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#include "Halide.h"
#include <stdio.h>
using namespace Halide;
Expr u8(Expr a) {
return cast<uint8_t>(a);
}
/* Do n unrolled iterations of game of life on a torus */
Func gameOfLife(ImageParam input, int n) {
Var x, y;
Func in;
if (n == 1) {
in(x, y) = input(x, y);
} else {
in = gameOfLife(input, n - 1);
in.compute_root();
}
Expr w = input.width(), h = input.height();
Expr W = (x + w - 1) % w, E = (x + 1) % w, N = (y + h - 1) % h, S = (y + 1) % h;
Expr livingNeighbors = (in(W, N) + in(x, N) +
in(E, N) + in(W, y) +
in(E, y) + in(W, S) +
in(x, S) + in(E, S));
Expr alive = in(x, y) != 0;
Func output;
output(x, y) = select(livingNeighbors == 3 || (alive && livingNeighbors == 2), u8(1), u8(0));
return output;
}
int main(int argc, char **argv) {
Buffer<uint8_t> board1(32, 32), board2(32, 32), board3(32, 32);
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 32; x++) {
uint8_t val = ((rand() & 0xff) < 128) ? 1 : 0;
board1(x, y) = val;
board2(x, y) = val;
board3(x, y) = val;
}
}
ImageParam input(UInt(8), 2);
{
// Outer loop in C
Func oneIteration = gameOfLife(input, 1);
Func twoIterations = gameOfLife(input, 2);
for (int i = 0; i < 10; i++) {
input.set(board1);
board1 = oneIteration.realize({32, 32});
input.set(board1);
board1 = oneIteration.realize({32, 32});
input.set(board2);
board2 = twoIterations.realize({32, 32});
/*
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 32; x++) {
printf(board1(x, y) ? "#" : " ");
}
printf("|");
for (int x = 0; x < 32; x++) {
printf(board2(x, y) ? "#" : " ");
}
printf("\n");
}
*/
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 32; x++) {
if (board1(x, y) != board2(x, y)) {
printf("At timestep %d, boards one and two disagree at %d, %d: %d vs %d\n",
i, x, y, board1(x, y), board2(x, y));
return 1;
}
}
}
}
}
{
// Outer loop in Halide using a reduction
Func life;
// Initialize step
Var x, y, z;
life(x, y, z) = input(x, y);
// Update step
Expr w = input.width(), h = input.height();
RDom t(0, w, 0, h, 0, 21);
Expr lastT = (t.z + 1) % 2;
Expr W = (t.x + w - 1) % w, E = (t.x + 1) % w, N = (t.y + h - 1) % h, S = (t.y + 1) % h;
Expr alive = life(t.x, t.y, lastT) != u8(0);
Expr livingNeighbors = (life(W, N, lastT) + life(t.x, N, lastT) +
life(E, N, lastT) + life(W, t.y, lastT) +
life(E, t.y, lastT) + life(W, S, lastT) +
life(t.x, S, lastT) + life(E, S, lastT));
life(t.x, t.y, t.z % 2) = select(livingNeighbors == 3 || (alive && livingNeighbors == 2), u8(1), u8(0));
life.compute_root();
Func output;
output(x, y) = life(x, y, 1);
input.set(board3);
output.realize(board3);
/*
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 32; x++) {
printf(board1(x, y) ? "#" : " ");
}
printf("|");
for (int x = 0; x < 32; x++) {
printf(board3(x, y) ? "#" : " ");
}
printf("\n");
}
*/
for (int y = 0; y < 32; y++) {
for (int x = 0; x < 32; x++) {
if (board1(x, y) != board3(x, y)) {
printf("Boards one and three disagree at %d, %d: %d vs %d\n",
x, y, board1(x, y), board3(x, y));
return 1;
}
}
}
}
printf("Success!\n");
return 0;
}
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