Created
September 2, 2020 20:23
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// the donut code with fixed-point arithmetic; no sines, cosines, square roots, or anything. | |
// a1k0n 2020 | |
#include <stdio.h> | |
#include <string.h> | |
#include <unistd.h> | |
#define R(mul,shift,x,y) \ | |
_=x; \ | |
x -= mul*y>>shift; \ | |
y += mul*_>>shift; \ | |
_ = 3145728-x*x-y*y>>11; \ | |
x = x*_>>10; \ | |
y = y*_>>10; | |
char b[1760], z[1760]; | |
void main() { | |
int sA=1024,cA=0,sB=1024,cB=0,_; | |
for (;;) { | |
memset(b, 32, 1760); // text buffer | |
memset(z, 127, 1760); // z buffer | |
int sj=0, cj=1024; | |
for (int j = 0; j < 90; j++) { | |
int si = 0, ci = 1024; // sine and cosine of angle i | |
for (int i = 0; i < 324; i++) { | |
int R1 = 1, R2 = 2048, K2 = 5120*1024; | |
int x0 = R1*cj + R2, | |
x1 = ci*x0 >> 10, | |
x2 = cA*sj >> 10, | |
x3 = si*x0 >> 10, | |
x4 = R1*x2 - (sA*x3 >> 10), | |
x5 = sA*sj >> 10, | |
x6 = K2 + R1*1024*x5 + cA*x3, | |
x7 = cj*si >> 10, | |
x = 40 + 30*(cB*x1 - sB*x4)/x6, | |
y = 12 + 15*(cB*x4 + sB*x1)/x6, | |
N = (-cA*x7 - cB*((-sA*x7>>10) + x2) - ci*(cj*sB >> 10) >> 10) - x5 >> 7; | |
int o = x + 80 * y; | |
char zz = (x6-K2)>>15; | |
if (22 > y && y > 0 && x > 0 && 80 > x && zz < z[o]) { | |
z[o] = zz; | |
b[o] = ".,-~:;=!*#$@"[N > 0 ? N : 0]; | |
} | |
R(5, 8, ci, si) // rotate i | |
} | |
R(9, 7, cj, sj) // rotate j | |
} | |
for (int k = 0; 1761 > k; k++) | |
putchar(k % 80 ? b[k] : 10); | |
R(5, 7, cA, sA); | |
R(5, 8, cB, sB); | |
usleep(15000); | |
printf("\x1b[23A"); | |
} | |
} |
sorry, might be dumb question here.
what operations is that _=x;? tried googling but no gd results there
was compiling it with clang... or that syntax works on GCC?
sorry, might be dumb question here.
what operations is that _=x;? tried googling but no gd results there
was compiling it with clang... or that syntax works on GCC?
There's an integer variable named _. So fundamentally it's the same operation as x=y;
The #define was cribbed from the obfuscated version and it's still a bit obfuscated, haha
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To run on the LiteX risc-v core, I had to change
char
tosigned char
for the two buffers, useputsnonl
instead ofprintf
andbusy_wait(15)
instead ofusleep(15000)
. You will also need to set up an interrupt handler or it will crash on boot.