// -----------------------------------------------------------------------------
// Apply.hc
//
// (c) The University of Glasgow 2002
//
// Application-related bits.
//
// -----------------------------------------------------------------------------

#include "Stg.h"
#include "Rts.h"
#include "RtsFlags.h"
#include "Storage.h"
#include "RtsUtils.h"
#include "Printer.h"
#include "Sanity.h"
#include "Apply.h"

#include <stdio.h>

// ----------------------------------------------------------------------------
// Evaluate a closure and return it.
//
//      stg_ap_0_info   <--- Sp
//
// NOTE: this needs to be a polymorphic return point, because we can't
// be sure that the thing being evaluated is not a function.

// These names are just to keep VEC_POLY_INFO_TABLE() happy - all the
// entry points in the polymorphic info table point to the same code.
#define stg_ap_0_0_ret stg_ap_0_ret
#define stg_ap_0_1_ret stg_ap_0_ret
#define stg_ap_0_2_ret stg_ap_0_ret
#define stg_ap_0_3_ret stg_ap_0_ret
#define stg_ap_0_4_ret stg_ap_0_ret
#define stg_ap_0_5_ret stg_ap_0_ret
#define stg_ap_0_6_ret stg_ap_0_ret
#define stg_ap_0_7_ret stg_ap_0_ret

VEC_POLY_INFO_TABLE(stg_ap_0,
	       MK_SMALL_BITMAP(0/*framsize*/, 0/*bitmap*/),
	       0,0,0,RET_SMALL,,EF_);
F_
stg_ap_0_ret(void)
{ 
    // fn is in R1, no args on the stack
    StgInfoTable *info;
    nat arity;
    FB_;

    IF_DEBUG(apply,fprintf(stderr, "stg_ap_0_ret... "); printClosure(R1.cl));
    IF_DEBUG(sanity,checkStackChunk(Sp+1,CurrentTSO->stack + CurrentTSO->stack_size));

    Sp++;
    ENTER();
    FE_
}

/* -----------------------------------------------------------------------------
   Entry Code for a PAP.

   This entry code is *only* called by one of the stg_ap functions.
   On entry: Sp points to the remaining arguments on the stack.  If
   the stack check fails, we can just push the PAP on the stack and
   return to the scheduler.

   On entry: R1 points to the PAP.  The rest of the function's
   arguments (apart from those that are already in the PAP) are on the
   stack, starting at Sp[0].  R2 contains an info table which
   describes these arguments, which is used in the event that the
   stack check in the entry code below fails.  The info table is
   currently one of the stg_ap_*_ret family, as this code is always
   entered from those functions.

   The idea is to copy the chunk of stack from the PAP object onto the
   stack / into registers, and enter the function.
   -------------------------------------------------------------------------- */

INFO_TABLE(stg_PAP_info,stg_PAP_entry,/*special layout*/0,0,PAP,,EF_,"PAP","PAP");
STGFUN(stg_PAP_entry)
{
  nat Words;
  StgPtr p;
  nat i;
  StgPAP *pap;
  FB_
    
  pap = (StgPAP *) R1.p;

  Words = pap->n_args;

  // Check for stack overflow and bump the stack pointer.
  // We have a hand-rolled stack check fragment here, because none of
  // the canned ones suit this situation.
  if ((Sp - Words) < SpLim) {
      // there is a return address in R2 in the event of a
      // stack check failure.  The various stg_apply functions arrange
      // this before calling stg_PAP_entry.
      Sp--; 
      Sp[0] = R2.w;
      JMP_(stg_gc_unpt_r1);
  }
  Sp -= Words;

  // profiling
  TICK_ENT_PAP(pap);
  LDV_ENTER(pap);
  // Enter PAP cost centre -- lexical scoping only
  ENTER_CCS_PAP_CL(pap);

  R1.cl = pap->fun;
  p = (P_)(pap->payload);

  // Reload the stack
  for (i=0; i<Words; i++) {
      Sp[i] = (W_) *p++;
  }

  // Off we go!
  TICK_ENT_VIA_NODE();

#ifdef NO_ARG_REGS
  JMP_(GET_ENTRY(R1.cl));
#else
  {
      StgFunInfoTable *info;
      info = get_fun_itbl(R1.cl);
      if (info->fun_type == ARG_GEN || info->fun_type == ARG_GEN_BIG) {
	  JMP_(info->slow_apply);
      } else if (info->fun_type == ARG_BCO) {
	  Sp -= 2;
	  Sp[1] = R1.w;
	  Sp[0] = (W_)&stg_apply_interp_info;
	  JMP_(stg_yield_to_interpreter);
      } else {
	  JMP_(stg_ap_stack_entries[info->fun_type]);
      }
  }
#endif
  FE_
}

/* -----------------------------------------------------------------------------
   Entry Code for an AP (a PAP with arity zero).

   The entry code is very similar to a PAP, except there are no
   further arguments on the stack to worry about, so the stack check
   is simpler.  We must also push an update frame on the stack before
   applying the function.
   -------------------------------------------------------------------------- */

INFO_TABLE(stg_AP_info,stg_AP_entry,/*special layout*/0,0,AP,,EF_,"AP","AP");
STGFUN(stg_AP_entry)
{
  nat Words;
  P_ p;
  nat i;
  StgAP *ap;

  FB_
    
  ap = (StgAP *) R1.p;
  
  Words = ap->n_args;

  // Check for stack overflow.  IMPORTANT: use a _NP check here,
  // because if the check fails, we might end up blackholing this very
  // closure, in which case we must enter the blackhole on return rather
  // than continuing to evaluate the now-defunct closure.
  STK_CHK_NP(Words+sizeofW(StgUpdateFrame),);

  PUSH_UPD_FRAME(R1.p, 0);
  Sp -= sizeofW(StgUpdateFrame) + Words;

  TICK_ENT_AP(ap);
  LDV_ENTER(ap);

  // Enter PAP cost centre -- lexical scoping only
  ENTER_CCS_PAP_CL(ap);   /* ToDo: ENTER_CC_AP_CL */

  R1.cl = ap->fun;
  p = (P_)(ap->payload);

  // Reload the stack
  for (i=0; i<Words; i++) Sp[i] = (W_) *p++;

  // Off we go!
  TICK_ENT_VIA_NODE();

#ifdef NO_ARG_REGS
  JMP_(GET_ENTRY(R1.cl));
#else
  {
      StgFunInfoTable *info;
      info = get_fun_itbl(R1.cl);
      if (info->fun_type == ARG_GEN || info->fun_type == ARG_GEN_BIG) {
	  JMP_(info->slow_apply);
      } else if (info->fun_type == ARG_BCO) {
	  Sp -= 2;
	  Sp[1] = R1.w;
	  Sp[0] = (W_)&stg_apply_interp_info;
	  JMP_(stg_yield_to_interpreter);
      } else {
	  JMP_(stg_ap_stack_entries[info->fun_type]);
      }
  }
#endif
  FE_
}

/* -----------------------------------------------------------------------------
   Entry Code for an AP_STACK.

   Very similar to a PAP and AP.  The layout is the same as PAP
   and AP, except that the payload is a chunk of stack instead of
   being described by the function's info table.  Like an AP,
   there are no further arguments on the stack to worry about.
   However, the function closure (ap->fun) does not necessarily point
   directly to a function, so we have to enter it using stg_ap_0.
   -------------------------------------------------------------------------- */

INFO_TABLE(stg_AP_STACK_info,stg_AP_STACK_entry,/*special layout*/0,0,AP_STACK,,EF_,"AP_STACK","AP_STACK");
STGFUN(stg_AP_STACK_entry)
{
  nat Words;
  P_ p;
  nat i;
  StgAP_STACK *ap;

  FB_
    
  ap = (StgAP_STACK *) R1.p;
  
  Words = ap->size;

  // Check for stack overflow.  IMPORTANT: use a _NP check here,
  // because if the check fails, we might end up blackholing this very
  // closure, in which case we must enter the blackhole on return rather
  // than continuing to evaluate the now-defunct closure.
  STK_CHK_NP(Words+sizeofW(StgUpdateFrame),);

  PUSH_UPD_FRAME(R1.p, 0);
  Sp -= sizeofW(StgUpdateFrame) + Words;

  TICK_ENT_AP(ap);
  LDV_ENTER(ap);

  // Enter PAP cost centre -- lexical scoping only */
  ENTER_CCS_PAP_CL(ap);   /* ToDo: ENTER_CC_AP_STACK_CL */

  R1.cl = ap->fun;
  p = (P_)(ap->payload);

  // Reload the stack
  for (i=0; i<Words; i++) Sp[i] = (W_) *p++;

  // Off we go!
  TICK_ENT_VIA_NODE();
  ENTER();
  FE_
}