Routines
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B63D: concatenate
Used by the routine at AD9E.
add strings, the first string is in the descriptor, the second string is in line
B63D A5 65 LDA $65 get descriptor pointer high byte
B63F 48 PHA put on stack
B640 A5 64 LDA $64 get descriptor pointer low byte
B642 48 PHA put on stack
B643 20 83 AE JSR $AE83 get value from line
B646 20 8F AD JSR $AD8F check if source is string, else do type mismatch
B649 68 PLA get descriptor pointer low byte back
B64A 85 6F STA $6F set pointer low byte
B64C 68 PLA get descriptor pointer high byte back
B64D 85 70 STA $70 set pointer high byte
B64F A0 00 LDY #$00 clear index
B651 B1 6F LDA ($6F),Y get length of first string from descriptor
B653 18 CLC clear carry for add
B654 71 64 ADC ($64),Y add length of second string
B656 90 05 BCC $B65D branch if no overflow
B658 A2 17 LDX #$17 else error $17, string too long error
B65A 4C 37 A4 JMP $A437 do error #X then warm start
B65D 20 75 B4 JSR $B475 copy descriptor pointer and make string space A bytes long
B660 20 7A B6 JSR $B67A copy string from descriptor to utility pointer
B663 A5 50 LDA $50 get descriptor pointer low byte
B665 A4 51 LDY $51 get descriptor pointer high byte
B667 20 AA B6 JSR $B6AA pop (YA) descriptor off stack or from top of string space
returns with A = length, X = pointer low byte, Y = pointer high byte
B66A 20 8C B6 JSR $B68C store string from pointer to utility pointer
B66D A5 6F LDA $6F get descriptor pointer low byte
B66F A4 70 LDY $70 get descriptor pointer high byte
B671 20 AA B6 JSR $B6AA pop (YA) descriptor off stack or from top of string space
returns with A = length, X = pointer low byte, Y = pointer high byte
B674 20 CA B4 JSR $B4CA check space on descriptor stack then put string address and length on descriptor stack and update stack pointers
B677 4C B8 AD JMP $ADB8 continue evaluation
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