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sample and sample_valid

 
WFDB_Sample sample(WFDB_Signal s, WFDB_Time t)
int sample_valid(void)
Return:

n
(from 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.
0
(from sample_valid): The most recent value returned by sample was invalid
1
(from sample_valid): The most recent value returned by sample was valid

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.

There are three ways in which sample can be invoked with invalid input arguments. In each case, sample_valid returns 0, but sample attempts to return a reasonable value. If s is invalid, sample returns the value of signal 0 at the specified time. If t is negative, the returned value is that of sample number zero of the specified signal. If t specifies a sample number beyond the end of the record, the returned value is that of the last valid sample of the specified signal. 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.



George B. Moody (george@mit.edu)