opcodes/alpha-dis.c

/* alpha-dis.c -- Disassemble Alpha AXP instructions
   Copyright (C) 1996-2025 Free Software Foundation, Inc.
   Contributed by Richard Henderson <rth@tamu.edu>,
   patterned after the PPC opcode handling written by Ian Lance Taylor.

   This file is part of libopcodes.

   This library is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   It is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
   License for more details.

   You should have received a copy of the GNU General Public License
   along with this file; see the file COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#include "sysdep.h"
#include <stdio.h>
#include "disassemble.h"
#include "opcode/alpha.h"

/* OSF register names.  */

static const char * const osf_regnames[64] = {
  "v0", "t0", "t1", "t2", "t3", "t4", "t5", "t6",
  "t7", "s0", "s1", "s2", "s3", "s4", "s5", "fp",
  "a0", "a1", "a2", "a3", "a4", "a5", "t8", "t9",
  "t10", "t11", "ra", "t12", "at", "gp", "sp", "zero",
  "$f0", "$f1", "$f2", "$f3", "$f4", "$f5", "$f6", "$f7",
  "$f8", "$f9", "$f10", "$f11", "$f12", "$f13", "$f14", "$f15",
  "$f16", "$f17", "$f18", "$f19", "$f20", "$f21", "$f22", "$f23",
  "$f24", "$f25", "$f26", "$f27", "$f28", "$f29", "$f30", "$f31"
};

/* VMS register names.  */

static const char * const vms_regnames[64] = {
  "R0", "R1", "R2", "R3", "R4", "R5", "R6", "R7",
  "R8", "R9", "R10", "R11", "R12", "R13", "R14", "R15",
  "R16", "R17", "R18", "R19", "R20", "R21", "R22", "R23",
  "R24", "AI", "RA", "PV", "AT", "FP", "SP", "RZ",
  "F0", "F1", "F2", "F3", "F4", "F5", "F6", "F7",
  "F8", "F9", "F10", "F11", "F12", "F13", "F14", "F15",
  "F16", "F17", "F18", "F19", "F20", "F21", "F22", "F23",
  "F24", "F25", "F26", "F27", "F28", "F29", "F30", "FZ"
};

/* Disassemble Alpha instructions.  */

int
print_insn_alpha (bfd_vma memaddr, struct disassemble_info *info)
{
  static const struct alpha_opcode *opcode_index[AXP_NOPS+1];
  const char * const * regnames;
  const struct alpha_opcode *opcode, *opcode_end;
  const unsigned char *opindex;
  unsigned insn, op, isa_mask;
  int need_comma;

  /* Initialize the majorop table the first time through */
  if (!opcode_index[0])
    {
      opcode = alpha_opcodes;
      opcode_end = opcode + alpha_num_opcodes;

      for (op = 0; op < AXP_NOPS; ++op)
	{
	  opcode_index[op] = opcode;
	  while (opcode < opcode_end && op == AXP_OP (opcode->opcode))
	    ++opcode;
	}
      opcode_index[op] = opcode;
    }

  if (info->flavour == bfd_target_evax_flavour)
    regnames = vms_regnames;
  else
    regnames = osf_regnames;

  isa_mask = AXP_OPCODE_NOPAL;
  switch (info->mach)
    {
    case bfd_mach_alpha_ev4:
      isa_mask |= AXP_OPCODE_EV4;
      break;
    case bfd_mach_alpha_ev5:
      isa_mask |= AXP_OPCODE_EV5;
      break;
    case bfd_mach_alpha_ev6:
      isa_mask |= AXP_OPCODE_EV6;
      break;
    }

  /* Read the insn into a host word */
  {
    bfd_byte buffer[4];
    int status = (*info->read_memory_func) (memaddr, buffer, 4, info);
    if (status != 0)
      {
	(*info->memory_error_func) (status, memaddr, info);
	return -1;
      }
    insn = bfd_getl32 (buffer);
  }

  /* Get the major opcode of the instruction.  */
  op = AXP_OP (insn);

  /* Find the first match in the opcode table.  */
  opcode_end = opcode_index[op + 1];
  for (opcode = opcode_index[op]; opcode < opcode_end; ++opcode)
    {
      if ((insn ^ opcode->opcode) & opcode->mask)
	continue;

      if (!(opcode->flags & isa_mask))
	continue;

      /* Make two passes over the operands.  First see if any of them
	 have extraction functions, and, if they do, make sure the
	 instruction is valid.  */
      {
	int invalid = 0;
	for (opindex = opcode->operands; *opindex != 0; opindex++)
	  {
	    const struct alpha_operand *operand = alpha_operands + *opindex;
	    if (operand->extract)
	      (*operand->extract) (insn, &invalid);
	  }
	if (invalid)
	  continue;
      }

      /* The instruction is valid.  */
      goto found;
    }

  /* No instruction found */
  (*info->fprintf_func) (info->stream, ".long %#08x", insn);

  return 4;

 found:
  (*info->fprintf_func) (info->stream, "%s", opcode->name);
  if (opcode->operands[0] != 0)
    (*info->fprintf_func) (info->stream, "\t");

  /* Now extract and print the operands.  */
  need_comma = 0;
  for (opindex = opcode->operands; *opindex != 0; opindex++)
    {
      const struct alpha_operand *operand = alpha_operands + *opindex;
      int value;

      /* Operands that are marked FAKE are simply ignored.  We
	 already made sure that the extract function considered
	 the instruction to be valid.  */
      if ((operand->flags & AXP_OPERAND_FAKE) != 0)
	continue;

      /* Extract the value from the instruction.  */
      if (operand->extract)
	value = (*operand->extract) (insn, (int *) NULL);
      else
	{
	  value = (insn >> operand->shift) & ((1 << operand->bits) - 1);
	  if (operand->flags & AXP_OPERAND_SIGNED)
	    {
	      int signbit = 1 << (operand->bits - 1);
	      value = (value ^ signbit) - signbit;
	    }
	}

      if (need_comma &&
	  ((operand->flags & (AXP_OPERAND_PARENS | AXP_OPERAND_COMMA))
	   != AXP_OPERAND_PARENS))
	{
	  (*info->fprintf_func) (info->stream, ",");
	}
      if (operand->flags & AXP_OPERAND_PARENS)
	(*info->fprintf_func) (info->stream, "(");

      /* Print the operand as directed by the flags.  */
      if (operand->flags & AXP_OPERAND_IR)
	(*info->fprintf_func) (info->stream, "%s", regnames[value]);
      else if (operand->flags & AXP_OPERAND_FPR)
	(*info->fprintf_func) (info->stream, "%s", regnames[value + 32]);
      else if (operand->flags & AXP_OPERAND_RELATIVE)
	(*info->print_address_func) (memaddr + 4 + value, info);
      else if (operand->flags & AXP_OPERAND_SIGNED)
	(*info->fprintf_func) (info->stream, "%d", value);
      else
	(*info->fprintf_func) (info->stream, "%#x", value);

      if (operand->flags & AXP_OPERAND_PARENS)
	(*info->fprintf_func) (info->stream, ")");
      need_comma = 1;
    }

  return 4;
}