prog8/examples/mandelbrot.p8

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%import textio
%import floats
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%zeropage basicsafe
; Note: this program is compatible with C64 and CX16.
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main {
const uword width = 30
const uword height = 20
const ubyte max_iter = 16
sub start() {
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txt.print("calculating mandelbrot fractal...")
%asm {{
stx P8ZP_SCRATCH_REG
; reset the jiffy clock
ldx #0
ldy #0
lda #0
jsr c64.SETTIM
ldx P8ZP_SCRATCH_REG
}}
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ubyte pixelx
ubyte pixely
for pixely in 0 to height-1 {
float yy = (pixely as float)/0.4/height - 1.0
for pixelx in 0 to width-1 {
float xx = (pixelx as float)/0.3/width - 2.2
float xsquared = 0.0
float ysquared = 0.0
float x = 0.0
float y = 0.0
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ubyte iter = 0
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while iter<max_iter and xsquared+ysquared<4.0 {
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y = x*y*2.0 + yy
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x = xsquared - ysquared + xx
xsquared = x*x
ysquared = y*y
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iter++
}
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txt.setcc(pixelx+4, pixely+1, 160, max_iter-iter)
}
}
ubyte time_lo
ubyte time_mid
ubyte time_hi
%asm {{
stx P8ZP_SCRATCH_REG
jsr c64.RDTIM ; A/X/Y
sta time_lo
stx time_mid
sty time_hi
ldx P8ZP_SCRATCH_REG
}}
float duration = ((mkword(time_mid, time_lo) as float) + (time_hi as float)*65536.0) / 60
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txt.plot(0, 21)
txt.print("finished in ")
floats.print_f(duration)
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txt.print(" seconds!\n")
}
}