Commodore Disk User Volume 4 #3/Commodore_Disk_User_Vol.4_3_1991_-.d64/display.asm

Assembly Source File | 2022-10-26 | 6KB | 429 lines

E
_ pROGRAM TO LIST LAZY GREENIUS ASSEMBLER PROGRAMS

_ dEFINE A START LOCATION

ORG $1350

_ DEFINE THE STORAGE LOCATIONS USED

LOADADDR = $2000
BSOUT= $FFD2
PO= $FA
LO        = $FC
ENRES 2
CTRES 2
CBRES 2
SAVEPORES 2

_ cODE START
_ INPUT IS a=FILENAME LENGTH
_          x=FILENAME ADDRESS LOW
_          y=FILENAME ADDRESS HIGH
_ BANK WILL HAVE BEEN SET BEFORE THIS PROGRAM WAS CALLED

 $FFBD_ SET NAME
 #0
 #0
 $FF68_ SET BANK
 #0
 #8
 #0
 $FFBA_ SET LFS
 #0
 #>LOADADDR
 #<LOADADDR
 $FFD5_ LOAD
 ERROR
{CBM-A} EN
{CBM-E} EN+1
 DISPLAY
ERROR{CBM-N}_ RETURN ERROR IN a

_
_ nOW WE DISPLAY THE SCREEN
_
DISPLAYEQU *
 #147
 BSOUT
 #1
 #>LOADADDR
{CBM-P} PO
{CBM-P} CT
 #<LOADADDR
{CBM-P} PO+1
{CBM-P} CT+1
 #0
DISPSCREQU *
 [PO],Y
 #13
 NOCHECK

 #26
 EXITLINE
NOCHECKEQU *
 OUTCHAR
 PO
 NOINC9
 PO+1
NOINC9EQU *
 PO+1_ ASSUME THAT THERE IS AT LEAST ONE CHARACTER
 EN+1_ IN THE FILE AND THAT EN IS THE POSITION
 DISPSCR_ AFTER THIS CHARACTER SO PO COULD EQUAL EN
 PO_ AT SOME POINT IF WE REACH THE END BEFORE
 EN_ BEFORE THE END OF THE SCREEN
 DISPSCR
EXITLINEEQU *_ END OF FILE OR LAST cr WOULD MEAN 26TH LINE
 PO

 #1
{CBM-P} CB
 PO+1
 #0
{CBM-P} CB+1
_
_ CONTROL THE INPUT
_
LOOPKEYEQU *
 #3
LOOPDEL1EQU *
 #0
LOOPDEL2EQU *

 LOOPDEL2

 LOOPDEL1
 $D4
 #83
 SCRDOWN
 #84
 SCRUP
 #7
 SHIFT
 #41
 PRT
 #57
 LOOPKEY
 #0
{CBM-N}
SHIFT $D3
 SCRUP
 #1
 SCRDOWN
 LOOPKEY
PRT PRINT
SCRUPEQU *
 CB+1_ IF CB < EN THEN SCROLL UP
 EN+1
 EXTRA3
 LOOPKEY
 SCROLLUP
EXTRA3 CB
 EN
 LOOPKEY
 SCROLLUP
_
_ DO THE SCROLL DOWN LOGIC
_
SCRDOWNEQU *_ IF CT > LOADADDR THEN CONTINUE
 CT+1
 #<LOADADDR
 LOOPKEY_ IF CT(HIGH) < LOADADDR THEN CT < LOADADDR
 POSSIBLE_ IF CT(HIGH) = LOADADDR THEN POSSIBLE
 DODOWN_ DEFINITE
POSSIBLE  EQU *
 #>LOADADDR
 CT
 LOOPKEY
DODOWNEQU *
 #27
 BSOUT
 #87
 BSOUT_ SCROLL THE SCREEN DOWN
 #19_ HOME THE CURSOR
 BSOUT
_
_ START OF THE LOGIC TO SCAN FOR THE PREVIOUS LINE
_
 CT
{CBM-D}
{CBM-Q} #2
{CBM-P} PO
{CBM-P} SAVEPO
 CT+1
{CBM-Q} #0
{CBM-P} PO+1_ PO=CT-2 POINT PAST LAST CR
{CBM-P} SAVEPO+1_ SAVE CT-2
 #0
LOOPUP1EQU *_ LOCATE THE START OF THE LINE
 [PO],Y
 #13_ HAVE WE FOUND A cr
 FNDUP1_ YES SO STOP
 PO_ PO=PO-1
 PO
 #$FF
 NODEC1
 PO+1
NODEC1EQU *
 PO+1_ IF PO <= LOADADDR THEN STOP
 #<LOADADDR
 SETSTART
 EXTRA1
 LOOPUP1
EXTRA1EQU *
 PO
 #>LOADADDR
 LOOPUP1
SETSTART  EQU *
 #>LOADADDR
{CBM-P} PO
 #<LOADADDR
{CBM-P} PO+1
 NOINC1

FNDUP1EQU *_ FOUND EITHER THE cr OR START OF TEXT
 PO_ POINT TO NEXT CHAR IF cr FOUND
 NOINC1_ IF START OF TEXT THEN WE WOULD HAVE GONE
 PO+1_ GONE PAST THE START BY 1 SO INCREMENT
_
_ IF PO > CT-2 THEN ALL WE FOUND WAS A CARRIAGE RETURN ON THE  LAST LINE
_ SO DON'T DISPLAY ANYTHING
_
NOINC1EQU *
 PO
{CBM-P} CT
 PO+1
{CBM-P} CT+1_ THIS WILL BE THE NEW CURRENT TOP
 SAVEPO+1
 PO+1
 LEAVE1
 EXTRA2
 DISP
EXTRA2EQU *
 SAVEPO
 PO
 LEAVE1
DISP EQU *
 [PO],Y
 OUTCHAR
 PO
 SAVEPO
 INCPO
 PO+1
 SAVEPO+1
 LEAVE1
INCPOEQU *
 PO
 DISP
 PO+1
 DISP
_
_ DISPLAYED THE LINE IF >40 THEN WE WOULD HAVE HAD TO SCROLL DOWN TWICE
_
LEAVE1EQU *
_
_ tHIS LOGIC JUST LOOKS FOR THE CURRENT BOTTOM START OF LINE
_
 CB
{CBM-D}
{CBM-Q} #2
{CBM-P} PO
 CB+1
{CBM-Q} #0
{CBM-P} PO+1_ PO=CT-2 POINT PAST LAST CR
 #0
LOOPUP2EQU *_ LOCATE THE START OF THE LINE
 [PO],Y
 #13
 FNDUP2
 PO
 PO
 #$FF
 LOOPUP2
 PO+1
 LOOPUP2
FNDUP2EQU *
 PO
 NOINC2
 PO+1
NOINC2EQU *
 PO
{CBM-P} CB
 PO+1
{CBM-P} CB+1
 LOOPKEY

_
_ HERE IS THE LOGIC TO SCROLL UP.
_
SCROLLUPEQU *
 #27
 BSOUT
 #86
 BSOUT_ SCROLL UP
 #19
 BSOUT_ HOME CURSOR
 #24_ 24 CURSOR DOWNS
 #17
LOOPCUREQU *
 BSOUT

 LOOPCUR
_
_ HERE WE GO...
_
 CB
{CBM-P} PO
 CB+1
{CBM-P} PO+1
 #0
LOOPITEQU *
 [PO],Y
 #13
 LEAVE4
 OUTCHAR
 PO
 CHECK2
 PO+1
CHECK2EQU *
 PO+1
 EN+1
 LOOPIT
 EXTRA4
 LEAVE4
EXTRA4EQU *
 PO
 EN
 LOOPIT
LEAVE4EQU *
 PO
 NOINC4
 PO+1
NOINC4EQU *
 PO
{CBM-P} CB
 PO+1
{CBM-P} CB+1
_
_ LINE NOW DISPLAYED SO LETS LOCATE THE CURRENT TOP
_
 CT
{CBM-P} PO
 CT+1
{CBM-P} PO+1
LOOP5EQU *
 [PO],Y
 PO
 FORWARD
 PO+1
FORWARDEQU *
 #13
 LOOP5
 PO
{CBM-P} CT
 PO+1
{CBM-P} CT+1
 LOOPKEY
_
_ nOW OUTPUT CHARACTERS AND CONVERT THE TOKENS
_
OUTCHAREQU *
{CBM-A} SAVEX
{CBM-E} SAVEY
 #128
 CONVERT
 BSOUT
EXITCHAREQU *
 SAVEX
 SAVEY
{CBM-N}
CONVERTEQU *
{CBM-D}
{CBM-Q} #128
{CBM-R}
 #>TABLE
{CBM-P} LO
 #<TABLE
{CBM-P} LO+1
 #0
 OUTIT
LOOP9EQU *
 LO

 #3
{CBM-P} LO
 LO+1
 #0
{CBM-P} LO+1

 LOOP9
OUTITEQU *
 #0
LOOP8EQU *
 [LO],Y
 BSOUT
 EXITCHAR

 #3
 LOOP8
          _ SET A GOOD RETURN CODE
 EXITCHAR
TABLE EQU *
DB  "ADCANDASLBCCBCSBEQBITBMIBNEBPLBRKBVCBVSCLCCLDCLICLVCMPCPXCPY"
DB  "DECDEXDEYEORINCINXINYJMPJSRLDALDXLDYLSRNOPORAPHAPHPPLAPLPROL"
DB  "RORRTIRTSSBCSECSEDSEISTASTXSTYTAXTAYTSXTXATXSTYA"
SAVEXRES 1
SAVEYRES 1

_
_ ROUTINE TO PRINT FROM LOADADDR TO EN
_
PRINTEQU *
 #0_ SET LENGTH TO ZERO
 $FFBD
 #1
 #4
 #7
 $FFBA_ SET lfs
 $FFC0_ OPEN THE FILE
 PRTCONT1
PRTERROR1EQU *
 LOOPKEY
PRTCONT1EQU *
 #1
 $FFC9_ bsout ROUTED THE LOGICAL FILE NUMBER DEF
 PRTCONT2
PRTERROR2 EQU *
 #1
 $FFC3_ CLOSE THE la
 PRTERROR1
PRTCONT2  EQU *
 #>LOADADDR
{CBM-P} PO
 #<LOADADDR
{CBM-P} PO+1
 #0
LOOPPRTEQU *
 PO
 EN
 INCLOOP
 PO+1
 EN+1
 PRTFIN
INCLOOP   EQU *
 [PO],Y
 OUTCHAR
 PRTFIN
 $D4
 #13_ S KEY PRESSED ?
 PRTFIN
 PO
 LOOPPRT
 PO+1
 LOOPPRT
PRTFINEQU *
 $FFCC_ RESET THE CHANNELS
 PRTERROR2_ RESET BSOUT AND CLOSE THE FILE AND EXIT


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