src/HOL/MicroJava/JVM/Opstack.thy
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     1 (*  Title:      HOL/MicroJava/JVM/Opstack.thy
       
     2     ID:         $Id$
       
     3     Author:     Cornelia Pusch
       
     4     Copyright   1999 Technische Universitaet Muenchen
       
     5 
       
     6 Manipulation of operand stack
       
     7 *)
       
     8 
       
     9 Opstack = JVMState +
       
    10 
       
    11 (** instructions for the direct manipulation of the operand stack **)
       
    12 
       
    13 datatype 
       
    14  op_stack = 
       
    15    Pop
       
    16  | Dup
       
    17  | Dup_x1
       
    18  | Dup_x2
       
    19  | Swap
       
    20 	  
       
    21 consts
       
    22  exec_os :: "[op_stack,opstack,p_count] \\<Rightarrow> (opstack \\<times> p_count)" 
       
    23 
       
    24 primrec 
       
    25   "exec_os Pop stk pc = (tl stk , pc+1)"
       
    26 
       
    27   "exec_os Dup stk pc = (hd stk # stk , pc+1)"
       
    28 
       
    29   "exec_os Dup_x1 stk pc = (hd stk # hd (tl stk) # hd stk # (tl (tl stk)) , pc+1)"
       
    30 
       
    31   "exec_os Dup_x2 stk pc = (hd stk # hd (tl stk) # (hd (tl (tl stk))) # hd stk # (tl (tl (tl stk))) , pc+1)"
       
    32 
       
    33   "exec_os Swap stk pc = 
       
    34 	(let (val1,val2) = (hd stk,hd (tl stk))
       
    35 	 in
       
    36 	 (val2#val1#(tl (tl stk)) , pc+1))"
       
    37 
       
    38 end