From 495ffc4777522e40941753e3b1b79c02f84b25b4 Mon Sep 17 00:00:00 2001
From: Grafting Rayman <156515434+GraftingRayman@users.noreply.github.com>
Date: Fri, 17 Jan 2025 11:00:30 +0000
Subject: Add files via upload

---
 r_basicsr/ops/fused_act/fused_act.py | 95 ++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 r_basicsr/ops/fused_act/fused_act.py

(limited to 'r_basicsr/ops/fused_act/fused_act.py')

diff --git a/r_basicsr/ops/fused_act/fused_act.py b/r_basicsr/ops/fused_act/fused_act.py
new file mode 100644
index 0000000..876c959
--- /dev/null
+++ b/r_basicsr/ops/fused_act/fused_act.py
@@ -0,0 +1,95 @@
+# modify from https://github.com/rosinality/stylegan2-pytorch/blob/master/op/fused_act.py # noqa:E501
+
+import os
+import torch
+from torch import nn
+from torch.autograd import Function
+
+BASICSR_JIT = os.getenv('BASICSR_JIT')
+if BASICSR_JIT == 'True':
+    from torch.utils.cpp_extension import load
+    module_path = os.path.dirname(__file__)
+    fused_act_ext = load(
+        'fused',
+        sources=[
+            os.path.join(module_path, 'src', 'fused_bias_act.cpp'),
+            os.path.join(module_path, 'src', 'fused_bias_act_kernel.cu'),
+        ],
+    )
+else:
+    try:
+        from . import fused_act_ext
+    except ImportError:
+        pass
+        # avoid annoying print output
+        # print(f'Cannot import deform_conv_ext. Error: {error}. You may need to: \n '
+        #       '1. compile with BASICSR_EXT=True. or\n '
+        #       '2. set BASICSR_JIT=True during running')
+
+
+class FusedLeakyReLUFunctionBackward(Function):
+
+    @staticmethod
+    def forward(ctx, grad_output, out, negative_slope, scale):
+        ctx.save_for_backward(out)
+        ctx.negative_slope = negative_slope
+        ctx.scale = scale
+
+        empty = grad_output.new_empty(0)
+
+        grad_input = fused_act_ext.fused_bias_act(grad_output, empty, out, 3, 1, negative_slope, scale)
+
+        dim = [0]
+
+        if grad_input.ndim > 2:
+            dim += list(range(2, grad_input.ndim))
+
+        grad_bias = grad_input.sum(dim).detach()
+
+        return grad_input, grad_bias
+
+    @staticmethod
+    def backward(ctx, gradgrad_input, gradgrad_bias):
+        out, = ctx.saved_tensors
+        gradgrad_out = fused_act_ext.fused_bias_act(gradgrad_input, gradgrad_bias, out, 3, 1, ctx.negative_slope,
+                                                    ctx.scale)
+
+        return gradgrad_out, None, None, None
+
+
+class FusedLeakyReLUFunction(Function):
+
+    @staticmethod
+    def forward(ctx, input, bias, negative_slope, scale):
+        empty = input.new_empty(0)
+        out = fused_act_ext.fused_bias_act(input, bias, empty, 3, 0, negative_slope, scale)
+        ctx.save_for_backward(out)
+        ctx.negative_slope = negative_slope
+        ctx.scale = scale
+
+        return out
+
+    @staticmethod
+    def backward(ctx, grad_output):
+        out, = ctx.saved_tensors
+
+        grad_input, grad_bias = FusedLeakyReLUFunctionBackward.apply(grad_output, out, ctx.negative_slope, ctx.scale)
+
+        return grad_input, grad_bias, None, None
+
+
+class FusedLeakyReLU(nn.Module):
+
+    def __init__(self, channel, negative_slope=0.2, scale=2**0.5):
+        super().__init__()
+
+        self.bias = nn.Parameter(torch.zeros(channel))
+        self.negative_slope = negative_slope
+        self.scale = scale
+
+    def forward(self, input):
+        return fused_leaky_relu(input, self.bias, self.negative_slope, self.scale)
+
+
+def fused_leaky_relu(input, bias, negative_slope=0.2, scale=2**0.5):
+    return FusedLeakyReLUFunction.apply(input, bias, negative_slope, scale)
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