nios2-dis.c

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/* Altera Nios II disassemble routines
   Copyright (C) 2012, 2013 Free Software Foundation, Inc.
   Contributed by Nigel Gray (ngray@altera.com).
   Contributed by Mentor Graphics, Inc.
 
   This file is part of the GNU opcodes library.
 
   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 "disas-asm.h"
#include "opcode/nios2.h"
#include "libiberty.h"
#include <string.h>
#include <assert.h>
#include <stdlib.h>
 
/* No symbol table is available when this code runs out in an embedded
   system as when it is used for disassembler support in a monitor.  */
#if !defined(EMBEDDED_ENV)
#define SYMTAB_AVAILABLE 1
#include "elf-bfd.h"
//#include "elf/nios2.h"
#endif
 
/* Length of Nios II instruction in bytes.  */
#define INSNLEN 4
 
/* Data structures used by the opcode hash table.  */
typedef struct _nios2_opcode_hash
{
  const struct nios2_opcode *opcode;
  struct _nios2_opcode_hash *next;
} nios2_opcode_hash;
 
static bfd_boolean nios2_hash_init = 0;
static nios2_opcode_hash *nios2_hash[(OP_MASK_OP) + 1];
 
/* Separate hash table for pseudo-ops.  */
static nios2_opcode_hash *nios2_ps_hash[(OP_MASK_OP) + 1];
 
/* Function to initialize the opcode hash table.  */
static void
nios2_init_opcode_hash (void)
{
  unsigned int i;
  register const struct nios2_opcode *op;
 
  for (i = 0; i <= OP_MASK_OP; ++i) {
      nios2_hash[0] = NULL;
  }
  for (i = 0; i <= OP_MASK_OP; i++) {
      for (op = nios2_opcodes; op < &nios2_opcodes[NUMOPCODES]; op++) {
          nios2_opcode_hash *new_hash;
          nios2_opcode_hash **bucket = NULL;
 
          if ((op->pinfo & NIOS2_INSN_MACRO) == NIOS2_INSN_MACRO) {
              if (i == ((op->match >> OP_SH_OP) & OP_MASK_OP) && (op->pinfo & (NIOS2_INSN_MACRO_MOV | NIOS2_INSN_MACRO_MOVI) & 0x7fffffff)) {
                  bucket = &(nios2_ps_hash[i]);
              }
          } else if (i == ((op->match >> OP_SH_OP) & OP_MASK_OP)) {
              bucket = &(nios2_hash[i]);
          }
 
          if (bucket) {
              new_hash =
                  (nios2_opcode_hash *)malloc (sizeof (nios2_opcode_hash));
              if (!new_hash) {
                  fprintf (stderr,
                      "error allocating memory...broken disassembler\n");
                  abort ();
              }
              new_hash->opcode = op;
              new_hash->next = NULL;
              while (*bucket) {
                  bucket = &((*bucket)->next);
              }
              *bucket = new_hash;
          }
      }
  }
  nios2_hash_init = 1;
#ifdef DEBUG_HASHTABLE
  for (i = 0; i <= OP_MASK_OP; ++i)
    {
      nios2_opcode_hash *tmp_hash = nios2_hash[i];
      printf ("index: 0x%02X    ops: ", i);
      while (tmp_hash != NULL)
    {
      printf ("%s ", tmp_hash->opcode->name);
      tmp_hash = tmp_hash->next;
    }
      printf ("\n");
    }
 
  for (i = 0; i <= OP_MASK_OP; ++i)
    {
      nios2_opcode_hash *tmp_hash = nios2_ps_hash[i];
      printf ("index: 0x%02X    ops: ", i);
      while (tmp_hash != NULL)
    {
      printf ("%s ", tmp_hash->opcode->name);
      tmp_hash = tmp_hash->next;
    }
      printf ("\n");
    }
#endif /* DEBUG_HASHTABLE */
}
 
/* Return a pointer to an nios2_opcode struct for a given instruction
   opcode, or NULL if there is an error.  */
const struct nios2_opcode *
nios2_find_opcode_hash (unsigned long opcode)
{
  nios2_opcode_hash *entry;
 
  /* Build a hash table to shorten the search time.  */
  if (!nios2_hash_init) {
      nios2_init_opcode_hash ();
  }
 
  /* First look in the pseudo-op hashtable.  */
  for (entry = nios2_ps_hash[(opcode >> OP_SH_OP) & OP_MASK_OP];
      entry; entry = entry->next) {
      if (entry->opcode->match == (opcode & entry->opcode->mask)) {
          return entry->opcode;
      }
  }
 
  /* Otherwise look in the main hashtable.  */
  for (entry = nios2_hash[(opcode >> OP_SH_OP) & OP_MASK_OP];
      entry; entry = entry->next) {
      if (entry->opcode->match == (opcode & entry->opcode->mask)) {
          return entry->opcode;
      }
  }
 
  return NULL;
}
 
/* There are 32 regular registers, 32 coprocessor registers,
   and 32 control registers.  */
#define NUMREGNAMES 32
 
/* Return a pointer to the base of the coprocessor register name array.  */
static struct nios2_reg *
nios2_coprocessor_regs (void)
{
  static struct nios2_reg *cached = NULL;
  
  if (!cached)
    {
      int i;
      for (i = NUMREGNAMES; i < nios2_num_regs; i++) {
          if (!strcmp (nios2_regs[i].name, "c0")) {
              cached = nios2_regs + i;
              break;
          }
      }
      assert (cached);
    }
  return cached;
}
 
/* Return a pointer to the base of the control register name array.  */
static struct nios2_reg *
nios2_control_regs (void)
{
  static struct nios2_reg *cached = NULL;
  
  if (!cached)
    {
      int i;
      for (i = NUMREGNAMES; i < nios2_num_regs; i++) {
          if (!strcmp (nios2_regs[i].name, "status")) {
              cached = nios2_regs + i;
              break;
          }
      }
      assert (cached);
    }
  return cached;
}
 
/* The function nios2_print_insn_arg uses the character pointed
   to by ARGPTR to determine how it print the next token or separator
   character in the arguments to an instruction.  */
static int
nios2_print_insn_arg (const char *argptr,
              unsigned long opcode, bfd_vma address,
              disassemble_info *info)
{
  unsigned long i = 0;
  struct nios2_reg *reg_base;
 
  switch (*argptr)
    {
    case ',':
    case '(':
    case ')':
      (*info->fprintf_func) (info->stream, "%c", *argptr);
      break;
    case 'd':
      i = GET_INSN_FIELD (RRD, opcode);
 
      if (GET_INSN_FIELD (OP, opcode) == OP_MATCH_CUSTOM && GET_INSN_FIELD (CUSTOM_C, opcode) == 0) {
          reg_base = nios2_coprocessor_regs ();
      } else {
          reg_base = nios2_regs;
      }
 
      if (i < NUMREGNAMES) {
          (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
      } else {
          (*info->fprintf_func) (info->stream, "unknown");
      }
      break;
    case 's':
      i = GET_INSN_FIELD (RRS, opcode);
 
      if (GET_INSN_FIELD (OP, opcode) == OP_MATCH_CUSTOM && GET_INSN_FIELD (CUSTOM_A, opcode) == 0) {
          reg_base = nios2_coprocessor_regs ();
      } else {
          reg_base = nios2_regs;
      }
 
      if (i < NUMREGNAMES) {
          (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
      } else {
          (*info->fprintf_func) (info->stream, "unknown");
      }
      break;
    case 't':
      i = GET_INSN_FIELD (RRT, opcode);
 
      if (GET_INSN_FIELD (OP, opcode) == OP_MATCH_CUSTOM && GET_INSN_FIELD (CUSTOM_B, opcode) == 0) {
          reg_base = nios2_coprocessor_regs ();
      } else {
          reg_base = nios2_regs;
      }
 
      if (i < NUMREGNAMES) {
          (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
      } else {
          (*info->fprintf_func) (info->stream, "unknown");
      }
      break;
    case 'i':
      /* 16-bit signed immediate.  */
      i = (int) (GET_INSN_FIELD (IMM16, opcode) << 16) >> 16;
      (*info->fprintf_func) (info->stream, "%ld", i);
      break;
    case 'u':
      /* 16-bit unsigned immediate.  */
      i = GET_INSN_FIELD (IMM16, opcode);
      (*info->fprintf_func) (info->stream, "%ld", i);
      break;
    case 'o':
      /* 16-bit signed immediate address offset.  */
      i = (int) (GET_INSN_FIELD (IMM16, opcode) << 16) >> 16;
      address = address + 4 + i;
      (*info->print_address_func) (address, info);
      break;
    case 'p':
      /* 5-bit unsigned immediate.  */
      i = GET_INSN_FIELD (CACHE_OPX, opcode);
      (*info->fprintf_func) (info->stream, "%ld", i);
      break;
    case 'j':
      /* 5-bit unsigned immediate.  */
      i = GET_INSN_FIELD (IMM5, opcode);
      (*info->fprintf_func) (info->stream, "%ld", i);
      break;
    case 'l':
      /* 8-bit unsigned immediate.  */
      /* FIXME - not yet implemented */
      i = GET_INSN_FIELD (CUSTOM_N, opcode);
      (*info->fprintf_func) (info->stream, "%lu", i);
      break;
    case 'm':
      /* 26-bit unsigned immediate.  */
      i = GET_INSN_FIELD (IMM26, opcode);
      /* This translates to an address because it's only used in call
     instructions.  */
      address = (address & 0xf0000000) | (i << 2);
      (*info->print_address_func) (address, info);
      break;
    case 'c':
      /* Control register index.  */
      i = GET_INSN_FIELD (IMM5, opcode);
      reg_base = nios2_control_regs ();
      (*info->fprintf_func) (info->stream, "%s", reg_base[i].name);
      break;
    case 'b':
      i = GET_INSN_FIELD (IMM5, opcode);
      (*info->fprintf_func) (info->stream, "%ld", i);
      break;
    default:
      (*info->fprintf_func) (info->stream, "unknown");
      break;
    }
  return 0;
}
 
/* nios2_disassemble does all the work of disassembling a Nios II
   instruction opcode.  */
static int
nios2_disassemble (bfd_vma address, unsigned long opcode,
           disassemble_info *info)
{
  const struct nios2_opcode *op;
 
  info->bytes_per_line = INSNLEN;
  info->bytes_per_chunk = INSNLEN;
  info->display_endian = info->endian;
  info->insn_info_valid = 1;
  info->branch_delay_insns = 0;
  info->data_size = 0;
  info->insn_type = dis_nonbranch;
  info->target = 0;
  info->target2 = 0;
 
  /* Find the major opcode and use this to disassemble
     the instruction and its arguments.  */
  op = nios2_find_opcode_hash (opcode);
 
  if (op != NULL)
    {
      bfd_boolean is_nop = FALSE;
      if (op->pinfo == NIOS2_INSN_MACRO_MOV)
    {
      /* Check for mov r0, r0 and change to nop.  */
      int dst, src;
      dst = GET_INSN_FIELD (RRD, opcode);
      src = GET_INSN_FIELD (RRS, opcode);
      if (dst == 0 && src == 0)
        {
          (*info->fprintf_func) (info->stream, "nop");
          is_nop = TRUE;
      } else {
          (*info->fprintf_func) (info->stream, "%s", op->name);
      }
      } else {
          (*info->fprintf_func) (info->stream, "%s", op->name);
      }
 
      if (!is_nop)
    {
      const char *argstr = op->args;
      if (argstr != NULL && *argstr != '\0')
        {
          (*info->fprintf_func) (info->stream, " ");
          while (*argstr != '\0')
        {
          nios2_print_insn_arg (argstr, opcode, address, info);
          ++argstr;
        }
        }
    }
    }
  else
    {
      /* Handle undefined instructions.  */
      info->insn_type = dis_noninsn;
      (*info->fprintf_func) (info->stream, "0x%lx", opcode);
    }
  /* Tell the caller how far to advance the program counter.  */
  return INSNLEN;
}
 
 
/* print_insn_nios2 is the main disassemble function for Nios II.
   The function diassembler(abfd) (source in disassemble.c) returns a
   pointer to this either print_insn_big_nios2 or
   print_insn_little_nios2, which in turn call this function when the
   bfd machine type is Nios II. print_insn_nios2 reads the
   instruction word at the address given, and prints the disassembled
   instruction on the stream info->stream using info->fprintf_func. */
 
static int
print_insn_nios2 (bfd_vma address, disassemble_info *info,
          enum bfd_endian endianness)
{
  bfd_byte buffer[INSNLEN];
  int status;
 
  status = (*info->read_memory_func) (address, buffer, INSNLEN, info);
  if (status == 0)
    {
      unsigned long insn;
      if (endianness == BFD_ENDIAN_BIG) {
          insn = (unsigned long)bfd_getb32 (buffer);
      } else {
          insn = (unsigned long)bfd_getl32 (buffer);
      }
      status = nios2_disassemble (address, insn, info);
    }
  else
    {
      (*info->memory_error_func) (status, address, info);
      status = -1;
    }
  return status;
}
 
/* These two functions are the main entry points, accessed from
   disassemble.c.  */
int
print_insn_big_nios2 (bfd_vma address, disassemble_info *info)
{
  return print_insn_nios2 (address, info, BFD_ENDIAN_BIG);
}
 
int
print_insn_little_nios2 (bfd_vma address, disassemble_info *info)
{
  return print_insn_nios2 (address, info, BFD_ENDIAN_LITTLE);
}