Checks to see whether a specified event or events has occurred on the device.
#include <sys/device.h> #include <sys/comio.h>
int ddselect (devno, events, reventp, chan) dev_t devno; ushort events; ushort *reventp; int chan;
| devno | Specifies major and minor device numbers. | ||||||||
| events | Specifies conditions to check. The conditions are denoted by the bitwise OR of one or more of the following:
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| reventp | Points to the result of condition checks. A bitwise OR of the following conditions is returned:
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| chan | Specifies the channel number assigned by the device handler's ddmpx entry point. |
Note: This entry point should not be called by a kernel-mode process.
The ddselect communications PDH entry point checks and returns the status of 1 or more conditions for a user-mode process. It works the same way the common ddselect device driver entry point does.
A ddselect entry point can be called from the process environment only.
In general, communication device handlers use the common return codes defined for an entry point. However, device handlers for specific communication devices may return device-specific codes. The common return codes for the ddselect entry point are the following:
The ddmpx entry point.