Socket_Select (changes)
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» SWI Calls
» Socket_Select
Socket_Select
(SWI &41211)
| Entry | |
|---|---|
| R0 | Number of descriptors to consider from each set |
| R1 | Pointer to a read set |
| R2 | Pointer to a write set |
| R3 | Pointer to a exception set |
| R4 | Pointer to a 2 word timeout value |
| Exit | |
|---|---|
| R0 | Number of descriptors which became ready |
Use
The purpose of this call is to wait until one of the descriptors becomes ready based on the read/write/exception masks provided, or a timeout occurs.
Berkeley sockets equivalence
This SWI directly corresponds to the function select and would ordinarily be called from C using the select() function in socklib.h.
Notes
The value on entry in R0 would typically be the highest bit set to inspect plus one in each of the masks. For example if the socket descriptors were 3 + 4 + 5 then there are 6 descriptors to consider (0 to 5 inclusive). Setting it to a larger value than necessary just wastes processor time looking at descriptors which are of no interest.
See also
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