From f7c5c19af1b4638958c6875c6f691b2c9aa05a94 Mon Sep 17 00:00:00 2001 From: skal Date: Sat, 14 Feb 2026 00:27:53 +0100 Subject: CNN v2: Fix weight buffer offset bug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Root cause: Binary format is [header:20B][layer_info:20B×N][weights]. Both cnn_test and CNNv2Effect uploaded entire file to weights_buffer, but shader reads weights_buffer[0] expecting first weight, not header. Fix: Skip header + layer_info when uploading to GPU buffer. - cnn_test.cc: Calculate weights_offset, upload only weights section - cnn_v2_effect.cc: Same fix for runtime effect Before: layer_0 output showed [R, uv_x, uv_y, black] (wrong channels) After: layer_0 output shows [R, G, B, D] (correct identity mapping) Tests: 34/36 passing (2 unrelated failures) --- src/gpu/effects/cnn_v2_effect.cc | 14 +++++++++----- tools/cnn_test.cc | 13 +++++++++---- 2 files changed, 18 insertions(+), 9 deletions(-) diff --git a/src/gpu/effects/cnn_v2_effect.cc b/src/gpu/effects/cnn_v2_effect.cc index 3985723..366a232 100644 --- a/src/gpu/effects/cnn_v2_effect.cc +++ b/src/gpu/effects/cnn_v2_effect.cc @@ -111,17 +111,21 @@ void CNNv2Effect::load_weights() { layer_info_.push_back(info); } - // Create GPU storage buffer for weights - // Buffer contains: header + layer info + packed f16 weights (as u32) + // Create GPU storage buffer for weights (skip header + layer info, upload only weights) + size_t header_size = 20; // 5 u32 + size_t layer_info_size = 20 * num_layers; // 5 u32 per layer + size_t weights_offset = header_size + layer_info_size; + size_t weights_only_size = weights_size - weights_offset; + WGPUBufferDescriptor buffer_desc = {}; - buffer_desc.size = weights_size; + buffer_desc.size = weights_only_size; buffer_desc.usage = WGPUBufferUsage_Storage | WGPUBufferUsage_CopyDst; buffer_desc.mappedAtCreation = false; weights_buffer_ = wgpuDeviceCreateBuffer(ctx_.device, &buffer_desc); - // Upload weights data - wgpuQueueWriteBuffer(ctx_.queue, weights_buffer_, 0, weights_data, weights_size); + // Upload only weights (skip header + layer info) + wgpuQueueWriteBuffer(ctx_.queue, weights_buffer_, 0, weights_data + weights_offset, weights_only_size); // Create uniform buffers for layer params (one per layer) for (uint32_t i = 0; i < num_layers; ++i) { diff --git a/tools/cnn_test.cc b/tools/cnn_test.cc index 4599512..c504c3d 100644 --- a/tools/cnn_test.cc +++ b/tools/cnn_test.cc @@ -684,15 +684,20 @@ static bool process_cnn_v2(WGPUDevice device, WGPUQueue queue, info.out_channels, info.weight_count); } - // Create weights storage buffer + // Create weights storage buffer (skip header + layer info, upload only weights) + size_t header_size = 20; // 5 u32 + size_t layer_info_size = 20 * layer_info.size(); // 5 u32 per layer + size_t weights_offset = header_size + layer_info_size; + size_t weights_only_size = weights_size - weights_offset; + WGPUBufferDescriptor weights_buffer_desc = {}; - weights_buffer_desc.size = weights_size; + weights_buffer_desc.size = weights_only_size; weights_buffer_desc.usage = WGPUBufferUsage_Storage | WGPUBufferUsage_CopyDst; weights_buffer_desc.mappedAtCreation = false; WGPUBuffer weights_buffer = wgpuDeviceCreateBuffer(device, &weights_buffer_desc); - wgpuQueueWriteBuffer(queue, weights_buffer, 0, weights_data, weights_size); + wgpuQueueWriteBuffer(queue, weights_buffer, 0, weights_data + weights_offset, weights_only_size); // Create input view const WGPUTextureViewDescriptor view_desc = { @@ -1051,7 +1056,7 @@ static bool process_cnn_v2(WGPUDevice device, WGPUQueue queue, layer_bg_entries[3].binding = 3; layer_bg_entries[3].buffer = weights_buffer; - layer_bg_entries[3].size = weights_size; + layer_bg_entries[3].size = weights_only_size; layer_bg_entries[4].binding = 4; layer_bg_entries[4].buffer = layer_params_buffers[i]; -- cgit v1.2.3