/* Switch immediate operands from little endian to big endian. */

#include "config.h"
#include "misc.h"
#include "mlvalues.h"
#include "instruct.h"
#include "reverse.h"

/* We don't need this code if 1- the machine is little-endian, or 2- the
   machine has alignment constraints, in which case the interpreter does word
   accesses byte per byte, in little-endian mode, regardless of the
   native endianness.
*/

#if defined(MOSML_BIG_ENDIAN) && !defined(ALIGNMENT)

void fixup_endianness(p, len)
     register bytecode_t p;
     asize_t len;
{
  register bytecode_t q;
  int n;

  q = p + len;
  while(p < q) {
    switch(*p++) {
      /* Instructions with one one-byte + one two-byte argument */
    case C_CALLN: case APPTERM:
      p++; /* fall through */
      /* Instructions with a two-byte immediate argument */
    case PUSHACC: case ACCESS: case POP: case ASSIGN:
    case PUSHENVACC: case ENVACC: case DUMMY: case RETURN: 
    case SETGLOBAL: case GETGLOBAL: 
    case APPTERM1: case APPTERM2: case APPTERM3: case APPTERM4:
    case PUSH_ENV1_APPTERM1: case PUSH_ENV1_APPTERM2: 
    case PUSH_ENV1_APPTERM3: case PUSH_ENV1_APPTERM4: 
    case PUSH_GETGLOBAL: 
    case PUSH_GETGLOBAL_APPLY1: case PUSH_GETGLOBAL_APPLY2:
    case PUSH_GETGLOBAL_APPLY3: case PUSH_GETGLOBAL_APPLY4:
    case GETFIELD: case SETFIELD:
    case C_CALL1: case C_CALL2: case C_CALL3: case C_CALL4:
    case C_CALL5: 
    case CONSTSHORT:
      Reverse_short(p);
      p += 2;
      break;

      /* Instructions with a one-byte and a four-byte immediate argument */
    case CLOSURE: case CLOSREC: case BRANCHIFNEQTAG: 
      p++; /* fall through */
      /* Instructions with a four-byte immediate argument */
    case PUSH_RETADDR: case PUSHTRAP:
    case BRANCH: case BRANCHIF: case BRANCHIFNOT: case POPBRANCHIFNOT:
    case BRANCHIFEQ: case BRANCHIFNEQ: case BRANCHIFLT:
    case BRANCHIFGT: case BRANCHIFLE: case BRANCHIFGE:
    case MAKEBLOCK: case PUSHCONSTINT: case CONSTINT:
      Reverse_word(p);
      p += 4;
      break;
      /* Instructions with two two-byte immediate arguments */
    case PUSH_GETGLOBAL_APPTERM1: case PUSH_GETGLOBAL_APPTERM2: 
    case PUSH_GETGLOBAL_APPTERM3: case PUSH_GETGLOBAL_APPTERM4: 
      Reverse_short(p);
      Reverse_short(p+2);
      p += 4;
      break;
      /* Instructions with two four-byte immediate arguments */
    case BRANCHINTERVAL: 
      Reverse_word(p);
      Reverse_word(p+4);
      p += 8;
      break;
      /* Special case for switch */
    case SWITCH:
      n = *p++;
      while (n > 0) {
        Reverse_word(p);
        p += 4;
        n--;
      }
      break;
      /* Instructions with a one-byte immediate argument */
    case APPLY: case GRAB: case PUSHATOM: case ATOM: 
    case MAKEBLOCK1: case MAKEBLOCK2: case MAKEBLOCK3: case MAKEBLOCK4:
    case CONSTBYTE: 
      p++;
      break;
    }
  }
}

#endif