add fun with nhwc convs

test/external/external_nhwc_conv.py

@@ -0,0 +1,38 @@
+from tinygrad import Tensor, nn, Context, GlobalCounters
+
+if __name__ == "__main__":
+  conv = nn.Conv2d(64, 128, 3)
+  img = Tensor.randn((1,64,128,128))
+  with Context(DEBUG=0, BEAM=0):
+    Tensor.realize(img, conv.weight, conv.bias)
+
+  tst = conv(img).permute(0,2,3,1).realize()
+  print(tst.shape)
+
+  print("NEW")
+  img_perm = img.permute(0,2,3,1).contiguous()
+  print(img_perm.shape)
+  pp = img_perm.permute(0,3,1,2)._pool((3,3)).permute(0,2,3,4,5,1)
+
+  def hwio(pp, conv):
+    pp = pp.unsqueeze(-1)
+    weight = conv.weight.permute(2,3,1,0).contiguous()
+    print(pp.shape, weight.shape, (pp*weight).shape)
+    return (pp * weight).sum([-4,-3, -2])
+
+  def ohwi(pp, conv):
+    pp = pp.unsqueeze(-4)
+    weight = conv.weight.permute(0,2,3,1).contiguous()
+    print(pp.shape, weight.shape, (pp*weight).shape)
+    return (pp * weight).sum([-3,-2,-1])
+
+  for f in [hwio, ohwi]:
+    GlobalCounters.reset()
+    print("\n**************", f.__name__, "**************")
+    out = f(pp, conv)
+    out.realize()
+    print(out.shape)
+
+    with Context(DEBUG=0, BEAM=0):
+      err = (tst-out).square()
+      print(err.mean().item(), err.max().item())