module Platform.AArch64.Descriptor

import Compiler.MachineAArch64
import Compiler.MachineAArch64Assembly

-- AAPCS64 twin of Runtime.NativeDescriptor: x0 input/result, x6 scratch.
-- The sign check preserves kernel errno before the unsigned INT_MAX bound.
-- No callee-saved or interpreter registers are touched.
def aarch64DescriptorAssembly =
  (constructor
    AArch64Assembly
    AArch64AssemblyEmit
    (constructor
      AArch64Instruction
      AArch64CompareImmediate
      (constructor AArch64Register AArch64X0)
      0)
    (constructor
      AArch64Assembly
      AArch64AssemblyBranchIf
      (constructor AArch64Condition AArch64Minus)
      b"return"
      (constructor
        AArch64Assembly
        AArch64AssemblyEmit
        (constructor
          AArch64Instruction
          AArch64MoveWideZero
          (constructor AArch64Register AArch64X6)
          65535
          (constructor AArch64HalfwordShift AArch64Shift0))
        (constructor
          AArch64Assembly
          AArch64AssemblyEmit
          (constructor
            AArch64Instruction
            AArch64MoveWideKeep
            (constructor AArch64Register AArch64X6)
            32767
            (constructor AArch64HalfwordShift AArch64Shift16))
          (constructor
            AArch64Assembly
            AArch64AssemblyEmit
            (constructor
              AArch64Instruction
              AArch64CompareRegister
              (constructor AArch64Register AArch64X0)
              (constructor AArch64Register AArch64X6))
            (constructor
              AArch64Assembly
              AArch64AssemblyBranchIf
              (constructor AArch64Condition AArch64UnsignedHigher)
              b"invalid"
              (constructor
                AArch64Assembly
                AArch64AssemblyEmit
                (constructor
                  AArch64Instruction
                  AArch64MoveWideZero
                  (constructor AArch64Register AArch64X0)
                  0
                  (constructor AArch64HalfwordShift AArch64Shift0))
                (constructor
                  AArch64Assembly
                  AArch64AssemblyBranch
                  b"return"
                  (constructor
                    AArch64Assembly
                    AArch64AssemblyLabel
                    b"invalid"
                    (constructor
                      AArch64Assembly
                      AArch64AssemblyEmit
                      (constructor
                        AArch64Instruction
                        AArch64MoveWideZero
                        (constructor AArch64Register AArch64X0)
                        0
                        (constructor AArch64HalfwordShift AArch64Shift0))
                      (constructor
                        AArch64Assembly
                        AArch64AssemblyEmit
                        (constructor
                          AArch64Instruction
                          AArch64MoveWideZero
                          (constructor AArch64Register AArch64X6)
                          22
                          (constructor AArch64HalfwordShift AArch64Shift0))
                        (constructor
                          AArch64Assembly
                          AArch64AssemblyEmit
                          (constructor
                            AArch64Instruction
                            AArch64SubtractRegister
                            (constructor AArch64Register AArch64X0)
                            (constructor AArch64Register AArch64X0)
                            (constructor AArch64Register AArch64X6))
                          (constructor
                            AArch64Assembly
                            AArch64AssemblyLabel
                            b"return"
                            (constructor
                              AArch64Assembly
                              AArch64AssemblyEmit
                              (constructor AArch64Instruction AArch64Return)
                              (constructor AArch64Assembly AArch64AssemblyEnd)))))))))))))))

def aarch64DescriptorCode : Bytes =
  (eliminate
    AArch64AssemblyResult
    (lambda unrestricted current : (family AArch64AssemblyResult) . Bytes)
    (aarch64Assemble aarch64DescriptorAssembly)
    (branch AArch64AssemblyEncoded code . code)
    (branch AArch64AssemblyEncodeDuplicateLabel name . b"")
    (branch AArch64AssemblyMissingLabel name . b"")
    (branch AArch64AssemblyDisplacementOutOfRange name . b"")
    (branch AArch64AssemblyOperandRefused value . b""))