module Platform.AArch64.FloatRoutine

import Compiler.MachineAArch64
import Compiler.MachineAArch64Assembly
import Platform.AArch64.RoutineEmitter

-- x0 holds a binary64 value's bits, not a pointer. Only x0/x1 and flags
-- change. Eleven exponent bits equal to 2047 identify infinities/NaNs;
-- all finite values, including signed zero and subnormals, return zero.
def aarch64Float64FiniteAssembly =
  (ahrEmit
    (constructor
      AArch64Instruction
      AArch64ShiftRightImmediate
      (constructor AArch64Register AArch64X0)
      (constructor AArch64Register AArch64X0)
      52)
    (ahrMovImm
      (constructor AArch64Register AArch64X1)
      2047
      (ahrEmit
        (constructor
          AArch64Instruction
          AArch64AndRegister
          (constructor AArch64Register AArch64X0)
          (constructor AArch64Register AArch64X0)
          (constructor AArch64Register AArch64X1))
        (ahrEmit
          (constructor
            AArch64Instruction
            AArch64CompareImmediate
            (constructor AArch64Register AArch64X0)
            2047)
          (constructor
            AArch64Assembly
            AArch64AssemblyBranchIf
            (constructor AArch64Condition AArch64NotEqual)
            b"finite"
            (ahrMovImm
              (constructor AArch64Register AArch64X0)
              1
              (ahrReturn
                (ahrLabel
                  b"finite"
                  (ahrMovImm (constructor AArch64Register AArch64X0) 0 (ahrReturn ahrEnd))))))))))

def aarch64Float64FiniteCode =
  (aarch64RoutineBytes aarch64Float64FiniteAssembly)