.txbuffrq Method

Function:	For the selected socket (selection is made through sock.num), pre-requests numpages number of buffer pages (1 page = 256 bytes) for the TX buffer of the socket.
Syntax:	sock.txbuffrq(numpages as {byte \| word}) as {byte \| word}
Returns:	Actual number of pages that can be allocated.
See Also:	sock.tx2buffrq

Part	Description
numpages	Requested numbers of buffer pages to allocate. For the time being, the maximum allowed value is 255.

Details

Actual allocation happens when the sys.buffalloc method is used. The socket is unable to TX data if its TX buffer has 0 capacity. The actual current buffer capacity can be checked through sock.txbuffsize, which returns the buffer capacity in bytes. The relationship between the two is as follows: sock.txbuffsize = num_pages * 256 - X (or = 0 when num_pages = 0), where "num_pages" is the number of buffer pages that was GRANTED through the sock.txbuffrq. The "- X" is because a number of bytes is needed for internal buffer variables. X = 17 bytes on 16-bit platforms and 33 bytes on 32-bit platforms. Platform type is specified in your platform documentation.

Buffer allocation will not work if the socket to which this buffer belongs is not idle (sock.statesimple is not at 0 — PL_SSTS_CLOSED) at the time when sys.buffalloc executes. You can only change the buffer sizes of sockets that are idle.

Older devices had smaller RAM sizes, so the numpages argument and the value returned by the method were of the byte type. The maximum possible number of pages, therefore, could not exceed 255. On newer devices with larger RAM capacities, this method takes and returns word values. Inspect the method's declaration on the platform you are using to make sure you know the data type it employs.

A warning note icon. For the time being, the maximum number of pages that can be allocated for the RX buffer is still limited to 255. This limitation will be removed in future releases of TiOS.