src/common/Constants.h

// Copyright 2017 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COMMON_CONSTANTS_H_
#define COMMON_CONSTANTS_H_

#include <cstdint>

static constexpr uint32_t kMaxBindGroups = 4u;
static constexpr uint8_t kMaxVertexAttributes = 16u;
static constexpr uint8_t kMaxVertexBuffers = 8u;
static constexpr uint32_t kMaxVertexBufferArrayStride = 2048u;
static constexpr uint32_t kNumStages = 3;
static constexpr uint8_t kMaxColorAttachments = 8u;
static constexpr uint32_t kTextureBytesPerRowAlignment = 256u;
static constexpr uint32_t kMaxInterStageShaderComponents = 60u;
static constexpr uint32_t kMaxInterStageShaderVariables = kMaxInterStageShaderComponents / 4;

// Compute constants
static constexpr uint32_t kMaxComputeWorkgroupStorageSize = 16352u;
static constexpr uint32_t kMaxComputeWorkgroupInvocations = 256u;
static constexpr uint32_t kMaxComputePerDimensionDispatchSize = 65535u;
static constexpr uint32_t kMaxComputeWorkgroupSizeX = 256;
static constexpr uint32_t kMaxComputeWorkgroupSizeY = 256;
static constexpr uint32_t kMaxComputeWorkgroupSizeZ = 64;

// Per stage limits
static constexpr uint32_t kMaxSampledTexturesPerShaderStage = 16;
static constexpr uint32_t kMaxSamplersPerShaderStage = 16;
static constexpr uint32_t kMaxStorageBuffersPerShaderStage = 8;
static constexpr uint32_t kMaxStorageTexturesPerShaderStage = 4;
static constexpr uint32_t kMaxUniformBuffersPerShaderStage = 12;

// Per pipeline layout limits
static constexpr uint32_t kMaxDynamicUniformBuffersPerPipelineLayout = 8u;
static constexpr uint32_t kMaxDynamicStorageBuffersPerPipelineLayout = 4u;

// Buffer binding constraints
static constexpr uint64_t kMaxUniformBufferBindingSize = 16384u;
static constexpr uint64_t kMaxStorageBufferBindingSize = 134217728u;
static constexpr uint64_t kMinUniformBufferOffsetAlignment = 256u;
static constexpr uint64_t kMinStorageBufferOffsetAlignment = 256u;

// Indirect command sizes
static constexpr uint64_t kDispatchIndirectSize = 3 * sizeof(uint32_t);
static constexpr uint64_t kDrawIndirectSize = 4 * sizeof(uint32_t);
static constexpr uint64_t kDrawIndexedIndirectSize = 5 * sizeof(uint32_t);

// Non spec defined constants.
static constexpr float kLodMin = 0.0;
static constexpr float kLodMax = 1000.0;

// Max texture size constants
static constexpr uint32_t kMaxTextureDimension1D = 8192u;
static constexpr uint32_t kMaxTextureDimension2D = 8192u;
static constexpr uint32_t kMaxTextureDimension3D = 2048u;
static constexpr uint32_t kMaxTextureArrayLayers = 256u;
static constexpr uint32_t kMaxTexture2DMipLevels = 14u;
static_assert(1 << (kMaxTexture2DMipLevels - 1) == kMaxTextureDimension2D,
              "kMaxTexture2DMipLevels and kMaxTextureDimension2D size mismatch");

// Offset alignment for CopyB2B. Strictly speaking this alignment is required only
// on macOS, but we decide to do it on all platforms.
static constexpr uint64_t kCopyBufferToBufferOffsetAlignment = 4u;

// The maximum size of visibilityResultBuffer is 256KB on Metal, to fit the restriction, limit the
// maximum size of query set to 64KB. The size of a query is 8-bytes, the maximum query count is 64
// * 1024 / 8.
static constexpr uint32_t kMaxQueryCount = 8192u;

// An external texture occupies multiple binding slots. These are the per-external-texture bindings
// needed.
static constexpr uint8_t kSampledTexturesPerExternalTexture = 3u;
static constexpr uint8_t kSamplersPerExternalTexture = 1u;
static constexpr uint8_t kUniformsPerExternalTexture = 1u;

#endif  // COMMON_CONSTANTS_H_