tc-tahoe.c

基于4个mips核的noc设计

  int reg = -1;			/* major register, -1 means absent */
  int imreg = -1;		/* Major register in immediate mode */
  int ndx = -1;			/* index register number, -1 means absent */
  char dec_inc = ' ';		/* Is the SP auto-incremented '+' or
				   auto-decremented '-' or neither ' '.  */
  int immediate = 0;		/* 1 if '$' immediate mode */
  int call_width = 0;		/* If the caller casts the displacement */
  int abs_width = 0;		/* The width of the absolute displacment */
  int com_width = 0;		/* Displacement width required by branch */
  int deferred = 0;		/* 1 if '*' deferral is used */
  byte disp_size = 0;		/* How big is this operand. 0 == don't know */
  char *op_bad = "";		/* Bad operand error */

  char *tp, *temp, c;		/* Temporary holders */

  char access = topP->top_access;	/* Save on a deref.  */
  char width = topP->top_width;

  int really_none = 0;		/* Empty expressions evaluate to 0
				   but I need to know if it's there or not */
  expressionS *expP;		/* -> expression values for this operand */

  /* Does this command restrict the displacement size.  */
  if (access == 'b')
    com_width = (width == 'b' ? 1 :
		 (width == 'w' ? 2 :
		  (width == 'l' ? 4 : 0)));

  *optex = '\0';		/* This is kind of a back stop for all
				   the searches to fail on if needed.*/
  if (*point == '*')
    {				/* A dereference? */
      deferred = 1;
      point++;
    }

  /* Force words into a certain mode */
  /* Bitch, Bitch, Bitch! */
  /*
   * Using the ^ operator is ambigous. If I have an absolute label
   * called 'w' set to, say 2, and I have the expression 'w^1', do I get
   * 1, forced to be in word displacement mode, or do I get the value of
   * 'w' or'ed with 1 (3 in this case).
   * The default is 'w' as an offset, so that's what I use.
   * Stick with `, it does the same, and isn't ambig.
   */

  if (*point != '\0' && ((point[1] == '^') || (point[1] == '`')))
    switch (*point)
      {
      case 'b':
      case 'B':
      case 'w':
      case 'W':
      case 'l':
      case 'L':
	if (com_width)
	  as_warn (_("Casting a branch displacement is bad form, and is ignored."));
	else
	  {
	    c = (isupper (*point) ? tolower (*point) : *point);
	    call_width = ((c == 'b') ? 1 :
			  ((c == 'w') ? 2 : 4));
	  }
	point += 2;
	break;
      }

  /* Setting immediate mode */
  if (*point == '$')
    {
      immediate = 1;
      point++;
    }

  /*
   * I've pulled off all the easy stuff off the front, move to the end and
   * yank.
   */

  for (end = point; *end != '\0'; end++)	/* Move to the end.  */
    ;

  if (end != point)		/* Null string? */
    end--;

  if (end > point && *end == ' ' && end[-1] != '\'')
    end--;			/* Hop white space */

  /* Is this an index reg.  */
  if ((*end == ']') && (end[-1] != '\''))
    {
      temp = end;

      /* Find opening brace.  */
      for (--end; (*end != '[' && end != point); end--)
	;

      /* If I found the opening brace, get the index register number.  */
      if (*end == '[')
	{
	  tp = end + 1;		/* tp should point to the start of a reg.  */
	  ndx = tahoe_reg_parse (&tp);
	  if (tp != temp)
	    {			/* Reg. parse error.  */
	      ndx = -1;
	    }
	  else
	    {
	      end--;		/* Found it, move past brace.  */
	    }
	  if (ndx == -1)
	    {
	      op_bad = _("Couldn't parse the [index] in this operand.");
	      end = point;	/* Force all the rest of the tests to fail.  */
	    }
	}
      else
	{
	  op_bad = _("Couldn't find the opening '[' for the index of this operand.");
	  end = point;		/* Force all the rest of the tests to fail.  */
	}
    }

  /* Post increment? */
  if (*end == '+')
    {
      dec_inc = '+';
      /* was:    *end--; */
      end--;
    }

  /* register in parens? */
  if ((*end == ')') && (end[-1] != '\''))
    {
      temp = end;

      /* Find opening paren.  */
      for (--end; (*end != '(' && end != point); end--)
	;

      /* If I found the opening paren, get the register number.  */
      if (*end == '(')
	{
	  tp = end + 1;
	  reg = tahoe_reg_parse (&tp);
	  if (tp != temp)
	    {
	      /* Not a register, but could be part of the expression.  */
	      reg = -1;
	      end = temp;	/* Rest the pointer back */
	    }
	  else
	    {
	      end--;		/* Found the reg. move before opening paren.  */
	    }
	}
      else
	{
	  op_bad = _("Couldn't find the opening '(' for the deref of this operand.");
	  end = point;		/* Force all the rest of the tests to fail.  */
	}
    }

  /* Pre decrement? */
  if (*end == '-')
    {
      if (dec_inc != ' ')
	{
	  op_bad = _("Operand can't be both pre-inc and post-dec.");
	  end = point;
	}
      else
	{
	  dec_inc = '-';
	  /* was:      *end--; */
	  end--;
	}
    }

  /*
   * Everything between point and end is the 'expression', unless it's
   * a register name.
   */

  c = end[1];
  end[1] = '\0';

  tp = point;
  imreg = tahoe_reg_parse (&point);	/* Get the immediate register
				      if it is there.*/
  if (*point != '\0')
    {
      /* If there is junk after point, then the it's not immediate reg.  */
      point = tp;
      imreg = -1;
    }

  if (imreg != -1 && reg != -1)
    op_bad = _("I parsed 2 registers in this operand.");

  /*
   * Evaluate whats left of the expression to see if it's valid.
   * Note again: This assumes that the calling expression has saved
   * input_line_pointer. (Nag, nag, nag!)
   */

  if (*op_bad == '\0')
    {
      /* Statement has no syntax goofs yet: let's sniff the expression.  */
      input_line_pointer = point;
      expP = &(topP->exp_of_operand);
      topP->seg_of_operand = expression (expP);
      switch (expP->X_op)
	{
	case O_absent:
	  /* No expression. For BSD4.2 compatibility, missing expression is
	     absolute 0 */
	  expP->X_op = O_constant;
	  expP->X_add_number = 0;
	  really_none = 1;
	case O_constant:
	  /* for SEG_ABSOLUTE, we shouldnt need to set X_op_symbol,
	     X_add_symbol to any particular value.  */
	  /* But, we will program defensively. Since this situation occurs
	     rarely so it costs us little to do so.  */
	  expP->X_add_symbol = NULL;
	  expP->X_op_symbol = NULL;
	  /* How many bytes are needed to express this abs value? */
	  abs_width =
	    ((((expP->X_add_number & 0xFFFFFF80) == 0) ||
	      ((expP->X_add_number & 0xFFFFFF80) == 0xFFFFFF80)) ? 1 :
	     (((expP->X_add_number & 0xFFFF8000) == 0) ||
	      ((expP->X_add_number & 0xFFFF8000) == 0xFFFF8000)) ? 2 : 4);

	case O_symbol:
	  break;

	default:
	  /*
	   * Major bug. We can't handle the case of a operator
	   * expression in a synthetic opcode variable-length
	   * instruction.  We don't have a frag type that is smart
	   * enough to relax a operator, and so we just force all
	   * operators to behave like SEG_PASS1s.  Clearly, if there is
	   * a demand we can invent a new or modified frag type and
	   * then coding up a frag for this case will be easy.
	   */
	  need_pass_2 = 1;
	  op_bad = _("Can't relocate expression error.");
	  break;

	case O_big:
	  /* This is an error. Tahoe doesn't allow any expressions
	     bigger that a 32 bit long word. Any bigger has to be referenced
	     by address.  */
	  op_bad = _("Expression is too large for a 32 bits.");
	  break;
	}
      if (*input_line_pointer != '\0')
	{
	  op_bad = _("Junk at end of expression.");
	}
    }

  end[1] = c;

  /* I'm done, so restore optex */
  *optex = segfault;

  /*
   * At this point in the game, we (in theory) have all the components of
   * the operand at least parsed. Now it's time to check for syntax/semantic
   * errors, and build the mode.
   * This is what I have:
   *   deferred = 1 if '*'
   *   call_width = 0,1,2,4
   *   abs_width = 0,1,2,4
   *   com_width = 0,1,2,4
   *   immediate = 1 if '$'
   *   ndx = -1 or reg num
   *   dec_inc = '-' or '+' or ' '
   *   reg = -1 or reg num
   *   imreg = -1 or reg num
   *   topP->exp_of_operand
   *   really_none
   */
  /* Is there a displacement size? */
  disp_size = (call_width ? call_width :
	       (com_width ? com_width :
		abs_width ? abs_width : 0));

  if (*op_bad == '\0')
    {
      if (imreg != -1)
	{
	  /* Rn */
	  mode = TAHOE_DIRECT_REG;
	  if (deferred || immediate || (dec_inc != ' ') ||
	      (reg != -1) || !really_none)
	    op_bad = _("Syntax error in direct register mode.");
	  else if (ndx != -1)
	    op_bad = _("You can't index a register in direct register mode.");
	  else if (imreg == SP_REG && access == 'r')
	    op_bad =
	      _("SP can't be the source operand with direct register addressing.");
	  else if (access == 'a')
	    op_bad = _("Can't take the address of a register.");
	  else if (access == 'b')
	    op_bad = _("Direct Register can't be used in a branch.");
	  else if (width == 'q' && ((imreg % 2) || (imreg > 13)))
	    op_bad = _("For quad access, the register must be even and < 14.");
	  else if (call_width)
	    op_bad = _("You can't cast a direct register.");

	  if (*op_bad == '\0')
	    {
	      /* No errors, check for warnings */
	      if (width == 'q' && imreg == 12)
		as_warn (_("Using reg 14 for quadwords can tromp the FP register."));

	      reg = imreg;
	    }

	  /* We know: imm = -1 */
	}
      else if (dec_inc == '-')
	{
	  /* -(SP) */
	  mode = TAHOE_AUTO_DEC;
	  if (deferred || immediate || !really_none)
	    op_bad = _("Syntax error in auto-dec mode.");
	  else if (ndx != -1)
	    op_bad = _("You can't have an index auto dec mode.");
	  else if (access == 'r')
	    op_bad = _("Auto dec mode cant be used for reading.");
	  else if (reg != SP_REG)
	    op_bad = _("Auto dec only works of the SP register.");
	  else if (access == 'b')
	    op_bad = _("Auto dec can't be used in a branch.");
	  else if (width == 'q')
	    op_bad = _("Auto dec won't work with quadwords.");

	  /* We know: imm = -1, dec_inc != '-' */
	}
      else if (dec_inc == '+')
	{
	  if (immediate || !really_none)
	    op_bad = _("Syntax error in one of the auto-inc modes.");
	  else if (deferred)
	    {
	      /* *(SP)+ */
	      mode = TAHOE_AUTO_INC_DEFERRED;
	      if (reg != SP_REG)
		op_bad = _("Auto inc deferred only works of the SP register.");
	      else if (ndx != -1)
		op_bad = _("You can't have an index auto inc deferred mode.");
	      else if (access == 'b')
		op_bad = _("Auto inc can't be used in a branch.");
	    }
	  else
	    {
	      /* (SP)+ */
	      mode = TAHOE_AUTO_INC;
	      if (access == 'm' || access == 'w')
		op_bad = _("You can't write to an auto inc register.");
	      else if (reg != SP_REG)
		op_bad = _("Auto inc only works of the SP register.");
	      else if (access == 'b')
		op_bad = _("Auto inc can't be used in a branch.");
	      else if (width == 'q')
		op_bad = _("Auto inc won't work with quadwords.");
	      else if (ndx != -1)
		op_bad = _("You can't have an index in auto inc mode.");
	    }

	  /* We know: imm = -1, dec_inc == ' ' */
	}
      else if (reg != -1)
	{
	  if ((ndx != -1) && (reg == SP_REG))
	    op_bad = _("You can't index the sp register.");
	  if (deferred)
	    {
	      /* *<disp>(Rn) */
	      mode = TAHOE_REG_DISP_DEFERRED;
	      if (immediate)
		op_bad = _("Syntax error in register displaced mode.");
	    }
	  else if (really_none)
	    {
	      /* (Rn) */
	      mode = TAHOE_REG_DEFERRED;
	      /* if reg = SP then cant be indexed */
	    }
	  else
	    {
	      /* <disp>(Rn) */
	      mode = TAHOE_REG_DISP;
	    }

	  /* We know: imm = -1, dec_inc == ' ', Reg = -1 */
	}
      else
	{
	  if (really_none)
	    op_bad = _("An offest is needed for this operand.");
	  if (deferred && immediate)
	    {
	      /* *$<ADDR> */
	      mode = TAHOE_ABSOLUTE_ADDR;
	      disp_size = 4;
	    }
	  else if (immediate)
	    {
	      /* $<disp> */
	      mode = TAHOE_IMMEDIATE;
	      if (ndx != -1)
		op_bad = _("You can't index a register in immediate mode.");
	      if (access == 'a')
		op_bad = _("Immediate access can't be used as an address.");
	      /* ponder the wisdom of a cast because it doesn't do any good.  */
	    }
	  else if (deferred)
	    {
	      /* *<disp> */
	      mode = TAHOE_DISP_REL_DEFERRED;
	    }
	  else
	    {
	      /* <disp> */
	      mode = TAHOE_DISPLACED_RELATIVE;
	    }
	}
    }

  /*
   * At this point, all the errors we can do have be checked for.
   * We can build the 'top'.  */

  topP->top_ndx = ndx;
  topP->top_reg = reg;
  topP->top_mode = mode;
  topP->top_error = op_bad;
  topP->top_dispsize = disp_size;
}				/* tip_op */

/*
 *                  t i p ( )
 *
 * This converts a string into a tahoe instruction.
 * The string must be a bare single instruction in tahoe (with BSD4 frobs)
 * format.
 * It provides at most one fatal error message (which stops the scan)
 * some warning messages as it finds them.
 * The tahoe instruction is returned in exploded form.
 *
 * The exploded instruction is returned to a struct tit of your choice.
 * #include "tahoe-inst.h" to know what a struct tit is.
 *
 */

static void
tip (titP, instring)
     struct tit *titP;		/* We build an exploded instruction here.  */
     char *instring;		/* Text of a vax instruction: we modify.  */
{
  register struct tot_wot *twP = NULL;	/* How to bit-encode this opcode.  */
  register char *p;		/* 1/skip whitespace.2/scan vot_how */
  register char *q;		/*  */
  register unsigned char count;	/* counts number of operands seen */
  register struct top *operandp;/* scan operands in struct tit */
  register char *alloperr = "";	/* error over all operands */
  register char c;		/* Remember char, (we clobber it
				   with '\0' temporarily).  */
  char *save_input_line_pointer;

  if (*instring == ' ')
    ++instring;			/* Skip leading whitespace.  */
  for (p = instring; *p && *p != ' '; p++)
    ;				/* MUST end in end-of-string or
				   exactly 1 space.  */
  /* Scanned up to end of operation-code.  */
  /* Operation-code is ended with whitespace.  */
  if (p == instring)
    {
      titP->tit_error = _("No operator");
      count = 0;
      titP->tit_opcode = 0;
    }
  else
    {
      c = *p;
      *p = '\0';
      /*
     * Here with instring pointing to what better be an op-name, and p
     * pointing to character just past that.
     * We trust instring points to an op-name, with no whitespace.
     */
      twP = (struct tot_wot *) hash_find (op_hash, instring);
      *p = c;			/* Restore char after op-code.  */
      if (twP == 0)
	{