AppleIIAsm-Collection/source/disk20_minidisk_A/T.THLINE.SUB.MIN

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THLINE
PLA
STA RETADR
PLA
STA RETADR+1
PLA
STA :F
PLA
STA :Y
PLA
STA :X2
PLA
STA :X1
LDA ERRCTRL
CMP #1
BEQ :CHKERR
JMP :ERREND
:CHKERR
LDA :X1
CMP :X2
BCS :ERRTOOHI ; X1 => X2
LDA :X1
CMP #39
BCS :ERRXOVF ; X VALUE OVERFLOW
LDA :X2
CMP #40 ; MAX COLS + 1
BCS :ERRXOVF
LDA :Y
CMP #24 ; MAX ROWS + 1
BCS :ERRYOVF
JMP :ERREND
:ERRTOOHI
_ERR :E_SID;:E_XHI;:E_DMP1;:X1;#4
JMP :ERREND
:ERRXOVF
_ERR :E_SID;:E_XOF;:E_DMP1;:X1;#4
JMP :ERREND
:ERRYOVF
_ERR :E_SID;:E_YOF;:E_DMP1;:X1;#4
JMP :ERREND
:ERREND
LDA :Y ; LOAD ROW
LDY :X1 ; LOAD X START POS
:LOOP
JSR $F847 ; GBASCALC ROUTINE
LDA :F
STA ($26),Y ; PUSH TO SCREEN MEMORY
LDA :Y
INY ; INCREASE X POS
CPY :X2 ; IF LESS THAN X END POS
BNE :LOOP ; REPEAT UNTIL DONE
:EXIT
LDA RETADR+1
PHA
LDA RETADR
PHA
RTS
:X1 DS 1
:X2 DS 1
:Y DS 1
:F DS 1 ; FILL CHAR
:E_SID ASC "THLINE (THLIN MACRO)",00
:E_DMP1 ASC "DUMPING X1(1) X1(1) Y(1) F(1)",00
:E_XHI ASC "X1 MUST BE LOWER THAN X2.",00
:E_XOF ASC "X > # OF AVAILABLE COLUMNS.",00
:E_YOF ASC "Y > # OF AVAILABLE ROWS",00