vax.c

早期freebsd实现

/* You should use ".word ..." statements after the "case ...". */

  {"", ""}			/* empty is end sentinel */

};				/* synthetic_votstrs */

/*
 *                  v i p _ b e g i n ( )
 *
 * Call me once before you decode any lines.
 * I decode votstrs into a hash table at op_hash (which I create).
 * I return an error text: hopefully "".
 * If you want, I will include the 'synthetic' jXXX instructions in the
 * instruction table.
 * You must nominate metacharacters for eg DEC's "#", "@", "^".
 */

char *
vip_begin (synthetic_too, immediate, indirect, displen)
     int synthetic_too;		/* TRUE means include jXXX op-codes. */
     char *immediate, *indirect, *displen;
{
  register const struct vot *vP;	/* scan votstrs */
  register char *retval;	/* error text */

  char *hash_insert ();		/*  */
  char *hash_new ();		/* lies */

  if ((op_hash = hash_new ()))
    {
      retval = "";		/* OK so far */
      for (vP = votstrs; *vP->vot_name && !*retval; vP++)
	{
	  retval = hash_insert (op_hash, vP->vot_name, &vP->vot_detail);
	}
      if (synthetic_too)
	{
	  for (vP = synthetic_votstrs; *vP->vot_name && !*retval; vP++)
	    {
	      retval = hash_insert (op_hash, vP->vot_name, &vP->vot_detail);
	    }
	}
    }
  else
    {
      retval = "virtual memory exceeded";
    }
#ifndef CONST_TABLE
  vip_op_defaults (immediate, indirect, displen);
#endif

  return (retval);
}


/*
 *                  v i p _ e n d ( )
 *
 * Call me once after you have decoded all lines.
 * I do any cleaning-up needed.
 *
 * We don't have to do any cleanup ourselves: all of our operand
 * symbol table is static, and free()ing it is naughty.
 */
vip_end ()
{
}

/*
 *                  v i p ( )
 *
 * This converts a string into a vax instruction.
 * The string must be a bare single instruction in dec-vax (with BSD4 frobs)
 * format.
 * It provides some error messages: at most one fatal error message (which
 * stops the scan) and at most one warning message for each operand.
 * The vax instruction is returned in exploded form, since we have no
 * knowledge of how you parse (or evaluate) your expressions.
 * We do however strip off and decode addressing modes and operation
 * mnemonic.
 *
 * The exploded instruction is returned to a struct vit of your choice.
 * #include "vax-inst.h" to know what a struct vit is.
 *
 * This function's value is a string. If it is not "" then an internal
 * logic error was found: read this code to assign meaning to the string.
 * No argument string should generate such an error string:
 * it means a bug in our code, not in the user's text.
 *
 * You MUST have called vip_begin() once and vip_end() never before using
 * this function.
 */

char *				/* "" or bug string */
vip (vitP, instring)
     struct vit *vitP;		/* We build an exploded instruction here. */
     char *instring;		/* Text of a vax instruction: we modify. */
{
  register struct vot_wot *vwP;	/* How to bit-encode this opcode. */
  register char *p;		/* 1/skip whitespace.2/scan vot_how */
  register char *q;		/*  */
  register char *bug;		/* "" or program logic error */
  register unsigned char count;	/* counts number of operands seen */
  register struct vop *operandp;/* scan operands in struct vit */
  register char *alloperr;	/* error over all operands */
  register char c;		/* Remember char, (we clobber it */
  /* with '\0' temporarily). */
  register vax_opcodeT oc;	/* Op-code of this instruction. */

  struct vot_wot *hash_find ();
  char *vip_op ();

  bug = "";
  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 == 0)
    {
      vitP->vit_error = "No operator";
      count = 0;
      bzero (vitP->vit_opcode, sizeof (vitP->vit_opcode));
    }
  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.
       */
      vwP = hash_find (op_hash, instring);
      *p = c;			/* Restore char after op-code. */
      if (vwP == 0)
	{
	  vitP->vit_error = "Unknown operator";
	  count = 0;
	  bzero (vitP->vit_opcode, sizeof (vitP->vit_opcode));
	}
      else
	{
	  /*
	   * We found a match! So lets pick up as many operands as the
	   * instruction wants, and even gripe if there are too many.
	   * We expect comma to seperate each operand.
	   * We let instring track the text, while p tracks a part of the
	   * struct vot.
	   */
	  /*
	   * The lines below know about 2-byte opcodes starting FD,FE or FF.
	   * They also understand synthetic opcodes. Note:
	   * we return 32 bits of opcode, including bucky bits, BUT
	   * an opcode length is either 8 or 16 bits for vit_opcode_nbytes.
	   */
	  oc = vwP->vot_code;	/* The op-code. */
	  vitP->vit_opcode_nbytes = (oc & 0xFF) >= 0xFD ? 2 : 1;
	  md_number_to_chars (vitP->vit_opcode, oc, 4);
	  count = 0;		/* no operands seen yet */
	  instring = p;		/* point just past operation code */
	  alloperr = "";
	  for (p = vwP->vot_how, operandp = vitP->vit_operand;
	       !*alloperr && !*bug && *p;
	       operandp++, p += 2
	    )
	    {
	      /*
	       * Here to parse one operand. Leave instring pointing just
	       * past any one ',' that marks the end of this operand.
	       */
	      if (!p[1])
		bug = "p";	/* ODD(!!) number of bytes in vot_how?? */
	      else if (*instring)
		{
		  for (q = instring; (c = *q) && c != ','; q++)
		    ;
		  /*
		   * Q points to ',' or '\0' that ends argument. C is that
		   * character.
		   */
		  *q = 0;
		  operandp->vop_width = p[1];
		  operandp->vop_nbytes = vax_operand_width_size[p[1]];
		  operandp->vop_access = p[0];
		  bug = vip_op (instring, operandp);
		  *q = c;	/* Restore input text. */
		  if (*(operandp->vop_error))
		    alloperr = "Bad operand";
		  instring = q + (c ? 1 : 0);	/* next operand (if any) */
		  count++;	/*  won another argument, may have an operr */
		}
	      else
		alloperr = "Not enough operands";
	    }
	  if (!*alloperr)
	    {
	      if (*instring == ' ')
		instring++;	/* Skip whitespace. */
	      if (*instring)
		alloperr = "Too many operands";
	    }
	  vitP->vit_error = alloperr;
	}
    }
  vitP->vit_operands = count;
  return (bug);
}

#ifdef test

/*
 * Test program for above.
 */

struct vit myvit;		/* build an exploded vax instruction here */
char answer[100];		/* human types a line of vax assembler here */
char *mybug;			/* "" or an internal logic diagnostic */
int mycount;			/* number of operands */
struct vop *myvop;		/* scan operands from myvit */
int mysynth;			/* TRUE means want synthetic opcodes. */
char my_immediate[200];
char my_indirect[200];
char my_displen[200];

char *vip ();

main ()
{
  char *p;
  char *vip_begin ();

  printf ("0 means no synthetic instructions.   ");
  printf ("Value for vip_begin?  ");
  gets (answer);
  sscanf (answer, "%d", &mysynth);
  printf ("Synthetic opcodes %s be included.\n", mysynth ? "will" : "will not");
  printf ("enter immediate symbols eg enter #   ");
  gets (my_immediate);
  printf ("enter indirect symbols  eg enter @   ");
  gets (my_indirect);
  printf ("enter displen symbols   eg enter ^   ");
  gets (my_displen);
  if (*(p = vip_begin (mysynth, my_immediate, my_indirect, my_displen)))
    {
      error ("vip_begin=%s", p);
    }
  printf ("An empty input line will quit you from the vax instruction parser\n");
  for (;;)
    {
      printf ("vax instruction: ");
      fflush (stdout);
      gets (answer);
      if (!*answer)
	{
	  break;		/* out of for each input text loop */
	}
      mybug = vip (&myvit, answer);
      if (*mybug)
	{
	  printf ("BUG:\"%s\"\n", mybug);
	}
      if (*myvit.vit_error)
	{
	  printf ("ERR:\"%s\"\n", myvit.vit_error);
	}
      printf ("opcode=");
      for (mycount = myvit.vit_opcode_nbytes, p = myvit.vit_opcode;
	   mycount;
	   mycount--, p++
	)
	{
	  printf ("%02x ", *p & 0xFF);
	}
      printf ("   operand count=%d.\n", mycount = myvit.vit_operands);
      for (myvop = myvit.vit_operand; mycount; mycount--, myvop++)
	{
	  printf ("mode=%xx reg=%xx ndx=%xx len='%c'=%c%c%d. expr=\"",
		  myvop->vop_mode, myvop->vop_reg, myvop->vop_ndx,
		  myvop->vop_short, myvop->vop_access, myvop->vop_width,
		  myvop->vop_nbytes);
	  for (p = myvop->vop_expr_begin; p <= myvop->vop_expr_end; p++)
	    {
	      putchar (*p);
	    }
	  printf ("\"\n");
	  if (*myvop->vop_error)
	    {
	      printf ("  err:\"%s\"\n", myvop->vop_error);
	    }
	  if (*myvop->vop_warn)
	    {
	      printf ("  wrn:\"%s\"\n", myvop->vop_warn);
	    }
	}
    }
  vip_end ();
  exit ();
}

#endif /* #ifdef test */

/* end of vax_ins_parse.c */

 /* JF this used to be a separate file also */
/* vax_reg_parse.c - convert a VAX register name to a number */

/* Copyright (C) 1987 Free Software Foundation, Inc. A part of GNU. */

/*
 *          v a x _ r e g _ p a r s e ( )
 *
 * Take 3 char.s, the last of which may be `\0` (non-existent)
 * and return the VAX register number that they represent.
 *
 * Return -1 if they don't form a register name. Good names return
 * a number from 0:15 inclusive.
 *
 * Case is not important in a name.
 *
 * Register names understood are:
 *
 *	R0
 *	R1
 *	R2
 *	R3
 *	R4
 *	R5
 *	R6
 * 	R7
 *	R8
 *	R9
 *	R10
 *	R11
 *	R12	AP
 *	R13	FP
 *	R14	SP
 *	R15	PC
 *
 */

#include <ctype.h>
#define AP (12)
#define FP (13)
#define SP (14)
#define PC (15)

int				/* return -1 or 0:15 */
vax_reg_parse (c1, c2, c3)	/* 3 chars of register name */
     char c1, c2, c3;		/* c3 == 0 if 2-character reg name */
{
  register int retval;		/* return -1:15 */

  retval = -1;

  if (isupper (c1))
    c1 = tolower (c1);
  if (isupper (c2))
    c2 = tolower (c2);
  if (isdigit (c2) && c1 == 'r')
    {
      retval = c2 - '0';
      if (isdigit (c3))
	{
	  retval = retval * 10 + c3 - '0';
	  retval = (retval > 15) ? -1 : retval;
	  /* clamp the register value to 1 hex digit */
	}
      else if (c3)
	retval = -1;		/* c3 must be '\0' or a digit */
    }
  else if (c3)			/* There are no three letter regs */
    retval = -1;
  else if (c2 == 'p')
    {
      switch (c1)
	{
	case 's':
	  retval = SP;
	  break;
	case 'f':
	  retval = FP;
	  break;
	case 'a':
	  retval = AP;
	  break;
	default:
	  retval = -1;
	}
    }
  else if (c1 == 'p' && c2 == 'c')
    retval = PC;
  else
    retval = -1;
  return (retval);
}

/* end: vax_reg_parse.c */

 /* JF this was another separate prog */
/* vip_op.c - parse 1 VAX instr's operand.(C)1986 Free Software Foundation. */

/* JF #include <ctype.h> */
/* #include "vax_inst.h" */

/*
 *               v i p _ o p ( )
 *
 * Parse a vax operand in DEC assembler notation.
 * For speed, expect a string of whitespace to be reduced to a single ' '.
 * This is the case for GNU AS, and is easy for other DEC-compatible
 * assemblers.
 *
 * Knowledge about DEC VAX assembler operand notation lives here.
 * This doesn't even know what a register name is, except it believes
 * all register names are 2 or 3 characters, and lets vax_reg_parse() say
 * what number each name represents.
 * It does, however, know that PC, SP etc are special registers so it can
 * detect addressing modes that are silly for those registers.
 *
 * Where possible, it delivers 1 fatal or 1 warning message if the operand
 * is suspect. Exactly what we test for is still evolving.
 */

/*
 *		   	B u g s
 *
 *	Arg block.
 *
 * There were a number of 'mismatched argument type' bugs to vip_op.
 * The most general solution is to typedef each (of many) arguments.
 * We used instead a typedef'd argument block. This is less modular
 * than using seperate return pointers for each result, but runs faster
 * on most engines, and seems to keep programmers happy. It will have
 * to be done properly if we ever want to use vip_op as a general-purpose
 * module (it was designed to be).
 *
 *	G^
 *
 * Doesn't support DEC "G^" format operands. These always take 5 bytes
 * to express, and code as modes 8F or 9F. Reason: "G^" deprives you of
 * optimising to (say) a "B^" if you are lucky in the way you link.
 * When someone builds a linker smart enough to convert "G^" to "B^", "W^"
 * when