HP 3000 Manuals HP 3000 Manuals
Error Handling
Three types of errors can occur when an intrinsic is executed:
* Condition code errors. Such errors are generally recoverable
since control returns to the calling program. The operating
system maintains condition codes to provide backward compatibility
with previous (MPE V/E-based) operating systems.
* Status parameter errors. When you include the status parameter in
the intrinsic call, it returns status information to the calling
routine. For some intrinsics, both the condition code and the
special status parameter can return information; other intrinsics
use only one of these to return information.
* Abort errors. Such errors occur when a calling program passes
illegal parameters to an intrinsic or does not have the required
capability for the intrinsic. An abort error terminates the
process.
Condition Code Errors
Some intrinsics have an associated condition code. A condition code is a
temporary value providing information about what happened during
execution. The condition code is affected by many intrinsics and should
be checked immediately upon return from an intrinsic.
A condition code has three possible values (CCG, CCL, or CCE) and has the
general meaning as indicated in Table 2-3 . Specific meanings are
listed under the individual intrinsic called.
Table 2-3. Condition Code Descriptions
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| | | |
| Value | Condition Code | Description |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| 0 | CCG (>) | Condition Code Greater Than. A warning or special |
| | | condition occurred but may not have affected the |
| | | execution of the request. (For example, the request was |
| | | executed, but default values were assumed as intrinsic |
| | | call parameters.) |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| 1 | CCL (<) | Condition Code Less Than. The request was not granted, |
| | | but the error condition may be recoverable. |
| | | |
-----------------------------------------------------------------------------------------------
| | | |
| 2 | CCE (=) | Condition Code Equal. Generally indicates that the |
| | | request was granted. |
| | | |
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Status Parameter Errors
Some intrinsics use the status parameter to return information on the
status of the intrinsic call. This parameter is a native mode (NM)
implementation of the condition code feature with extended capabilities.
The status parameter is a 32-bit signed integer value passed by
reference.
NOTE It is good programming practice to specify the status parameter and
check its value after an intrinsic call. If an error or warning
condition is encountered and the status parameter was not
specified, the intrinsic causes the calling process to abort.
The status parameter is read in two 16-bit fields:
Bits Value/Meaning
16:16 status.subsys: identifies the subsystem that initiated the
error or warning.
0:16 status.info: identifies the type of error or warning. Refer to
each intrinsic for possible values.
Table 2-4 and Table 2-5 represent the possible values returned by
the status parameter.
Table 2-4. Status.subsys Parameter Identifiers
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| | |
| Subsystem | Subsystem |
| ID | |
| | |
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| | |
| 0 | Successful (no errors) |
| | |
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| | |
| 9 | CM Loader |
| | |
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| | |
| 098 | System Aborts |
| | |
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| | |
| 100 | Switch |
| | |
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| | |
| 101 | Memory Manager |
| | |
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| | |
| 102 | Process Manager |
| | |
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| | |
| 103 | Stack Unwind |
| | |
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| | |
| 104 | NM Loader |
| | |
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| | |
| 107 | Virtual Space Management |
| | |
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| | |
| 108 | Table Management |
| | |
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| | |
| 110 | Clock/Timer Manager |
| | |
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| | |
| 111 | High-Level I/O |
| | |
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| | |
| 113 | Low-Level I/O |
| | |
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| | |
| 114 | HP-IO Channel Manager |
| | |
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| | |
| 116 | HP-IB Adapter Manager |
| | |
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| | |
| 121 | CS80 Disk Manager |
| | |
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| | |
| 122 | Port (IPC) Facility |
| | |
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| | |
| 123 | Dispatcher |
| | |
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| | |
| 127 | CIPER Device Manager |
| | |
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| | |
| 128 | Terminal I/O Manager for Logging |
| | |
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| | |
| 130 | Page Printer Device Manager |
| | |
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| | |
| 133 | Measurement Interface |
| | |
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| | |
| 143 | File System |
| | |
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| | |
| 145 | Secondary Storage Management |
| | |
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| | |
| 151 | Transaction Management |
| | |
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| | |
| 153 | File System Label Management |
| | |
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| | |
| 154 | CM Support Routines |
| | |
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| | |
| 155 | Job and Session |
| | |
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Table 2-4. Status.subsys Parameter Identifiers (cont.)
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| | |
| Subsystem | Subsystem |
| ID | |
| | |
---------------------------------------------------------------------------------------------
| | |
| 158 | Break Handling |
| | |
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| | |
| 161 | Command Interpreter |
| | |
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| | |
| 165 | Debug Low-Level Breakpoint Management |
| | |
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| | |
| 169 | CM Debugger |
| | |
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| | |
| 185 | File System Storage Management |
| | |
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| | |
| 187 | Error Management |
| | |
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| | |
| 188 | CM Emulator, Translator, OCT |
| | |
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| | |
| 193 | Floating-Point Conversion |
| | |
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| | |
| 195 | Hewlett-Packard SORT |
| | |
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| | |
| 196 | Hewlett-Packard MERGE |
| | |
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| | |
| 198 | Eagle A-MUX Device Manager |
| | |
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| | |
| 200 | U-Code Trap Handler |
| | |
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| | |
| 201 | Data Communication Buffer Manager |
| | |
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| | |
| 206 | System Logging |
| | |
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| | |
| 213 | I/O Services |
| | |
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| | |
| 221 | Intrinsic Aborts |
| | |
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| | |
| 222 | Intrinsic Names |
| | |
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Table 2-5. Status.info Parameter Identifiers
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| | |
| Value | Description |
| | |
---------------------------------------------------------------------------------------------
| | |
| 0 | Normal |
| | |
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| | |
| <0 | Indicates an error condition |
| | |
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| | |
| >0 | Indicates a warning condition |
| | |
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Abort Errors
Software traps are interrupts generated by software events in which the
operating system interrupts the normal flow of a process' execution.
Some intrinsics generate a software trap when they detect certain error
conditions. Normally, if an intrinsic causes a trap, the system trap
handler aborts the user program. However, you can write a procedure to
handle abort errors and use it in place of the default system trap
handler, which will permit recovery from errors in certain cases. For
more information on handling traps, refer to Trap Handling Programmer's
Guide (32650-90026).
When a program is aborted in a batch job, the operating system removes
the job from the system unless you precede the command that caused the
error with a CONTINUE command. If the program is aborted in an
interactive session, the system returns control to the parent process.