dsps_sqrt_f32_ansi.c File Reference

#include "dsps_sqrt.h"
#include <math.h>

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Functions
float	dsps_sqrtf_f32_ansi (float f)
	square root approximation
esp_err_t	dsps_sqrt_f32_ansi (const float *input, float *output, int len)
	square root approximation
float	dsps_inverted_sqrtf_f32_ansi (float data)
	inverted square root approximation

Function Documentation

dsps_inverted_sqrtf_f32_ansi()

float dsps_inverted_sqrtf_f32_ansi

(

float

data

)

inverted square root approximation

The function takes inverted square root approximation x ~ 1/sqrt(y); The implementation use ANSI C and could be compiled and run on any platform

Parameters

[in]

data

input value

Returns

• inverted square root value

Definition at line 44 of file dsps_sqrt_f32_ansi.c.

{
    const float x2 = data * 0.5F;
    const float threehalfs = 1.5F;
 
    union {
        float f;
        uint32_t i;
    } conv = {data}; // member 'f' set to value of 'data'.
    conv.i  = 0x5f3759df - ( conv.i >> 1 );
    conv.f  *= ( threehalfs - ( x2 * conv.f * conv.f ) );
    return conv.f;
}

References data.

dsps_sqrt_f32_ansi()

esp_err_t dsps_sqrt_f32_ansi	(	const float *	input,
		float *	output,
		int	len )

square root approximation

The function takes square root approximation x[i] ~ sqrt(y[i]); i=[0..len) The implementation use ANSI C and could be compiled and run on any platform

Parameters

[in]	input	input array
	output	output array
	len	amount of operations for arrays

Returns

• ESP_OK on success
• One of the error codes from DSP library

Definition at line 29 of file dsps_sqrt_f32_ansi.c.

{
    if (NULL == input) {
        return ESP_ERR_DSP_PARAM_OUTOFRANGE;
    }
    if (NULL == output) {
        return ESP_ERR_DSP_PARAM_OUTOFRANGE;
    }
 
    for (int i = 0 ; i < len ; i++) {
        output[i] = dsps_sqrtf_f32_ansi(input[i]);
    }
    return ESP_OK;
}

References dsps_sqrtf_f32_ansi(), ESP_ERR_DSP_PARAM_OUTOFRANGE, and ESP_OK.

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dsps_sqrtf_f32_ansi()

float dsps_sqrtf_f32_ansi ( const float data )

inline

square root approximation

The function takes square root approximation x ~ sqrt(y); The implementation use ANSI C and could be compiled and run on any platform

Parameters

[in]

data

input value

Returns

• square root value

Definition at line 19 of file dsps_sqrt_f32_ansi.c.

{
    int result;
    int *f_ptr = (int *)&f;
    result = 0x1fbb4000 + (*f_ptr >> 1);
    const int *p = &result;
    float *f_result = (float *)p;
    return *f_result;
}

Referenced by dsps_sqrt_f32_ansi().

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