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WFDB_Sample sample(WFDB_Signal s, WFDB_Time t) int sample_valid(void) |
sample
): The value (in raw adus) of sample number t
in open signal s,if successful, or the value of the previous
successfully read sample.
sample_valid
): The most recent value returned by
sample
was valid
sample_valid
): The most recent t given to sample
follows the end of the record
sample_valid
): The most recent value returned by
sample
was invalid (because signal s is not available at time
t)
The sample
function allows the caller to read samples of the
currently open input signals in any order. The first argument is a
signal number (a non-negative integer between 0 and nsig-1,
where nsig is the number of open input signals), and the second
is a time, expressed as a non-negative sample number. If sample
is invoked with valid input arguments, the companion function
sample_valid
returns 1.
The sample_valid
function can be used to check the results of the most
recent invocation of sample
. If sample_valid
returns 1, the
latest value returned by sample
is valid. sample_valid
returns 0
if sample
has most recently returned a padded value following the end of
the record. This allows code that uses sample
to use the condition
`sample_valid() != 0' (or simply `sample_valid()' to determine if
more samples are available. If sample_valid
returns -1, the most recent
value returned by sample
was WFDB_INVALID_SAMPLE
(because the
requested signal s was unavailable at the requested time t). Use
the condition `sample_valid() > 0' to check if the most recent value
returned by sample
is a valid value (e.g., suitable for inclusion in a
running average or similar calculation).
For an example of the use of sample
and sample_valid
,
see section Example 7: A General-Purpose FIR Filter.
Be sure to call wfdbquit
before exiting from any program that
uses sample
, to be certain that dynamically allocated memory
used by sample
is freed.
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