/* -*-C-*-

$Id: cmpint.h,v 10.14 2007/01/05 21:19:25 cph Exp $

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

MIT/GNU Scheme is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

*/

/* Macros for the interface between compiled code and interpreted code. */

/* Stack Gap Operations: */

/* With_Stack_Gap opens a gap Gap_Size wide Gap_Position cells above the
 * top of the stack.  Code must push Gap_Size objects.  It executes Code
 * with the stack pointer placed so that these objects will fill the gap.
 */

#define With_Stack_Gap(Gap_Size, Gap_Position, Code)			\
{									\
  long size_to_move = (Gap_Position);					\
  SCHEME_OBJECT * Destination = (STACK_LOC (- (Gap_Size)));		\
  SCHEME_OBJECT * Saved_Destination = Destination;			\
  while ((--size_to_move) >= 0)						\
    (STACK_LOCATIVE_POP (Destination)) = (STACK_POP ());		\
  Code;									\
  sp_register = Saved_Destination;					\
}

/* Close_Stack_Gap closes a gap Gap_Size wide Gap_Position cells above the
 * top of the stack.  The contents of the gap are lost.
 */

#define Close_Stack_Gap(Gap_Size, Gap_Position, extra_code)		\
{									\
  long size_to_move;							\
  SCHEME_OBJECT *Source;						\
									\
  size_to_move = (Gap_Position);					\
  Source = (STACK_LOC (size_to_move));					\
  sp_register = (STACK_LOC ((Gap_Size) + size_to_move));		\
  extra_code;								\
  while (--size_to_move >= 0)						\
  {									\
    STACK_PUSH (STACK_LOCATIVE_PUSH (Source));				\
  }									\
}

/* Going from interpreted code to compiled code */

/* Tail recursion is handled as follows:
   if the return code is `reenter_compiled_code', it is discarded,
   and the two contiguous interpreter segments on the stack are
   merged.
 */

/* Apply interface:
   calling a compiled procedure with a frame nslots long.
 */

#define apply_compiled_setup(nslots)					\
{									\
  long frame_size;							\
									\
  frame_size = (nslots);						\
  if (STACK_REF(frame_size + CONTINUATION_RETURN_CODE) ==		\
      (MAKE_OBJECT (TC_RETURN_CODE, RC_REENTER_COMPILED_CODE)))		\
  {									\
    /* Merge compiled code segments on the stack. */			\
    Close_Stack_Gap (CONTINUATION_SIZE,					\
		     frame_size,					\
		   {							\
		     long segment_size =				\
		       (OBJECT_DATUM					\
			(STACK_REF					\
			 (CONTINUATION_EXPRESSION -			\
			  CONTINUATION_SIZE)));				\
		     last_return_code = (STACK_LOC (segment_size));	\
		   });							\
    /* Undo the subproblem rotation. */					\
    Compiler_End_Subproblem();						\
  }									\
  else									\
  {									\
    /* Make a new compiled code segment which includes this frame. */	\
    /* History need not be hacked here. */				\
    With_Stack_Gap(1,							\
		   frame_size,						\
		 {							\
		   last_return_code = (STACK_LOC (0));			\
		   STACK_PUSH (return_to_interpreter);			\
		 });							\
  }									\
}

/* Eval interface:
   executing a compiled expression.
 */

#define execute_compiled_setup()					\
{									\
  if (STACK_REF(CONTINUATION_RETURN_CODE) ==				\
      (MAKE_OBJECT (TC_RETURN_CODE, RC_REENTER_COMPILED_CODE)))		\
  {									\
    /* Merge compiled code segments on the stack. */			\
    long segment_size;							\
									\
    Restore_Cont();							\
    segment_size = OBJECT_DATUM (exp_register);				\
    last_return_code = (STACK_LOC (segment_size));			\
    /* Undo the subproblem rotation. */					\
    Compiler_End_Subproblem();						\
  }									\
    else								\
  {									\
    /* Make a new compiled code segment on the stack. */		\
    /* History need not be hacked here. */				\
    last_return_code = (STACK_LOC (0));					\
    STACK_PUSH (return_to_interpreter);					\
  }									\
}

/* Pop return interface:
   Returning to compiled code from the interpreter.
 */

#define compiled_code_restart()						\
{									\
  long segment_size = OBJECT_DATUM (exp_register);			\
  last_return_code = (STACK_LOC (segment_size));			\
  /* Undo the subproblem rotation. */					\
  Compiler_End_Subproblem();						\
}

/* Going from compiled code to interpreted code */

/* Tail recursion is handled in the following way:
   if the return address is `return_to_interpreter', it is discarded,
   and the two contiguous interpreter segments on the stack are
   merged.
 */

/* Apply interface:
   calling an interpreted procedure (or unsafe primitive)
   with a frame nslots long.
 */

#define compiler_apply_procedure(nslots)				\
{									\
  long frame_size = (nslots);						\
  if ((STACK_REF (frame_size)) == return_to_interpreter)		\
  {									\
    Close_Stack_Gap(1, frame_size, {});					\
    /* Set up the current rib. */					\
    Compiler_New_Reduction ();						\
  }									\
  else									\
    { /* Make a new interpreter segment which includes this frame. */	\
      With_Stack_Gap							\
	(CONTINUATION_SIZE,						\
	 frame_size,							\
	 {								\
	   long segment_size =						\
	     (STACK_LOCATIVE_DIFFERENCE					\
	      (last_return_code, (STACK_LOC (0))));			\
	   exp_register = (LONG_TO_UNSIGNED_FIXNUM (segment_size));	\
	   Store_Return (RC_REENTER_COMPILED_CODE);			\
	   Save_Cont ();						\
	 });								\
      /* Rotate history to a new subproblem. */				\
      Compiler_New_Subproblem ();					\
    }									\
}

/* Pop Return interface:
   returning to the interpreter from compiled code.
   Nothing needs to be done at this time.
 */

#define compiled_code_done()

/* Various handlers for backing out of compiled code. */

/* Backing out of apply. */

#define apply_compiled_backout()					\
{									\
  compiler_apply_procedure(STACK_ENV_EXTRA_SLOTS +			\
			   OBJECT_DATUM (STACK_REF (STACK_ENV_HEADER)));\
}

/* Backing out of eval. */

#define execute_compiled_backout()					\
{									\
  if ((STACK_REF (0)) == return_to_interpreter)				\
  {									\
    /* Set up the current rib. */					\
    Compiler_New_Reduction ();						\
  }									\
  else									\
  {									\
    long segment_size =							\
      (STACK_LOCATIVE_DIFFERENCE (last_return_code, (STACK_LOC (0))));	\
    exp_register = (LONG_TO_UNSIGNED_FIXNUM (segment_size));		\
    Store_Return (RC_REENTER_COMPILED_CODE);				\
    Save_Cont ();							\
    /* Rotate history to a new subproblem. */				\
    Compiler_New_Subproblem ();						\
  }									\
}

/* Backing out because of special errors or interrupts.
   The microcode has already setup a return code with a #F.
   No tail recursion in this case.
   ***
       Is the history manipulation correct?
       Does Microcode_Error do something special?
   ***
 */

#define compiled_error_backout()					\
{									\
  long segment_size;							\
									\
  Restore_Cont();							\
  segment_size =							\
    (STACK_LOCATIVE_DIFFERENCE (last_return_code, (STACK_LOC (0))));	\
  exp_register = (LONG_TO_UNSIGNED_FIXNUM (segment_size));		\
  /* The Store_Return is a NOP, the Save_Cont is done by the code	\
     that follows. */							\
  /* Store_Return (OBJECT_DATUM (ret_register)); */			\
  /* Save_Cont (); */							\
  Compiler_New_Subproblem ();						\
}

extern long EXFUN (apply_compiled_procedure, (void));
extern long EXFUN (comp_access_restart, (void));
extern long EXFUN (comp_assignment_restart, (void));
extern long EXFUN (comp_assignment_trap_restart, (void));
extern long EXFUN (comp_cache_lookup_apply_restart, (void));
extern long EXFUN (comp_definition_restart, (void));
extern long EXFUN (comp_error_restart, (void));
extern long EXFUN (comp_interrupt_restart, (void));
extern long EXFUN (comp_link_caches_restart, (void));
extern long EXFUN (comp_lookup_apply_restart, (void));
extern long EXFUN (comp_lookup_trap_restart, (void));
extern long EXFUN (comp_op_lookup_trap_restart, (void));
extern long EXFUN (comp_reference_restart, (void));
extern long EXFUN (comp_safe_lookup_trap_restart, (void));
extern long EXFUN (comp_safe_reference_restart, (void));
extern long EXFUN (comp_unassigned_p_restart, (void));
extern long EXFUN (comp_unassigned_p_trap_restart, (void));
extern long EXFUN (comp_unbound_p_restart, (void));
extern long EXFUN (enter_compiled_expression, (void));
extern long EXFUN (return_to_compiled_code, (void));

extern SCHEME_OBJECT * EXFUN
  (compiled_entry_to_block_address, (SCHEME_OBJECT));

extern void EXFUN (compiled_entry_type, (SCHEME_OBJECT, long *));
