//===- HLSLRootSignature.h - HLSL Root Signature helper objects -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file This file contains helper objects for working with HLSL Root
/// Signatures.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H
#define LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H

#include "llvm/Support/DXILABI.h"
#include <variant>

namespace llvm {
namespace hlsl {
namespace rootsig {

// Definition of the various enumerations and flags

enum class DescriptorRangeFlags : unsigned {
  None = 0,
  DescriptorsVolatile = 0x1,
  DataVolatile = 0x2,
  DataStaticWhileSetAtExecute = 0x4,
  DataStatic = 0x8,
  DescriptorsStaticKeepingBufferBoundsChecks = 0x10000,
  ValidFlags = 0x1000f,
  ValidSamplerFlags = DescriptorsVolatile,
};

enum class ShaderVisibility {
  All = 0,
  Vertex = 1,
  Hull = 2,
  Domain = 3,
  Geometry = 4,
  Pixel = 5,
  Amplification = 6,
  Mesh = 7,
};

// Definitions of the in-memory data layout structures

// Models the different registers: bReg | tReg | uReg | sReg
enum class RegisterType { BReg, TReg, UReg, SReg };
struct Register {
  RegisterType ViewType;
  uint32_t Number;
};

// Models the end of a descriptor table and stores its visibility
struct DescriptorTable {
  ShaderVisibility Visibility = ShaderVisibility::All;
  uint32_t NumClauses = 0; // The number of clauses in the table
};

static const uint32_t NumDescriptorsUnbounded = 0xffffffff;
static const uint32_t DescriptorTableOffsetAppend = 0xffffffff;
// Models DTClause : CBV | SRV | UAV | Sampler, by collecting like parameters
using ClauseType = llvm::dxil::ResourceClass;
struct DescriptorTableClause {
  ClauseType Type;
  Register Reg;
  uint32_t NumDescriptors = 1;
  uint32_t Space = 0;
  uint32_t Offset = DescriptorTableOffsetAppend;
  DescriptorRangeFlags Flags;

  void setDefaultFlags() {
    switch (Type) {
    case ClauseType::CBuffer:
    case ClauseType::SRV:
      Flags = DescriptorRangeFlags::DataStaticWhileSetAtExecute;
      break;
    case ClauseType::UAV:
      Flags = DescriptorRangeFlags::DataVolatile;
      break;
    case ClauseType::Sampler:
      Flags = DescriptorRangeFlags::None;
      break;
    }
  }
};

// Models RootElement : DescriptorTable | DescriptorTableClause
using RootElement = std::variant<DescriptorTable, DescriptorTableClause>;

} // namespace rootsig
} // namespace hlsl
} // namespace llvm

#endif // LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H