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NM and CM callable. Determines the status of the mailbox used by its parent or child.
Process handling (PH) capability is required. Syntax | |
U16 I16V I16
mailstatus:=MAIL(pin,length);
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Functional Return | |
- mailstatus
16-bit unsigned integer (assigned functional return) Returns the status of the mailbox:
| Value | Meaning |
|---|
| 0 | Mailbox empty. | | 1 | Contains previous outgoing mail from this
calling process that the destination process has not yet collected. | | 2 | Contains incoming mail awaiting collection by
this calling process. The length of the mail is returned
in length. | | 3 | An error occurred, an invalid pin was specified,
or a bounds check failed. | | 4 | Temporarily inaccessible, other intrinsics are using it
in the preparation or analysis of mail. |
Parameters | |
- pin
16-bit signed integer by value (required) Passes the mailbox to be tested. If pin specifies the
mailbox of a child process, it must be the
process identification number (PIN) of
that child. Zero specifies the mailbox of a parent process.
- length
16 bit signed integer by reference (required) Returns the length, in half words, of any incoming mail in the mailbox.
Operation Notes | |
If the mailbox contains mail that is awaiting collection by this process,
the length of this message (in half words) is returned to the calling
process in the length parameter. This enables the calling
process to initialize its stack in preparation for receipt of the message. Condition Codes | |
- CCE (2)
Request granted. The mailbox mailstatus was tested. - CCG (0)
Request denied. An illegal pin parameter was specified.
The value of 3 is returned to the calling process through mailstatus. - CCL (1)
Request denied. The length parameter defines stack address
that does not have write access.
Related Information | |
- Intrinsics
None - Commands
None - Manuals
Interprocess Communication Programmer's Guide (32650-90019)
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