implements support for ARM Modified Immediate Constants

Surprisingly we didn't support them

lib/arm/arm_mov.ml

@@ -9,8 +9,35 @@ open Arm_flags
 module Env = Arm_env
 module Shift = Arm_shift
 
+let width = 32
+
+
+(** Modified Immediate Constants  *)
+module MIC : sig
+  val decode : op -> op
+end = struct
+  let ror value bits =
+    let p1 = Word.(value lsr bits) in
+    let rs = Word.(of_int ~width 32 - bits) in
+    let p2 = Word.(value lsl rs) in
+    Word.(p1 lor p2)
+
+  let mic x =
+    let shift = Word.extract_exn ~hi:11 ~lo:8 x
+    and value = Word.extract_exn ~hi:7 ~lo:0 x in
+    if Word.is_zero shift then value
+    else
+      let shift = Word.extract_exn ~hi:31 shift in
+      let value = Word.extract_exn ~hi:31 value in
+      ror value Word.(shift + shift)
+
+  let decode = function
+    | `Imm x -> `Imm (mic x)
+    | other -> other
+end
 
 let lift ?dest src1 ?src2 (itype ) ?sreg ?simm raw ~wflag cond =
+  let src2 = Option.map src2 ~f:MIC.decode in
   let dest : var = match dest with
     | None     -> tmp reg32_t
     | Some (`Reg reg) -> Env.of_reg reg