Back in 2017 I wrote a rust compile time mandelbrot using horrid hacks using associated types, but then Rust 1.46.0 landed with const fn being able to use loops and if's and I thought I'd try a rewrite.
// (c) Dave Gilbert dave@treblig.org 2020
const LSIZE: usize = 32;
const SSIZE: usize = LSIZE*(LSIZE+1);
const fn manpoint(x: i64, y: i64) -> u8 {
let mut ti : i64 = 0;
let mut tr : i64 = 0;
let mut zi : i64 = 0;
let mut zr : i64 = 0;
let mut iter : u8 = 128;
while iter > 0 && (ti + tr < (4 << 16)) {
zi = (((((2<<16)*zr) >> 16) * zi)>>16) + y;
zr = tr-ti+x;
tr = (zr*zr) >> 16;
ti = (zi*zi) >> 16;
iter-=1;
}
(iter % 20) + 64
}
const fn manline() -> [u8;SSIZE] {
let mut y : i64 = -2 << 16;
let xstep : i64 = (4 << 16) / (LSIZE as i64);
let ystep : i64 = (4 << 16) / (LSIZE as i64);
let mut yi = 0;
let mut res : [u8;SSIZE] = [32;SSIZE];
while yi < LSIZE {
let mut x : i64 = -2 << 16;
let mut xi = 0;
while xi < LSIZE {
res[yi*(LSIZE+1)+xi] = manpoint(x, y);
x+=xstep;
xi+=1;
}
res[yi*(LSIZE+1)+LSIZE]=10;
y+=ystep;
yi+=1;
}
res
}
const BROT: [u8;SSIZE] = manline();
fn main() {
println!("Const val={}", std::str::from_utf8(&BROT).unwrap());
}
Heck that's boring!
So now lets compile it
[dg@major ~]$ rustc -O const.rs --emit asm; grep -i ascii const.s|tr '\\' '\012' .ascii "called `Result::unwrap()` on an `Err` value" .ascii "Const val=" .ascii "GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG nGGGGGGGGGGGFFFFFFFFFFFGGGGGGGGGG nGGGGGGGGGFFFFFFFFFFFFFFFGGGGGGGG nGGGGGGGFFFFFFFFFFFFFFFFFFFGGGGGG nGGGGGGFFFFFFFFFFFFFFFFFFFFFGGGGG nGGGGGFFFFFFFFFFFFFFFFFFFFFFFGGGG nGGGGFFFFFEEEEEEEFFFFFFFFFFFFFGGG nGGGFFFEEEEEEEDCCDEEFFFFFFFFFFFGG nGGGFFEEEEEEDDCBO@DDEFFFFFFFFFFGG nGGFEEEEEEEDDDCO@SCDDEEFFFFFFFFFG nGGFEEEEEEDDCBAF@NACDEEFFFFFFFFFG nGFEEEEEDDCCSHH@@@@KQDEEFFFFFFFFF nGEEEEEDCCCBP@@@@@@@SCEEEFFFFFFFF nGEEDDCNA@A@@@@@@@@@KCDEEFFFFFFFF nGDDDCBS@@DO@@@@@@@@@CDEEFFFFFFFF nGDDBAQI@@@B@@@@@@@@KCDEEFFFFFFFF nG@@@@@@@@@@@@@@@@@@ACDEEFFFFFFFF nGDDBAQI@@@B@@@@@@@@KCDEEFFFFFFFF nGDDDCBS@@DO@@@@@@@@@CDEEFFFFFFFF nGEEDDCNA@A@@@@@@@@@KCDEEFFFFFFFF nGEEEEEDCCCBP@@@@@@@SCEEEFFFFFFFF nGFEEEEEDDCCSH@@@@@JQDEEFFFFFFFFF nGGFEEEEEEDDCBAF@NACDEEFFFFFFFFFG nGGFEEEEEEEDDDCO@SCDDEEFFFFFFFFFG nGGGFFEEEEEEDDCBO@DDEFFFFFFFFFFGG nGGGFFFEEEEEEEDCCDEEFFFFFFFFFFFGG nGGGGFFFFFEEEEEEEFFFFFFFFFFFFFGGG nGGGGGFFFFFFFFFFFFFFFFFFFFFFFGGGG nGGGGGGFFFFFFFFFFFFFFFFFFFFFGGGGG nGGGGGGGFFFFFFFFFFFFFFFFFFFGGGGGG nGGGGGGGGGFFFFFFFFFFFFFFFGGGGGGGG nGGGGGGGGGGGFFFFFFFFFFFGGGGGGGGGG n" .ascii "const.rs"and there we are.
Boring!
The compiler isn't required to compile stuff at compile time unless you force it to be used in a constant context, hence the BROT in that code.
In 1.46.0 you can't use floating point yet, so we're still using integer.
(c)David Alan Gilbert 2020
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