/* frags.c - manage frags - Copyright (C) 1987 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 <string.h> #include "as.h" #include "sections.h" #include "obstack.h" #include "frags.h" #include "messages.h" struct obstack frags = { 0 }; /* All, and only, frags live here. */ fragS *frag_now = NULL; /* -> current frag we are building. */ fragS zero_address_frag = { 0, /* fr_address */ NULL, /* fr_next */ 0, /* fr_fix */ 0, /* fr_var */ 0, /* fr_symbol */ 0, /* fr_offset */ NULL, /* fr_opcode */ rs_fill, /* fr_type */ 0, /* fr_subtype */ {0} /* fr_literal [0] */ }; /* * frag_grow() * * Internal. * Try to augment current frag by nchars chars. * If there is no room, close of the current frag with a ".fill 0" * and begin a new frag. Unless the new frag has nchars chars available * do not return. Do not set up any fields of *now_frag. */ static void frag_grow( int nchars) { if(frags.chunk_size == 0){ know(flagseen['n']); as_fatal("with -n a section directive must be seen before assembly " "can begin"); } if (obstack_room (&frags) < nchars) { unsigned int n,oldn; long oldc; frag_wane (frag_now); frag_new (0); oldn=(unsigned)-1; oldc=frags.chunk_size; frags.chunk_size=2*nchars; while((n=obstack_room(&frags))<nchars && n<oldn) { frag_wane(frag_now); frag_new(0); oldn=n; } frags.chunk_size=oldc; } if (obstack_room (&frags) < nchars) as_fatal ("Can't extend frag %d. chars", nchars); } /* * frag_new() * * Call this to close off a completed frag, and start up a new (empty) * frag, in the same subsegment as the old frag. * [frchain_now remains the same but frag_now is updated.] * Because this calculates the correct value of fr_fix by * looking at the obstack 'frags', it needs to know how many * characters at the end of the old frag belong to (the maximal) * fr_var: the rest must belong to fr_fix. * It doesn't actually set up the old frag's fr_var: you may have * set fr_var == 1, but allocated 10 chars to the end of the frag: * in this case you pass old_frags_var_max_size == 10. * * Make a new frag, initialising some components. Link new frag at end * of frchain_now. */ void frag_new( int old_frags_var_max_size) /* Number of chars (already allocated on obstack frags) in variable_length part of frag. */ { register fragS * former_last_fragP; /* char *throw_away_pointer; JF unused */ register frchainS * frchP; long tmp; /* JF */ if(frags.chunk_size == 0){ know(flagseen['n']); as_fatal("with -n a section directive must be seen before assembly " "can begin"); } frag_now->fr_fix = (char *) (obstack_next_free (&frags)) - (frag_now->fr_literal) - old_frags_var_max_size; /* Fix up old frag's fr_fix. */ obstack_finish (&frags); /* This will align the obstack so the */ /* next struct we allocate on it will */ /* begin at a correct boundary. */ frchP = frchain_now; know (frchP); former_last_fragP = frchP->frch_last; know (former_last_fragP); know (former_last_fragP == frag_now); obstack_blank (&frags, SIZEOF_STRUCT_FRAG); /* We expect this will begin at a correct */ /* boundary for a struct. */ tmp=obstack_alignment_mask(&frags); obstack_alignment_mask(&frags)=0; /* Turn off alignment */ /* If we ever hit a machine where strings must be aligned, we Lose Big */ frag_now=(fragS *)obstack_finish(&frags); obstack_alignment_mask(&frags)=tmp; /* Restore alignment */ /* Just in case we don't get zero'd bytes */ memset(frag_now, '\0', SIZEOF_STRUCT_FRAG); /* obstack_unaligned_done (&frags, &frag_now); */ /* know (frags.obstack_c_next_free == frag_now->fr_literal); */ /* Generally, frag_now->points to an */ /* address rounded up to next alignment. */ /* However, characters will add to obstack */ /* frags IMMEDIATELY after the struct frag, */ /* even if they are not starting at an */ /* alignment address. */ former_last_fragP->fr_next = frag_now; frchP->frch_last = frag_now; frag_now->fr_next = NULL; } /* frag_new() */ /* * frag_more() * * Start a new frag unless we have n more chars of room in the current frag. * Close off the old frag with a .fill 0. * * Return the address of the 1st char to write into. Advance * frag_now_growth past the new chars. */ char * frag_more( int nchars) { register char *retval; frag_grow (nchars); retval = obstack_next_free (&frags); obstack_blank_fast (&frags, nchars); return (retval); } /* frag_more() */ /* * frag_var() * * Start a new frag unless we have max_chars more chars of room in the current frag. * Close off the old frag with a .fill 0. * * Set up a machine_dependent relaxable frag, then start a new frag. * Return the address of the 1st char of the var part of the old frag * to write into. */ char * frag_var( relax_stateT type, int max_chars, int var, relax_substateT subtype, symbolS *symbol, long offset, char *opcode) { register char *retval; frag_grow (max_chars); retval = obstack_next_free (&frags); obstack_blank_fast (&frags, max_chars); frag_now->fr_var = var; frag_now->fr_type = type; frag_now->fr_subtype = subtype; frag_now->fr_symbol = symbol; frag_now->fr_offset = offset; frag_now->fr_opcode = opcode; frag_new (max_chars); return (retval); } /* frag_var() */ /* * frag_wane() * * Reduce the variable end of a frag to a harmless state. */ void frag_wane( fragS *fragP) { fragP->fr_type = rs_fill; fragP->fr_offset = 0; fragP->fr_var = 0; } /* * frag_align() * * Make a frag for ".align foo,bar". Call is "frag_align (foo,bar);". * Foo & bar are absolute integers. * * Call to close off the current frag with a ".align", then start a new * (so far empty) frag, in the same subsegment as the last frag. */ void frag_align( int alignment, int fill_character) { *(frag_var (rs_align, 1, 1, (relax_substateT)0, (symbolS *)0, (long)alignment, (char *)0)) = fill_character; } /* end: frags.c */