mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-27 01:51:35 +00:00
166 lines
6.2 KiB
NASM
166 lines
6.2 KiB
NASM
ORG 04000H
|
|
; LOAD 04000H
|
|
; MSX cartridge header @ 0x4000 - 0x400f
|
|
dw 0x4241
|
|
dw Start
|
|
dw Start
|
|
dw 0,0,0,0,0
|
|
|
|
; ******************************
|
|
; * BIOS STANDARD ROUTINES *
|
|
; ******************************
|
|
|
|
RDSLT: EQU 000CH
|
|
CNVCHR: EQU 00ABH
|
|
MAPXYC: EQU 0111H
|
|
SETC: EQU 0120H
|
|
|
|
; ******************************
|
|
; * WORKSPACE VARIABLES *
|
|
; ******************************
|
|
|
|
FORCLR: EQU 0F3E9H
|
|
ATRBYT: EQU 0F3F2H
|
|
CGPNT: EQU 0F91FH
|
|
PATWRK: EQU 0FC40H
|
|
SCRMOD: EQU 0FCAFH
|
|
GRPACX: EQU 0FCB7H
|
|
GRPACY: EQU 0FCB9H
|
|
|
|
; ******************************
|
|
; * CONTROL CHARACTERS *
|
|
; ******************************
|
|
|
|
CR: EQU 13
|
|
|
|
Start:
|
|
GFORTY: CP 3 ; String type?
|
|
RET NZ ;
|
|
LD A,(SCRMOD) ; Mode
|
|
CP 2 ; Graphics?
|
|
RET NZ ;
|
|
EX DE,HL ; HL->Descriptor
|
|
LD B,(HL) ; B=String len
|
|
INC HL ;
|
|
LD E,(HL) ; Address LSB
|
|
INC HL ;
|
|
LD D,(HL) ; DE->String
|
|
INC B ;
|
|
GF2: DEC B ; Finished?
|
|
RET Z ;
|
|
LD A,(DE) ; A=Chr from string
|
|
CALL GPRINT ; Print it
|
|
INC DE ;
|
|
JR GF2 ; Next chr
|
|
GPRINT: PUSH AF ;
|
|
PUSH BC ;
|
|
PUSH DE ;
|
|
PUSH HL ;
|
|
PUSH IY ;
|
|
LD BC,(GRPACX) ; BC=X coord
|
|
LD DE,(GRPACY) ; DE=Y coord
|
|
CALL GDC ; Decode chr
|
|
LD (GRPACX),BC ; New X coord
|
|
LD (GRPACY),DE ; New Y coord
|
|
POP IY ;
|
|
POP HL ;
|
|
POP DE ;
|
|
POP BC ;
|
|
POP AF ;
|
|
RET ;
|
|
|
|
GDC: CALL CNVCHR ; Check graphic
|
|
RET NC ; NC=Header
|
|
JR NZ,GD2 ; NZ=Converted
|
|
CP CR ; Carriage Return?
|
|
JR Z,GCRLF ;
|
|
CP 20H ; Other control?
|
|
RET C ; Ignore
|
|
GD2: LD L,A ;
|
|
LD H,0 ; HL=Chr code
|
|
ADD HL,HL ;
|
|
ADD HL,HL ;
|
|
ADD HL,HL ; HL=Chr*8
|
|
PUSH BC ; X coord
|
|
PUSH DE ; Y coord
|
|
LD DE,(CGPNT+1) ; Character set
|
|
ADD HL,DE ; HL->Pattern
|
|
LD DE,PATWRK ; DE->Buffer
|
|
LD B,8 ; Eight byte pattern
|
|
GD3: PUSH BC ;
|
|
PUSH DE ;
|
|
LD A,(CGPNT) ; Slot ID
|
|
CALL RDSLT ; Get pattern
|
|
EI ;
|
|
POP DE ;
|
|
POP BC ;
|
|
LD (DE),A ; Put in buffer
|
|
INC DE ;
|
|
INC HL ;
|
|
DJNZ GD3 ; Next
|
|
POP DE ;
|
|
POP BC ;
|
|
LD A,(FORCLR) ; Current colour
|
|
LD (ATRBYT),A ; Set ink
|
|
LD IY,PATWRK ; IY->Patterns
|
|
PUSH DE ;
|
|
LD H,8 ; Max dot rows
|
|
GD4: BIT 7,D ; Pos Y coord?
|
|
JR NZ,GD8 ;
|
|
CALL BMDROW ; Bottom most row?
|
|
JR C,GD9 ; C=Y too large
|
|
PUSH BC ;
|
|
LD L,6 ; Max dot cols
|
|
LD A,(IY+0) ; A=Pattern row
|
|
GD5: BIT 7,B ; Pos X coord
|
|
JR NZ,GD6 ;
|
|
CALL RMDCOL ; Rightmost col?
|
|
JR C,GD7 ; C=X too large
|
|
BIT 7,A ; Pattern bit
|
|
JR Z,GD6 ; Z=0 Pixel
|
|
PUSH AF ;
|
|
PUSH DE ;
|
|
PUSH HL ;
|
|
CALL MAPXYC ; Map coords
|
|
CALL SETC ; Set pixel
|
|
POP HL ;
|
|
POP DE ;
|
|
POP AF ;
|
|
GD6: RLCA ; Shift pattern
|
|
INC BC ; X=X+1
|
|
DEC L ; Finished dot cols?
|
|
JR NZ,GD5 ;
|
|
GD7: POP BC ; Initial X coord
|
|
GD8: INC IY ; Next pattern byte
|
|
INC DE ; Y=Y+1
|
|
DEC H ; Finished dot rows?
|
|
JR NZ,GD4 ;
|
|
GD9: POP DE ; Initial Y coord
|
|
LD HL,6 ; Step
|
|
ADD HL,BC ; X=X+6
|
|
LD B,H ;
|
|
LD C,L ; BC=New X coord
|
|
CALL RMDCOL ; Rightmost col?
|
|
RET NC ;
|
|
|
|
GCRLF: LD BC,0 ; X=0
|
|
LD HL,8 ;
|
|
ADD HL,DE ;
|
|
EX DE,HL ; Y=Y+8
|
|
RET ;
|
|
|
|
BMDROW: PUSH HL ;
|
|
LD HL,191 ; Bottom dot row
|
|
OR A ;
|
|
SBC HL,DE ; Check Y coord
|
|
POP HL ;
|
|
RET ; C=Below screen
|
|
|
|
RMDCOL: PUSH HL ;
|
|
LD HL,239 ; Rightmost dot col
|
|
OR A ;
|
|
SBC HL,BC ; Check X coord
|
|
POP HL ;
|
|
RET ; C=Beyond right
|
|
|
|
END |