RECEIVEMAIL
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Syntax
U16 I16V UDS U16V mailstatus := RECEIVEMAIL (pin, location, waitflag);
Functional Return
- mailstatus
16-bit unsigned integer (assigned functional return)
Returns one of the following values:
Value Meaning 0 Mailbox empty and waitflag bit (15:1) = 0. 1 No message collected, the mailbox contained outgoing mail from the receiving process. 2 Message collected successfully. 3 Error occurred because an invalid pin was specified or a bounds check failed. 4 Request denied, waitflag specified that the receiving process wait for mail if the mailbox is empty, but the other process sharing the mailbox is already suspended, waiting for mail. If both processes were suspended, neither could activate the other, and they may be deadlocked.
Parameters
- pin
16-bit signed integer by value (required)
The process sending the mail. If you specify a child process, pin is the process identification number (PIN) of that process. If you specify a parent process, pin is zero.
- location
user-defined structure (required)
The buffer where the message is written.
- waitflag
16-bit unsigned integer by value (required)
The action to be taken if the mailbox is empty. This is determined by the setting of bit (15:1), which has the following settings:
Value Meaning 0 Return immediately to the calling process. 1 Wait until incoming mail is ready for collection.
Operation Notes
The RECEIVEMAIL intrinsic lets a process collect mail transmitted to it by its parent or a child. If the mailbox for the receiving process is empty, the action taken depends on the waitflag parameter specified in the RECEIVEMAIL intrinsic call. If the mailbox is currently in use by another process, RECEIVEMAIL waits until the mailbox is free before accessing it.
Condition Codes
| CCE (2) | Request granted. The mail was collected (value 2 is returned to mailstatus) or the mail was not collected because the mailbox contained outgoing mail from the receiving process (value 1 is returned to mailstatus). |
| CCG (0) | Request denied. An illegal pin parameter (value 3 is returned to mailstatus). |
| CCL (1) | Request denied. The location parameter does not allow write access on the stack address (value 3 is returned to mailstatus) or because both sending and receiving processes are waiting for incoming mail, causing a deadlock (value 4 is returned to mailstatus). |
Related Information
| Intrinsics | MAIL, SENDMAIL |
| Manuals | Interprocess Communication Programmer's Guide |
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