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33 lines
910 B
Plaintext
33 lines
910 B
Plaintext
require'vcs'
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TIM_OVERSCAN = 50 -- TIM64T, 3200 cycles = ~ 42 scanlines
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TIM_VBLANK = 61 -- TIM64T, 3904 cycles = ~ 51 scanlines
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TIM_KERNEL = 17 -- T1024T, 17408 cycles = ~229 scanlines
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location(0xf000, 0xffff)
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section{'vectors', org=0xfffc} dc.w start,start
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local kernel = function()
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ldx#0xd0 @_loop sta WSYNC stx COLUBK dex bne _loop
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end
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local wait = function() local l=label() lda INTIM bne l end
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@@start
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-- clear zeropage
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cld ldx#0 txa @_clear dex tsx pha bne _clear
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@main
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-- overscan
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sta WSYNC lda#2 sta VBLANK lda#TIM_OVERSCAN sta TIM64T wait()
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-- vblank
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lda#0b1110 @_vsync sta WSYNC sta VSYNC lsr bne _vsync
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lda#2 sta VBLANK lda#TIM_VBLANK sta TIM64T wait() sta WSYNC sta VBLANK
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-- kernel
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lda#TIM_KERNEL sta T1024T kernel() wait()
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jmp main
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writebin(filename..'.bin')
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writesym(filename..'.sym')
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print(stats)
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