65 lines
1.8 KiB
ArmAsm
65 lines
1.8 KiB
ArmAsm
include "../include/registers.i"
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include "hardware/dmabits.i"
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include "hardware/intbits.i"
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LVL3_INT_VECTOR equ $6c
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SCREEN_WIDTH equ 320
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SCREEN_HEIGHT equ 256
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SCREEN_WIDTH_BYTES equ (SCREEN_WIDTH/8)
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SCREEN_BIT_DEPTH equ 1
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SCREEN_RES equ 8 ; 8=lo resolution, 4=hi resolution
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RASTER_X_START equ $81 ; hard coded coordinates from hardware manual
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RASTER_Y_START equ $2c
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RASTER_X_STOP equ RASTER_X_START+SCREEN_WIDTH
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RASTER_Y_STOP equ RASTER_Y_START+SCREEN_HEIGHT
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entry:
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;; custom chip base globally in a6
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lea CUSTOM,a6
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move #$7ff,DMACON(a6) ; disable all dma
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move #$7fff,INTENA(a6) ; disable all interrupts
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;; poke bitplane pointers into the copper list
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lea bitplane(pc),a0
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lea _BPL1PTL(pc),a1
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move.l a0,d0
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move.w d0,(a1) ; poke BPL1PTL
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swap d0
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lea _BPL1PTH(pc),a1
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move.w d0,(a1) ; poke BPL1PTH
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;; set up playfield
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move.w #(RASTER_Y_START<<8)|RASTER_X_START,DIWSTRT(a6)
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move.w #((RASTER_Y_STOP-256)<<8)|(RASTER_X_STOP-256),DIWSTOP(a6)
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move.w #(RASTER_X_START/2-SCREEN_RES),DDFSTRT(a6)
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move.w #(RASTER_X_START/2-SCREEN_RES)+(8*((SCREEN_WIDTH/16)-1)),DDFSTOP(a6)
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move.w #(SCREEN_BIT_DEPTH<<12)|$200,BPLCON0(a6)
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move.w #SCREEN_WIDTH_BYTES*SCREEN_BIT_DEPTH-SCREEN_WIDTH_BYTES,BPL1MOD(a6)
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;; install copper list, then enable dma and selected interrupts
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lea copper(pc),a0
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move.l a0,COP1LC(a6)
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move.w COPJMP1(a6),d0
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move.w #(DMAF_SETCLR!DMAF_COPPER!DMAF_RASTER!DMAF_MASTER),DMACON(a6)
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move.w #(INTF_SETCLR|INTF_INTEN|INTF_EXTER),INTENA(a6)
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.mainLoop:
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bra.b .mainLoop
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copper:
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dc.w BPL1PTH
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_BPL1PTH:
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dc.w 0 ; hi word address of the bitplane will be poked once we know it
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dc.w BPL1PTL
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_BPL1PTL:
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dc.w 0 ; lo word address of the bitplane will be poked once we know it
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dc.w COLOR00,$0000
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include "out/copper-list.s"
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dc.l $fffffffe
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bitplane:
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dcb.b (SCREEN_WIDTH*SCREEN_HEIGHT)/8,$00
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