void levinson_durbin(
scalar R[], /* order+1 autocorrelation coeff */
scalar lpcs[], /* order+1 LPC's */
int order /* order of the LPC analysis */
)
{
scalar a[order+1][order+1];
scalar sum, e, k;
int i,j; /* loop variables */
scalar ZERO = fl_to_numb(0.0);
e = R[0]; /* Equation 38a, Makhoul */
for(i=1; i<=order; i++) {
sum = ZERO;
for(j=1; j<=i-1; j++)
sum = s_add(sum, s_mul(a[i-1][j],R[i-j]));
k = s_mul(-1.0, s_div(s_add(R[i], sum),e)); /* Equation 38b, Makhoul */
if (s_abs(k) > fl_to_numb(1.0))
k = ZERO;
a[i][i] = k;
for(j=1; j<=i-1; j++)
a[i][j] = s_add(a[i-1][j] , s_mul(k,a[i-1][i-j])); /* Equation 38c, Makhoul */
e = s_mul(e, s_sub(fl_to_numb(1.0),s_mul(k,k))); /* Equation 38d, Makhoul */
}
for(i=1; i<=order; i++)
lpcs[i] = a[order][i];
lpcs[0] = fl_to_numb(1.0);
}
void hanning_window(
scalar Sn[], /* input frame of speech samples */
scalar Wn[], /* output frame of windowed samples */
int Nsam /* number of samples */
)
{
int i; /* loop variable */
scalar HALF = fl_to_numb(0.5);
scalar PI2_ = fl_to_numb(2*PI);
scalar Nsam_ = int_to_numb(Nsam-1);
for(i=0; i<Nsam; i++){
scalar sc_cos = s_mul(HALF,s_cos(s_mul( PI2_, s_div(fl_to_numb((float)i),Nsam_))));
scalar sc_a = s_sub(HALF, sc_cos);
Wn[i] = s_mul(Sn[i], sc_a);
}
}
void *nlp_create(
int m /* analysis window size */
)
{
NLP *nlp;
int i;
assert(m <= PMAX_M);
nlp = (NLP*)malloc(sizeof(NLP));
if (nlp == NULL)
return NULL;
nlp->m = m;
scalar PI2_ = fl_to_numb(2*PI);
scalar DEC_ = int_to_numb(m/DEC - 1);
scalar HALF = fl_to_numb(.5);
scalar ZERO = fl_to_numb(0.0);
scalar a, b, c;
for(i=0; i<m/DEC; i++) {
a = s_div(s_mul(PI2_, int_to_numb(i) ) , DEC_);
b = s_mul(HALF,s_cos(a));
nlp->w[i] = s_sub(HALF, b);
//nlp->w[i] = 0.5 - 0.5*cosf(2*PI*i/(m/DEC-1));
}
for(i=0; i<PMAX_M; i++)
nlp->sq[i] = ZERO;
nlp->mem_x = ZERO;
nlp->mem_y = ZERO;
for(i=0; i<NLP_NTAP; i++)
nlp->mem_fir[i] = ZERO;
nlp->fft_cfg = kiss_fft_alloc (PE_FFT_SIZE, 0, NULL, NULL);
assert(nlp->fft_cfg != NULL);
return (void*)nlp;
}
void
mp_sdiv(MINT *a, short n, MINT *q, short *r)
{
MINT x, y;
short sign;
sign = 1;
x.len = a->len;
x.val = a->val;
if (n < 0) {
sign = -sign;
n = -n;
}
if (x.len < 0) {
sign = -sign;
x.len = -x.len;
}
s_div(&x, n, &y, r);
_mp_xfree(q);
q->val = y.val;
q->len = sign * y.len;
*r = *r * sign;
}
