File syn_goertzel.h¶

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Integer-Only Goertzel Algorithm Single-Frequency Tone Detector. More...

#include "../common/syn_defs.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

Classes¶

Type	Name
struct	SYN_Goertzel Goertzel Filter Instance State.

Public Functions¶

Type	Name
uint64_t	syn_goertzel_get_magnitude_sq (const SYN_Goertzel * g) Calculate the squared magnitude \|X(k)\|^2 at the end of a sample block.
SYN_Status	syn_goertzel_init (SYN_Goertzel * g, uint32_t sample_rate_hz, uint32_t target_freq_hz, size_t block_size) Initialize a Goertzel Filter instance.
size_t	syn_goertzel_process_block (SYN_Goertzel * g, const int16_t * samples, size_t count) Process a buffer of 16-bit PCM samples through the Goertzel filter.
SYN_Status	syn_goertzel_process_sample (SYN_Goertzel * g, int16_t sample) Process a single 16-bit PCM sample through the Goertzel filter.
SYN_Status	syn_goertzel_reset (SYN_Goertzel * g) Reset Goertzel filter delay accumulators for a new sample block.

Detailed Description¶

Provides a zero-malloc fixed-point implementation of the Goertzel algorithm for efficient single-frequency magnitude evaluation and DTMF tone decoding on resource-constrained microcontrollers without running full FFTs.

Public Functions Documentation¶

function syn_goertzel_get_magnitude_sq¶

Calculate the squared magnitude |X(k)|^2 at the end of a sample block.

uint64_t syn_goertzel_get_magnitude_sq (
    const SYN_Goertzel * g
)

Parameters:

g Pointer to Goertzel instance.

Returns:

64-bit squared magnitude value |X(k)|^2 (or 0 if invalid).

function syn_goertzel_init¶

Initialize a Goertzel Filter instance.

SYN_Status syn_goertzel_init (
    SYN_Goertzel * g,
    uint32_t sample_rate_hz,
    uint32_t target_freq_hz,
    size_t block_size
)

Parameters:

g Pointer to Goertzel instance.
sample_rate_hz Sampling frequency in Hz (e.g. 8000).
target_freq_hz Target tone frequency in Hz (e.g. 697 for DTMF row 1).
block_size Sample block size N (e.g. 205).

Returns:

SYN_OK on success, or SYN_INVALID_PARAM.

function syn_goertzel_process_block¶

Process a buffer of 16-bit PCM samples through the Goertzel filter.

size_t syn_goertzel_process_block (
    SYN_Goertzel * g,
    const int16_t * samples,
    size_t count
)

Parameters:

g Pointer to Goertzel instance.
samples Array of 16-bit signed PCM input samples.
count Sample count in array.

Returns:

Number of samples actually processed.

function syn_goertzel_process_sample¶

Process a single 16-bit PCM sample through the Goertzel filter.

SYN_Status syn_goertzel_process_sample (
    SYN_Goertzel * g,
    int16_t sample
)

Parameters:

g Pointer to Goertzel instance.
sample 16-bit signed PCM input sample.

Returns:

SYN_OK on success, or SYN_INVALID_PARAM.

function syn_goertzel_reset¶

Reset Goertzel filter delay accumulators for a new sample block.

SYN_Status syn_goertzel_reset (
    SYN_Goertzel * g
)

Parameters:

g Pointer to Goertzel instance.

Returns:

SYN_OK on success, or SYN_INVALID_PARAM.

The documentation for this class was generated from the following file src/syntropic/dsp/syn_goertzel.h