OS_ReadLine (changes)
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OS SWI Calls
» OS_ReadLine
OS_ReadLine
(SWI &0E)
This SWI does not work correctly under RISC OS 5
| Entry | |
|---|---|
| R0 | Buffer + flags (flags ignored in RISC OS 5) |
| R1 | Size of buffer -1 (maximum number of bytes to return, excluding CR) |
| R2 | Lowest char allowed |
| R3 | Highest char allowed |
| R4 | Character to output (if R0 bit 30 set) (ignored in RISC OS 5) |
| Exit | |
|---|---|
| R0 | “Corrupted” (all implementations return the buffer address, minus flags) |
| R1 | |
| R2 | “Corrupted” (all implementations preserve R2) |
| R3 | “Corrupted” (all implementations preserve R3) |
| R4 | Preserved |
| C flag is set if input is terminated by an escape condition | |
Use
This SWI is deprecated, because the use of flag bits in address values makes it unsafe to use on systems with 32bit logical memory maps. Please use OS_ReadLine32 instead.
The purpose of this call is to read a line from the current input stream.
Notes
Input is terminated with Return, Ctrl-J or Escape. Delete and Backspace deletes last char entered. Ctrl-U empties buffer.
When the buffer is full, each successive attempt to enter a character results in a Ctrl-G ‘beep’.
Other than RISC OS 5, ReadLineV uses this API. RISC OS 5’s ReadLineV uses the OS_ReadLine32 API instead.
RISC OS Six introduced a flag in the top bit of R1 to select the OS_ReadLine32 API instead. This identifies the API in use on ReadLineV in 26bit processor modes.
See also
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