The BBC and Master Computer Public Domain Library
Next non-space Char PTRA
Submitted by Steve Fewell
Routine: NextCharPTRA
Name: Next non-space Char PTRA
Starting Address: &8ED5
Exit: Move past spaces in BASIC's Text
Pointer A and return the next Character in the string (A).
Description:
Reads past any space characters found at the current position in the PTRA.
Returns with the next non-space Character from PTRA in A, and with the PTRA
Offset pointing to this value.
Routine &8CD7 returns the next non-space character in PTRA, and also sets
the zero flag is the character is 'X' or 'x', or clears the zero flag is the
character is not 'X' or 'x'. Bit 5 of the ASCII value is cleared to return any
lower case ASCII characters as upper case.
Routine &8CDF returns the next non-space character in PTRA, and also sets
the zero flag is the character is a hash ('#'), or clears the zero flag is the
character is not a hash.
Routine &8CE5 returns the next non-space character in PTRA, and also sets
the zero flag is the character is a comma (','), or clears the zero flag is the
character is not a comma.
Disassembly for the Next non-space Char PTRA routine
| 8EE0 | 164 010 | A4 0A | LDY &0A | |
| 8EE2 | 230 010 | E6 0A | INC &0A | |
| 8EE4 | 177 011 | B1 0B | LDA (&0B),Y | |
| 8EE6 | 201 032 | C9 20 | CMP#&20 | |
| 8EE8 | 240 246 | F0 F6 | BEQ -10 --> &8EE0 | |
| 8EEA | ` | 096 | 60 | RTS |
Get Next non-space Char PTRA and compare with 'X' or 'x'
| 8CD7 | 032 224 142 | 20 E0 8E | JSR &8EE0 | |
| 8CDA | ) | 041 223 | 29 DF | AND#&DF |
| 8CDC | X | 201 088 | C9 58 | CMP#&58 |
| 8CDE | ` | 096 | 60 | RTS |
Get Next non-space Char PTRA and compare with '#'
| 8CDF | 032 224 142 | 20 E0 8E | JSR &8EE0 | |
| 8CE2 | # | 201 035 | C9 23 | CMP#&23 |
| 8CE4 | ` | 096 | 60 | RTS |
Get Next non-space Char PTRA and compare with ','
| 8CE5 | 032 224 142 | 20 E0 8E | JSR &8EE0 | |
| 8CE8 | , | 201 044 | C9 2C | CMP#&2C |
| 8CEA | ` | 096 | 60 | RTS |
