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#include "Halide.h"
#include <stdio.h>
using namespace Halide;
int main(int argc, char **argv) {
Var x, y;
{
// Define a reduction with two update steps
Func f;
f(x) = sin(x);
RDom r1(1, 10);
Expr xl = r1; // left to right pass
Expr xr = 10 - r1; // right to left pass
f(xl) = f(xl - 1) + f(xl);
f(xr) = f(xr + 1) + f(xr);
Buffer<float> result = f.realize({11});
// The same thing in C
float ref[11];
for (int i = 0; i < 11; i++) {
ref[i] = sinf(i);
}
for (int i = 1; i < 11; i++) {
ref[i] += ref[i - 1];
}
for (int i = 9; i >= 0; i--) {
ref[i] += ref[i + 1];
}
for (int i = 0; i < 11; i++) {
if (fabs(result(i) - ref[i]) > 0.0001f) {
printf("result(%d) = %f instead of %f\n",
i, result(i), ref[i]);
return 1;
}
}
}
{
// Define a reduction that fills an array, integrates it, then
// manually change certain values. One of the values will
// depend on another function.
Func f, g;
g(x) = x * x;
f(x) = x;
// Integrate from 1 to 10
RDom r(1, 10);
f(r) = f(r) + f(r - 1);
// Clobber two values
f(17) = 8;
f(109) = 4;
// Clobber a range using another func
RDom r2(4, 5);
f(r2) = g(r2);
g.compute_at(f, r2);
Buffer<int> result = f.realize({110});
int correct[110];
for (int i = 0; i < 110; i++) {
correct[i] = i;
}
for (int i = 1; i < 11; i++) {
correct[i] += correct[i - 1];
}
correct[17] = 8;
correct[109] = 4;
for (int i = 4; i < 9; i++) {
correct[i] = i * i;
}
for (int i = 0; i < 110; i++) {
if (correct[i] != result(i)) {
printf("result(%d) = %d instead of %d\n",
i, result(i), correct[i]);
return 1;
}
}
}
{
// Create a fully unrolled fibonacci routine composed almost
// entirely of single assignment statements. The horror!
Func f;
f(x) = 1;
for (int i = 2; i < 20; i++) {
f(i) = f(i - 1) + f(i - 2);
}
Buffer<int> result = f.realize({20});
int ref[20];
ref[0] = 1;
ref[1] = 1;
for (int i = 2; i < 20; i++) {
ref[i] = ref[i - 1] + ref[i - 2];
if (ref[i] != result(i)) {
printf("fibonacci(%d) = %d instead of %d\n",
i, result(i), ref[i]);
return 1;
}
}
}
{
// Make an integral image
Func f;
f(x, y) = sin(x + y);
RDom r(1, 99);
f(x, r) += f(x, r - 1);
f(r, y) += f(r - 1, y);
// Walk down the image in vectors
f.update(0).vectorize(x, 4);
// Walk across the image in parallel.
f.update(1).reorder(r.x, y).parallel(y);
Buffer<float> result = f.realize({100, 100});
// Now the equivalent in C (cheating and using Halide for the initial image)
Buffer<float> ref = lambda(x, y, sin(x + y)).realize({100, 100});
for (int y = 1; y < 100; y++) {
for (int x = 0; x < 100; x++) {
ref(x, y) += ref(x, y - 1);
}
}
for (int y = 0; y < 100; y++) {
for (int x = 1; x < 100; x++) {
ref(x, y) += ref(x - 1, y);
}
}
// Check they're the same
for (int y = 0; y < 100; y++) {
for (int x = 0; x < 100; x++) {
if (fabs(ref(x, y) - result(x, y)) > 0.0001f) {
printf("integral image at (%d, %d) = %f instead of %f\n",
x, y, result(x, y), ref(x, y));
return 1;
}
}
}
}
printf("Success!\n");
return 0;
}
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