/**************************************************************************/
/*  metal_device_properties.mm                                            */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/**************************************************************************/
/*                                                                        */
/* Portions of this code were derived from MoltenVK.                      */
/*                                                                        */
/* Copyright (c) 2015-2023 The Brenwill Workshop Ltd.                     */
/* (http://www.brenwill.com)                                              */
/*                                                                        */
/* Licensed under the Apache License, Version 2.0 (the "License");        */
/* you may not use this file except in compliance with the License.       */
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/**************************************************************************/

#import "metal_device_properties.h"

#import <Metal/Metal.h>
#import <spirv_cross.hpp>
#import <spirv_msl.hpp>

// Common scaling multipliers.
#define KIBI (1024)
#define MEBI (KIBI * KIBI)

#if (TARGET_OS_OSX && __MAC_OS_X_VERSION_MAX_ALLOWED < 140000) || (TARGET_OS_IOS && __IPHONE_OS_VERSION_MAX_ALLOWED < 170000)
#define MTLGPUFamilyApple9 (MTLGPUFamily)1009
#endif

API_AVAILABLE(macos(11.0), ios(14.0))
MTLGPUFamily &operator--(MTLGPUFamily &p_family) {
	p_family = static_cast<MTLGPUFamily>(static_cast<int>(p_family) - 1);
	if (p_family < MTLGPUFamilyApple1) {
		p_family = MTLGPUFamilyApple9;
	}

	return p_family;
}

void MetalDeviceProperties::init_features(id<MTLDevice> p_device) {
	features = {};

	features.highestFamily = MTLGPUFamilyApple1;
	for (MTLGPUFamily family = MTLGPUFamilyApple9; family >= MTLGPUFamilyApple1; --family) {
		if ([p_device supportsFamily:family]) {
			features.highestFamily = family;
			break;
		}
	}

	features.hostMemoryPageSize = sysconf(_SC_PAGESIZE);

	for (SampleCount sc = SampleCount1; sc <= SampleCount64; sc <<= 1) {
		if ([p_device supportsTextureSampleCount:sc]) {
			features.supportedSampleCounts |= sc;
		}
	}

	features.layeredRendering = [p_device supportsFamily:MTLGPUFamilyApple5];
	features.multisampleLayeredRendering = [p_device supportsFamily:MTLGPUFamilyApple7];
	features.tessellationShader = [p_device supportsFamily:MTLGPUFamilyApple3];
	features.imageCubeArray = [p_device supportsFamily:MTLGPUFamilyApple3];
	features.quadPermute = [p_device supportsFamily:MTLGPUFamilyApple4];
	features.simdPermute = [p_device supportsFamily:MTLGPUFamilyApple6];
	features.simdReduction = [p_device supportsFamily:MTLGPUFamilyApple7];

	MTLCompileOptions *opts = [MTLCompileOptions new];
	features.mslVersionEnum = opts.languageVersion; // By default, Metal uses the most recent language version.

#define setMSLVersion(m_maj, m_min) \
	features.mslVersion = SPIRV_CROSS_NAMESPACE::CompilerMSL::Options::make_msl_version(m_maj, m_min)

	switch (features.mslVersionEnum) {
#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 150000 || __IPHONE_OS_VERSION_MAX_ALLOWED >= 180000
		case MTLLanguageVersion3_2:
			setMSLVersion(3, 2);
			break;
#endif
#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 140000 || __IPHONE_OS_VERSION_MAX_ALLOWED >= 170000
		case MTLLanguageVersion3_1:
			setMSLVersion(3, 1);
			break;
#endif
		case MTLLanguageVersion3_0:
			setMSLVersion(3, 0);
			break;
		case MTLLanguageVersion2_4:
			setMSLVersion(2, 4);
			break;
		case MTLLanguageVersion2_3:
			setMSLVersion(2, 3);
			break;
		case MTLLanguageVersion2_2:
			setMSLVersion(2, 2);
			break;
		case MTLLanguageVersion2_1:
			setMSLVersion(2, 1);
			break;
		case MTLLanguageVersion2_0:
			setMSLVersion(2, 0);
			break;
		case MTLLanguageVersion1_2:
			setMSLVersion(1, 2);
			break;
		case MTLLanguageVersion1_1:
			setMSLVersion(1, 1);
			break;
#if TARGET_OS_IPHONE && !TARGET_OS_MACCATALYST
		case MTLLanguageVersion1_0:
			setMSLVersion(1, 0);
			break;
#endif
	}
}

void MetalDeviceProperties::init_limits(id<MTLDevice> p_device) {
	using std::max;
	using std::min;

	// FST: https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf

	// FST: Maximum number of layers per 1D texture array, 2D texture array, or 3D texture.
	limits.maxImageArrayLayers = 2048;
	if ([p_device supportsFamily:MTLGPUFamilyApple3]) {
		// FST: Maximum 2D texture width and height.
		limits.maxFramebufferWidth = 16384;
		limits.maxFramebufferHeight = 16384;
		limits.maxViewportDimensionX = 16384;
		limits.maxViewportDimensionY = 16384;
		// FST: Maximum 1D texture width.
		limits.maxImageDimension1D = 16384;
		// FST: Maximum 2D texture width and height.
		limits.maxImageDimension2D = 16384;
		// FST: Maximum cube map texture width and height.
		limits.maxImageDimensionCube = 16384;
	} else {
		// FST: Maximum 2D texture width and height.
		limits.maxFramebufferWidth = 8192;
		limits.maxFramebufferHeight = 8192;
		limits.maxViewportDimensionX = 8192;
		limits.maxViewportDimensionY = 8192;
		// FST: Maximum 1D texture width.
		limits.maxImageDimension1D = 8192;
		// FST: Maximum 2D texture width and height.
		limits.maxImageDimension2D = 8192;
		// FST: Maximum cube map texture width and height.
		limits.maxImageDimensionCube = 8192;
	}
	// FST: Maximum 3D texture width, height, and depth.
	limits.maxImageDimension3D = 2048;

	limits.maxThreadsPerThreadGroup = p_device.maxThreadsPerThreadgroup;
	// No effective limits.
	limits.maxComputeWorkGroupCount = { std::numeric_limits<uint32_t>::max(), std::numeric_limits<uint32_t>::max(), std::numeric_limits<uint32_t>::max() };
	// https://github.com/KhronosGroup/MoltenVK/blob/568cc3acc0e2299931fdaecaaa1fc3ec5b4af281/MoltenVK/MoltenVK/GPUObjects/MVKDevice.h#L85
	limits.maxBoundDescriptorSets = SPIRV_CROSS_NAMESPACE::kMaxArgumentBuffers;
	// FST: Maximum number of color render targets per render pass descriptor.
	limits.maxColorAttachments = 8;

	// Maximum number of textures the device can access, per stage, from an argument buffer.
	if ([p_device supportsFamily:MTLGPUFamilyApple6]) {
		limits.maxTexturesPerArgumentBuffer = 1'000'000;
	} else if ([p_device supportsFamily:MTLGPUFamilyApple4]) {
		limits.maxTexturesPerArgumentBuffer = 96;
	} else {
		limits.maxTexturesPerArgumentBuffer = 31;
	}

	// Maximum number of samplers the device can access, per stage, from an argument buffer.
	if ([p_device supportsFamily:MTLGPUFamilyApple6]) {
		limits.maxSamplersPerArgumentBuffer = 1024;
	} else {
		limits.maxSamplersPerArgumentBuffer = 16;
	}

	// Maximum number of buffers the device can access, per stage, from an argument buffer.
	if ([p_device supportsFamily:MTLGPUFamilyApple6]) {
		limits.maxBuffersPerArgumentBuffer = std::numeric_limits<uint64_t>::max();
	} else if ([p_device supportsFamily:MTLGPUFamilyApple4]) {
		limits.maxBuffersPerArgumentBuffer = 96;
	} else {
		limits.maxBuffersPerArgumentBuffer = 31;
	}

	limits.minSubgroupSize = limits.maxSubgroupSize = 1;
	// These values were taken from MoltenVK.
	if (features.simdPermute) {
		limits.minSubgroupSize = 4;
		limits.maxSubgroupSize = 32;
	} else if (features.quadPermute) {
		limits.minSubgroupSize = limits.maxSubgroupSize = 4;
	}

	limits.subgroupSupportedShaderStages.set_flag(RDD::ShaderStage::SHADER_STAGE_COMPUTE_BIT);
	if (features.tessellationShader) {
		limits.subgroupSupportedShaderStages.set_flag(RDD::ShaderStage::SHADER_STAGE_TESSELATION_CONTROL_BIT);
	}
	limits.subgroupSupportedShaderStages.set_flag(RDD::ShaderStage::SHADER_STAGE_FRAGMENT_BIT);

	limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_BASIC_BIT);
	if (features.simdPermute || features.quadPermute) {
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_VOTE_BIT);
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_BALLOT_BIT);
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_SHUFFLE_BIT);
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_SHUFFLE_RELATIVE_BIT);
	}

	if (features.simdReduction) {
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_ARITHMETIC_BIT);
	}

	if (features.quadPermute) {
		limits.subgroupSupportedOperations.set_flag(RD::SubgroupOperations::SUBGROUP_QUAD_BIT);
	}

	limits.maxBufferLength = p_device.maxBufferLength;

	// FST: Maximum size of vertex descriptor layout stride.
	limits.maxVertexDescriptorLayoutStride = std::numeric_limits<uint64_t>::max();

	// Maximum number of viewports.
	if ([p_device supportsFamily:MTLGPUFamilyApple5]) {
		limits.maxViewports = 16;
	} else {
		limits.maxViewports = 1;
	}

	limits.maxPerStageBufferCount = 31;
	limits.maxPerStageSamplerCount = 16;
	if ([p_device supportsFamily:MTLGPUFamilyApple6]) {
		limits.maxPerStageTextureCount = 128;
	} else if ([p_device supportsFamily:MTLGPUFamilyApple4]) {
		limits.maxPerStageTextureCount = 96;
	} else {
		limits.maxPerStageTextureCount = 31;
	}

	limits.maxVertexInputAttributes = 31;
	limits.maxVertexInputBindings = 31;
	limits.maxVertexInputBindingStride = (2 * KIBI);

#if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
	limits.minUniformBufferOffsetAlignment = 64;
#endif

#if TARGET_OS_OSX
	// This is Apple Silicon specific.
	limits.minUniformBufferOffsetAlignment = 16;
#endif

	limits.maxDrawIndexedIndexValue = std::numeric_limits<uint32_t>::max() - 1;
}

MetalDeviceProperties::MetalDeviceProperties(id<MTLDevice> p_device) {
	init_features(p_device);
	init_limits(p_device);
}

MetalDeviceProperties::~MetalDeviceProperties() {
}

SampleCount MetalDeviceProperties::find_nearest_supported_sample_count(RenderingDevice::TextureSamples p_samples) const {
	SampleCount supported = features.supportedSampleCounts;
	if (supported & sample_count[p_samples]) {
		return sample_count[p_samples];
	}

	SampleCount requested_sample_count = sample_count[p_samples];
	// Find the nearest supported sample count.
	while (requested_sample_count > SampleCount1) {
		if (supported & requested_sample_count) {
			return requested_sample_count;
		}
		requested_sample_count = (SampleCount)(requested_sample_count >> 1);
	}

	return SampleCount1;
}

// region static members

const SampleCount MetalDeviceProperties::sample_count[RenderingDevice::TextureSamples::TEXTURE_SAMPLES_MAX] = {
	SampleCount1,
	SampleCount2,
	SampleCount4,
	SampleCount8,
	SampleCount16,
	SampleCount32,
	SampleCount64,
};

// endregion