libffi/src/powerpc/ffi_darwin.c

   1 /* -----------------------------------------------------------------------
   2    ffi.c - Copyright (c) 1998 Geoffrey Keating
   3
   4    PowerPC Foreign Function Interface
   5
   6    Darwin ABI support (c) 2001 John Hornkvist
   7    AIX ABI support (c) 2002 Free Software Foundation, Inc.
   8
   9    Permission is hereby granted, free of charge, to any person obtaining
  10    a copy of this software and associated documentation files (the
  11    ``Software''), to deal in the Software without restriction, including
  12    without limitation the rights to use, copy, modify, merge, publish,
  13    distribute, sublicense, and/or sell copies of the Software, and to
  14    permit persons to whom the Software is furnished to do so, subject to
  15    the following conditions:
  16
  17    The above copyright notice and this permission notice shall be included
  18    in all copies or substantial portions of the Software.
  19
  20    THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS
  21    OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  23    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR
  24    OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  25    ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  26    OTHER DEALINGS IN THE SOFTWARE.
  27    ----------------------------------------------------------------------- */
  28 #include <ffi.h>
  29 #include <ffi_common.h>
  30
  31 #include <stdlib.h>
  32
  33 extern void ffi_closure_ASM(void);
  34
  35 enum {
  36   /* The assembly depends on these exact flags.  */
  37   FLAG_RETURNS_NOTHING  = 1 << (31-30), /* These go in cr7 */
  38   FLAG_RETURNS_FP       = 1 << (31-29),
  39   FLAG_RETURNS_64BITS   = 1 << (31-28),
  40
  41   FLAG_ARG_NEEDS_COPY   = 1 << (31- 7),
  42   FLAG_FP_ARGUMENTS     = 1 << (31- 6), /* cr1.eq; specified by ABI */
  43   FLAG_4_GPR_ARGUMENTS  = 1 << (31- 5),
  44   FLAG_RETVAL_REFERENCE = 1 << (31- 4)
  45 };
  46
  47 /* About the DARWIN ABI.  */
  48 enum {
  49   NUM_GPR_ARG_REGISTERS = 8,
  50   NUM_FPR_ARG_REGISTERS = 13
  51 };
  52 enum { ASM_NEEDS_REGISTERS = 4 };
  53
  54 /* ffi_prep_args is called by the assembly routine once stack space
  55    has been allocated for the function's arguments.
  56
  57    The stack layout we want looks like this:
  58
  59    |   Return address from ffi_call_DARWIN      |       higher addresses
  60    |--------------------------------------------|
  61    |   Previous backchain pointer       4       |       stack pointer here
  62    |--------------------------------------------|<+ <<< on entry to
  63    |   Saved r28-r31                    4*4     | |     ffi_call_DARWIN
  64    |--------------------------------------------| |
  65    |   Parameters             (at least 8*4=32) | |
  66    |--------------------------------------------| |
  67    |   Space for GPR2                   4       | |
  68    |--------------------------------------------| |     stack   |
  69    |   Reserved                       2*4       | |     grows   |
  70    |--------------------------------------------| |     down    V
  71    |   Space for callee's LR            4       | |
  72    |--------------------------------------------| |     lower addresses
  73    |   Saved CR                         4       | |
  74    |--------------------------------------------| |     stack pointer here
  75    |   Current backchain pointer        4       |-/     during
  76    |--------------------------------------------|   <<< ffi_call_DARWIN
  77
  78    */
  79
  80 /*@-exportheader@*/
  81 void ffi_prep_args(extended_cif *ecif, unsigned *const stack)
  82 /*@=exportheader@*/
  83 {
  84   const unsigned bytes = ecif->cif->bytes;
  85   const unsigned flags = ecif->cif->flags;
  86
  87   /* 'stacktop' points at the previous backchain pointer.  */
  88   unsigned *const stacktop = stack + (ecif->cif->bytes / sizeof(unsigned));
  89
  90   /* 'fpr_base' points at the space for fpr1, and grows upwards as
  91      we use FPR registers.  */
  92   double *fpr_base = (double*) (stacktop - ASM_NEEDS_REGISTERS) - NUM_FPR_ARG_REGISTERS;
  93   int fparg_count = 0;
  94
  95
  96   /* 'next_arg' grows up as we put parameters in it.  */
  97   unsigned *next_arg = stack + 6; // 6 reserved posistions.
  98
  99   int i=ecif->cif->nargs;
 100   double double_tmp;
 101   float float_tmp;
 102   void **p_argv = ecif->avalue;
 103   unsigned gprvalue;
 104   ffi_type** ptr = ecif->cif->arg_types;
 105
 106   /* Check that everything starts aligned properly.  */
 107   FFI_ASSERT(((unsigned)(char *)stack & 0xF) == 0);
 108   FFI_ASSERT(((unsigned)(char *)stacktop & 0xF) == 0);
 109   FFI_ASSERT((bytes & 0xF) == 0);
 110
 111   /* Deal with return values that are actually pass-by-reference.  */
 112   // Rule:
 113   // Return values are referenced by r3, so r4 is the first parameter.
 114   if (flags & FLAG_RETVAL_REFERENCE)
 115     *next_arg++ = (unsigned)(char *)ecif->rvalue;
 116
 117   /* Now for the arguments.  */
 118   for (;
 119        i > 0;
 120        i--, ptr++, p_argv++)
 121     {
 122       switch ((*ptr)->type)
 123         {
 124         /* If a floating-point parameter appears before all of the general-
 125            purpose registers are filled, the corresponding GPRs that match
 126            the size of the floating-point parameter are skipped.  */
 127         case FFI_TYPE_FLOAT:
 128           double_tmp = *(float *)*p_argv;
 129           if (fparg_count >= NUM_FPR_ARG_REGISTERS)
 130             *(double *)next_arg = double_tmp;
 131           else
 132             *fpr_base++ = double_tmp;
 133           next_arg++;
 134           fparg_count++;
 135           FFI_ASSERT(flags & FLAG_FP_ARGUMENTS);
 136           break;
 137         case FFI_TYPE_DOUBLE:
 138           double_tmp = *(double *)*p_argv;
 139           if (fparg_count >= NUM_FPR_ARG_REGISTERS)
 140             *(double *)next_arg = double_tmp;
 141           else
 142             *fpr_base++ = double_tmp;
 143           next_arg += 2;
 144           fparg_count++;
 145           FFI_ASSERT(flags & FLAG_FP_ARGUMENTS);
 146           break;
 147
 148         case FFI_TYPE_UINT64:
 149         case FFI_TYPE_SINT64:
 150           *(long long *)next_arg = *(long long *)*p_argv;
 151           next_arg+=2;
 152           break;
 153         case FFI_TYPE_UINT8:
 154           gprvalue = *(unsigned char *)*p_argv;
 155           goto putgpr;
 156         case FFI_TYPE_SINT8:
 157           gprvalue = *(signed char *)*p_argv;
 158           goto putgpr;
 159         case FFI_TYPE_UINT16:
 160           gprvalue = *(unsigned short *)*p_argv;
 161           goto putgpr;
 162         case FFI_TYPE_SINT16:
 163           gprvalue = *(signed short *)*p_argv;
 164           goto putgpr;
 165
 166         case FFI_TYPE_STRUCT:
 167
 168 #if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
 169         case FFI_TYPE_LONGDOUBLE:
 170 #endif
 171
 172           memcpy((char*)next_arg, (char *)*p_argv, (*ptr)->size);
 173           next_arg+=(((((*ptr)->size) + 3) & ~0x3)/4);
 174         break;
 175
 176         case FFI_TYPE_INT:
 177         case FFI_TYPE_UINT32:
 178         case FFI_TYPE_SINT32:
 179         case FFI_TYPE_POINTER:
 180           gprvalue = *(unsigned *)*p_argv;
 181         putgpr:
 182           *next_arg++ = gprvalue;
 183           break;
 184         default:
 185           break;
 186         }
 187     }
 188
 189   /* Check that we didn't overrun the stack...  */
 190   //FFI_ASSERT(copy_space >= (char *)next_arg);
 191   //FFI_ASSERT(gpr_base <= stacktop - ASM_NEEDS_REGISTERS);
 192   //FFI_ASSERT((unsigned *)fpr_base
 193   //         <= stacktop - ASM_NEEDS_REGISTERS - NUM_GPR_ARG_REGISTERS);
 194   //FFI_ASSERT(flags & FLAG_4_GPR_ARGUMENTS || intarg_count <= 4);
 195 }
 196
 197 /* Perform machine dependent cif processing */
 198 ffi_status ffi_prep_cif_machdep(ffi_cif *cif)
 199 {
 200   /* All this is for the DARWIN ABI.  */
 201   int i;
 202   ffi_type **ptr;
 203   unsigned bytes;
 204   int fparg_count = 0, intarg_count = 0;
 205   unsigned flags = 0;
 206   unsigned struct_copy_size = 0;
 207
 208   /* All the machine-independent calculation of cif->bytes will be wrong.
 209      Redo the calculation for DARWIN.  */
 210
 211   /* Space for the frame pointer, callee's LR, CR, etc, and for
 212      the asm's temp regs.  */
 213
 214   bytes = (6 + ASM_NEEDS_REGISTERS) * sizeof(long);
 215
 216   /* Return value handling.  The rules are as follows:
 217      - 32-bit (or less) integer values are returned in gpr3;
 218      - Structures of size <= 4 bytes also returned in gpr3;
 219      - 64-bit integer values and structures between 5 and 8 bytes are returned
 220        in gpr3 and gpr4;
 221      - Single/double FP values are returned in fpr1;
 222      - Long double FP (if not equivalent to double) values are returned in
 223        fpr1 and fpr2;
 224      - Larger structures values are allocated space and a pointer is passed
 225        as the first argument.  */
 226   switch (cif->rtype->type)
 227     {
 228 #if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
 229     case FFI_TYPE_LONGDOUBLE:
 230 #endif
 231       /* Fall through.  */
 232     case FFI_TYPE_DOUBLE:
 233       flags |= FLAG_RETURNS_64BITS;
 234       /* Fall through.  */
 235     case FFI_TYPE_FLOAT:
 236       flags |= FLAG_RETURNS_FP;
 237       break;
 238
 239     case FFI_TYPE_UINT64:
 240     case FFI_TYPE_SINT64:
 241       flags |= FLAG_RETURNS_64BITS;
 242       break;
 243
 244     case FFI_TYPE_STRUCT:
 245       flags |= FLAG_RETVAL_REFERENCE;
 246       flags |= FLAG_RETURNS_NOTHING;
 247       intarg_count++;
 248       break;
 249     case FFI_TYPE_VOID:
 250       flags |= FLAG_RETURNS_NOTHING;
 251       break;
 252
 253     default:
 254       /* Returns 32-bit integer, or similar.  Nothing to do here.  */
 255       break;
 256     }
 257
 258   /* The first NUM_GPR_ARG_REGISTERS words of integer arguments, and the
 259      first NUM_FPR_ARG_REGISTERS fp arguments, go in registers; the rest
 260      goes on the stack.  Structures and long doubles (if not equivalent
 261      to double) are passed as a pointer to a copy of the structure.
 262      Stuff on the stack needs to keep proper alignment.  */
 263   for (ptr = cif->arg_types, i = cif->nargs; i > 0; i--, ptr++)
 264     {
 265       switch ((*ptr)->type)
 266         {
 267         case FFI_TYPE_FLOAT:
 268         case FFI_TYPE_DOUBLE:
 269           fparg_count++;
 270           /* If this FP arg is going on the stack, it must be
 271              8-byte-aligned.  */
 272           if (fparg_count > NUM_FPR_ARG_REGISTERS
 273               && intarg_count%2 != 0)
 274             intarg_count++;
 275           break;
 276
 277         case FFI_TYPE_UINT64:
 278         case FFI_TYPE_SINT64:
 279           /* 'long long' arguments are passed as two words, but
 280              either both words must fit in registers or both go
 281              on the stack.  If they go on the stack, they must
 282              be 8-byte-aligned.  */
 283           if (intarg_count == NUM_GPR_ARG_REGISTERS-1
 284               || intarg_count >= NUM_GPR_ARG_REGISTERS && intarg_count%2 != 0)
 285             intarg_count++;
 286           intarg_count += 2;
 287           break;
 288
 289         case FFI_TYPE_STRUCT:
 290 #if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
 291         case FFI_TYPE_LONGDOUBLE:
 292 #endif
 293           intarg_count+=(((*ptr)->size + 3) & ~0x3)/4;
 294           break;
 295
 296         default:
 297           /* Everything else is passed as a 4-byte word in a GPR, either
 298              the object itself or a pointer to it.  */
 299           intarg_count++;
 300           break;
 301         }
 302     }
 303
 304   if (fparg_count != 0)
 305     flags |= FLAG_FP_ARGUMENTS;
 306   if (struct_copy_size != 0)
 307     flags |= FLAG_ARG_NEEDS_COPY;
 308
 309   /* Space for the FPR registers, if needed.  */
 310   if (fparg_count != 0)
 311     bytes += NUM_FPR_ARG_REGISTERS * sizeof(double);
 312
 313   /* Stack space.  */
 314   if ((intarg_count + 2 * fparg_count) > NUM_GPR_ARG_REGISTERS)
 315     bytes += (intarg_count + 2 * fparg_count) * sizeof(long);
 316   else
 317     bytes += NUM_GPR_ARG_REGISTERS * sizeof(long);
 318
 319   /* The stack space allocated needs to be a multiple of 16 bytes.  */
 320   bytes = (bytes + 15) & ~0xF;
 321
 322   cif->flags = flags;
 323   cif->bytes = bytes;
 324
 325   return FFI_OK;
 326 }
 327
 328 /*@-declundef@*/
 329 /*@-exportheader@*/
 330 extern void ffi_call_AIX(/*@out@*/ extended_cif *,
 331                          unsigned, unsigned,
 332                          /*@out@*/ unsigned *,
 333                          void (*fn)(),
 334                          void (*fn2)());
 335 extern void ffi_call_DARWIN(/*@out@*/ extended_cif *,
 336                             unsigned, unsigned,
 337                             /*@out@*/ unsigned *,
 338                             void (*fn)(),
 339                             void (*fn2)());
 340 /*@=declundef@*/
 341 /*@=exportheader@*/
 342
 343 void ffi_call(/*@dependent@*/ ffi_cif *cif,
 344               void (*fn)(),
 345               /*@out@*/ void *rvalue,
 346               /*@dependent@*/ void **avalue)
 347 {
 348   extended_cif ecif;
 349
 350   ecif.cif = cif;
 351   ecif.avalue = avalue;
 352
 353   /* If the return value is a struct and we don't have a return */
 354   /* value address then we need to make one                     */
 355
 356   if ((rvalue == NULL) &&
 357       (cif->rtype->type == FFI_TYPE_STRUCT))
 358     {
 359       /*@-sysunrecog@*/
 360       ecif.rvalue = alloca(cif->rtype->size);
 361       /*@=sysunrecog@*/
 362     }
 363   else
 364     ecif.rvalue = rvalue;
 365
 366   switch (cif->abi)
 367     {
 368     case FFI_AIX:
 369       /*@-usedef@*/
 370       ffi_call_AIX(&ecif, -cif->bytes,
 371                    cif->flags, ecif.rvalue, fn, ffi_prep_args);
 372       /*@=usedef@*/
 373       break;
 374     case FFI_DARWIN:
 375       /*@-usedef@*/
 376       ffi_call_DARWIN(&ecif, -cif->bytes,
 377                       cif->flags, ecif.rvalue, fn, ffi_prep_args);
 378       /*@=usedef@*/
 379       break;
 380     default:
 381       FFI_ASSERT(0);
 382       break;
 383     }
 384 }
 385
 386 static void flush_icache(char *);
 387 static void flush_range(char *, int);
 388
 389 /* The layout of a function descriptor.  A C function pointer really    */
 390 /* points to one of these.                                              */
 391
 392 typedef struct aix_fd_struct {
 393     void *code_pointer;
 394     void *toc;
 395 } aix_fd;
 396
 397 /* here I'd like to add the stack frame layout we use in darwin_closure.S
 398  * and aix_clsoure.S
 399  *
 400 /* SP previous -> +---------------------------------------+ <--- child frame
 401                   | back chain to caller 4                |
 402                   +---------------------------------------+ 4
 403                   | saved CR 4                            |
 404                   +---------------------------------------+ 8
 405                   | saved LR 4                            |
 406                   +---------------------------------------+ 12
 407                   | reserved for compilers 4              |
 408                   +---------------------------------------+ 16
 409                   | reserved for binders 4                |
 410                   +---------------------------------------+ 20
 411                   | saved TOC pointer 4                   |
 412                   +---------------------------------------+ 24
 413                   | always reserved 8*4=32 (previous GPRs)|
 414                   | according to the linkage convention   |
 415                   | from AIX                              |
 416                   +---------------------------------------+ 56
 417                   | our FPR area 13*8=104                 |
 418                   | f1                                    |
 419                   | .                                     |
 420                   | f13                                   |
 421                   +---------------------------------------+ 160
 422                   | result area 8                         |
 423                   +---------------------------------------+ 168
 424                   | alignement to the next multiple of 16 |
 425 SP current -->    +---------------------------------------+ 176 <- parent frame
 426                   | back chain to caller 4                |
 427                   +---------------------------------------+ 180
 428                   | saved CR 4                            |
 429                   +---------------------------------------+ 184
 430                   | saved LR 4                            |
 431                   +---------------------------------------+ 188
 432                   | reserved for compilers 4              |
 433                   +---------------------------------------+ 192
 434                   | reserved for binders 4                |
 435                   +---------------------------------------+ 196
 436                   | saved TOC pointer 4                   |
 437                   +---------------------------------------+ 200
 438                   | always reserved 8*4=32  we store our  |
 439                   | GPRs here                             |
 440                   | r3                                    |
 441                   | .                                     |
 442                   | r10                                   |
 443                   +---------------------------------------+ 232
 444                   | PST area, overflow part               |
 445                   +---------------------------------------+ xxx
 446                   | ????                                  |
 447                   +---------------------------------------+ xxx
 448
 449 */
 450 ffi_status
 451 ffi_prep_closure (ffi_closure* closure,
 452                   ffi_cif* cif,
 453                   void (*fun)(ffi_cif*, void*, void**, void*),
 454                   void *user_data)
 455 {
 456   unsigned int *tramp;
 457   struct ffi_aix_trampoline_struct *tramp_aix;
 458   aix_fd *fd;
 459
 460   switch (cif->abi)
 461     {
 462     case FFI_DARWIN:
 463
 464       FFI_ASSERT (cif->abi == FFI_DARWIN);
 465
 466       tramp = (unsigned int *) &closure->tramp[0];
 467       tramp[0] = 0x7c0802a6;  /*   mflr    r0 */
 468       tramp[1] = 0x4800000d;  /*   bl      10 <trampoline_initial+0x10> */
 469       tramp[4] = 0x7d6802a6;  /*   mflr    r11 */
 470       tramp[5] = 0x818b0000;  /*   lwz     r12,0(r11)  /* function address */
 471       tramp[6] = 0x7c0803a6;  /*   mtlr    r0  */
 472       tramp[7] = 0x7d8903a6;  /*   mtctr   r12 */
 473       tramp[8] = 0x816b0004;  /*   lwz     r11,4(r11)  /* static chain */
 474       tramp[9] = 0x4e800420;  /*   bctr */
 475       *(void **) &tramp[2] = (void *)ffi_closure_ASM; /* function */
 476       *(void **) &tramp[3] = (void *)closure;          /* context */
 477
 478       closure->cif = cif;
 479       closure->fun = fun;
 480       closure->user_data = user_data;
 481
 482       /* Flush the icache. Only necessary on Darwin  */
 483       flush_range(&closure->tramp[0],FFI_TRAMPOLINE_SIZE);
 484
 485       break;
 486
 487     case FFI_AIX:
 488
 489       tramp_aix = (struct ffi_aix_trampoline_struct *) (closure->tramp);
 490       fd = (aix_fd *)(void *)ffi_closure_ASM;
 491
 492       FFI_ASSERT (cif->abi == FFI_AIX);
 493
 494       tramp_aix->code_pointer = fd->code_pointer;
 495       tramp_aix->toc = fd->toc;
 496       tramp_aix->static_chain = closure;
 497       closure->cif = cif;
 498       closure->fun = fun;
 499       closure->user_data = user_data;
 500
 501     default:
 502
 503       FFI_ASSERT(0);
 504       break;
 505     }
 506   return FFI_OK;
 507 }
 508
 509 static void
 510 flush_icache(char *addr)
 511 {
 512 #ifndef _AIX
 513   __asm__ volatile (
 514                 "dcbf 0,%0;"
 515                 "sync;"
 516                 "icbi 0,%0;"
 517                 "sync;"
 518                 "isync;"
 519                 : : "r"(addr) : "memory");
 520 #endif
 521 }
 522
 523 static void
 524 flush_range(char * addr1, int size)
 525 {
 526 #define MIN_LINE_SIZE 32
 527   int i;
 528   for (i = 0; i < size; i += MIN_LINE_SIZE)
 529     flush_icache(addr1+i);
 530   flush_icache(addr1+size-1);
 531 }
 532
 533 int ffi_closure_helper_DARWIN (ffi_closure*, void*, unsigned long*,
 534                                      unsigned long*, unsigned long*);
 535
 536 /* Basically the trampoline invokes ffi_closure_ASM, and on
 537  * entry, r11 holds the address of the closure.
 538  * After storing the registers that could possibly contain
 539  * parameters to be passed into the stack frame and setting
 540  * up space for a return value, ffi_closure_ASM invokes the
 541  * following helper function to do most of the work
 542  */
 543
 544 int
 545 ffi_closure_helper_DARWIN (ffi_closure* closure, void * rvalue,
 546             unsigned long * pgr, unsigned long * pfr,
 547             unsigned long * pst)
 548 {
 549   /* rvalue is the pointer to space for return value in closure assembly */
 550   /* pgr is the pointer to where r3-r10 are stored in ffi_closure_ASM */
 551   /* pfr is the pointer to where f1-f13 are stored in ffi_closure_ASM */
 552   /* pst is the pointer to outgoing parameter stack in original caller */
 553
 554   void **          avalue;
 555   ffi_type **      arg_types;
 556   long             i, avn;
 557   long             nf;   /* number of floating registers already used */
 558   long             ng;   /* number of general registers already used */
 559   ffi_cif *        cif;
 560   double           temp;
 561
 562   cif = closure->cif;
 563   avalue = alloca(cif->nargs * sizeof(void *));
 564
 565   nf = 0;
 566   ng = 0;
 567
 568   /* Copy the caller's structure return value address so that the closure
 569      returns the data directly to the caller.  */
 570   if (cif->rtype->type == FFI_TYPE_STRUCT)
 571     {
 572       rvalue = (void *)pgr;
 573       ng++;
 574       pgr++;
 575     }
 576
 577   i = 0;
 578   avn = cif->nargs;
 579   arg_types = cif->arg_types;
 580
 581   /* Grab the addresses of the arguments from the stack frame.  */
 582   while (i < avn)
 583     {
 584       switch (arg_types[i]->type)
 585         {
 586         case FFI_TYPE_SINT8:
 587         case FFI_TYPE_UINT8:
 588         /* there are 8 gpr registers used to pass values */
 589           if (ng < 8) {
 590              avalue[i] = (((char *)pgr)+3);
 591              ng++;
 592              pgr++;
 593           } else {
 594              avalue[i] = (((char *)pst)+3);
 595              pst++;
 596           }
 597           break;
 598
 599         case FFI_TYPE_SINT16:
 600         case FFI_TYPE_UINT16:
 601         /* there are 8 gpr registers used to pass values */
 602           if (ng < 8) {
 603              avalue[i] = (((char *)pgr)+2);
 604              ng++;
 605              pgr++;
 606           } else {
 607              avalue[i] = (((char *)pst)+2);
 608              pst++;
 609           }
 610           break;
 611
 612         case FFI_TYPE_SINT32:
 613         case FFI_TYPE_UINT32:
 614         case FFI_TYPE_POINTER:
 615         case FFI_TYPE_STRUCT:
 616         /* there are 8 gpr registers used to pass values */
 617           if (ng < 8) {
 618              avalue[i] = pgr;
 619              ng++;
 620              pgr++;
 621           } else {
 622              avalue[i] = pst;
 623              pst++;
 624           }
 625           break;
 626
 627         case FFI_TYPE_SINT64:
 628         case FFI_TYPE_UINT64:
 629           /* long long ints are passed in two gpr's if available or in
 630            * the pst, one place is a bit odd, when a long long passes
 631            * the boundary between gpr and pst area we have to increment
 632            * the pst by one.
 633            */
 634            if (ng < 7) {
 635               avalue[i] = pgr;
 636               ng+=2;
 637               pgr+=2;
 638            } else if (ng == 7) {
 639               avalue[i] = pgr;
 640               ng++;
 641               pgr++;
 642               pst++;
 643            } else {
 644               avalue[i] = pst;
 645               pst+=2;
 646            }
 647            break;
 648
 649         case FFI_TYPE_FLOAT:
 650           /* a float value consumes a GPR
 651            *
 652            * there are 13 64bit floating point registers
 653            */
 654
 655           if ((ng > 7) && (nf < 13)) {
 656              pst++;
 657           }
 658           if (nf < 13) {
 659              temp = *(double*)pfr;
 660              *(float*)pfr = (float)temp;
 661              avalue[i] = pfr;
 662              nf++;
 663              pfr+=2;
 664              ng++;
 665              pgr++;
 666
 667           } else {
 668              avalue[i] = pst;
 669              nf++;
 670              pst++;
 671           }
 672           break;
 673
 674         case FFI_TYPE_DOUBLE:
 675           /* a double value consumes two GPRs
 676            *
 677            * there are 13 64bit floating point registers
 678            */
 679
 680           if ((ng == 7) && (nf < 13)) {
 681              pst++;     /* if only one gpr is left the double steals it */
 682           } else if ((ng > 7) && (nf < 13)) {
 683              pst+=2;    /* a double consumes two GPRs in Darwin/AIX */
 684           }
 685           if (nf < 13) {
 686              avalue[i] = pfr;
 687              nf++;
 688              pfr+=2;
 689              ng+=2;
 690              pgr+=2;
 691
 692           } else {
 693              avalue[i] = pst;
 694              nf++;
 695              pst+=2;
 696           }
 697           break;
 698
 699         default:
 700           FFI_ASSERT(0);
 701
 702         }
 703
 704       i++;
 705     }
 706
 707   (closure->fun) (cif, rvalue, avalue, closure->user_data);
 708
 709   /* Tell ffi_closure_ASM to perform return type promotions.  */
 710   return cif->rtype->type;
 711
 712 }