Freeway_Read (changes)
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Freeway
» SWI Calls
» Freeway_Read
Freeway_Read
(SWI &47A82)
| Entry | |
|---|---|
| R0 | Read flags |
| R1 | Type number |
| R2 | Pointer to object name, 0 terminated |
| R3 | Length of buffer for object descriptor |
| R4 | Pointer to object descriptor, or 0 for none |
| R5 | Object authentication value if present, otherwise undefined |
| Exit | |
|---|---|
| R3 | Length of held object descriptor |
| R5 | IP address of computer which holds the object |
Read Flags
| Bit | Value | Meaning |
|---|---|---|
| 0 | 1 | Authentication value provided |
| 3 – 31 | 0 | Reserved (must be zero) |
Use
The purpose of this call is to read information about the attributes of an object.
Notes
The type number and object name must be provided. The SWI returns the IP address of the holder, and optionally the descriptor. The length of a held object descriptor may be read by setting R4 to 0 on entry. However in this case there is no guarantee that the object attributes will not have changed, or that the object will still exist, if the SWI is called again some time later.
An error is returned if the type number is unknown, or the object name is unknown, or if a supplied authentication value does not match the object’s own authentication value, or if a supplied object descriptor buffer is too short; in this case the actual length is returned in R3.
See also
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