IPC@CHIP Documentation - SC12 @CHIP-RTOS V1.10

ES:DI
Pointer to a 12 byte message to be sent
Return Value
Comments
DX = 0 success AX: 0
DX != 0 failure AX: contains error code
If one or more tasks are waiting at the exchange for a message, the message will be immediately given
to the task waiting at the head of the exchange's wait queue. This will result in an immediate task switch
if the task receiving the message is higher priority than the task that is sending the message.
The format of the 12 byte message being sent is defined by the application program. These 12 bytes
can contain a pointer to further data, if required. This API copies these 12 bytes into an internal
message envelope, so the message at [ES:DI] need not persist beyond the call to this API. (However,
any data referenced by pointers contained in the message would, of course, need to be maintained until
the message is received by some task.)
The message mailbox priority in CX is applicable for cases where messages are accumulating on the
exchange for which there are no immediate waiting message consumer tasks. In this case, a message
from the highest priority non-empty mailbox FIFO queue will be given to the next caller of either
RTX_GET_MSG or RTX_WAIT_MSG.
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RTOS Message Exchange Manager
Interrupt 0xAD service 0x53: RTX_GET_MSG, Poll Message Exchange
Parameters
AH
BX
ES:DI
Get an available message from a specified Message Exchange without waiting.
0x53 (= RTX_GET_MSG)
Message Exchange ID acquired by RTX_CREATE_MSG call.
Output Parameter: Pointer to a 12 byte user buffer for storing the message (if any).
Return Value
Comments
DX = 0 success AX: 0, Location at [ES:DI] holds the message
DX != 0 failure AX: contains error code, invalid ID or -28: no message available
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