modifiers

#define rotate_right(v, n) (v >> n | v << (32 - n))

/* ARM immediate encoding routine 
 * Based on Binutils' ARM port
 */
ac_modifier_encode(aimm)
{
  unsigned int a;
  unsigned int i;

#define rotate_left(v, n) (v << n | v >> (32 - n))

  for (i = 0; i < 32; i += 2)
    if ((a = rotate_left (reloc->input, i)) <= 0xff) {
      reloc->Type_DPI3.rotate = i >> 1;
      reloc->Type_DPI3.imm8 = a; 
      return;
    }

  reloc->error = 1;
}

ac_modifier_decode(aimm)
{
  reloc->output = rotate_right(reloc->input, (reloc->Type_DPI3.rotate << 1));
}

/*
 * "Branch" and "Branch and Link" instructions immediate modifier
 * Coded as 24bit, 2 times right shifted (ARM ISA is 32bits word aligned)
 * pc-relative + 8 offset.
 */
ac_modifier_encode(bimm)
{
  reloc->output = (reloc->input - reloc->address - 8) >>2;
}

ac_modifier_decode(bimm)
{
  int val = (int) reloc->input;
  if (val & 0x00800000)
    val |= 0xFF000000;
  reloc->output = (val << 2) + reloc->address + 8;
}


/*
 * "Branch and Exchange to thumb mode" instruction immediate modifier
 * Coded as 24bit, 2 times right shifted (Thumb instructions is
 * 16bits word aligned, so bit 1 is coded in field "H")
 * pc-relative + 8 offset.
 */
ac_modifier_encode(bximm)
{
  unsigned int modifiedImm = reloc->input;
  modifiedImm = modifiedImm - reloc->address - 8;

  reloc->Type_BBLT.h = (modifiedImm >> 1) & 0x01;
  reloc->Type_BBLT.offset = modifiedImm >> 2;
}

ac_modifier_decode(bximm)
{
  reloc->output = (reloc->input << 2) + reloc->address + 8;
}

/* Converts pc-relative immediates, rotated - used only
 * in ADR pseudo instruction
 */
ac_modifier_encode(pcrelrot)
{
  unsigned int pcrelat = reloc->input - reloc->address - 8;
  unsigned int a;
  unsigned int i;

  // Determines if ADR will be ADD or SUB
  if ((pcrelat & 0x80000000) == 0)
    reloc->Type_DPI3.func1 = 0x04; // ADD
  else
    {
      reloc->Type_DPI3.func1 = 0x02; // SUB
      pcrelat = 0 - pcrelat;
    }

  for (i = 0; i < 32; i += 2)
    if ((a = rotate_left (pcrelat, i)) <= 0xff) {
      reloc->Type_DPI3.rotate = ((i >> 1)&0xF);
      reloc->Type_DPI3.imm8 = (a & 0xFF);
      return;
    }

  reloc->error = 1;
}

ac_modifier_decode(pcrelrot)
{
  reloc->error = 0;
}

/* converts pc-relative immediate (used only in pseudo LDR)
 */
ac_modifier_encode(pcrelldr)
{
  unsigned int pcrelat = reloc->input - reloc->address - 8;
  // Determines if LDR will have negative or positive offset
  if ((pcrelat & 0x80000000) == 0)
    reloc->Type_LSI.u = 0x01; // ADD
  else
    {
      reloc->Type_LSI.u = 0x00; // SUB
      pcrelat = 0 - pcrelat;
    }
  reloc->Type_LSI.imm12 = 0xFFF & pcrelat;
}
ac_modifier_decode(pcrelldr)
{
  reloc->output = reloc->input + reloc->address + 8;
}

/* Multiple data transfer register list element - codifies
 * a register number into a bit in the register list.
 * Uses the list operator to obtain list of registers parsed.
 */
ac_modifier_encode(dorlist)
{
  int init_range = -1;
  unsigned i = 0;
  
  while (list_results_has_data(reloc->list_results))
  {
    char separator = list_results_get_separator(reloc->list_results);
    unsigned int result = list_results_next(&(reloc->list_results));
    if (init_range != -1)
    {
      for (i = init_range; i <= result; i++)
	reloc->output = reloc->output | (1 << i);
    }
    else
      reloc->output = reloc->output | (1 << result);
    init_range = -1;
    if (separator == '-')
      init_range = result;    
  }	
}

ac_modifier_decode(dorlist)
{
  unsigned i = 0;
  unsigned val = reloc->input;
  
  for (i = 0; i < 16; i++)
  {
    unsigned aux = val >> i;
    if (aux & 1) {
      list_results_store(&(reloc->list_results), i);
    }
  }
}