151 lines
3.9 KiB
Forth
151 lines
3.9 KiB
Forth
# Mandelbrot set
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#
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# Install:
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# $ git clone https://github.com/akkartik/mu
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# $ cd mu
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# Build on Linux:
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# $ ./translate mandelbrot.mu
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# Build on other platforms (slow):
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# $ ./translate_emulated mandelbrot.mu
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# Run:
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# $ qemu-system-i386 code.img
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fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
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mandelbrot screen
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}
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fn mandelbrot screen: (addr screen) {
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var a/eax: int <- copy 0
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var b/ecx: int <- copy 0
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a, b <- screen-size screen
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var width/esi: int <- copy a
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width <- shift-left 3/log2-font-width
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var height/edi: int <- copy b
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height <- shift-left 4/log2-font-height
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var y/ecx: int <- copy 0
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{
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compare y, height
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break-if->=
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var imaginary/xmm1: float <- viewport-to-imaginary y, width, height
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var x/edx: int <- copy 0
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{
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compare x, width
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break-if->=
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var real/xmm0: float <- viewport-to-real x, width
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var iterations/eax: int <- mandelbrot-iterations-for-point real, imaginary, 0x400/max
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compare iterations, 0x400/max
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{
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break-if->=
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pixel screen, x, y, 0xf/white
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}
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compare iterations, 0x400/max
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{
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break-if-<
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pixel screen, x, y, 0/black
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}
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x <- increment
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loop
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}
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y <- increment
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loop
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}
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}
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fn mandelbrot-iterations-for-point real: float, imaginary: float, max: int -> _/eax: int {
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var zero: float
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var x/xmm0: float <- copy zero
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var y/xmm1: float <- copy zero
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var iterations/ecx: int <- copy 0
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{
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var done?/eax: boolean <- mandelbrot-done? x, y
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compare done?, 0/false
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break-if-!=
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compare iterations, max
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break-if->=
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var newx/xmm2: float <- mandelbrot-x x, y, real
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var newy/xmm3: float <- mandelbrot-y x, y, imaginary
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x <- copy newx
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y <- copy newy
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iterations <- increment
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loop
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}
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return iterations
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}
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fn mandelbrot-done? x: float, y: float -> _/eax: boolean {
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# x*x + y*y > 4
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var x2/xmm0: float <- copy x
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x2 <- multiply x
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var y2/xmm1: float <- copy y
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y2 <- multiply y
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var sum/xmm0: float <- copy x2
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sum <- add y2
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var four/eax: int <- copy 4
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var four-f/xmm1: float <- convert four
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compare sum, four-f
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{
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break-if-float>
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return 0/false
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}
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return 1/true
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}
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fn mandelbrot-x x: float, y: float, real: float -> _/xmm2: float {
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# x*x - y*y + real
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var x2/xmm0: float <- copy x
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x2 <- multiply x
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var y2/xmm1: float <- copy y
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y2 <- multiply y
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var result/xmm0: float <- copy x2
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result <- subtract y2
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result <- add real
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return result
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}
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fn mandelbrot-y x: float, y: float, imaginary: float -> _/xmm3: float {
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# 2*x*y + imaginary
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var two/eax: int <- copy 2
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var result/xmm0: float <- convert two
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result <- multiply x
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result <- multiply y
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result <- add imaginary
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return result
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}
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# Scale (x, y) pixel coordinates to a complex plane where the viewport width
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# ranges from -2 to +2. Viewport height just follows the viewport's aspect
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# ratio.
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fn viewport-to-real x: int, width: int -> _/xmm0: float {
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# (x - width/2)*4/width
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var result/xmm0: float <- convert x
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var width-f/xmm1: float <- convert width
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var two/eax: int <- copy 2
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var two-f/xmm2: float <- convert two
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var half-width-f/xmm2: float <- reciprocal two-f
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half-width-f <- multiply width-f
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result <- subtract half-width-f
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var four/eax: int <- copy 4
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var four-f/xmm2: float <- convert four
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result <- multiply four-f
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result <- divide width-f
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return result
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}
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fn viewport-to-imaginary y: int, width: int, height: int -> _/xmm1: float {
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# (y - height/2)*4/width
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var result/xmm0: float <- convert y
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var height-f/xmm1: float <- convert height
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var half-height-f/xmm1: float <- copy height-f
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var two/eax: int <- copy 2
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var two-f/xmm2: float <- convert two
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half-height-f <- divide two-f
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result <- subtract half-height-f
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var four/eax: int <- copy 4
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var four-f/xmm1: float <- convert four
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result <- multiply four-f
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var width-f/xmm1: float <- convert width
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result <- divide width-f
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return result
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}
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