TCP/IP API Functions
4.2.10tcp_sleep()
This function is called from the TCP code when a TCP operation is blocked by a temporary lack of resources, typically a lack of free buffers.
Syntax
void tcp_sleep(void *ptr) where:
ptr |
is the memory address of some structure relevant to the current task. The |
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tcp_wakeup() function will be called from elsewhere in the stack to |
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restart this task. The tcp_wakeup() function is called with the same |
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memory address. |
Return value
None.
Usage
This function should allow the tasking system to attempt to run each task at least once and then return. The calling code then retests the condition and either:
•proceeds
•times out
•calls tcp_sleep() again.
See the detailed description of this in TCP on page 2-12.
ARM DUI 0079B |
Copyright © 1998 and 1999 ARM Limited. All rights reserved. |
4-13 |
TCP/IP API Functions
4.2.11tcp_wakeup()
This function is called by the TCP/IP code when an incoming packet or timeout causes a previously blocked process to become runable.
Syntax
void tcp_wakeup(void *ptr) where:
ptr |
is the memory address that the sleeping process passed to tcp_sleep(). |
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All tasks that called tcp_sleep() with this address will be woken. |
Return value
None.
Usage
This function should cause all processes that were sleeping because of a call to tcp_sleep() with the same value for ptr to be marked as runable. In a superloop system, tcp_wakeup() performs no action because tcp_sleep() does not block. Instead, tcp_sleep() calls the nonportable superloop function, tk_yield(). It is possible for tcp_wakeup() to be called even if no process is currently blocked in tcp_sleep().
4-14 |
Copyright © 1998 and 1999 ARM Limited. All rights reserved. |
ARM DUI 0079B |