(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.(** Rounding modes *)

Inductive mode := mode_NE | mode_ZR | mode_DN | mode_UP | mode_NA.Definition round_mode m :=
  match m with
  | mode_NE => ZnearestE
  | mode_ZR => Ztrunc
  | mode_DN => Zfloor
  | mode_UP => Zceil
  | mode_NA => ZnearestA
  end.Definition choice_mode m sx mx lx :=
  match m with
  | mode_NE => cond_incr (round_N (negb (Zeven mx)) lx) mx
  | mode_ZR => mx
  | mode_DN => cond_incr (round_sign_DN sx lx) mx
  | mode_UP => cond_incr (round_sign_UP sx lx) mx
  | mode_NA => cond_incr (round_N true lx) mx
  end.Global Instance valid_rnd_round_mode : forall m, Valid_rnd (round_mode m).Definition overflow_to_inf m s :=
  match m with
  | mode_NE => true
  | mode_NA => true
  | mode_ZR => false
  | mode_UP => negb s
  | mode_DN => s
  end.Definition binary_overflow m s :=
  if overflow_to_inf m s then F754_infinity s
  else F754_finite s (match (Zpower 2 prec - 1)%Z with Zpos p => p | _ => xH end) (emax - prec).Definition binary_round_aux mode sx mx ex lx :=
  let '(mrs', e') := shr_fexp (Zpos mx) ex lx in
  let '(mrs'', e'') := shr_fexp (choice_mode mode sx (shr_m mrs') (loc_of_shr_record mrs')) e' loc_Exact in
  match shr_m mrs'' with
  | Z0 => F754_zero sx
  | Zpos m => if Zle_bool e'' (emax - prec) then F754_finite sx m e'' else binary_overflow mode sx
  | _ => F754_nan false xH (* dummy *)
  end.

Theorem binary_round_aux_correct : forall mode x mx ex lx, inbetween_float radix2 (Zpos mx) ex (Rabs x) lx -> (ex <= fexp (Zdigits radix2 (Zpos mx) + ex))%Z -> let z := binary_round_aux mode (Rlt_bool x 0) mx ex lx in valid_binary z = true /\ if Rlt_bool (Rabs (round radix2 fexp (round_mode mode) x)) (bpow radix2 emax) then FF2R radix2 z = round radix2 fexp (round_mode mode) x /\ is_finite_FF z = true /\ sign_FF z = Rlt_bool x 0 else z = binary_overflow mode (Rlt_bool x 0).