Specifications

Comedi
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Description
When a Comedilib function fails, it usually returns -1 or NULL, depending on the return type. An internal library variable stores
an error number, which can be retrieved by calling comedi_errno() This error number can be converted to a human-readable
form by the functions comedi_perror() and comedi_strerror().
These functions are intended to mimic the behavior of the standard C library functions perror(), strerror(), and errno.
In particular, Comedilib functions sometimes return an error that is generated inside the C library; the comedi error message in
this case is the same as the C library.
The function comedi_errno() returns an integer describing the most recent Comedilib error. This integer may be used as the
errnum parameter for comedi_strerror().
5.4.5.2 comedi_loglevel
comedi_loglevel — change Comedilib logging properties
Synopsis
#include <comedilib.h>
int comedi_loglevel(int loglevel);
Description
This function affects the output of debugging and error messages from Comedilib. By increasing the log level loglevel,
additional debugging information will be printed. Error and debugging messages are printed to the standard error output stream
stderr.
The default loglevel can be set by using the environment variable COMEDI_LOGLEVEL. The default log level is 1.
In order to conserve resources, some debugging information is disabled by default when Comedilib is compiled.
The meaning of the log levels is as follows:
Loglevel Behavior
0 Comedilib prints nothing.
1
(default) Comedilib prints error messages when there is a self-consistency error (i.e., an internal
bug.)
2 Comedilib prints an error message when an invalid parameter is passed.
3
Comedilib prints an error message whenever an error is generated in the Comedilib library or in the
C library, when called by Comedilib.
4 Comedilib prints a lot of junk.
Return value
This function returns the previous log level.
5.4.5.3 comedi_perror
comedi_perror — print a Comedilib error message
Synopsis
#include <comedilib.h>
void comedi_perror(const char * s);