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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);
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
- Manual
Interprocess Communication Programmer's Guide
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