ftp.nice.ch/pub/next/developer/languages/lisp/AKCL.1.599.s.tar.gz#/gas-1.38.1.hacked/i860.c

This is i860.c in view mode; [Download] [Up]

/* i860.c -- Assemble for the I860
   Copyright (C) 1989 Free Software Foundation, Inc.

This file is part of GAS, the GNU Assembler.

GAS 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.

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


#include <stdio.h>
#include <ctype.h>

#include "i860-opcode.h"
#include "as.h"
#include "frags.h"
#include "struc-symbol.h"
#include "flonum.h"
#include "expr.h"
#include "hash.h"
#include "md.h"
#include "i860.h"	/* position dependent redefine */
#include "write.h"
#include "read.h"
#include "symbols.h"

void md_begin();
void md_end();
void md_number_to_chars();
void md_assemble();
char *md_atof();
void md_convert_frag();
void md_create_short_jump();
void md_create_long_jump();
int  md_estimate_size_before_relax();
void md_number_to_imm();
void md_number_to_disp();
void md_number_to_field();
void md_ri_to_chars();
static void i860_ip();
void emit_relocations();

const relax_typeS md_relax_table[] = { 0 };

/* handle of the OPCODE hash table */
static struct hash_control *op_hash = NULL;

static void s_dual(), s_enddual();
static void s_atmp();

const pseudo_typeS
md_pseudo_table[] = {
    { "dual",       s_dual,     4 },
    { "enddual",    s_enddual,  4 },
    { "atmp",	    s_atmp,	4 },
    { NULL,         0,          0 },
};

int md_short_jump_size = 4;
int md_long_jump_size = 4;
int omagic  =  OMAGIC;  /* Magic number for header */

/* This array holds the chars that always start a comment.  If the
    pre-processor is disabled, these aren't very useful */
char comment_chars[] = "!/";	/* JF removed '|' from comment_chars */

/* This array holds the chars that only start a comment at the beginning of
   a line.  If the line seems to have the form '# 123 filename'
   .line and .file directives will appear in the pre-processed output */
/* Note that input_file.c hand checks for '#' at the beginning of the
   first line of the input file.  This is because the compiler outputs
   #NO_APP at the beginning of its output. */
/* Also note that '/*' will always start a comment */
char line_comment_chars[] = "#/";

/* Chars that can be used to separate mant from exp in floating point nums */
char EXP_CHARS[] = "eE";

/* Chars that mean this number is a floating point constant */
/* As in 0f12.456 */
/* or    0d1.2345e12 */
char FLT_CHARS[] = "rRsSfFdDxXpP";

/* Also be aware that MAXIMUM_NUMBER_OF_CHARS_FOR_FLOAT may have to be
   changed in read.c .  Ideally it shouldn't have to know about it at all,
   but nothing is ideal around here.
 */
int size_reloc_info = sizeof(struct relocation_info);

static unsigned char octal[256];
#define isoctal(c)  octal[c]
static unsigned char toHex[256];

struct i860_it {
    char    *error;
    unsigned long opcode;
    struct nlist *nlistp;
    expressionS exp;
    int pcrel;
    enum expand_type expand;
    enum highlow_type highlow;
    enum reloc_type reloc;
} the_insn;

#ifdef __STDC__
static void print_insn(struct i860_it *insn);
static int getExpression(char *str);
#else
static void print_insn();
static int getExpression();
#endif
static char *expr_end;
static char last_expand;	/* error if expansion after branch */

enum dual
{
    DUAL_OFF = 0, DUAL_ON, DUAL_DDOT, DUAL_ONDDOT,
};
static enum dual dual_mode = DUAL_OFF;	/* dual-instruction mode */

static void
s_dual()	/* floating point instructions have dual set */
{
    dual_mode = DUAL_ON;
}

static void
s_enddual()	/* floating point instructions have dual set */
{
    dual_mode = DUAL_OFF;
}

static int atmp = 31; /* temporary register for pseudo's */

static void
s_atmp()
{
    register int temp;
    if (strncmp(input_line_pointer, "sp", 2) == 0) {
      input_line_pointer += 2;
      atmp = 2;
    }
    else if (strncmp(input_line_pointer, "fp", 2) == 0) {
      input_line_pointer += 2;
      atmp = 3;
    }
    else if (strncmp(input_line_pointer, "r", 1) == 0) {
      input_line_pointer += 1;
      temp = get_absolute_expression();
      if (temp >= 0 && temp <= 31)
          atmp = temp;
        else
            as_warn("Unknown temporary pseudo register");
    }
    else {
        as_warn("Unknown temporary pseudo register");
    }
    demand_empty_rest_of_line();
    return;
}

/* This function is called once, at assembler startup time.  It should
   set up all the tables, etc. that the MD part of the assembler will need.  */
void
md_begin()
{
  register char *retval = NULL;
  int lose = 0;
  register unsigned int i = 0;

  op_hash = hash_new();
  if (op_hash == NULL)
    as_fatal("Virtual memory exhausted");

  while (i < NUMOPCODES)
    {
      const char *name = i860_opcodes[i].name;
      retval = hash_insert(op_hash, name, &i860_opcodes[i]);
      if(retval != NULL && *retval != '\0')
	{
	  fprintf (stderr, "internal error: can't hash `%s': %s\n",
		   i860_opcodes[i].name, retval);
	  lose = 1;
	}
      do
	{
	  if (i860_opcodes[i].match & i860_opcodes[i].lose)
	    {
	      fprintf (stderr, "internal error: losing opcode: `%s' \"%s\"\n",
		       i860_opcodes[i].name, i860_opcodes[i].args);
	      lose = 1;
	    }
	  ++i;
	} while (i < NUMOPCODES
		 && !strcmp(i860_opcodes[i].name, name));
    }

  if (lose)
    as_fatal ("Broken assembler.  No assembly attempted.");

  for (i = '0'; i < '8'; ++i)
    octal[i] = 1;
  for (i = '0'; i <= '9'; ++i)
    toHex[i] = i - '0';
  for (i = 'a'; i <= 'f'; ++i)
    toHex[i] = i + 10 - 'a';
  for (i = 'A'; i <= 'F'; ++i)
    toHex[i] = i + 10 - 'A';
}

void
md_end()
{
    return;
}

void
md_assemble(str)
    char *str;
{
    char *toP;
    int rsd;
    int no_opcodes = 1;
    int i;
    struct i860_it pseudo[3];

    assert(str);
    i860_ip(str);

    /* check for expandable flag to produce pseudo-instructions */
    if (the_insn.expand != 0 && the_insn.highlow == NO_SPEC) {
	for (i = 0; i < 3; i++)
	    pseudo[i] = the_insn;

	switch (the_insn.expand) {

	case E_DELAY:
		no_opcodes = 1;
		break;

	case E_MOV:
	    if (the_insn.exp.X_add_symbol == NULL &&
	        the_insn.exp.X_subtract_symbol == NULL &&
		(the_insn.exp.X_add_number < (1 << 15) &&
		 the_insn.exp.X_add_number >= -(1 << 15)))
		break;
	    /* or l%const,r0,ireg_dest */
	    pseudo[0].opcode = (the_insn.opcode & 0x001f0000) | 0xe4000000;
	    pseudo[0].highlow = PAIR;
	    /* orh h%const,ireg_dest,ireg_dest */
	    pseudo[1].opcode = (the_insn.opcode & 0x03ffffff) | 0xec000000 |
		((the_insn.opcode & 0x001f0000) << 5);
	    pseudo[1].highlow = HIGH;
	    no_opcodes = 2;
	    break;

	case E_ADDR:
	    if (the_insn.exp.X_add_symbol == NULL &&
	        the_insn.exp.X_subtract_symbol == NULL)
		break;
	    /* orh ha%addr_expr,r0,r31 */
	    pseudo[0].opcode = 0xec000000 | (atmp<<16);
	    pseudo[0].highlow = HIGHADJ;
	    pseudo[0].reloc = LOW0;	/* must overwrite */
	    /* l%addr_expr(r31),ireg_dest */
	    pseudo[1].opcode = (the_insn.opcode & ~0x003e0000) | (atmp << 21);
	    pseudo[1].highlow = PAIR;
	    no_opcodes = 2;
	    break;

	case E_U32:	/* 2nd version emulates Intel as, not doc. */
	    if (the_insn.exp.X_add_symbol == NULL &&
	        the_insn.exp.X_subtract_symbol == NULL &&
		(the_insn.exp.X_add_number < (1 << 16) &&
		 the_insn.exp.X_add_number >= 0))
		break;
	    /* $(opcode)h h%const,ireg_src2,ireg_dest
	    pseudo[0].opcode = (the_insn.opcode & 0xf3ffffff) | 0x0c000000; */
	    /* $(opcode)h h%const,ireg_src2,r31 */
	    pseudo[0].opcode = (the_insn.opcode & 0xf3e0ffff) | 0x0c000000 |
		(atmp << 16);
	    pseudo[0].highlow = HIGH;
	    /* $(opcode) l%const,ireg_dest,ireg_dest
	    pseudo[1].opcode = (the_insn.opcode & 0xf01f0000) | 0x04000000 |
		((the_insn.opcode & 0x001f0000) << 5); */
	    /* $(opcode) l%const,r31,ireg_dest */
	    pseudo[1].opcode = (the_insn.opcode & 0xf01f0000) | 0x04000000 |
		(atmp << 21);
	    pseudo[1].highlow = PAIR;
	    no_opcodes = 2;
	    break;

	case E_AND:	/* 2nd version emulates Intel as, not doc. */
	    if (the_insn.exp.X_add_symbol == NULL &&
	        the_insn.exp.X_subtract_symbol == NULL &&
		(the_insn.exp.X_add_number < (1 << 16) &&
		 the_insn.exp.X_add_number >= 0))
		break;
	    /* andnot h%const,ireg_src2,ireg_dest
	    pseudo[0].opcode = (the_insn.opcode & 0x03ffffff) | 0xd4000000; */
	    /* andnot h%const,ireg_src2,r31 */
	    pseudo[0].opcode = (the_insn.opcode & 0x03e0ffff) | 0xd4000000 |
		(atmp << 16);
	    pseudo[0].highlow = HIGH;
	    pseudo[0].exp.X_add_number = -1 - the_insn.exp.X_add_number;
	    /* andnot l%const,ireg_dest,ireg_dest
	    pseudo[1].opcode = (the_insn.opcode & 0x001f0000) | 0xd4000000 |
		((the_insn.opcode & 0x001f0000) << 5); */
	    /* andnot l%const,r31,ireg_dest */
	    pseudo[1].opcode = (the_insn.opcode & 0x001f0000) | 0xd4000000 |
		(atmp << 21);
	    pseudo[1].highlow = PAIR;
	    pseudo[1].exp.X_add_number = -1 - the_insn.exp.X_add_number;
	    no_opcodes = 2;
	    break;

	case E_S32:
	    if (the_insn.exp.X_add_symbol == NULL &&
	        the_insn.exp.X_subtract_symbol == NULL &&
		(the_insn.exp.X_add_number < (1 << 15) &&
		 the_insn.exp.X_add_number >= -(1 << 15)))
		break;
	    /* orh h%const,r0,r31 */
	    pseudo[0].opcode = 0xec000000 | (atmp << 16);
	    pseudo[0].highlow = HIGH;
	    /* or l%const,r31,r31 */
	    pseudo[1].opcode = 0xe4000000 | (atmp << 21) | (atmp << 16);
	    pseudo[1].highlow = PAIR;
	    /* r31,ireg_src2,ireg_dest */
	    pseudo[2].opcode = (the_insn.opcode & ~0x0400ffff) | (atmp << 11);
	    pseudo[2].reloc = NO_RELOC;
	    no_opcodes = 3;
	    break;

    	default:
	    abort();
	}

        the_insn = pseudo[0];
	/* check for expanded opcode after branch or in dual */
	if (no_opcodes > 1 && last_expand == TRUE)
	    as_warn("Expanded opcode after delayed branch: `%s'", str);
	if (no_opcodes > 1 && dual_mode != DUAL_OFF)
	    as_warn("Expanded opcode in dual mode: `%s'", str);
    }

    i = 0;
    do {	/* always produce at least one opcode */
        toP = frag_more(4);
        /* put out the opcode */
        md_number_to_chars(toP, the_insn.opcode, 4);

	/* check for expanded opcode after branch or in dual */
	last_expand = the_insn.pcrel;

        /* put out the symbol-dependent stuff */
        if (the_insn.reloc != NO_RELOC) {
	    fix_new(
	        frag_now,                           /* which frag */
	        (toP - frag_now->fr_literal), /* where */
	        4,                                  /* size */
	        the_insn.exp.X_add_symbol,
	        the_insn.exp.X_subtract_symbol,
	        the_insn.exp.X_add_number,
	        the_insn.pcrel,
		/* merge bit fields into one argument */
		(int)(((the_insn.highlow & 0x3) << 4) | (the_insn.reloc & 0xf))
	    );
        }
        the_insn = pseudo[++i];
    } while (--no_opcodes > 0);

}

static void
i860_ip(str)
    char *str;
{
    char *s;
    const char *args;
    char c;
    unsigned long i;
    struct i860_opcode *insn;
    char *argsStart;
    unsigned long   opcode;
    unsigned int mask;
    int match = FALSE;
    int comma = 0;


    for (s = str; islower(*s) || *s == '.' || *s == '3'; ++s)
	;
    switch (*s) {

    case '\0':
	break;

    case ',':
	comma = 1;

	/*FALLTHROUGH*/

    case ' ':
	*s++ = '\0';
	break;

    default:
	    as_warn("Unknown opcode: `%s'", str);
	    exit(1);
    }

    if (strncmp(str, "d.", 2) == 0) {	/* check for d. opcode prefix */
	if (dual_mode == DUAL_ON)
	    dual_mode = DUAL_ONDDOT;
	else
	    dual_mode = DUAL_DDOT;
	str += 2;
    }

    if ((insn = (struct i860_opcode *) hash_find(op_hash, str)) == NULL) {
	if (dual_mode == DUAL_DDOT || dual_mode == DUAL_ONDDOT)
	    str -= 2;
	as_warn("Unknown opcode: `%s'", str);
	return;
    }
    if (comma) {
	*--s = ',';
    }
    argsStart = s;
    for (;;) {
	opcode = insn->match;
	bzero(&the_insn, sizeof(the_insn));
	the_insn.reloc = NO_RELOC;

	/*
	 * Build the opcode, checking as we go to make
	 * sure that the operands match
	 */
	for (args = insn->args; ; ++args) {
	    switch (*args) {

	    case '\0':  /* end of args */
		if (*s == '\0') {
		    match = TRUE;
		}
		break;

	    case '+':
	    case '(':   /* these must match exactly */
	    case ')':
	    case ',':
	    case ' ':
		if (*s++ == *args)
		    continue;
		break;

	    case '#':   /* must be at least one digit */
		if (isdigit(*s++)) {
		    while (isdigit(*s)) {
			++s;
		    }
		    continue;
		}
		break;

	    case '1':   /* next operand must be a register */
	    case '2':
	    case 'd':
		switch (*s) {

		case 'f':   /* frame pointer */
		    s++;
		    if (*s++ == 'p') {
			mask = 0x3;
			break;
		    }
		    goto error;

		case 's':   /* stack pointer */
		    s++;
		    if (*s++ == 'p') {
			mask= 0x2;
			break;
		    }
		    goto error;

		case 'r': /* any register */
		    s++;
		    if (!isdigit(c = *s++)) {
			goto error;
		    }
		    if (isdigit(*s)) {
		        if ((c = 10 * (c - '0') + (*s++ - '0')) >= 32) {
			    goto error;
			}
		    } else {
			c -= '0';
		    }
		    mask= c;
		    break;

		default:	/* not this opcode */
		    goto error;
		}
		/*
		 * Got the register, now figure out where
		 * it goes in the opcode.
		 */
		switch (*args) {

		case '1':
		    opcode |= mask << 11;
		    continue;

		case '2':
		    opcode |= mask << 21;
		    continue;

		case 'd':
		    opcode |= mask << 16;
		    continue;

		}
		break;

	    case 'e':    /* next operand is a floating point register */
	    case 'f':
	    case 'g':
	        if (*s++ == 'f' && isdigit(*s)) {
		    mask = *s++;
		    if (isdigit(*s)) {
			mask = 10 * (mask - '0') + (*s++ - '0');
			if (mask >= 32) {
			    break;
			}
		    } else {
			mask -= '0';
		    }
		    switch (*args) {

		    case 'e':
			opcode |= mask << 11;
			continue;

		    case 'f':
			opcode |= mask << 21;
			continue;

		    case 'g':
			opcode |= mask << 16;
			if (dual_mode != DUAL_OFF)
			    opcode |= (1 << 9);	/* dual mode instruction */
			if (dual_mode == DUAL_DDOT)
			    dual_mode = DUAL_OFF;
			if (dual_mode == DUAL_ONDDOT)
			    dual_mode = DUAL_ON;
			if ((opcode & (1 << 10)) && (mask == ((opcode >> 11) & 0x1f)))
			    as_warn("Fsr1 equals fdest with Pipelining");
			continue;
		    }
		}
		break;

	    case 'c': /* next operand must be a control register */
		if (strncmp(s, "fir", 3) == 0) {
		    opcode |= 0x0 << 21;
		    s += 3;
		    continue;
		}
		if (strncmp(s, "psr", 3) == 0) {
		    opcode |= 0x1 << 21;
		    s += 3;
		    continue;
		}
		if (strncmp(s, "dirbase", 7) == 0) {
		    opcode |= 0x2 << 21;
		    s += 7;
		    continue;
		}
		if (strncmp(s, "db", 2) == 0) {
		    opcode |= 0x3 << 21;
		    s += 2;
		    continue;
		}
		if (strncmp(s, "fsr", 3) == 0) {
		    opcode |= 0x4 << 21;
		    s += 3;
		    continue;
		}
		if (strncmp(s, "epsr", 4) == 0) {
		    opcode |= 0x5 << 21;
		    s += 4;
		    continue;
		}
		break;

	    case '5':   /* 5 bit immediate in src1 */
		bzero(&the_insn, sizeof(the_insn));
		if ( !getExpression(s)) {
		    s = expr_end;
	    	    if (the_insn.exp.X_add_number & ~0x1f)
		        as_warn("5-bit immediate too large");
	    	    opcode |= (the_insn.exp.X_add_number & 0x1f) << 11;
		    bzero(&the_insn, sizeof(the_insn));
		    the_insn.reloc = NO_RELOC;
		    continue;
		}
		break;

	    case 'l':   /* 26 bit immediate, relative branch */
		the_insn.reloc = BRADDR;
		the_insn.pcrel = TRUE;
		goto immediate;

	    case 's':   /* 16 bit immediate, split relative branch */
			/* upper 5 bits of offset in dest field */
		the_insn.pcrel = TRUE;
		the_insn.reloc = SPLIT0;
		goto immediate;

	    case 'S':   /* 16 bit immediate, split (st), aligned */
		if (opcode & (1 << 28))
		    if (opcode & 0x1)
			the_insn.reloc = SPLIT2;
		    else
			the_insn.reloc = SPLIT1;
		else
		    the_insn.reloc = SPLIT0;
		goto immediate;

	    case 'I':   /* 16 bit immediate, aligned */
		if (opcode & (1 << 28))
		    if (opcode & 0x1)
			the_insn.reloc = LOW2;
		    else
			the_insn.reloc = LOW1;
		else
		    the_insn.reloc = LOW0;
		goto immediate;

	    case 'i':   /* 16 bit immediate */
		the_insn.reloc = LOW0;

		/*FALLTHROUGH*/

	    immediate:
		if(*s==' ')
		  s++;
		if (strncmp(s, "ha%", 3) == 0) {
		    the_insn.highlow = HIGHADJ;
		    s += 3;
		} else if (strncmp(s, "h%", 2) == 0) {
		    the_insn.highlow = HIGH;
		    s += 2;
		} else if (strncmp(s, "l%", 2) == 0) {
		    the_insn.highlow = PAIR;
		    s += 2;
		}
		the_insn.expand = insn->expand; 

		/* Note that if the getExpression() fails, we will still have
		   created U entries in the symbol table for the 'symbols'
		   in the input string.  Try not to create U symbols for
		   registers, etc. */

		if ( !getExpression(s)) {
		    s = expr_end;
		    continue;
		}
		break;

	    default:
		abort();
	    }
	    break;
	}
	error:
	if (match == FALSE)
	  {
	    /* Args don't match.  */
	    if (&insn[1] - i860_opcodes < NUMOPCODES
		&& !strcmp(insn->name, insn[1].name))
	      {
		++insn;
		s = argsStart;
		continue;
	      }
	    else
	      {
		as_warn("Illegal operands");
		return;
	      }
	  }
	break;
    }

    the_insn.opcode = opcode;
    return;
}

static int
getExpression(str)
    char *str;
{
    char *save_in;
    segT seg;

    save_in = input_line_pointer;
    input_line_pointer = str;
    switch (seg = expression(&the_insn.exp)) {

    case SEG_ABSOLUTE:
    case SEG_TEXT:
    case SEG_DATA:
    case SEG_BSS:
    case SEG_UNKNOWN:
    case SEG_DIFFERENCE:
    case SEG_BIG:
    case SEG_NONE:
	break;

    default:
	the_insn.error = "bad segment";
	expr_end = input_line_pointer;
	input_line_pointer=save_in;
	return 1;
    }
    expr_end = input_line_pointer;
    input_line_pointer = save_in;
    return 0;
}


/*
    This is identical to the md_atof in m68k.c.  I think this is right,
    but I'm not sure.

   Turn a string in input_line_pointer into a floating point constant of type
   type, and store the appropriate bytes in *litP.  The number of LITTLENUMS
   emitted is stored in *sizeP .  An error message is returned, or NULL on OK.
 */

/* Equal to MAX_PRECISION in atof-ieee.c */
#define MAX_LITTLENUMS 6

char *
md_atof(type,litP,sizeP)
    char type;
    char *litP;
    int *sizeP;
{
    int	prec;
    LITTLENUM_TYPE words[MAX_LITTLENUMS];
    LITTLENUM_TYPE *wordP;
    char	*t;
    char	*atof_ieee();

    switch(type) {

    case 'f':
    case 'F':
    case 's':
    case 'S':
	prec = 2;
	break;

    case 'd':
    case 'D':
    case 'r':
    case 'R':
	prec = 4;
	break;

    case 'x':
    case 'X':
	prec = 6;
	break;

    case 'p':
    case 'P':
	prec = 6;
	break;

    default:
	*sizeP=0;
	return "Bad call to MD_ATOF()";
    }
    t=atof_ieee(input_line_pointer,type,words);
    if(t)
	input_line_pointer=t;
    *sizeP=prec * sizeof(LITTLENUM_TYPE);
    for(wordP=words;prec--;) {
	md_number_to_chars(litP,(long)(*wordP++),sizeof(LITTLENUM_TYPE));
	litP+=sizeof(LITTLENUM_TYPE);
    }
    return "";	/* Someone should teach Dean about null pointers */
}

/*
 * Write out big-endian.
 */
void
md_number_to_chars(buf,val,n)
    char *buf;
    long val;
    int n;
{
    switch(n) {

    case 4:
	*buf++ = val >> 24;
	*buf++ = val >> 16;
    case 2:
	*buf++ = val >> 8;
    case 1:
	*buf = val;
	break;

    default:
	abort();
    }
    return;
}

void
md_number_to_imm(buf,val,n, fixP, seg_type)
    char *buf;
    long val;
    int n;
    fixS *fixP;
    int seg_type;
{
    enum reloc_type reloc = fixP->fx_r_type & 0xf;
    enum highlow_type highlow = (fixP->fx_r_type >> 4) & 0x3;

    assert(buf);
    assert(n == 4);	/* always on i860 */

    switch(highlow)
    {

    case HIGHADJ:	/* adjusts the high-order 16-bits */
	if (val & (1 << 15))
	    val += (1 << 16);

	    /*FALLTHROUGH*/

    case HIGH:	/* selects the high-order 16-bits */
	val >>= 16;
	break;

    case PAIR:	/* selects the low-order 16-bits */
	val = val & 0xffff;
	break;

    default:
	break;
    }

    switch(reloc)
    {

    case BRADDR:	/* br,call,bc,bc.t,bnc,bnc.t w/26-bit immediate */
	if (fixP->fx_pcrel != TRUE)
	    as_warn("26-bit branch w/o pc relative set: 0x%08x", val);
	val >>= 2;	/* align pcrel offset, see manual */

	if (val >= (1 << 25) || val < -(1 << 25))	/* check for overflow */
	    as_warn("26-bit branch offset overflow: 0x%08x", val);
	buf[0] = (buf[0] & 0xfc) | ((val >> 24) & 0x3);
	buf[1] = val >> 16;
	buf[2] = val >> 8;
	buf[3] = val;
	break;

    case SPLIT2:	/* 16 bit immediate, 4-byte aligned */
	if (val & 0x3)
	    as_warn("16-bit immediate 4-byte alignment error: 0x%08x", val);
	val &= ~0x3;	/* 4-byte align value */
	/*FALLTHROUGH*/
    case SPLIT1:	/* 16 bit immediate, 2-byte aligned */
	if (val & 0x1)
	    as_warn("16-bit immediate 2-byte alignment error: 0x%08x", val);
	val &= ~0x1;	/* 2-byte align value */
	/*FALLTHROUGH*/
    case SPLIT0:	/* st,bla,bte,btne w/16-bit immediate */
	if (fixP->fx_pcrel == TRUE)
	    val >>= 2;	/* align pcrel offset, see manual */
	/* check for bounds */
	if (highlow != PAIR && (val >= (1 << 16) || val < -(1 << 15)))
	    as_warn("16-bit branch offset overflow: 0x%08x", val);
	buf[1] = (buf[1] & ~0x1f) | ((val >> 11) & 0x1f);
	buf[2] = (buf[2] & ~0x7) | ((val >> 8) & 0x7);
	buf[3] |= val;	/* perserve bottom opcode bits */	
	break;

    case LOW4:	/* fld,pfld,pst,flush 16-byte aligned */
	if (val & 0xf)
	    as_warn("16-bit immediate 16-byte alignment error: 0x%08x", val);
	val &= ~0xf;	/* 16-byte align value */
	/*FALLTHROUGH*/
    case LOW3:	/* fld,pfld,pst,flush 8-byte aligned */
	if (val & 0x7)
	    as_warn("16-bit immediate 8-byte alignment error: 0x%08x", val);
	val &= ~0x7;	/* 8-byte align value */
	/*FALLTHROUGH*/
    case LOW2:	/* 16 bit immediate, 4-byte aligned */
	if (val & 0x3)
	    as_warn("16-bit immediate 4-byte alignment error: 0x%08x", val);
	val &= ~0x3;	/* 4-byte align value */
	/*FALLTHROUGH*/
    case LOW1:	/* 16 bit immediate, 2-byte aligned */
	if (val & 0x1)
	    as_warn("16-bit immediate 2-byte alignment error: 0x%08x", val);
	val &= ~0x1;	/* 2-byte align value */
	/*FALLTHROUGH*/
    case LOW0:	/* 16 bit immediate, byte aligned */
	/* check for bounds */
	if (highlow != PAIR && (val >= (1 << 16) || val < -(1 << 15)))
	    as_warn("16-bit immediate overflow: 0x%08x", val);
	buf[2] = val >> 8;
	buf[3] |= val;	/* perserve bottom opcode bits */	
	break;

    case NO_RELOC:
    default:
	as_warn("bad relocation type: 0x%02x", reloc);
	break;
    }
    return;
}

/* should never be called for i860 */
void
md_create_short_jump(ptr, from_addr, to_addr, frag, to_symbol)
    char *ptr;
    long from_addr, to_addr;
{
    fprintf(stderr, "i860_create_short_jmp\n");
    abort();
}

/* should never be called for i860 */
void
md_number_to_disp(buf,val,n)
    char	*buf;
    long	val;
{
    fprintf(stderr, "md_number_to_disp\n");
    abort();
}

/* should never be called for i860 */
void
md_number_to_field(buf,val,fix)
    char *buf;
    long val;
    void *fix;
{
    fprintf(stderr, "i860_number_to_field\n");
    abort();
}

/* the bit-field entries in the relocation_info struct plays hell 
   with the byte-order problems of cross-assembly.  So as a hack,
   I added this mach. dependent ri twiddler.  Ugly, but it gets
   you there. -KWK */
/* on i860: first 4 bytes are normal unsigned long address, next three
   bytes are index, most sig. byte first.  Byte 7 is broken up with
   bit 7 as pcrel, bit 6 as extern, and the lower six bits as
   relocation type (highlow 5-4).  Next 4 bytes are long int addend. */
/* Thanx and a tip of the hat to Michael Bloom, mb@ttidca.tti.com */
void
md_ri_to_chars(ri_p, ri)
     struct relocation_info *ri_p, ri;
{
#if 0
  unsigned char the_bytes[sizeof(*ri_p)];
  
  /* this is easy */
  md_number_to_chars(the_bytes, ri.r_address, sizeof(ri.r_address));
  /* now the fun stuff */
  the_bytes[4] = (ri.r_index >> 16) & 0x0ff;
  the_bytes[5] = (ri.r_index >> 8) & 0x0ff;
  the_bytes[6] = ri.r_index & 0x0ff;
  the_bytes[7] = ((ri.r_extern << 7)  & 0x80) | (0 & 0x60) | (ri.r_type & 0x1F);
  /* Also easy */
  md_number_to_chars(&the_bytes[8], ri.r_addend, sizeof(ri.r_addend));
  /* now put it back where you found it, Junior... */
  bcopy (the_bytes, (char *)ri_p, sizeof(*ri_p));
#endif
}

/* should never be called for i860 */
void
md_convert_frag(fragP)
    register fragS *fragP;
{
    fprintf(stderr, "i860_convert_frag\n");
    abort();
}

/* should never be called for i860 */
void
md_create_long_jump(ptr, from_addr, to_addr, frag, to_symbol)
    char	*ptr;
    long	from_addr,
	        to_addr;
    fragS	*frag;
    symbolS	*to_symbol;
{
    fprintf(stderr, "i860_create_long_jump\n");
    abort();
}

/* should never be called for i860 */
int
md_estimate_size_before_relax(fragP, segtype)
    register fragS *fragP;
{
    fprintf(stderr, "i860_estimate_size_before_relax\n");
    abort();
    return 0;
}

/* for debugging only, must match enum reloc_type */
static char *Reloc[] = {
    "NO_RELOC",
    "BRADDR", 
    "LOW0", 
    "LOW1", 
    "LOW2", 
    "LOW3", 
    "LOW4", 
    "SPLIT0", 
    "SPLIT1", 
    "SPLIT2", 
    "RELOC_32", 
};
static char *Highlow[] = {
    "NO_SPEC",
    "PAIR", 
    "HIGH", 
    "HIGHADJ", 
};
static void
print_insn(insn)
    struct i860_it *insn;
{
    if (insn->error) {
	fprintf(stderr, "ERROR: %s\n");
    }
    fprintf(stderr, "opcode=0x%08x\t", insn->opcode);
    fprintf(stderr, "expand=0x%08x\t", insn->expand);
    fprintf(stderr, "reloc = %s\t", Reloc[insn->reloc]);
    fprintf(stderr, "highlow = %s\n", Highlow[insn->highlow]);
    fprintf(stderr, "exp =  {\n");
    fprintf(stderr, "\t\tX_add_symbol = %s\n",
	insn->exp.X_add_symbol ?
	(insn->exp.X_add_symbol->sy_name ? 
	insn->exp.X_add_symbol->sy_name : "???") : "0");
    fprintf(stderr, "\t\tX_sub_symbol = %s\n",
	insn->exp.X_subtract_symbol ?
	    (insn->exp.X_subtract_symbol->sy_name ? 
	        insn->exp.X_subtract_symbol->sy_name : "???") : "0");
    fprintf(stderr, "\t\tX_add_number = %d\n",
	insn->exp.X_add_number);
    fprintf(stderr, "}\n");
    return;
}

int
md_parse_option(argP,cntP,vecP)
    char **argP;
    int *cntP;
    char ***vecP;
{
    return 1;
}

/*
 * I860 relocations are completely different, so it needs
 * this machine dependent routine to emit them.
 */
void
emit_relocations(fixP, segment_address_in_file)
    register fixS *fixP;
    relax_addressT segment_address_in_file;
{
    struct reloc_info_i860 ri;
    register symbolS *symbolP;
    extern char *next_object_file_charP;
    long add_number;

    bzero((char *) &ri, sizeof(ri));
    for (; fixP; fixP = fixP->fx_next) {

	if (fixP->fx_r_type & ~0x3f) {
	    fprintf(stderr, "fixP->fx_r_type = %d\n", fixP->fx_r_type);
	    abort();
	}
	ri.r_pcrel = fixP->fx_pcrel;
	ri.r_type = fixP->fx_r_type;

	if ((symbolP = fixP->fx_addsy) != NULL) {
	    ri.r_address = fixP->fx_frag->fr_address +
	        fixP->fx_where - segment_address_in_file;
	    if ((symbolP->sy_type & N_TYPE) == N_UNDF) {
		ri.r_extern = 1;
		ri.r_symbolnum = symbolP->sy_number;
	    } else {
		ri.r_extern = 0;
		ri.r_symbolnum = symbolP->sy_type & N_TYPE;
	    }
	    if (symbolP && symbolP->sy_frag) {
		ri.r_addend = symbolP->sy_frag->fr_address;
	    }
	    ri.r_type = fixP->fx_r_type;
	    if (fixP->fx_pcrel) {
		/* preserve actual offset vs. pc + 4 */
		ri.r_addend -= (ri.r_address + 4);
	    } else {
		ri.r_addend = fixP->fx_addnumber;
	    }

	    md_ri_to_chars((char *) &ri, ri);
	    append(&next_object_file_charP, (char *)& ri, sizeof(ri));
	}
    }
    return;
}

These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.