447 lines
12 KiB
C
447 lines
12 KiB
C
/* subsegs.c - subsegments -
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Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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1999, 2000, 2001, 2002, 2003, 2004, 2005
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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, 51 Franklin Street - Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* Segments & sub-segments. */
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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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frchainS *frchain_root, *frchain_now;
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static struct obstack frchains;
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/* Gas segment information for bfd_abs_section_ptr and
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bfd_und_section_ptr. */
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static segment_info_type *abs_seg_info;
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static segment_info_type *und_seg_info;
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static void subseg_set_rest (segT, subsegT);
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static fragS dummy_frag;
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static frchainS absolute_frchain;
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void
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subsegs_begin (void)
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{
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obstack_begin (&frchains, chunksize);
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#if __GNUC__ >= 2
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obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1;
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#endif
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frchain_root = NULL;
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frchain_now = NULL; /* Warn new_subseg() that we are booting. */
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frag_now = &dummy_frag;
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absolute_frchain.frch_seg = absolute_section;
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absolute_frchain.frch_subseg = 0;
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absolute_frchain.fix_root = absolute_frchain.fix_tail = 0;
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absolute_frchain.frch_frag_now = &zero_address_frag;
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absolute_frchain.frch_root = absolute_frchain.frch_last = &zero_address_frag;
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}
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/*
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* subseg_change()
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*
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* Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
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* subsegment. If we are already in the correct subsegment, change nothing.
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* This is used eg as a worker for subseg_set [which does make a new frag_now]
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* and for changing segments after we have read the source. We construct eg
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* fixSs even after the source file is read, so we do have to keep the
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* segment context correct.
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*/
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void
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subseg_change (register segT seg, register int subseg)
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{
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segment_info_type *seginfo;
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now_seg = seg;
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now_subseg = subseg;
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if (now_seg == absolute_section)
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return;
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seginfo = (segment_info_type *) bfd_get_section_userdata (stdoutput, seg);
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if (! seginfo)
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{
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seginfo = (segment_info_type *) xmalloc (sizeof (*seginfo));
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memset ((PTR) seginfo, 0, sizeof (*seginfo));
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seginfo->fix_root = NULL;
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seginfo->fix_tail = NULL;
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seginfo->bfd_section = seg;
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seginfo->sym = 0;
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if (seg == bfd_abs_section_ptr)
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abs_seg_info = seginfo;
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else if (seg == bfd_und_section_ptr)
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und_seg_info = seginfo;
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else
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bfd_set_section_userdata (stdoutput, seg, (PTR) seginfo);
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}
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}
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static void
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subseg_set_rest (segT seg, subsegT subseg)
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{
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register frchainS *frcP; /* crawl frchain chain */
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register frchainS **lastPP; /* address of last pointer */
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frchainS *newP; /* address of new frchain */
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mri_common_symbol = NULL;
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if (frag_now && frchain_now)
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frchain_now->frch_frag_now = frag_now;
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assert (frchain_now == 0
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|| now_seg == undefined_section
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|| now_seg == absolute_section
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|| frchain_now->frch_last == frag_now);
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subseg_change (seg, (int) subseg);
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if (seg == absolute_section)
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{
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frchain_now = &absolute_frchain;
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frag_now = &zero_address_frag;
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return;
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}
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assert (frchain_now == 0
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|| now_seg == undefined_section
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|| frchain_now->frch_last == frag_now);
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/*
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* Attempt to find or make a frchain for that sub seg.
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* Crawl along chain of frchainSs, begins @ frchain_root.
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* If we need to make a frchainS, link it into correct
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* position of chain rooted in frchain_root.
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*/
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for (frcP = *(lastPP = &frchain_root);
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frcP && frcP->frch_seg <= seg;
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frcP = *(lastPP = &frcP->frch_next))
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{
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if (frcP->frch_seg == seg
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&& frcP->frch_subseg >= subseg)
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{
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break;
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}
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}
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/*
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* frcP: Address of the 1st frchainS in correct segment with
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* frch_subseg >= subseg.
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* We want to either use this frchainS, or we want
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* to insert a new frchainS just before it.
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*
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* If frcP==NULL, then we are at the end of the chain
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* of frchainS-s. A NULL frcP means we fell off the end
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* of the chain looking for a
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* frch_subseg >= subseg, so we
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* must make a new frchainS.
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*
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* If we ever maintain a pointer to
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* the last frchainS in the chain, we change that pointer
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* ONLY when frcP==NULL.
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*
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* lastPP: Address of the pointer with value frcP;
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* Never NULL.
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* May point to frchain_root.
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*
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*/
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if (!frcP
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|| (frcP->frch_seg > seg
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|| frcP->frch_subseg > subseg)) /* Kinky logic only works with 2 segments. */
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{
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/*
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* This should be the only code that creates a frchainS.
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*/
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segment_info_type *seginfo;
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newP = (frchainS *) obstack_alloc (&frchains, sizeof (frchainS));
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newP->frch_subseg = subseg;
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newP->frch_seg = seg;
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newP->fix_root = NULL;
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newP->fix_tail = NULL;
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obstack_begin (&newP->frch_obstack, chunksize);
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#if __GNUC__ >= 2
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obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1;
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#endif
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newP->frch_frag_now = frag_alloc (&newP->frch_obstack);
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newP->frch_frag_now->fr_type = rs_fill;
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newP->frch_root = newP->frch_last = newP->frch_frag_now;
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*lastPP = newP;
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newP->frch_next = frcP; /* perhaps NULL */
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seginfo = seg_info (seg);
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if (seginfo && seginfo->frchainP == frcP)
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seginfo->frchainP = newP;
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frcP = newP;
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}
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/*
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* Here with frcP pointing to the frchainS for subseg.
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*/
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frchain_now = frcP;
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frag_now = frcP->frch_frag_now;
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assert (frchain_now->frch_last == frag_now);
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}
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/*
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* subseg_set(segT, subsegT)
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*
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* If you attempt to change to the current subsegment, nothing happens.
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*
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* In: segT, subsegT code for new subsegment.
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* frag_now -> incomplete frag for current subsegment.
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* If frag_now==NULL, then there is no old, incomplete frag, so
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* the old frag is not closed off.
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*
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* Out: now_subseg, now_seg updated.
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* Frchain_now points to the (possibly new) struct frchain for this
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* sub-segment.
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* Frchain_root updated if needed.
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*/
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segT
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subseg_get (const char *segname, int force_new)
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{
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segT secptr;
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segment_info_type *seginfo;
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const char *now_seg_name = (now_seg
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? bfd_get_section_name (stdoutput, now_seg)
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: 0);
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if (!force_new
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&& now_seg_name
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&& (now_seg_name == segname
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|| !strcmp (now_seg_name, segname)))
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return now_seg;
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if (!force_new)
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secptr = bfd_make_section_old_way (stdoutput, segname);
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else
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secptr = bfd_make_section_anyway (stdoutput, segname);
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#ifdef obj_sec_set_private_data
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obj_sec_set_private_data (stdoutput, secptr);
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#endif
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seginfo = seg_info (secptr);
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if (! seginfo)
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{
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/* Check whether output_section is set first because secptr may
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be bfd_abs_section_ptr. */
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if (secptr->output_section != secptr)
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secptr->output_section = secptr;
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seginfo = (segment_info_type *) xmalloc (sizeof (*seginfo));
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memset ((PTR) seginfo, 0, sizeof (*seginfo));
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seginfo->fix_root = NULL;
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seginfo->fix_tail = NULL;
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seginfo->bfd_section = secptr;
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if (secptr == bfd_abs_section_ptr)
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abs_seg_info = seginfo;
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else if (secptr == bfd_und_section_ptr)
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und_seg_info = seginfo;
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else
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bfd_set_section_userdata (stdoutput, secptr, (PTR) seginfo);
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seginfo->frchainP = NULL;
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seginfo->lineno_list_head = seginfo->lineno_list_tail = NULL;
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seginfo->sym = NULL;
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seginfo->dot = NULL;
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}
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return secptr;
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}
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segT
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subseg_new (const char *segname, subsegT subseg)
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{
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segT secptr;
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segment_info_type *seginfo;
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secptr = subseg_get (segname, 0);
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subseg_set_rest (secptr, subseg);
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seginfo = seg_info (secptr);
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if (! seginfo->frchainP)
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seginfo->frchainP = frchain_now;
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return secptr;
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}
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/* Like subseg_new, except a new section is always created, even if
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a section with that name already exists. */
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segT
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subseg_force_new (const char *segname, subsegT subseg)
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{
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segT secptr;
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segment_info_type *seginfo;
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secptr = subseg_get (segname, 1);
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subseg_set_rest (secptr, subseg);
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seginfo = seg_info (secptr);
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if (! seginfo->frchainP)
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seginfo->frchainP = frchain_now;
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return secptr;
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}
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void
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subseg_set (segT secptr, subsegT subseg)
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{
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if (! (secptr == now_seg && subseg == now_subseg))
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subseg_set_rest (secptr, subseg);
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mri_common_symbol = NULL;
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}
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#ifndef obj_sec_sym_ok_for_reloc
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#define obj_sec_sym_ok_for_reloc(SEC) 0
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#endif
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/* Get the gas information we are storing for a section. */
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segment_info_type *
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seg_info (segT sec)
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{
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if (sec == bfd_abs_section_ptr)
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return abs_seg_info;
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else if (sec == bfd_und_section_ptr)
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return und_seg_info;
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else
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return (segment_info_type *) bfd_get_section_userdata (stdoutput, sec);
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}
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symbolS *
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section_symbol (segT sec)
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{
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segment_info_type *seginfo = seg_info (sec);
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symbolS *s;
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if (seginfo == 0)
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abort ();
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if (seginfo->sym)
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return seginfo->sym;
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#ifndef EMIT_SECTION_SYMBOLS
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#define EMIT_SECTION_SYMBOLS 1
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#endif
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if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen)
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{
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/* Here we know it won't be going into the symbol table. */
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s = symbol_create (sec->symbol->name, sec, 0, &zero_address_frag);
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}
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else
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{
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segT seg;
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s = symbol_find (sec->symbol->name);
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/* We have to make sure it is the right symbol when we
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have multiple sections with the same section name. */
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if (s == NULL
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|| ((seg = S_GET_SEGMENT (s)) != sec
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&& seg != undefined_section))
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s = symbol_new (sec->symbol->name, sec, 0, &zero_address_frag);
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else if (seg == undefined_section)
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{
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S_SET_SEGMENT (s, sec);
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symbol_set_frag (s, &zero_address_frag);
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}
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}
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S_CLEAR_EXTERNAL (s);
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/* Use the BFD section symbol, if possible. */
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if (obj_sec_sym_ok_for_reloc (sec))
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symbol_set_bfdsym (s, sec->symbol);
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else
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symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM;
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seginfo->sym = s;
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return s;
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}
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/* Return whether the specified segment is thought to hold text. */
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int
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subseg_text_p (segT sec)
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{
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return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0;
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}
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/* Return non zero if SEC has at least one byte of data. It is
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possible that we'll return zero even on a non-empty section because
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we don't know all the fragment types, and it is possible that an
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fr_fix == 0 one still contributes data. Think of this as
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seg_definitely_not_empty_p. */
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int
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seg_not_empty_p (segT sec ATTRIBUTE_UNUSED)
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{
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segment_info_type *seginfo = seg_info (sec);
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frchainS *chain;
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fragS *frag;
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if (!seginfo)
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return 0;
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for (chain = seginfo->frchainP; chain; chain = chain->frch_next)
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{
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for (frag = chain->frch_root; frag; frag = frag->fr_next)
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if (frag->fr_fix)
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return 1;
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if (obstack_next_free (&chain->frch_obstack)
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!= chain->frch_last->fr_literal)
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return 1;
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}
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return 0;
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}
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void
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subsegs_print_statistics (FILE *file)
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{
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frchainS *frchp;
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fprintf (file, "frag chains:\n");
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for (frchp = frchain_root; frchp; frchp = frchp->frch_next)
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{
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int count = 0;
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fragS *fragp;
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/* If frch_subseg is non-zero, it's probably been chained onto
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the end of a previous subsection. Don't count it again. */
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if (frchp->frch_subseg != 0)
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continue;
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/* Skip gas-internal sections. */
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if (segment_name (frchp->frch_seg)[0] == '*')
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continue;
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for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next)
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{
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count++;
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}
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fprintf (file, "\n");
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fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp,
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segment_name (frchp->frch_seg), count);
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}
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}
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/* end of subsegs.c */
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