src/moxie/ffi.c

/* -----------------------------------------------------------------------
   ffi.c - Copyright (C) 2012, 2013, 2018  Anthony Green

   Moxie Foreign Function Interface

   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   ``Software''), to deal in the Software without restriction, including
   without limitation the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions:

   The above copyright notice and this permission notice shall be included
   in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   DEALINGS IN THE SOFTWARE.
   ----------------------------------------------------------------------- */

#include <ffi.h>
#include <ffi_common.h>

#include <stdlib.h>

/* ffi_prep_args is called by the assembly routine once stack space
   has been allocated for the function's arguments */

void *ffi_prep_args(char *stack, extended_cif *ecif)
{
  register unsigned int i;
  register void **p_argv;
  register char *argp;
  register ffi_type **p_arg;
  register int count = 0;

  p_argv = ecif->avalue;
  argp = stack;

  if (ecif->cif->rtype->type == FFI_TYPE_STRUCT)
    {
      *(void **) argp = ecif->rvalue;
      argp += 4;
    }

  for (i = ecif->cif->nargs, p_arg = ecif->cif->arg_types;
       (i != 0);
       i--, p_arg++)
    {
      size_t z;

      z = (*p_arg)->size;

      if ((*p_arg)->type == FFI_TYPE_STRUCT)
	{
	  z = sizeof(void*);
	  *(void **) argp = *p_argv;
	}
      else if (z < sizeof(int))
	{
	  z = sizeof(int);
	  switch ((*p_arg)->type)
	    {
	    case FFI_TYPE_SINT8:
	      *(signed int *) argp = (signed int)*(SINT8 *)(* p_argv);
	      break;

	    case FFI_TYPE_UINT8:
	      *(unsigned int *) argp = (unsigned int)*(UINT8 *)(* p_argv);
	      break;

	    case FFI_TYPE_SINT16:
	      *(signed int *) argp = (signed int)*(SINT16 *)(* p_argv);
	      break;

	    case FFI_TYPE_UINT16:
	      *(unsigned int *) argp = (unsigned int)*(UINT16 *)(* p_argv);
	      break;

	    default:
	      FFI_ASSERT(0);
	    }
	}
      else if (z == sizeof(int))
	{
	  *(unsigned int *) argp = (unsigned int)*(UINT32 *)(* p_argv);
	}
      else
	{
	  memcpy(argp, *p_argv, z);
	}
      p_argv++;
      argp += z;
      count += z;
    }

  return (stack + ((count > 24) ? 24 : FFI_ALIGN_DOWN(count, 8)));
}

/* Perform machine dependent cif processing */
ffi_status ffi_prep_cif_machdep(ffi_cif *cif)
{
  if (cif->rtype->type == FFI_TYPE_STRUCT)
    cif->flags = -1;
  else
    cif->flags = cif->rtype->size;

  cif->bytes = FFI_ALIGN (cif->bytes, 8);

  return FFI_OK;
}

extern void ffi_call_EABI(void *(*)(char *, extended_cif *),
			  extended_cif *,
			  unsigned, unsigned,
			  unsigned *,
			  void (*fn)(void));

void ffi_call(ffi_cif *cif,
	      void (*fn)(void),
	      void *rvalue,
	      void **avalue)
{
  extended_cif ecif;

  ecif.cif = cif;
  ecif.avalue = avalue;

  /* If the return value is a struct and we don't have a return	*/
  /* value address then we need to make one		        */

  if ((rvalue == NULL) &&
      (cif->rtype->type == FFI_TYPE_STRUCT))
    {
      ecif.rvalue = alloca(cif->rtype->size);
    }
  else
    ecif.rvalue = rvalue;

  switch (cif->abi)
    {
    case FFI_EABI:
      ffi_call_EABI(ffi_prep_args, &ecif, cif->bytes,
		    cif->flags, ecif.rvalue, fn);
      break;
    default:
      FFI_ASSERT(0);
      break;
    }
}

void ffi_closure_eabi (unsigned arg1, unsigned arg2, unsigned arg3,
		       unsigned arg4, unsigned arg5, unsigned arg6)
{
  /* This function is called by a trampoline.  The trampoline stows a
     pointer to the ffi_closure object in $r12.  We must save this
     pointer in a place that will persist while we do our work.  */
  register ffi_closure *creg __asm__ ("$r12");
  ffi_closure *closure = creg;

  /* Arguments that don't fit in registers are found on the stack
     at a fixed offset above the current frame pointer.  */
  register char *frame_pointer __asm__ ("$fp");

  /* Pointer to a struct return value.  */
  void *struct_rvalue = (void *) arg1;

  /* 6 words reserved for register args + 3 words from jsr */
  char *stack_args = frame_pointer + 9*4;

  /* Lay the register arguments down in a continuous chunk of memory.  */
  unsigned register_args[6] =
    { arg1, arg2, arg3, arg4, arg5, arg6 };
  char *register_args_ptr = (char *) register_args;

  ffi_cif *cif = closure->cif;
  ffi_type **arg_types = cif->arg_types;
  void **avalue = alloca (cif->nargs * sizeof(void *));
  char *ptr = (char *) register_args;
  int i;

  /* preserve struct type return pointer passing */
  if ((cif->rtype != NULL) && (cif->rtype->type == FFI_TYPE_STRUCT)) {
    ptr += 4;
    register_args_ptr = (char *)&register_args[1];
  }

  /* Find the address of each argument.  */
  for (i = 0; i < cif->nargs; i++)
    {
      switch (arg_types[i]->type)
	{
	case FFI_TYPE_SINT8:
	case FFI_TYPE_UINT8:
	  avalue[i] = ptr + 3;
	  break;
	case FFI_TYPE_SINT16:
	case FFI_TYPE_UINT16:
	  avalue[i] = ptr + 2;
	  break;
	case FFI_TYPE_SINT32:
	case FFI_TYPE_UINT32:
	case FFI_TYPE_FLOAT:
	case FFI_TYPE_POINTER:
	  avalue[i] = ptr;
	  break;
	case FFI_TYPE_STRUCT:
	  avalue[i] = *(void**)ptr;
	  break;
	default:
	  /* This is an 8-byte value.  */
	  if (ptr == (char *) &register_args[5])
	    {
	      /* The value is split across two locations */
	      unsigned *ip = alloca(8);
	      avalue[i] = ip;
	      ip[0] = *(unsigned *) ptr;
	      ip[1] = *(unsigned *) stack_args;
	    }
	  else
	    {
	      avalue[i] = ptr;
	    }
	  ptr += 4;
	  break;
	}
      ptr += 4;

      /* If we've handled more arguments than fit in registers,
	 start looking at the those passed on the stack.  */
      if (ptr == (char *) &register_args[6])
	ptr = stack_args;
      else if (ptr == (char *) &register_args[7])
	ptr = stack_args + 4;
    }

  /* Invoke the closure.  */
  if (cif->rtype && (cif->rtype->type == FFI_TYPE_STRUCT))
    {
      (closure->fun) (cif, struct_rvalue, avalue, closure->user_data);
    }
  else
    {
      /* Allocate space for the return value and call the function.  */
      long long rvalue;
      (closure->fun) (cif, &rvalue, avalue, closure->user_data);
      asm ("mov $r12, %0\n ld.l $r0, ($r12)\n ldo.l $r1, 4($r12)" : : "r" (&rvalue));
    }
}

ffi_status
ffi_prep_closure_loc (ffi_closure* closure,
		      ffi_cif* cif,
		      void (*fun)(ffi_cif*, void*, void**, void*),
		      void *user_data,
		      void *codeloc)
{
  unsigned short *tramp = (unsigned short *) &closure->tramp[0];
  unsigned long fn = (long) ffi_closure_eabi;
  unsigned long cls = (long) codeloc;

  if (cif->abi != FFI_EABI)
    return FFI_BAD_ABI;

  fn = (unsigned long) ffi_closure_eabi;

  tramp[0] = 0x01e0; /* ldi.l $r12, .... */
  tramp[1] = cls >> 16;
  tramp[2] = cls & 0xffff;
  tramp[3] = 0x1a00; /* jmpa .... */
  tramp[4] = fn >> 16;
  tramp[5] = fn & 0xffff;

  closure->cif = cif;
  closure->fun = fun;
  closure->user_data = user_data;

  return FFI_OK;
}