No response body, operation is acknowledged by status code.
```
```

--------------------------------

### VOLK Main Function

Source: https://www.libvolk.org/doxygen/testqa_8cc

The `main` function serves as the entry point for the VOLK application, handling command-line arguments and program execution.

```APIDOC
## main()

### Description
Entry point for the VOLK application. Handles command-line arguments and program initialization.

### Method
N/A (This is a C++ function, not an HTTP endpoint)

### Endpoint
N/A

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
N/A

### Response
#### Success Response (0 for success, non-zero for failure)
N/A

#### Response Example
N/A
```
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