// Lag
//
// lag -  lag
//
// DESCRIPTION
//
// Inputs:    1
// Outputs:   1
// Constants: 2


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


typedef struct {
    uint_t k;
    fp_t insert;
} ts_lag_params_t;

ts_parameter_t const ts_lag_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 2, .params_size = sizeof(ts_lag_params_t) };


uint_t ts_lag_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? ((ts_lag_params_t *)c)->k : 0 );
}

int ts_lag(
	fp_t * const *y, uint_t y_n,
	fp_t const * const *x, uint_t x_n,
	uint_t n, ts_constant_t const *c
)
{
	TS_PROLOGUE( ts_lag_p );
	if ( !c ) return -1;
	uint_t k = ((ts_lag_params_t *)c)->k;
	if (k == 0) return -1;

	fp_t insert = ((ts_lag_params_t *)c)->insert;

	if (n <= k) return -1;

	for (uint_t i = 0; i < k; ++i)
		y[0][i] = insert;

	for (uint_t i = k; i < n; ++i)
		y[0][i] = x[0][i - k];
	return 0;
}