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CFP_IO(3) manual page Table of Contents

Name

cfp_io - get information about an I/O device

Synopsis

#include <cfht/cfht.h>#include <cfht/cfp.h>struct cfp_io *cfp_io(name, data,
type)char *name;struct cfp_io *data;int type;
libcfht.a

The purpose of this function is to provide standardized access to the global I/O configuration file. The file itself makes it possible to change the I/O configuration without recompiling programs or requiring user interaction.

Name is a symbolic name used to look up information about a device. The information will be stored in a structure pointed to by data, with a pointer to the structure being returned. Data is allowed to be NULL, in which case cfp_io() uses internal storage space. Type is used to specify that only one kind of device is allowed. If type is set to -1, then any kind is allowed. Possible types are CFP_CAMAC, CFP_HPIB, and CFP_RS232. Most programs will probably specify a particular type. Making a program generic enough to handle multiple types would be quite difficult since the I/O libraries used are so different.

The structure is defined as follows:

struct cfp_io {
    int type;    /* CFP_HPIB, CFP_RS232, or CFP_CAMAC */
    char file[80];    /* device node name */
    int hpib;    /* HP-IB device address, or -1 */
    int branch;    /* CAMAC branch number, or -1 */
    int crate;    /* CAMAC crate number, or -1 */
    int module;    /* CAMAC module number, or -1 */
};

Type will contain the acquired type of device. CFP_RS232 devices should be controlled with standard tty driver calls. CFP_HPIB devices should be controlled with libhh.a calls. CFP_CAMAC devices should be controlled with libcamac.a calls.

File will contain the name of the special file to be used.

If the device is an HP-IB device, or a CAMAC device controlled through HP-IB, then hpib will be set to the HP-IB device address, else hpib will contain -1. (This is how CAMAC control through RS-232 is distinguished from CAMAC control through HP-IB).

If a CAMAC device is to be controlled through a system crate, branch highway system, then branch and crate will contain valid values, else -1 each. If the device is a CAMAC module and not just a crate or non-CAMAC device, then module will contain a valid number, else -1.

Note that the camac and hpib libraries use this function automatically, so that the only time a program should need to call cfp_io() is for acquiring RS-232 device paths.

Return Value

cfp_io returns a pointer to a struct cfp_io. If an error occurs, NULL is returned.

Errors

If an error has occurred, errno will be set as follows:

[EINVAL]: corrupt name.
[ENOTTY]: wrong type. Type was set to non -1 and did not match the acquired type.
[EIO]: corrupt file.

Note that cfp_getln() is used, and that errno may be set from that internal call.

Environment Variables

CFHTIOCONFIG: location of the "ioconfig" file. Note that the name of this environment variable is programmatically accessed via the CFHT_EIOCONFIG define and the default by the CFHT_IOCONFIG define. USE WITH CAUTION.
(name): Any name can be overridden by an environment variable of the same spelling. This provides an aliasing mechanism. USE WITH CAUTION.

Files

$CFHTIOCONFIG: I/O configuration override file
$cfhtdir/conf/ioconfig: default I/O configuration file.