cxvec_math: Add osmo_cxvec_delay function

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
master
Sylvain Munaut 11 years ago
parent 76671f27d0
commit d070919a98
  1. 4
      include/osmocom/dsp/cxvec_math.h
  2. 74
      src/cxvec_math.c

@ -78,6 +78,10 @@ struct osmo_cxvec *
osmo_cxvec_rotate(const struct osmo_cxvec *in, float freq_shift,
struct osmo_cxvec *out);
struct osmo_cxvec *
osmo_cxvec_delay(const struct osmo_cxvec *v, float delay,
struct osmo_cxvec *out);
/*! \brief Various possible types of convolution span */
enum osmo_cxvec_conv_type {
/*! \brief Full span (every possible overlap of f onto g) */

@ -128,6 +128,80 @@ osmo_cxvec_rotate(const struct osmo_cxvec *in, float rps,
return out;
}
/*! \brief Fractionally delay a vector while maintaining its length
* \param[in] in Input complex vector
* \param[in] delay The fractional delay to apply
* \param[out] out Output complex vector
* \returns The output complex vector (or NULL if error)
*
* The output always has the same length. Samples pushed out by
* the delays are lost and new ones filled with zeroes are pushed in.
*
* The output vector parameter 'out' can be NULL to allocate a new
* vector, or can be equal to the 'in' input vector to perform the
* transform in-place. If it's different, it must be long enough
* to contain the result (i.e. in->len)
*/
struct osmo_cxvec *
osmo_cxvec_delay(const struct osmo_cxvec *in, float delay,
struct osmo_cxvec *out)
{
int ofs_int = (int) roundf(delay);
float ofs_frac = delay - ofs_int;
const struct osmo_cxvec *shifted_vect = NULL;
int i, j;
/* Get output vector */
if (!out)
out = osmo_cxvec_alloc(in->len);
else if (out->max_len < in->len)
return NULL;
/* Set output length / flags */
out->len = in->len;
out->flags = in->flags;
/* Fractional offset (if reasonable) */
if (fabs(ofs_frac) > 0.05f) {
float complex _d[21];
struct osmo_cxvec _sinc_vect, *sinc_vect = &_sinc_vect;
/* Create sinc vector */
osmo_cxvec_init_from_data(sinc_vect, _d, 21);
for (i=0; i<21; i++)
sinc_vect->data[i] = osmo_sinc(M_PIf * (i - 10.0f - ofs_frac));
sinc_vect->flags |= CXVEC_FLG_REAL_ONLY;
/* Convolve */
shifted_vect = osmo_cxvec_convolve(sinc_vect, in, CONV_NO_DELAY, NULL);
}
if (!shifted_vect) /* Also covers failure of convolve ... */
shifted_vect = in;
/* Integer offset */
if (ofs_int < 0) {
ofs_int = - ofs_int;
for (i=0; i<(shifted_vect->len-ofs_int); i++)
out->data[i] = shifted_vect->data[i+ofs_int];
for (; i<in->len; i++)
out->data[i] = 0.0f;
} else {
for (i=in->len-1,j=shifted_vect->len-1; i>=ofs_int; i--, j--)
out->data[i] = shifted_vect->data[j-ofs_int];
for (; i>=0; i--)
out->data[i] = 0.0f;
}
/* Release */
if (in != shifted_vect)
osmo_cxvec_free((struct osmo_cxvec *)shifted_vect);
return out;
}
/*! \brief Convolve two complex vectors
* \param[in] f First input complex vector
* \param[in] g Second input complex vector

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