// Oscillator Cross
//
// oscillator_cross
//
// Oscillator crossover detector
//
// 
//
// Inputs:    1
// Outputs:   1
// Constants: 2


#include "ts.h"

typedef struct {
    fp_t fast;
    fp_t slow;
} ts_oscillator_cross_params_t;

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

uint_t ts_oscillator_cross_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? (uint_t)((ts_oscillator_cross_params_t const *)c)->slow : 0 );
}

int ts_oscillator_cross(
	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_oscillator_cross_p );
	if ( !c ) return -1;
    fp_t const fast = ((ts_oscillator_cross_params_t const *)c)->fast;
    fp_t const slow = ((ts_oscillator_cross_params_t const *)c)->slow;
    if (fast == 0 || slow == 0) return -1;
    fp_t const fast_a = 1.0 / fast;
    fp_t const slow_a = 1.0 / slow;
    fp_t fast_e = x[0][0];
    fp_t slow_e = x[0][0];
    uint_t const offset = (uint_t)slow;
    if (offset >= n) return -1;

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

    for( uint_t i = 1; i < n; ++i )
    {
        fp_t pf = fast_e;
        fp_t ps = slow_e;
        fast_e = fast_e + fast_a * ( x[0][i] - fast_e );
        slow_e = slow_e + slow_a * ( x[0][i] - slow_e );

        if( i >= offset )
        {
            if( fast_e > slow_e && pf <= ps )
                y[0][i] = 1;
            else if( fast_e < slow_e && pf >= ps )
                y[0][i] = -1;
            else
                y[0][i] = 0;
        }
    }
	return 0;
}