"""Minimal test: just the threshold rounding function in CuTeDSL."""
import torch
import cutlass
import cutlass.cute as cute
import cutlass.torch as cutlass_torch
from dsv4.kernels.gemm.fp4_quant import round_rne_u0_8


@cute.kernel
def threshold_test_kernel(
    input_f32: cute.Tensor,    # (1,) Float32 input
    output_i32: cute.Tensor,    # (1,) Int32 output
):
    tidx, _, _ = cute.arch.thread_idx()
    if tidx == cutlass.Int32(0):
        x = cute.arch.load(input_f32.iterator, cutlass.Float32)
        result = round_rne_u0_8(x)
        cute.arch.store(output_i32.iterator, result)


if __name__ == "__main__":
    x = torch.tensor([3.7], dtype=torch.float32, device='cuda')
    out = torch.zeros(1, dtype=torch.int32, device='cuda')
    xc = cutlass_torch.from_dlpack(x).mark_layout_dynamic(leading_dim=0)
    oc = cutlass_torch.from_dlpack(out).mark_layout_dynamic(leading_dim=0)
    
    print("Compiling...")
    compiled = cute.compile(threshold_test_kernel, xc, oc)
    print("Running...")
    compiled(xc, oc)
    print(f'round(3.7) = {out.item()} (expected 4)')