lib/delta.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50

// Delta
//
// delta - delta
//
// Calculates the delta between the current value and the value k samples ago
//
// y_i = x_i - x_i-k
//
// Inputs:    1
// Outputs:   1
// Constants: 1


#include "ts.h"


typedef struct {
    uint_t k;
} ts_delta_params_t;

ts_parameter_t const ts_delta_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_delta_params_t) };


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

int ts_delta(
	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_delta_p );
	if ( !c ) return -1;
	uint_t k = ((ts_delta_params_t *)c)->k;
	if (k == 0 || n < k) return -1;

	uint_t xi = k;

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