=> R0 = 3 (Modifying file)
R1-R7 vary, depending on the value of R9
R8 = filing system information word
R9 = Reason code
<= All registers preserved
Warns your program that a file is being modified. It is made when a program calls one of serveral SWI provided by FileSwitch module:
· reason codes 0-8 are caused by calls to OS_File
· reason codes 257-9 are caused by calls to OS_Find
· reason codes 520/1 are caused by calls to OS_FSControl
You may find it helpful to examine the documentation of the above FileSwitch SWI calls.
The following general points apply:
· all strings are 0-terminated except where specified
· all object names will already have been expanded by FileSwitch, checked for basic validity, and had filing system prefixes stripped
· object names will also be canonicalised, except under RISC OS 2.
This UpCall is made before the operation, which may subsequently fail. For example, you may receive a rename UpCall for a locked file, which will sebsequently fail to rename (because it's locked). If a file name is invalid for a given operation (eg you try to create a file with a wildcarded leafname) FileSwitch will generate an error, and no UpCall will be generated.
The call is used by the desktop filer to maintain its directory displays. It's provided for information only; if you wish to use this UpCall, you must not intercept it, nor must you alter the contents of any of these registers used to pass parameters.
See PRM 1, page 181
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