Lost Art of Code Optimization (or why you should grok Commodore 64)

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Lost Art of Code Optimisation or why you should grok the

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I don’t let old computers die mehowte  Michał Taszycki at

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I’m making weekly video course on programming Commodore64 64bites.com

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Commodore 64 is dead

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Today

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Back Then

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Today

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Back Then

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Back Then

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Back Then?

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Today!

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Today!

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How many games?! 0 10 20 30 40 50 60 70 80 2010 2011 2012 2013 2014 2015 games demos source - http://csdb.dk

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How many releases?! source - http://csdb.dk 0 210 420 630 840 1050 1260 1470 1680 1890 2100 2010 2011 2012 2013 2014 2015 all releases

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How many years?!

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How many years?!

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How many years?!

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How many years?!

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Commodore 64 8 bit registers 64 KB RAM 1 Mhz CPU

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Commodore 64 legendary sound chip 320x200 resolution 8 hardware sprites

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Commodore 64 it can’t even multiply

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Modern DEMO! Edge of Disgrace by Booze Design

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Coma Light 13 by Oxyron Modern DEMO!

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Comaland by Censor Design & Oxyron Modern DEMO!

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Pixel Shader varying vec3 N; varying vec3 v; void main(void) { vec3 L = normalize(gl_LightSource[0].position.xyz - v); vec4 Idiff = gl_FrontLightProduct[0].diffuse * max(dot(N,L), 0.0); Idiff = clamp(Idiff, 0.0, 1.0); gl_FragColor = Idiff; }

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“Raster Shader” irq: lda #$ff sta $d019 ldx #$05 d: dex bne d ldx #$00 c: ldy #$08 a: lda colors,x sta $d020 sta $d021 inx dey beq c txa ldx #$07 b: dex bne b tax cpx #$8c bcc a

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Enough Talking!

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Let’s code!

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Minimal program :BasicUpstart2(main) main: rts

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LDA address LDA #value Pamięć RAM ➞ Rejestr A STA address Rejestr A ➞ Pamięć RAM Most important instructions

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rts main: lda # sta background_color lda # sta border_color GRAY DARK_GRAY Border & Background .label border_color = $d020 .label background_color = $d021 :BasicUpstart2(main)

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Macros rts main: lda # sta background_color lda # sta border_color GRAY DARK_GRAY

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rts main: lda # sta background_color lda # sta border_color GRAY DARK_GRAY .macro background(color) { } Macros

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lda # sta background_color rts main: :background( ) color lda # sta border_color GRAY DARK_GRAY .macro background(color) { } Macros

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lda # sta background_color rts main: :background( ) color lda # sta border_color GRAY DARK_GRAY .macro background(color) { } Macros

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lda # sta background_color rts main: .macro border(color) { } :background( ) color lda # sta border_color GRAY DARK_GRAY .macro background(color) { } Macros

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:border( ) .macro background(color) { } lda # sta background_color rts main: .macro border(color) { } :background( ) color lda # sta border_color GRAY DARK_GRAY color Macros

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Raster Bar // long delay :background(BLACK) :background(DARK_GRAY)

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Delay :background(BLACK) :background(DARK_GRAY) nop

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:background(BLACK) :background(DARK_GRAY) nop nop Delay

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:background(BLACK) :background(DARK_GRAY) nop nop nop Delay

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:background(BLACK) :background(DARK_GRAY) nop // ... many more nops nop nop Delay

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:background(BLACK) :background(DARK_GRAY) .for (var i = 0; i < ; i++) { nop } 230 Delay

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.macro nops( ) { } .for (var i = 0; i < ; i++) { nop } :background(BLACK) :background(DARK_GRAY) 230 count Delay

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:nops( ) .macro nops( ) { } .for (var i = 0; i < ; i++) { nop } :background(BLACK) :background(DARK_GRAY) 230 count count Delay

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Interrupts raster_bars_irq: jmp irq_handler :nops( ) :background(BLACK) :background(DARK_GRAY) 230

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// Disable IRQ handling sei // inject the handler lda #raster_bars_irq sta irq_vector + 1 // Enable IRQ handling cli Interrupts

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// inject the handler lda #raster_bars_irq sta irq_vector + 1 Turn off timer cli sei

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cli sei Turn off timer

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cli sei // Disable the interrupt generated by timers lda #%01111111 sta cia1_interrupt_control_register sta cia2_interrupt_control_register // Negate already scheduled interrupts lda cia1_interrupt_control_register lda cia2_interrupt_control_register Turn off timer

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Turn on raster cli sei // Disable the interrupt generated by timers lda #%01111111 sta cia1_interrupt_control_register sta cia2_interrupt_control_register // Negate already scheduled interrupts lda cia1_interrupt_control_register lda cia2_interrupt_control_register // Enable raster interrupts lda #%00000001 sta vic2_interrupt_control_register

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Choose raster line cli sei // Disable the interrupt generated by timers lda #%01111111 sta cia1_interrupt_control_register sta cia2_interrupt_control_register // Negate already scheduled interrupts lda cia1_interrupt_control_register lda cia2_interrupt_control_register // Enable raster interrupts lda #%00000001 sta vic2_interrupt_control_register :request_raster_irq(106, raster_bars_irq)

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.macro request_raster_irq(line_number, handler) { } Choose raster line

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.macro request_raster_irq(line_number, handler) { } lda #handler sta irq_vector + 1 Choose raster line

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.macro request_raster_irq(line_number, handler) { } lda #handler sta irq_vector + 1 lda #line_number sta vic2_rasterline_register Choose raster line

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.macro request_raster_irq(line_number, handler) { } lda #handler sta irq_vector + 1 .if (line_number > 255) { :set_bits(screen_control_register, %10000000) } else { :clear_bits(screen_control_register, %10000000) } lda #line_number sta vic2_rasterline_register Choose raster line

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.macro set_bits(address, bit_mask) { lda address ora #bit_mask sta address } .macro clear_bits(address, bit_mask) { lda address and #255 - bit_mask sta address } Choose raster line

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Interrupt handled? jmp irq_handler raster_bars_irq: :background(BLACK) :nops(230) :background(DARK_GRAY)

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raster_bars_irq: :background(BLACK) :nops(230) :background(DARK_GRAY) lda #%00000001 sta vic2_interrupt_status_register jmp irq_handler Interrupt handled?

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raster_bars_irq: :background(BLACK) :nops(230) :background(DARK_GRAY) :exit_irq_handler() .macro exit_irq_handler() { } lda #%00000001 sta vic2_interrupt_status_register jmp irq_handler Interrupt handled?

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Stabilization :exit_irq_handler() raster_bars_irq: :nops(14) :background(BLACK) :nops(230) :background(DARK_GRAY)

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Raster Bars! :exit_irq_handler() raster_bars_irq:

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