dsps_cplx_gen.c File Reference

#include "dsps_cplx_gen.h"

Include dependency graph for dsps_cplx_gen.c:

Go to the source code of this file.

Functions
esp_err_t	dsps_cplx_gen_ansi (cplx_sig_t *cplx_gen, void *output, int32_t len)
	The function generates a complex signal.

Function Documentation

dsps_cplx_gen_ansi()

esp_err_t dsps_cplx_gen_ansi	(	cplx_sig_t *	cplx_gen,
		void *	output,
		int32_t	len )

The function generates a complex signal.

the generated complex signal is in the form of two harmonics signals in either 16-bit signed fixed point or 32-bit floating point

x[i]= A*sin(step*i + ph/180*Pi) x[i+1]= B*cos(step*i + ph/180*Pi) where step = 2*Pi*frequency

dsps_cplx_gen_ansi() - The implementation uses ANSI C and could be compiled and run on any platform dsps_cplx_gen_ae32() - Is targetted for Xtensa cores

Parameters

cplx_gen	pointer to the generator structure
output	output array (length of len*2), data type is void so both (S16_FIXED, F32_FLOAT) types could be used
len	length of the output signal

Returns

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

Definition at line 9 of file dsps_cplx_gen.c.

{
    // angle frequency is already cplx_gen->freq
    const int sin_to_cos = cplx_gen->lut_len / 4;
    float ph = cplx_gen->phase;
    const float fr = cplx_gen->freq;
    int sin_pos, cos_pos;
 
    for (int i = 0 ; i < len; i++) {
 
        if (ph < 0) {
            ph += 1.0;
        }
        if (ph >= 1.0) {
            ph -= 1.0;
        }
 
        sin_pos = (int)(ph * (cplx_gen->lut_len));
        cos_pos = (sin_pos + sin_to_cos) & (cplx_gen->lut_len - 1);
 
        if (cplx_gen->d_type == S16_FIXED) {
            ((int16_t *)output)[i * 2 + 0] = ((int16_t *)cplx_gen->lut)[cos_pos];
            ((int16_t *)output)[i * 2 + 1] = ((int16_t *)cplx_gen->lut)[sin_pos];
        } else {
            ((float *)output)[i * 2 + 0] = ((float *)cplx_gen->lut)[cos_pos];
            ((float *)output)[i * 2 + 1] = ((float *)cplx_gen->lut)[sin_pos];
        }
        ph += fr;
    }
 
    return ESP_OK;
}

References cplx_sig_s::d_type, ESP_OK, cplx_sig_s::freq, cplx_sig_s::lut, cplx_sig_s::lut_len, cplx_sig_s::phase, and S16_FIXED.