355 lines
9.7 KiB
C
355 lines
9.7 KiB
C
/* frags.c - manage frags -
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Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 1997
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Free Software Foundation, Inc.
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This file is part of GAS, the GNU Assembler.
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GAS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GAS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GAS; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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#include "as.h"
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#include "subsegs.h"
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#include "obstack.h"
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extern fragS zero_address_frag;
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extern fragS bss_address_frag;
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/* Initialization for frag routines. */
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void
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frag_init ()
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{
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zero_address_frag.fr_type = rs_fill;
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bss_address_frag.fr_type = rs_fill;
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}
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/* Allocate a frag on the specified obstack.
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Call this routine from everywhere else, so that all the weird alignment
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hackery can be done in just one place. */
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fragS *
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frag_alloc (ob)
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struct obstack *ob;
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{
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fragS *ptr;
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int oalign;
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(void) obstack_alloc (ob, 0);
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oalign = obstack_alignment_mask (ob);
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obstack_alignment_mask (ob) = 0;
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ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG);
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obstack_alignment_mask (ob) = oalign;
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memset (ptr, 0, SIZEOF_STRUCT_FRAG);
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return ptr;
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}
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/*
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* frag_grow()
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*
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* Try to augment current frag by nchars chars.
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* If there is no room, close of the current frag with a ".fill 0"
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* and begin a new frag. Unless the new frag has nchars chars available
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* do not return. Do not set up any fields of *now_frag.
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*/
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void
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frag_grow (nchars)
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unsigned int nchars;
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{
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if (obstack_room (&frchain_now->frch_obstack) < nchars)
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{
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unsigned int n, oldn;
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long oldc;
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frag_wane (frag_now);
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frag_new (0);
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oldn = (unsigned) -1;
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oldc = frchain_now->frch_obstack.chunk_size;
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frchain_now->frch_obstack.chunk_size = 2 * nchars;
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while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars
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&& n < oldn)
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{
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frag_wane (frag_now);
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frag_new (0);
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oldn = n;
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}
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frchain_now->frch_obstack.chunk_size = oldc;
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}
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if (obstack_room (&frchain_now->frch_obstack) < nchars)
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as_fatal ("Can't extend frag %d. chars", nchars);
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}
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/*
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* frag_new()
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*
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* Call this to close off a completed frag, and start up a new (empty)
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* frag, in the same subsegment as the old frag.
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* [frchain_now remains the same but frag_now is updated.]
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* Because this calculates the correct value of fr_fix by
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* looking at the obstack 'frags', it needs to know how many
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* characters at the end of the old frag belong to (the maximal)
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* fr_var: the rest must belong to fr_fix.
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* It doesn't actually set up the old frag's fr_var: you may have
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* set fr_var == 1, but allocated 10 chars to the end of the frag:
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* in this case you pass old_frags_var_max_size == 10.
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*
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* Make a new frag, initialising some components. Link new frag at end
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* of frchain_now.
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*/
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void
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frag_new (old_frags_var_max_size)
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/* Number of chars (already allocated on obstack frags) in
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variable_length part of frag. */
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int old_frags_var_max_size;
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{
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fragS *former_last_fragP;
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frchainS *frchP;
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assert (frchain_now->frch_last == frag_now);
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/* Fix up old frag's fr_fix. */
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frag_now->fr_fix = frag_now_fix () - old_frags_var_max_size;
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/* Make sure its type is valid. */
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assert (frag_now->fr_type != 0);
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/* This will align the obstack so the next struct we allocate on it
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will begin at a correct boundary. */
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obstack_finish (&frchain_now->frch_obstack);
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frchP = frchain_now;
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know (frchP);
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former_last_fragP = frchP->frch_last;
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assert (former_last_fragP != 0);
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assert (former_last_fragP == frag_now);
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frag_now = frag_alloc (&frchP->frch_obstack);
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as_where (&frag_now->fr_file, &frag_now->fr_line);
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/* Generally, frag_now->points to an address rounded up to next
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alignment. However, characters will add to obstack frags
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IMMEDIATELY after the struct frag, even if they are not starting
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at an alignment address. */
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former_last_fragP->fr_next = frag_now;
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frchP->frch_last = frag_now;
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#ifndef NO_LISTING
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{
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extern struct list_info_struct *listing_tail;
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frag_now->line = listing_tail;
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}
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#endif
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assert (frchain_now->frch_last == frag_now);
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frag_now->fr_next = NULL;
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} /* frag_new() */
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/*
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* frag_more()
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*
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* Start a new frag unless we have n more chars of room in the current frag.
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* Close off the old frag with a .fill 0.
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*
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* Return the address of the 1st char to write into. Advance
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* frag_now_growth past the new chars.
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*/
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char *
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frag_more (nchars)
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int nchars;
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{
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register char *retval;
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if (now_seg == absolute_section)
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{
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as_bad ("attempt to allocate data in absolute section");
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subseg_set (text_section, 0);
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}
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if (mri_common_symbol != NULL)
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{
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as_bad ("attempt to allocate data in common section");
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mri_common_symbol = NULL;
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}
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frag_grow (nchars);
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retval = obstack_next_free (&frchain_now->frch_obstack);
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obstack_blank_fast (&frchain_now->frch_obstack, nchars);
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return (retval);
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} /* frag_more() */
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/*
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* frag_var()
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*
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* Start a new frag unless we have max_chars more chars of room in the current frag.
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* Close off the old frag with a .fill 0.
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*
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* Set up a machine_dependent relaxable frag, then start a new frag.
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* Return the address of the 1st char of the var part of the old frag
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* to write into.
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*/
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char *
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frag_var (type, max_chars, var, subtype, symbol, offset, opcode)
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relax_stateT type;
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int max_chars;
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int var;
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relax_substateT subtype;
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symbolS *symbol;
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offsetT offset;
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char *opcode;
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{
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register char *retval;
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frag_grow (max_chars);
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retval = obstack_next_free (&frchain_now->frch_obstack);
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obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
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frag_now->fr_var = var;
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frag_now->fr_type = type;
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frag_now->fr_subtype = subtype;
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frag_now->fr_symbol = symbol;
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frag_now->fr_offset = offset;
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frag_now->fr_opcode = opcode;
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/* Default these to zero. Only the ns32k uses these but they can't be
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conditionally included in `struct frag'. See as.h. */
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frag_now->fr_targ.ns32k.pcrel_adjust = 0;
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frag_now->fr_targ.ns32k.bsr = 0;
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as_where (&frag_now->fr_file, &frag_now->fr_line);
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frag_new (max_chars);
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return (retval);
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}
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/*
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* frag_variant()
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*
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* OVE: This variant of frag_var assumes that space for the tail has been
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* allocated by caller.
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* No call to frag_grow is done.
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*/
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char *
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frag_variant (type, max_chars, var, subtype, symbol, offset, opcode)
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relax_stateT type;
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int max_chars;
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int var;
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relax_substateT subtype;
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symbolS *symbol;
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offsetT offset;
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char *opcode;
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{
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register char *retval;
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retval = obstack_next_free (&frchain_now->frch_obstack);
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frag_now->fr_var = var;
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frag_now->fr_type = type;
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frag_now->fr_subtype = subtype;
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frag_now->fr_symbol = symbol;
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frag_now->fr_offset = offset;
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frag_now->fr_opcode = opcode;
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/* Default these to zero. Only the ns32k uses these but they can't be
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conditionally included in `struct frag'. See as.h. */
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frag_now->fr_targ.ns32k.pcrel_adjust = 0;
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frag_now->fr_targ.ns32k.bsr = 0;
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as_where (&frag_now->fr_file, &frag_now->fr_line);
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frag_new (max_chars);
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return (retval);
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} /* frag_variant() */
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/*
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* frag_wane()
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*
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* Reduce the variable end of a frag to a harmless state.
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*/
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void
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frag_wane (fragP)
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register fragS *fragP;
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{
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fragP->fr_type = rs_fill;
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fragP->fr_offset = 0;
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fragP->fr_var = 0;
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}
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/* Make an alignment frag. The size of this frag will be adjusted to
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force the next frag to have the appropriate alignment. ALIGNMENT
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is the power of two to which to align. FILL_CHARACTER is the
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character to use to fill in any bytes which are skipped. MAX is
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the maximum number of characters to skip when doing the alignment,
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or 0 if there is no maximum. */
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void
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frag_align (alignment, fill_character, max)
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int alignment;
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int fill_character;
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int max;
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{
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if (now_seg == absolute_section)
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{
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addressT new_off;
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new_off = ((abs_section_offset + alignment - 1)
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&~ ((1 << alignment) - 1));
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if (max == 0 || new_off - abs_section_offset <= max)
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abs_section_offset = new_off;
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}
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else
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{
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char *p;
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p = frag_var (rs_align, 1, 1, (relax_substateT) max,
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(symbolS *) 0, (offsetT) alignment, (char *) 0);
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*p = fill_character;
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}
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}
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/* Make an alignment frag like frag_align, but fill with a repeating
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pattern rather than a single byte. ALIGNMENT is the power of two
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to which to align. FILL_PATTERN is the fill pattern to repeat in
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the bytes which are skipped. N_FILL is the number of bytes in
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FILL_PATTERN. MAX is the maximum number of characters to skip when
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doing the alignment, or 0 if there is no maximum. */
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void
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frag_align_pattern (alignment, fill_pattern, n_fill, max)
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int alignment;
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const char *fill_pattern;
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int n_fill;
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int max;
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{
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char *p;
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p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
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(symbolS *) 0, (offsetT) alignment, (char *) 0);
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memcpy (p, fill_pattern, n_fill);
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}
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int
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frag_now_fix ()
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{
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if (now_seg == absolute_section)
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return abs_section_offset;
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return ((char*)obstack_next_free (&frchain_now->frch_obstack)
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- frag_now->fr_literal);
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}
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void
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frag_append_1_char (datum)
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int datum;
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{
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if (obstack_room (&frchain_now->frch_obstack) <= 1)
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{
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frag_wane (frag_now);
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frag_new (0);
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}
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obstack_1grow (&frchain_now->frch_obstack, datum);
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}
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/* end of frags.c */
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