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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
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