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-rw-r--r--cli/tests/testdata/webgpu/computepass_shader.wgsl38
1 files changed, 38 insertions, 0 deletions
diff --git a/cli/tests/testdata/webgpu/computepass_shader.wgsl b/cli/tests/testdata/webgpu/computepass_shader.wgsl
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+++ b/cli/tests/testdata/webgpu/computepass_shader.wgsl
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+@group(0)
+@binding(0)
+var<storage, read_write> v_indices: array<u32>; // this is used as both input and output for convenience
+
+// The Collatz Conjecture states that for any integer n:
+// If n is even, n = n/2
+// If n is odd, n = 3n+1
+// And repeat this process for each new n, you will always eventually reach 1.
+// Though the conjecture has not been proven, no counterexample has ever been found.
+// This function returns how many times this recurrence needs to be applied to reach 1.
+fn collatz_iterations(n_base: u32) -> u32{
+ var n: u32 = n_base;
+ var i: u32 = 0u;
+ loop {
+ if (n <= 1u) {
+ break;
+ }
+ if (n % 2u == 0u) {
+ n = n / 2u;
+ }
+ else {
+ // Overflow? (i.e. 3*n + 1 > 0xffffffffu?)
+ if (n >= 1431655765u) { // 0x55555555u
+ return 4294967295u; // 0xffffffffu
+ }
+
+ n = 3u * n + 1u;
+ }
+ i = i + 1u;
+ }
+ return i;
+}
+
+@compute
+@workgroup_size(1)
+fn main(@builtin(global_invocation_id) global_id: vec3<u32>) {
+ v_indices[global_id.x] = collatz_iterations(v_indices[global_id.x]);
+}