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/* pvshell.h -- a generic Nyquist primitive, esp. for phase vocoder */
/* how many doubles to provide for miscellaneous state info */
#define PVSHELL_STATE_MAX 8
/* define some bits to return conditions */
#define PVSHELL_FLAG_TERMINATE 4
#define PVSHELL_FLAG_LOGICAL_STOP 8
/* this function is called to compute samples. It should compute n
* samples (floats == sample_type) and store them at out[i].
* You can return less than n samples by writing the actual number
* of samples computed into *n. Normally, you return zero.
* To indicate that the time of the FIRST sample is the logical stop
* time, return PVSHELL_FLAG_LOGICAL_STOP. (If the logical stop time
* is not at the first sample, but instead at sample j, then just
* return j samples (from 0 to j-1), save the rest of the samples,
* and the next time, the first sample will correspond to the logical
* stop time, so you can return PVSHELL_FLAG_LOGICAL_STOP.
* To indicate that the sound has terminated, return
* PVSHELL_FLAG_TERMINATE. This should be the only time you return
* zero samples. (As with logical stop time, if you have samples to
* return before termination, then do it, and return
* PVSHELL_FLAG_TERMINATE the next time you are called, at which
* point you've returned all the samples, so you can set *n = 0.
*/
struct pvshell_struct;
typedef long (*h_fn_type)(struct pvshell_struct *susp,
sample_block_values_type out, long *n);
typedef struct pvshell_struct {
sound_type f;
long f_cnt;
sample_block_values_type f_ptr;
sound_type g;
long g_cnt;
sample_block_values_type g_ptr;
long flags; /* for terminated and logically stopped flags */
// state is extra storage for whatever you like
double state[PVSHELL_STATE_MAX];
// h is a function that computes sound from f, g, x, y, state
h_fn_type h;
} pvshell_node, *pvshell_type;
/* to get samples from f or g, use these macros. For each sample, call
* PVSHELL_TEST_X to get logical stop and terminate flags (but do not
* fetch a sample). Then, if you want, call PVSHELL_FETCH_X to get the
* next sample. You can call PVSHELL_TEST_X multiple times before
* calling PVSHELL_FETCH_X, e.g. you can return exit a loop when you
* see a logical stop flag and later call PVSHELL_TEST_X again. You
* CANNOT call PVSHELL_FETCH_X multiples times without an intervening
* call to PVSHELL_TEST_X. Finally, the logical stop flag is only
* returned once. Normally you should write something like:
* new_flags = PVSHELL_TEST_F(susp);
* susp->flags | = new_flags; // remember flags
* if (new_flags) break;
* in the sample loop so that you will break when you see logical_stop.
* Outside the loop, you can return (*n ? 0 : susp->flags) which will
* return 0 if you computed samples before the logical stop was detected.
* Then the next time you are called, you will return the logical_stop
* flag because you saved it in susp->flags, and the flag applies to the
* *beginning* of the sample block. This code handles terminate too.
*/
long pvshell_test_f(pvshell_type susp);
long pvshell_test_g(pvshell_type susp);
#define PVSHELL_TEST_F(susp) ((susp)->f_cnt == 0 ? pvshell_test_f(susp) : 0)
#define PVSHELL_FETCH_F(susp) ((susp)->f_cnt--, (*(susp)->f_ptr++))
#define PVSHELL_TEST_G(susp) ((susp)->g_cnt == 0 ? pvshell_test_g(susp) : 0)
#define PVSHELL_FETCH_G(susp) ((susp)->g_cnt--, (*(susp)->g_ptr++))
/* snd_make_pvshell -- create an instance of pvshell.
name -- string name of the operation, for debugging & printing
(name is not copied. It must be a permanent, immutable string.)
sr -- sample rate of output sound
t0 -- start time of output sound
h -- function that computes samples of output
f -- first input sound, e.g. sound to be time-stretched
g -- second input sound, e.g. sound to control varying stretch factor
state -- initial state information needed by h
n -- number of doubles in state (< PVSHELL_STATE_MAX)
*/
sound_type snd_make_pvshell(char *name, rate_type sr, time_type t0,
h_fn_type h, sound_type f, sound_type g,
double *state, long n);
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