src/dawn/common/Constants.h

// Copyright 2017 The Dawn & Tint Authors
//
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// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
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#ifndef SRC_DAWN_COMMON_CONSTANTS_H_
#define SRC_DAWN_COMMON_CONSTANTS_H_

#include <cstddef>
#include <cstdint>

namespace dawn {

static constexpr uint32_t kMaxBindGroups = 4u;
static constexpr uint32_t kMaxBindingsPerBindGroup = 1000u;
static constexpr uint8_t kMaxVertexAttributes = 30u;
static constexpr uint8_t kMaxVertexBuffers = 8u;
static constexpr uint32_t kMaxVertexBufferArrayStride = 2048u;
static constexpr uint32_t kMaxBindGroupsPlusVertexBuffers = 24u;
static constexpr uint32_t kNumStages = 3;
static constexpr uint8_t kMaxColorAttachments = 8u;
static constexpr uint32_t kTextureBytesPerRowAlignment = 256u;
static constexpr uint32_t kQueryResolveAlignment = 256u;
static constexpr uint32_t kMaxInterStageShaderVariables = 16u;
static constexpr uint64_t kAssumedMaxBufferSize =
    0x80000000u;  // Use 2 GB when the limit is unavailable

// Per stage maximum limits used to optimized Dawn internals.
static constexpr uint32_t kMaxSampledTexturesPerShaderStage = 16;
static constexpr uint32_t kMaxSamplersPerShaderStage = 16;
static constexpr uint32_t kMaxStorageBuffersPerShaderStage = 10;
static constexpr uint32_t kMaxStorageTexturesPerShaderStage = 8;
static constexpr uint32_t kMaxUniformBuffersPerShaderStage = 12;

// 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;

// 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;

// Metal has a maximum size of 32Kb for a counter set buffer. Each query is 8 bytes.
// So, the maximum nymber of queries is 32Kb / 8.
static constexpr uint32_t kMaxQueryCount = 4096;

// An external texture occupies multiple binding slots. These are the per-external-texture bindings
// needed.
static constexpr uint8_t kSampledTexturesPerExternalTexture = 4u;
static constexpr uint8_t kSamplersPerExternalTexture = 1u;
static constexpr uint8_t kUniformsPerExternalTexture = 1u;

static constexpr uint8_t kMaxPLSSlots = 4;
static constexpr size_t kPLSSlotByteSize = 4;
static constexpr uint8_t kMaxPLSSize = kMaxPLSSlots * kPLSSlotByteSize;

// Wire buffer alignments.
static constexpr size_t kWireBufferAlignment = 8u;

// Timestamp query quantization mask to perform a granularity of ~0.1ms.
static constexpr uint32_t kTimestampQuantizationMask = 0xFFFF0000;

}  // namespace dawn

#endif  // SRC_DAWN_COMMON_CONSTANTS_H_