path: root/gdb/sparc-pinsn.c

/* Disassembler for the sparc.
   Copyright (C) 1989 Free Software Foundation, Inc.

This file is part of GDB, the GNU disassembler.

GDB 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 1, or (at your option)
any later version.

GDB 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 GDB; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <stdio.h>

#include "defs.h"
#include "param.h"
#include "symtab.h"
#include "sparc-opcode.h"

extern char *reg_names[];
#define	freg_names	(&reg_names[4 * 8])

union sparc_insn
  {
    unsigned long int code;
    struct
      {
	unsigned int OP:2;
#define	op	ldst.OP
	unsigned int RD:5;
#define	rd	ldst.RD
	unsigned int op3:6;
	unsigned int RS1:5;
#define	rs1	ldst.RS1
	unsigned int i:1;
	unsigned int ASI:8;
#define	asi	ldst.ASI
	unsigned int RS2:5;
#define	rs2	ldst.RS2
#define	shcnt	rs2
      } ldst;
    struct
      {
	unsigned int OP:2, RD:5, op3:6, RS1:5, i:1;
	unsigned int IMM13:13;
#define	imm13	IMM13.IMM13
      } IMM13;
    struct
      {
	unsigned int OP:2;
	unsigned int a:1;
	unsigned int cond:4;
	unsigned int op2:3;
	unsigned int DISP22:22;
#define	disp22	branch.DISP22
      } branch;
#define	imm22	disp22
    struct
      {
	unsigned int OP:2;
	unsigned int DISP30:30;
#define	disp30	call.DISP30
      } call;
  };

/* Nonzero if INSN is the opcode for a delayed branch.  */
static int
is_delayed_branch (insn)
     union sparc_insn insn;
{
  unsigned int i;

  for (i = 0; i < NUMOPCODES; ++i)
    {
      const struct sparc_opcode *opcode = &sparc_opcodes[i];
      if ((opcode->match & insn.code) == opcode->match
	  && (opcode->lose & insn.code) == 0
	  && (opcode->delayed))
	return 1;
    }
  return 0;
}

static int opcodes_sorted = 0;

/* Print one instruction from MEMADDR on STREAM.  */
int
print_insn (memaddr, stream)
     CORE_ADDR memaddr;
     FILE *stream;
{
  union sparc_insn insn;

  register unsigned int i;

  if (!opcodes_sorted)
    {
      static int compare_opcodes ();
      qsort ((char *) sparc_opcodes, NUMOPCODES,
	     sizeof (sparc_opcodes[0]), compare_opcodes);
      opcodes_sorted = 1;
    }

  read_memory (memaddr, &insn, sizeof (insn));

  for (i = 0; i < NUMOPCODES; ++i)
    {
      const struct sparc_opcode *opcode = &sparc_opcodes[i];
      if ((opcode->match & insn.code) == opcode->match
	  && (opcode->lose & insn.code) == 0)
	{
	  /* Nonzero means that we have found an instruction which has
	     the effect of adding or or'ing the imm13 field to rs1.  */
	  int imm_added_to_rs1 = 0;

	  /* Nonzero means that we have found a plus sign in the args
	     field of the opcode table.  */
	  int found_plus = 0;
	  
	  /* Do we have an 'or' instruction where rs1 is the same
	     as rsd, and which has the i bit set?  */
	  if (opcode->match == 0x80102000
	      && insn.rs1 == insn.rd)
	    imm_added_to_rs1 = 1;

	  if (index (opcode->args, 'S') != 0)
	    /* Reject the special case for `set'.
	       The real `sethi' will match.  */
	    continue;
	  if (insn.rs1 != insn.rd
	      && index (opcode->args, 'r') != 0)
	      /* Can't do simple format if source and dest are different.  */
	      continue;

	  fputs_filtered (opcode->name, stream);

	  {
	    register const char *s;

	    if (opcode->args[0] != ',')
	      fputs_filtered (" ", stream);
	    for (s = opcode->args; *s != '\0'; ++s)
	      {
		if (*s == ',')
		  {
		    fputs_filtered (",", stream);
		    ++s;
		    if (*s == 'a')
		      {
			fputs_filtered ("a", stream);
			++s;
		      }
		    fputs_filtered (" ", stream);
		  }

		switch (*s)
		  {
		  case '+':
		    found_plus = 1;

		    /* note fall-through */
		  default:
		    fprintf_filtered (stream, "%c", *s);
		    break;

		  case '#':
		    fputs_filtered ("0", stream);
		    break;

#define	reg(n)	fprintf_filtered (stream, "%%%s", reg_names[n])
		  case '1':
		  case 'r':
		    reg (insn.rs1);
		    break;

		  case '2':
		    reg (insn.rs2);
		    break;

		  case 'd':
		    reg (insn.rd);
		    break;
#undef	reg

#define	freg(n)	fprintf_filtered (stream, "%%%s", freg_names[n])
		  case 'e':
		    freg (insn.rs1);
		    break;

		  case 'f':
		    freg (insn.rs2);
		    break;

		  case 'g':
		    freg (insn.rd);
		    break;
#undef	freg

#define	creg(n)	fprintf_filtered (stream, "%%c%u", (unsigned int) (n))
		  case 'b':
		    creg (insn.rs1);
		    break;

		  case 'c':
		    creg (insn.rs2);
		    break;

		  case 'D':
		    creg (insn.rd);
		    break;
#undef	creg

		  case 'h':
		    fprintf_filtered (stream, "%%hi(%#x)",
				      (int) insn.imm22 << 10);
		    break;

		  case 'i':
		    {
		      /* We cannot trust the compiler to sign-extend
			 when extracting the bitfield, hence the shifts.  */
		      int imm = ((int) insn.imm13 << 19) >> 19;

		      /* Check to see whether we have a 1+i, and take
			 note of that fact.

			 Note: because of the way we sort the table,
			 we will be matching 1+i rather than i+1,
			 so it is OK to assume that i is after +,
			 not before it.  */
		      if (found_plus)
			imm_added_to_rs1 = 1;
		      
		      if (imm <= 9)
			fprintf_filtered (stream, "%d", imm);
		      else
			fprintf_filtered (stream, "%#x", imm);
		    }
		    break;

		  case 'L':
		    print_address ((CORE_ADDR) memaddr + insn.disp30 * 4,
				   stream);
		    break;

		  case 'l':
		    if ((insn.code >> 22) == 0)
		      /* Special case for `unimp'.  Don't try to turn
			 it's operand into a function offset.  */
		      fprintf_filtered (stream, "%#x",
					(int) (((int) insn.disp22 << 10) >> 10));
		    else
		      /* We cannot trust the compiler to sign-extend
			 when extracting the bitfield, hence the shifts.  */
		      print_address ((CORE_ADDR)
				     (memaddr
				      + (((int) insn.disp22 << 10) >> 10) * 4),
				     stream);
		    break;

		  case 'A':
		    fprintf_filtered (stream, "(%d)", (int) insn.asi);
		    break;

		  case 'C':
		    fputs_filtered ("%csr", stream);
		    break;

		  case 'F':
		    fputs_filtered ("%fsr", stream);
		    break;

		  case 'p':
		    fputs_filtered ("%psr", stream);
		    break;

		  case 'q':
		    fputs_filtered ("%fq", stream);
		    break;

		  case 'Q':
		    fputs_filtered ("%cq", stream);
		    break;

		  case 't':
		    fputs_filtered ("%tbr", stream);
		    break;

		  case 'w':
		    fputs_filtered ("%wim", stream);
		    break;

		  case 'y':
		    fputs_filtered ("%y", stream);
		    break;
		  }
	      }
	  }

	  /* If we are adding or or'ing something to rs1, then
	     check to see whether the previous instruction was
	     a sethi to the same register as in the sethi.
	     If so, attempt to print the result of the add or
	     or (in this context add and or do the same thing)
	     and its symbolic value.  */
	  if (imm_added_to_rs1)
	    {
	      union sparc_insn prev_insn;
	      int errcode;

	      errcode = read_memory (memaddr - 4,
				     &prev_insn, sizeof (prev_insn));

	      if (errcode == 0)
		{
		  /* If it is a delayed branch, we need to look at the
		     instruction before the delayed branch.  This handles
		     sequences such as

		     sethi %o1, %hi(_foo), %o1
		     call _printf
		     or %o1, %lo(_foo), %o1
		     */

		  if (is_delayed_branch (prev_insn))
		    errcode = read_memory (memaddr - 8,
					   &prev_insn, sizeof (prev_insn));
		}

	      /* If there was a problem reading memory, then assume
		 the previous instruction was not sethi.  */
	      if (errcode == 0)
		{
		  /* Is it sethi to the same register?  */
		  if ((prev_insn.code & 0xc1c00000) == 0x01000000
		      && prev_insn.rd == insn.rs1)
		    {
		      fprintf_filtered (stream, "\t! ");
		      /* We cannot trust the compiler to sign-extend
			 when extracting the bitfield, hence the shifts.  */
		      print_address (((int) prev_insn.imm22 << 10)
				     | (insn.imm13 << 19) >> 19, stream);
		    }
		}
	    }

	  return sizeof (insn);
	}
    }

  fprintf_filtered ("%#8x", insn.code);
  return sizeof (insn);
}


/* Compare opcodes A and B.  */

static int
compare_opcodes (a, b)
     char *a, *b;
{
  struct sparc_opcode *op0 = (struct sparc_opcode *) a;
  struct sparc_opcode *op1 = (struct sparc_opcode *) b;
  unsigned long int match0 = op0->match, match1 = op1->match;
  unsigned long int lose0 = op0->lose, lose1 = op1->lose;
  register unsigned int i;

  /* If a bit is set in both match and lose, there is something
     wrong with the opcode table.  */
  if (match0 & lose0)
    {
      fprintf (stderr, "Internal error:  bad sparc-opcode.h: \"%s\", %#.8x, %#.8x\n",
	       op0->name, match0, lose0);
      op0->lose &= ~op0->match;
      lose0 = op0->lose;
    }

  if (match1 & lose1)
    {
      fprintf (stderr, "Internal error: bad sparc-opcode.h: \"%s\", %#.8x, %#.8x\n",
	       op1->name, match1, lose1);
      op1->lose &= ~op1->match;
      lose1 = op1->lose;
    }

  /* Because the bits that are variable in one opcode are constant in
     another, it is important to order the opcodes in the right order.  */
  for (i = 0; i < 32; ++i)
    {
      unsigned long int x = 1 << i;
      int x0 = (match0 & x) != 0;
      int x1 = (match1 & x) != 0;

      if (x0 != x1)
	return x1 - x0;
    }

  for (i = 0; i < 32; ++i)
    {
      unsigned long int x = 1 << i;
      int x0 = (lose0 & x) != 0;
      int x1 = (lose1 & x) != 0;

      if (x0 != x1)
	return x1 - x0;
    }

  /* They are functionally equal.  So as long as the opcode table is
     valid, we can put whichever one first we want, on aesthetic grounds.  */
  {
    int length_diff = strlen (op0->args) - strlen (op1->args);
    if (length_diff != 0)
      /* Put the one with fewer arguments first.  */
      return length_diff;
  }

  /* Put 1+i before i+1.  */
  {
    char *p0 = (char *) index(op0->args, '+');
    char *p1 = (char *) index(op1->args, '+');

    if (p0 && p1)
      {
	/* There is a plus in both operands.  Note that a plus
	   sign cannot be the first character in args,
	   so the following [-1]'s are valid.  */
	if (p0[-1] == 'i' && p1[1] == 'i')
	  /* op0 is i+1 and op1 is 1+i, so op1 goes first.  */
	  return 1;
	if (p0[1] == 'i' && p1[-1] == 'i')
	  /* op0 is 1+i and op1 is i+1, so op0 goes first.  */
	  return -1;
      }
  }

  /* They are, as far as we can tell, identical.
     Since qsort may have rearranged the table partially, there is
     no way to tell which one was first in the opcode table as
     written, so just say there are equal.  */
  return 0;
}