| Op Code (Hex) | Extender | Operand 1 | Operand 2 | Operand 3-4 |
|---|---|---|---|---|
| SIGEXCP 10CA |
| Attribute template | Exception data | |
|
| ||||
| SIGEXCPB 1CCA | Branch options | Attribute template | Exception data | Branch targets |
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| SIGEXCPI 18CA | Indicator options | Attribute template | Exception data | Indicator targets |
Operand 1: Space pointer.
Operand 2: Space pointer.
Operand 3-4:
This instruction signals a new exception or resignals an existing exception to the thread. Optionally, the instruction branches to one of the specified targets based on the results of the signal and the selected branch options in the extender field, or it sets indicators based on the results of the signal. The signal is presented starting at the invocation identified in the signal template.
The template identified by operand 1 specifies the signal option and
starting point.
It must be 16-byte aligned in the space with the following format.
| Offset | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dec | Hex |
| Field Name |
| Data Type and Length | ||||||||||||
| 0 | 0 |
| Target invocation address |
| Space pointer or Invocation pointer | ||||||||||||
| 16 | 10 |
| Signal option |
| Char(1) | ||||||||||||
| 16 | 10 |
| Signal/resignal option |
| Bit 0 | ||||||||||||
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| ||||||||||||||
| 16 | 10 |
| Invoke PDEH (process default exception handler) option |
| Bit 1 | ||||||||||||
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| ||||||||||||||
| 16 | 10 |
| Exception description search control |
| Bit 2 | ||||||||||||
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| 16 | 10 |
| Reserved (binary 0) |
| Bits 3-7 | ||||||||||||
| 17 | 11 |
| Reserved (binary 0) |
| Char(1) | ||||||||||||
| 18 | 12 |
| First exception description to search |
| Bin(2) | ||||||||||||
| 20 | 14 |
| --- End --- |
|
| ||||||||||||
The target invocation address pointer uniquely identifies the invocation to which the exception is to be signalled. Signalling directly to the PDEH can not be accomplished via this instruction. If the target invocation address pointer locates neither a valid invocation entry nor the base invocation entry, the invalid invocation address (hex 1603) exception is signaled.
The invocation which issued this instruction will be checked to ensure it has the proper authority to send an exception message to the target invocation. If the authority check fails, activation group access violation (hex 2C12) exception will be signaled. If the program associated with the invocation has defined an exception description to handle the exception, the specified action is taken; otherwise, the PDEH is invoked unless the invoke PDEH option bit is 1 (the exception is considered ignored). If the base invocation entry is addressed instead of an existing invocation, the PDEH will be invoked.
A change has been made to the way in which exception handlers are determined for bound programs. The following description relates only to the invocation of exception handlers related to non-bound programs. In both instances the actions of signalling and handling have been broken apart.
| Note: |
Exception descriptions of an invocation are searched in ascending ODT number sequence. If the exception description search control specified exception description search control not present, the search begins with the first exception description defined in the ODT. Otherwise, the first exception description to search value identifies the relative number of the exception description to be used to start the search. The value must be a nonzero positive binary number determined by the order of definition of exception descriptions in the ODT. This value is also returned by the Sense Exception Description (SNSEXCPD) instruction. A value of 1 indicates that the first exception description in the invocation is to be used to begin the search. If the value is greater than the number of exception descriptions for the invocation, the template value invalid (hex 3801) exception is signaled. If an exception ID in an exception description corresponds to the signaled exception, the corresponding compare values are verified. If the compare value length in the exception description is less than the compare value length in the signal template, the length of the compare value in the exception description is used for the match. If the compare value length in the exception description is greater than the compare value length in the signal template, an automatic mismatch results. Machine-signaled exceptions have a 4-byte compare value of binary 0's. An exception description may monitor for an exception with a generic ID as follows:
An exception description may be in one of five states, each of which determines an action to be taken when the match criteria on the exception ID and compare value are met.
When control is given to an internal or branch point exception handler, all invocations up to, but not including, the exception handling invocation are terminated. Any invocation exit programs set for the terminated invocations will be given control before execution proceeds in the signaled exception handler. |
When this instruction is invoked with the resignal option, all invocations up to, but not including, the interrupted invocation are cancelled and the message is signalled to the next oldest invocation in the stack. This implies that the Return from Exception (RTNEXCP) instruction can no longer return to the invocation that issued the resignal request. Any cancel handlers set for the cancelled invocations will be given control before execution proceeds in the signaled exception handler.
If a failure to invoke an external exception handler or an invocation exit occurs, a failure to invoke program event is signaled. For each destroyed invocation, the invocation count in the corresponding activation entry (if any) is decremented by 1.
The template identified by operand 2 must be 16-byte
aligned in the space. It specifies the exception-related
data to be passed with the exception signal.
The format of the exception data is the same as that
returned by the Retrieve
Exception Data (RETEXCPD) instruction. The format is as follows:
| Offset | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dec | Hex |
| Field Name |
| Data Type and Length | ||||||||
| 0 | 0 |
| Template size |
| Char(8) | ||||||||
| 0 | 0 |
| Number of bytes of data to be signaled |
| Bin(4) | ||||||||
|
|
|
|
(must be at least 48 bytes)
| ||||||||||
| 4 | 4 |
| Number of bytes available for materialization |
| Bin(4) + | ||||||||
| 8 | 8 |
| Exception identification |
| Char(2) | ||||||||
| 10 | A |
| Compare value length (maximum of 32 bytes) |
| Bin(2) | ||||||||
| 12 | C |
| Compare value |
| Char(32) | ||||||||
| 44 | 2C |
| Reserved |
| Char(4) + | ||||||||
| 48 | 30 |
| Exception specific data |
| Char(*) | ||||||||
| * | * |
| --- End --- |
|
| ||||||||
| Note: | Fields shown here with a plus sign (+) are ignored by the instruction. |
The maximum size for exception specific data that is to accompany an exception signaled by the Signal Exception instruction is 65,503 bytes, including the standard exception data.
The following parameters will be given the following default values:
Message status - log message + retain + action pending
Initial monitor priority - 64
Interrupt class mask - Message generated by Signal Exception instruction
Source invocation - invocation issuing SIGEXCP instruction
The invocation which originated the exception must have proper activation group access to the target invocation. The following algorithm is used to determine this access.
If any of the access checks fail then an activation group access violation (hex 2C12) exception will be signaled.
06 Addressing
08 Argument/Parameter
10 Damage Encountered
16 Exception Management
1C Machine-Dependent
20 Machine Support
22 Object Access
24 Pointer Specification
2C Program Execution
2E Resource Control Limit
36 Space Management
38 Template Specification
44 Protection Violation