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Reintegrate wbw -> trunk

pull/3/head
wayne 13 years ago
parent
ed8b513dc3
commit
bba3b237b8
2 changed files with 242 additions and 344 deletions
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  1. 78
      Source/cvdu.asm
  2. 508
      Source/vdu.asm

78
Source/cvdu.asm
View File

@ -188,50 +188,12 @@ CVDU_VDASCR1:
POP DE ; RECOVER E
INC E ; INCREMENT IT
JR CVDU_VDASCR ; LOOP
;
;
;======================================================================
; CVDU DRIVER - PRIVATE DRIVER FUNCTIONS
;======================================================================
;
;----------------------------------------------------------------------
; MOS 8563 DISPLAY CONTROLLER CHIP INITIALIZATION
;----------------------------------------------------------------------
;
CVDU_CRTINIT:
LD C,0 ; START WITH REGISTER 0
LD B,37 ; INIT 37 REGISTERS
LD HL,CVDU_INIT8563 ; HL = POINTER TO THE DEFAULT VALUES
CVDU_CRTINIT1:
LD A,(HL) ; GET VALUE
CALL CVDU_WR ; WRITE IT
INC HL ; POINT TO NEXT VALUE
INC C ; POINT TO NEXT REGISTER
DJNZ CVDU_CRTINIT1 ; LOOP
RET
;
;----------------------------------------------------------------------
; LOAD FONT DATA
;----------------------------------------------------------------------
;
CVDU_LOADFONT:
LD HL,$2000 ; START OF FONT BUFFER
LD C,18 ; UPDATE ADDRESS REGISTER PAIR
CALL CVDU_WRX ; DO IT
LD HL,CVDU_FONTDATA ; POINTER TO FONT DATA
LD DE,$2000 ; LENGTH OF FONT DATA
LD C,31 ; DATA REGISTER
CVDU_LOADFONT1:
LD A,(HL) ; LOAD NEXT BYTE OF FONT DATA
CALL CVDU_WR ; WRITE IT
INC HL ; INCREMENT FONT DATA POINTER
DEC DE ; DECREMENT LOOP COUNTER
LD A,D ; CHECK DE...
OR E ; FOR COUNTER EXHAUSTED
JR NZ,CVDU_LOADFONT1 ; LOOP TILL DONE
RET
;
;----------------------------------------------------------------------
; UPDATE M8563 REGISTERS
; CVDU_WR WRITES VALUE IN A TO VDU REGISTER SPECIFIED IN C
; CVDU_WRX WRITES VALUE IN DE TO VDU REGISTER PAIR IN C, C+1
@ -282,6 +244,44 @@ CVDU_RDX:
RET
;
;----------------------------------------------------------------------
; MOS 8563 DISPLAY CONTROLLER CHIP INITIALIZATION
;----------------------------------------------------------------------
;
CVDU_CRTINIT:
LD C,0 ; START WITH REGISTER 0
LD B,37 ; INIT 37 REGISTERS
LD HL,CVDU_INIT8563 ; HL = POINTER TO THE DEFAULT VALUES
CVDU_CRTINIT1:
LD A,(HL) ; GET VALUE
CALL CVDU_WR ; WRITE IT
INC HL ; POINT TO NEXT VALUE
INC C ; POINT TO NEXT REGISTER
DJNZ CVDU_CRTINIT1 ; LOOP
RET
;
;----------------------------------------------------------------------
; LOAD FONT DATA
;----------------------------------------------------------------------
;
CVDU_LOADFONT:
LD HL,$2000 ; START OF FONT BUFFER
LD C,18 ; UPDATE ADDRESS REGISTER PAIR
CALL CVDU_WRX ; DO IT
LD HL,CVDU_FONTDATA ; POINTER TO FONT DATA
LD DE,$2000 ; LENGTH OF FONT DATA
LD C,31 ; DATA REGISTER
CVDU_LOADFONT1:
LD A,(HL) ; LOAD NEXT BYTE OF FONT DATA
CALL CVDU_WR ; WRITE IT
INC HL ; INCREMENT FONT DATA POINTER
DEC DE ; DECREMENT LOOP COUNTER
LD A,D ; CHECK DE...
OR E ; FOR COUNTER EXHAUSTED
JR NZ,CVDU_LOADFONT1 ; LOOP TILL DONE
RET
;
;----------------------------------------------------------------------
; SET CURSOR POSITION TO ROW IN D AND COLUMN IN E
;----------------------------------------------------------------------
;

508
Source/vdu.asm
View File

@ -7,6 +7,8 @@
;======================================================================
;
; TODO:
; - ADD REMAINING REGISTERS TO INIT
; - TRY 25 ROW MODE?
; - IMPLEMENT CONSTANTS FOR SCREEN DIMENSIONS
; - IMPLEMENT SET CURSOR STYLE (VDASCS) FUNCTION
; - IMPLEMENT ALTERNATE DISPLAY MODES?
@ -26,13 +28,15 @@ VDU_DATA .EQU 0F3h ; VDU DATA REGISTER
;======================================================================
;
VDU_INIT:
CALL VDU_CRTINIT ; INIT 6545 VDU CHIP
CALL VDUINIT ; INIT VDU
CALL PERF_ERASE_EOS ; CLEAR SCREEN
CALL PERF_CURSOR_HOME ; CURSOR HOME
RET
CALL VDU_CRTINIT ; INIT SY6845 VDU CHIP
VDU_RESET:
LD DE,0
LD (VDU_OFFSET),DE
CALL VDU_XY
LD A,' '
LD DE,1024*16
CALL VDU_FILL
XOR A
RET
;
@ -106,8 +110,8 @@ VDU_VDAINI:
VDU_VDAQRY:
LD C,$00 ; MODE ZERO IS ALL WE KNOW
LD DE,$1950 ; 25 ROWS ($19), 80 COLS ($50)
LD HL,0 ; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
LD DE,$1850 ; 24 ROWS ($18), 80 COLS ($50)
LD HL,0 ; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED
XOR A ; SIGNAL SUCCESS
RET
@ -118,348 +122,242 @@ VDU_VDASCS:
CALL PANIC ; NOT IMPLEMENTED (YET)
VDU_VDASCP:
LD A,E
LD (VDU_X),A
LD A,D
LD (VDU_Y),A
CALL VDU_XY
XOR A
RET
VDU_VDASAT:
; FIX: NOT IMPLEMENTED!!!
CALL PANIC
XOR A
RET
VDU_VDASCO:
; NOT SUPPORTED!!!
CALL PANIC
XOR A
RET
VDU_VDAWRC:
; PUSH CHARACTER OUT AT CURRENT POSITION
LD A,31 ; PREP VDU FOR DATA R/W
OUT (VDU_REG),A
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD A,E
OUT (VDU_RAMWR),A ; OUTPUT CHAR TO VDU
; UPDATE CURSOR POSITION TO FOLLOW CHARACTERS
LD HL,(VDU_DISPLAYPOS) ; GET CURRENT DISPLAY POSITION
INC HL ; INCREMENT IT
LD (VDU_DISPLAYPOS),HL ; STORE NEW DISPLAY POSITION
LD DE,(VDU_DISPLAY_START) ; GET DISPLAY START
ADD HL,DE ; ADD IT TO DISPLAY POSITION
LD A,14 ; UPDATE CURSOR POSITION
CALL VDU_HL2WREG_A ; SEND IT
; RETURN WITH SUCCESS
CALL VDU_PUTCHAR
XOR A
RET
VDU_VDAFIL:
LD A, 31 ; PREP VDU FOR DATA R/W
OUT (VDU_REG),A
VDU_VDAFIL1:
LD A,H ; CHECK NUMBER OF FILL CHARS LEFT
OR L
JR Z,VDU_VDAFIL2 ; ALL DONE, GO TO COMPLETION
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD A,E
OUT (VDU_RAMWR), A ; OUTPUT CHAR TO VDU
DEC HL ; DECREMENT COUNT
JR VDU_VDAFIL1 ; LOOP AS NEEDED
VDU_VDAFIL2:
CALL VDU_XY ; YES, MOVE CURSOR BACK TO ORIGINAL POSITION
XOR A ; RESULT = 0
LD A,E ; FILL CHARACTER GOES IN A
EX DE,HL ; FILL LENGTH GOES IN DE
CALL VDU_FILL ; DO THE FILL
XOR A ; SIGNAL SUCCESS
RET
VDU_VDASCR:
; FIX: IMPLEMENT REVERSE SCROLLING!!!
LD A,E
OR A
RET Z
PUSH DE
CALL DO_SCROLL
POP DE
DEC E
JR VDU_VDASCR
LD A,E ; LOAD E INTO A
OR A ; SET FLAGS
RET Z ; IF ZERO, WE ARE DONE
PUSH DE ; SAVE E
JP M,VDU_VDASCR1 ; E IS NEGATIVE, REVERSE SCROLL
CALL VDU_SCROLL ; SCROLL FORWARD ONE LINE
POP DE ; RECOVER E
DEC E ; DECREMENT IT
JR VDU_VDASCR ; LOOP
VDU_VDASCR1:
CALL VDU_RSCROLL ; SCROLL REVERSE ONE LINE
POP DE ; RECOVER E
INC E ; INCREMENT IT
JR VDU_VDASCR ; LOOP
;
;======================================================================
; CVDU DRIVER - PRIVATE DRIVER FUNCTIONS
;======================================================================
;
;----------------------------------------------------------------------
; WAIT FOR VDU TO BE READY FOR A DATA READ/WRITE
;----------------------------------------------------------------------
;
VDU_WAITRDY:
IN A,(VDU_STAT) ; READ STATUS
OR A ; SET FLAGS
RET M ; IF BIT 7 SET, THEN READY!
JR VDU_WAITRDY ; KEEP CHECKING
;;
;;__________________________________________________________________________________________________
;; INITIALIZATION
;;__________________________________________________________________________________________________
;INITVDU:
; CALL VDUINIT ; INIT VDU
; CALL PERF_ERASE_EOS ; CLEAR SCREEN
; CALL PERF_CURSOR_HOME ; CURSOR HOME
; RET
;
;__PERF_ERASE_EOL__________________________________________________________________________________
;
; PERFORM ERASE FROM CURSOR POS TO END OF LINE
;__________________________________________________________________________________________________
PERF_ERASE_EOL:
LD A,(VDU_X) ; GET CURRENT CURSOR X COORD
LD C,A ; STORE IT IN C
LD A,80 ; MOVE CURRENT LINE WIDTH INTO A
SUB C ; GET REMAINING POSITIONS ON CURRENT LINE
LD B,A ; MOVE IT INTO B
LD A,31 ; UPDATE TOGGLE VDU CHIP
OUT (VDU_REG),A
PERF_ERASE_EOL_LOOP:
CALL VDU_WAITRDY ; WAIT FOR VDU CHIP TO BE READY
LD A,32 ; MOVE SPACE CHARACTER INTO A
OUT (VDU_RAMWR),A ; WRITE IT TO SCREEN, VDU WILL AUTO INC TO NEXT ADDRESS
DJNZ PERF_ERASE_EOL_LOOP ; LOOP UNTIL DONE
CALL VDU_XY ; MOVE CURSOR BACK TO ORIGINAL POSITION
RET
;
;__PERF_ERASE_EOS__________________________________________________________________________________
;
; PERFORM ERASE FROM CURSOR POS TO END OF SCREEN
;__________________________________________________________________________________________________
PERF_ERASE_EOS:
LD HL,0780H ; SET SCREEN SIZE INTO HL
PUSH HL ; MOVE IT TO DE
POP DE
LD A,31 ; UPDATE TOGGLE VDU CHIP
OUT (VDU_REG),A
PERF_ERASE_EOS_LOOP:
CALL VDU_WAITRDY ; WAIT FOR VDU CHIP TO BE READY
LD A, ' ' ; MOVE SPACE CHARACTER INTO A
OUT (VDU_RAMWR),A ; WRITE IT TO SCREEN, VDU WILL AUTO INC TO NEXT ADDRESS
DEC DE ; DEC COUNTER
LD A,D ; IS COUNTER 0 YET?
OR E
JP NZ,PERF_ERASE_EOS_LOOP ; NO, LOOP
CALL VDU_XY ; YES, MOVE CURSOR BACK TO ORIGINAL POSITION
RET
;
;__PERF_CURSOR_HOME________________________________________________________________________________
;
; PERFORM CURSOR HOME
;__________________________________________________________________________________________________
PERF_CURSOR_HOME:
LD A,0 ; LOAD 0 INTO A
LD (VDU_X),A ; SET X COORD
LD (VDU_Y),A ; SET Y COORD
JP VDU_XY ; MOVE CURSOR TO POSITION
;
;__DO_SCROLL_______________________________________________________________________________________
;
; SCROLL THE SCREEN UP ONE LINE
;__________________________________________________________________________________________________
DO_SCROLL:
PUSH AF ; STORE AF
DO_SCROLL1:
PUSH HL ; STORE HL
PUSH BC ; STORE BC
LD A, 31 ; TOGGLE VDU FOR UPDATE
OUT (VDU_REG),A
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD HL, (VDU_DISPLAY_START) ; GET UP START OF DISPLAY
LD DE,0050H ; SET AMOUNT TO ADD
ADD HL,DE ; ADD TO START POS
LD (VDU_DISPLAY_START),HL ; STORE DISPLAY START
LD A, 12 ; SAVE START OF DISPLAY TO VDU
CALL VDU_HL2WREG_A
LD A,23 ; SET CURSOR TO BEGINNING OF LAST LINE
LD (VDU_Y),A
LD A,(VDU_X)
PUSH AF ; STORE X COORD
LD A,0
LD (VDU_X),A
CALL VDU_XY ; SET CURSOR POSITION TO BEGINNING OF LINE
CALL PERF_ERASE_EOL ; ERASE SCROLLED LINE
POP AF ; RESTORE X COORD
LD (VDU_X),A
CALL VDU_XY ; SET CURSOR POSITION
POP BC ; RESTORE BC
POP HL ; RESTORE HL
POP AF ; RESTORE AF
RET ;
;
;__REVERSE_SCROLL__________________________________________________________________________________
;
; SCROLL THE SCREEN DOWN ONE LINE
;__________________________________________________________________________________________________
REVERSE_SCROLL:
PUSH AF ; STORE AF
PUSH HL ; STORE HL
PUSH BC ; STORE BC
LD A, 31 ; TOGGLE VDU FOR UPDATE
OUT (VDU_REG),A
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD HL, (VDU_DISPLAY_START) ; GET UP START OF DISPLAY
LD DE,0FFB0H ; SET AMOUNT TO SUBTRACT (TWOS COMPLEMENT 50H)
ADD HL,DE ; ADD TO START POS
LD (VDU_DISPLAY_START),HL ; STORE DISPLAY START
LD A, 12 ; SAVE START OF DISPLAY TO VDU
CALL VDU_HL2WREG_A
LD A,23 ; SET CURSOR TO BEGINNING OF LAST LINE
LD (VDU_Y),A
LD A,(VDU_X)
PUSH AF ; STORE X COORD
LD A,0
LD (VDU_X),A
CALL VDU_XY ; SET CURSOR POSITION TO BEGINNING OF LINE
CALL PERF_ERASE_EOL ; ERASE SCROLLED LINE
POP AF ; RESTORE X COORD
LD (VDU_X),A
CALL VDU_XY ; SET CURSOR POSITION
POP BC ; RESTORE BC
POP HL ; RESTORE HL
POP AF ; RESTORE AF
;----------------------------------------------------------------------
; UPDATE SY6845 REGISTERS
; VDU_WRREG WRITES VALUE IN A TO VDU REGISTER SPECIFIED IN C
; VDU_WRREGX WRITES VALUE IN DE TO VDU REGISTER PAIR IN C, C+1
;----------------------------------------------------------------------
;
VDU_WRREG:
PUSH AF ; SAVE VALUE TO WRITE
LD A,C ; SET A TO CVDU REGISTER TO SELECT
OUT (VDU_REG),A ; WRITE IT TO SELECT THE REGISTER
POP AF ; RECOVER VALUE TO WRITE
OUT (VDU_DATA),A ; WRITE IT
RET
;
;__VDUINIT__________________________________________________________________________________________
VDU_WRREGX:
LD A,H ; SETUP MSB TO WRITE
CALL VDU_WRREG ; DO IT
INC C ; NEXT CVDU REGISTER
LD A,L ; SETUP LSB TO WRITE
JR VDU_WRREG ; DO IT & RETURN
;
;----------------------------------------------------------------------
; READ SY6845 REGISTERS
; VDU_RDREG READS VDU REGISTER SPECIFIED IN C AND RETURNS VALUE IN A
; VDU_RDREGX READS VDU REGISTER PAIR SPECIFIED BY C, C+1
; AND RETURNS VALUE IN HL
;----------------------------------------------------------------------
;
VDU_RDREG:
LD A,C ; SET A TO CVDU REGISTER TO SELECT
OUT (VDU_REG),A ; WRITE IT TO SELECT THE REGISTER
IN A,(VDU_DATA) ; READ IT
RET
;
; INITIALIZE VDU
;__________________________________________________________________________________________________
VDUINIT:
PUSH AF ; STORE AF
PUSH DE ; STORE DE
PUSH HL ; STORE HL
LD A, 31 ; TOGGLE VDU FOR UPDATE
OUT (VDU_REG),A
LD HL,0 ; SET-UP START OF DISPLAY
LD DE, 2048 ; SET-UP DISPLAY SIZE
LD A, 18 ; WRITE HL TO R18 AND R19 (UPDATE ADDRESS)
CALL VDU_HL2WREG_A ;
LD A, 31 ; TOGGLE VDU FOR UPDATE
OUT (VDU_REG),A
VDU_CRTSPACELOOP: ;
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD A, ' ' ; CLEAR SCREEN
OUT (VDU_RAMWR),A ; SEND SPACE TO DATAPORT
DEC DE ; DECREMENT DE
LD A,D ; IS ZERO?
OR E ;
JP NZ, VDU_CRTSPACELOOP ; NO, LOOP
LD A, 31 ; TOGGLE VDU FOR UPDATE
OUT (VDU_REG),A
LD HL, 0 ; SET UP START OF DISPLAY
LD (VDU_DISPLAY_START),HL ; STORE DISPLAY START
LD A, 12 ; SAVE START OF DISPLAY TO VDU
CALL VDU_HL2WREG_A ;
POP HL ;
POP DE ;
POP AF ;
CALL PERF_CURSOR_HOME ; CURSOR HOME
CALL PERF_ERASE_EOS ; CLEAR SCREEN
RET
;
;__VDU_HL2WREG_A___________________________________________________________________________________
;
; WRITE VALUE IN HL TO REGISTER IN A
; A: REGISTER TO UPDATE
; HL: WORD VALUE TO WRITE
;__________________________________________________________________________________________________
VDU_HL2WREG_A:
PUSH BC ; STORE BC
LD C,VDU_REG ; ADDRESS REGISTER
OUT (C),A ; SELECT REGISTER (A)
INC C ; NEXT WRITE IN REGISTER
OUT (C),H ; WRITE H TO SELECTED REGISTER
DEC C ; NEXT WRITE SELECT REGISTER
INC A ; INCREASE REGISTER NUMBER
OUT (C),A ; SELECT REGISTER (A+1)
INC C ; NEXT WRITE IN REGISTER
OUT (C),L ; WRITE L TO SELECTED REGISTER
POP BC ; RESTORE BC
RET
VDU_RDREGX:
CALL VDU_RDREG ; GET VALUE FROM REGISTER IN C
LD H,A ; SAVE IN H
INC C ; BUMP TO NEXT REGISTER OF PAIR
CALL VDU_RDREG ; READ THE VALUE
LD L,A ; SAVE IT IN L
RET
;
;__VDU_CRTINIT_____________________________________________________________________________________
;----------------------------------------------------------------------
; SY6845 DISPLAY CONTROLLER CHIP INITIALIZATION
;----------------------------------------------------------------------
;
; INIT VDU CHIP
;__________________________________________________________________________________________________
VDU_CRTINIT:
PUSH AF ; STORE AF
PUSH BC ; STORE BC
PUSH DE ; STORE DE
PUSH HL ; STORE HL
LD BC,010F2h ; B = 16, C = VDU_REG
LD HL,VDU_INIT6845 ; HL = POINTER TO THE DEFAULT VALUES
XOR A ; A = 0
VDU_CRTINITLOOP:
OUT (C), A ; VDU_REG SET REGISTER
INC C ; 0F3h
LD D,(HL) ; LOAD THE NEXT DEFAULT VALUE IN D
OUT (C),D ; 0F3h ADDRESS
DEC C ; VDU_REG
INC HL ; TAB + 1
INC A ; REG + 1
DJNZ VDU_CRTINITLOOP ; LOOP UNTIL DONE
POP HL ; RESTORE HL
POP DE ; RESTORE DE
POP BC ; RESTORE BC
POP AF ; RESTORE AF
LD C,0 ; START WITH REGISTER 0
LD B,16 ; INIT 16 REGISTERS
LD HL,VDU_INIT6845 ; HL = POINTER TO THE DEFAULT VALUES
VDU_CRTINIT1:
LD A,(HL) ; GET VALUE
CALL VDU_WRREG ; WRITE IT
INC HL ; POINT TO NEXT VALUE
INC C ; POINT TO NEXT REGISTER
DJNZ VDU_CRTINIT1 ; LOOP
RET
;
;__VDU_XY__________________________________________________________________________________________
;----------------------------------------------------------------------
; SET CURSOR POSITION TO ROW IN D AND COLUMN IN E
;----------------------------------------------------------------------
;
; MOVE CURSOR TO POSITON IN VDU_X AND VDU_Y
;__________________________________________________________________________________________________
VDU_XY:
PUSH AF ; STORE AF
LD A,E ; SAVE COLUMN NUMBER IN A
LD H,D ; SET H TO ROW NUMBER
LD E,80 ; SET E TO ROW LENGTH
CALL MULT8 ; MULTIPLY TO GET ROW OFFSET
LD E,A ; GET COLUMN BACK
ADD HL,DE ; ADD IT IN
LD (VDU_POS),HL ; SAVE THE RESULT (DISPLAY POSITION)
LD DE,(VDU_OFFSET) ; NOW GET THE BUFFER OFFSET
ADD HL,DE ; AND ADD THAT IN
LD C,14 ; CURSOR POSITION REGISTER PAIR
JP VDU_WRREGX ; DO IT AND RETURN
;
;----------------------------------------------------------------------
; WRITE VALULE IN A TO CURRENT VDU BUFFER POSTION, ADVANCE CURSOR
;----------------------------------------------------------------------
;
VDU_PUTCHAR:
LD B,A ; SAVE THE CHARACTER
; SET BUFFER WRITE POSITION
LD HL,(VDU_OFFSET)
LD DE,(VDU_POS)
ADD HL,DE
INC DE ; INC
LD (VDU_POS),DE ; SAVE NEW SCREEN POSITION
LD C,18 ; UPDATE ADDRESS REGISTER PAIR
CALL VDU_WRREGX ; DO IT
INC HL ; NEW CURSOR POSITION
LD C,14 ; CURSOR POSITION REGISTER PAIR
CALL VDU_WRREGX ; DO IT
LD A,31 ; PREP VDU FOR DATA R/W
OUT (VDU_REG),A
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD A,B
OUT (VDU_RAMWR),A ; OUTPUT CHAR TO VDU
RET
;
;----------------------------------------------------------------------
; FILL AREA IN BUFFER WITH SPECIFIED CHARACTER AND CURRENT COLOR/ATTRIBUTE
; STARTING AT THE CURRENT FRAME BUFFER POSITION
; A: FILL CHARACTER
; DE: NUMBER OF CHARACTERS TO FILL
;----------------------------------------------------------------------
;
VDU_FILL:
LD B,A ; SAVE THE FILL CHARACTER
LD A,(VDU_Y) ; PLACE Y COORD IN A
CP 24 ; IS 24?
JP Z,DO_SCROLL1 ; YES, MUST SCROLL
; SET FILL START POSITION
PUSH DE
LD HL,(VDU_OFFSET)
LD DE,(VDU_POS)
ADD HL,DE
LD C,18
CALL VDU_WRREGX
POP DE
PUSH BC ; STORE BC
PUSH DE ; STORE DE
LD A,(VDU_X) ;
LD H,A ;
LD A,(VDU_Y) ;
LD L,A ;
PUSH HL ; STORE HL
LD B, A ; B = Y COORD
LD DE, 80 ; MOVE LINE LENGTH INTO DE
LD HL, 0 ; MOVE 0 INTO HL
LD A, B ; A=B
CP 0 ; Y=0?
JP Z, VDU_YLOOPEND ; THEN DO NOT MULTIPLY BY 80
VDU_YLOOP: ; HL = 80 * Y
ADD HL, DE ; HL=HL+DE
DJNZ VDU_YLOOP ; LOOP
VDU_YLOOPEND: ;
POP DE ; DE = ORG HL
LD E, D ; E = X
LD D, 0 ; D = 0
ADD HL, DE ; HL = HL + X
LD (VDU_DISPLAYPOS), HL ;
PUSH HL ;
POP DE ;
LD HL,(VDU_DISPLAY_START) ;
ADD HL,DE ;
LD A, 18 ; SET UPDATE ADDRESS IN VDU
CALL VDU_HL2WREG_A ;
LD A, 31 ; TOGGLE VDU FOR UPDATE
; FILL LOOP
LD A,31 ; PREP VDU FOR DATA R/W
OUT (VDU_REG),A
LD A, 14 ; SET CURSOR POS
CALL VDU_HL2WREG_A ;
POP DE ; RESTORE DE
POP BC ; RESTORE BC
POP AF ; RESTORE AF
RET
VDU_FILL1:
LD A,D ; CHECK NUMBER OF FILL CHARS LEFT
OR E
RET Z ; ALL DONE, RETURN
CALL VDU_WAITRDY ; WAIT FOR VDU TO BE READY
LD A,B
OUT (VDU_RAMWR),A ; OUTPUT CHAR TO VDU
DEC DE ; DECREMENT COUNT
JR VDU_FILL1 ; LOOP
;
;----------------------------------------------------------------------
; SCROLL ENTIRE SCREEN FORWARD BY ONE LINE (CURSOR POSITION UNCHANGED)
;----------------------------------------------------------------------
;
VDU_SCROLL:
; SCROLL FORWARD BY ADDING ONE ROW TO DISPLAY START ADDRESS
LD HL,(VDU_OFFSET)
LD DE,80
ADD HL,DE
LD (VDU_OFFSET),HL
LD C,12
CALL VDU_WRREGX
; FILL EXPOSED LINE
LD HL,(VDU_POS)
PUSH HL
LD HL,23*80
LD (VDU_POS),HL
LD DE,80
LD A,' '
CALL VDU_FILL
POP HL
LD (VDU_POS),HL
; ADJUST CURSOR POSITION
LD HL,(VDU_OFFSET)
LD DE,(VDU_POS)
ADD HL,DE
LD C,14
JP VDU_WRREGX
;
;----------------------------------------------------------------------
; REVERSE SCROLL ENTIRE SCREEN BY ONE LINE (CURSOR POSITION UNCHANGED)
;----------------------------------------------------------------------
;
VDU_RSCROLL:
RET
;
;==================================================================================================
; VDU DRIVER - DATA
;==================================================================================================
;
VDU_X .DB 0 ; CURSOR X
VDU_Y .DB 0 ; CURSOR Y
VDU_DISPLAYPOS .DW 0 ; CURRENT DISPLAY POSITION
VDU_DISPLAY_START .DW 0 ; CURRENT DISPLAY POSITION
VDU_POS .DW 0 ; CURRENT DISPLAY POSITION
VDU_OFFSET .DW 0 ; CURRENT DISPLAY POSITION
;
;==================================================================================================
; VDU DRIVER - 6845 REGISTER INITIALIZATION
; VDU DRIVER - SY6845 REGISTER INITIALIZATION
;==================================================================================================
;
VDU_INIT6845:

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