The BBC and Master Computer Public Domain Library

9C6A Check for End of Statement

Submitted by Steve Fewell

Routine:9C6A
Name: Check for End of Statement
Starting Address: &9C6A
Entry criteria: &0A, &0B and &0C point to the input line.
Exit: Syntax Error if unexpected input is found at end of a statement.

Description:

This routine is called before a command (e.g. CLS) is executed to check that the BASIC
Statement line is terminated correctly, and contains no errors. If all is ok then
the routine returns sucessfully and the command is performed.
If errors are found on the input line, then a Syntax Error is generated.

The routine does the following:
Set Y to the offset which contains the next character to check. This will be &0A for the BASIC Text pointer A offset,
or, to &1B for the BASIC text pointer B offset (if called from routine &9C5A).
Get next character on the line (at the offset position), skiping any spaces found.
If the next character is ':' or '<return>' or 'ELSE' (token &8B) then the
line has been terminated correctly, so update the pointer (&B, &C) and set the pointer offset
to 1. Test whether an error has occurred, if no error then return (otherwise goto 9C41 to issue an 'Escape' error).

If the next character on the line is anything else then generate a Syntax Error.

Disassembly for the Check for End of Statement routine

Disassembly for the Check for End of Statement (PTR B) routine