gas/frags.h

   1 /* frags.h - Header file for the frag concept.
   2    Copyright 1987, 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001,
   3    2002, 2003, 2004 Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GAS; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20    02111-1307, USA.  */
  21
  22 #ifndef FRAGS_H
  23 #define FRAGS_H
  24
  25 #ifdef ANSI_PROTOTYPES
  26 struct obstack;
  27 #endif
  28
  29 /* A code fragment (frag) is some known number of chars, followed by some
  30    unknown number of chars. Typically the unknown number of chars is an
  31    instruction address whose size is yet unknown. We always know the greatest
  32    possible size the unknown number of chars may become, and reserve that
  33    much room at the end of the frag.
  34    Once created, frags do not change address during assembly.
  35    We chain the frags in (a) forward-linked list(s). The object-file address
  36    of the 1st char of a frag is generally not known until after relax().
  37    Many things at assembly time describe an address by {object-file-address
  38    of a particular frag}+offset.
  39
  40    BUG: it may be smarter to have a single pointer off to various different
  41    notes for different frag kinds.  See how code pans.  */
  42
  43 struct frag {
  44   /* Object file address (as an octet offset).  */
  45   addressT fr_address;
  46   /* When relaxing multiple times, remember the address the frag had
  47      in the last relax pass.  */
  48   addressT last_fr_address;
  49
  50   /* (Fixed) number of octets we know we have.  May be 0.  */
  51   offsetT fr_fix;
  52   /* May be used for (Variable) number of octets after above.
  53      The generic frag handling code no longer makes any use of fr_var.  */
  54   offsetT fr_var;
  55   /* For variable-length tail.  */
  56   offsetT fr_offset;
  57   /* For variable-length tail.  */
  58   symbolS *fr_symbol;
  59   /* Points to opcode low addr byte, for relaxation.  */
  60   char *fr_opcode;
  61
  62   /* Chain forward; ascending address order.  Rooted in frch_root.  */
  63   struct frag *fr_next;
  64
  65   /* Where the frag was created, or where it became a variant frag.  */
  66   char *fr_file;
  67   unsigned int fr_line;
  68
  69 #ifndef NO_LISTING
  70   struct list_info_struct *line;
  71 #endif
  72
  73   /* Flipped each relax pass so we can easily determine whether
  74      fr_address has been adjusted.  */
  75   unsigned int relax_marker:1;
  76
  77   /* Used to ensure that all insns are emitted on proper address
  78      boundaries.  */
  79   unsigned int has_code:1;
  80   unsigned int insn_addr:6;
  81
  82   /* What state is my tail in? */
  83   relax_stateT fr_type;
  84   relax_substateT fr_subtype;
  85
  86 #ifdef USING_CGEN
  87   /* Don't include this unless using CGEN to keep frag size down.  */
  88   struct {
  89     /* CGEN_INSN entry for this instruction.  */
  90     const struct cgen_insn *insn;
  91     /* Index into operand table.  */
  92     int opindex;
  93     /* Target specific data, usually reloc number.  */
  94     int opinfo;
  95   } fr_cgen;
  96 #endif
  97
  98 #ifdef TC_FRAG_TYPE
  99   TC_FRAG_TYPE tc_frag_data;
 100 #endif
 101
 102   /* Data begins here.  */
 103   char fr_literal[1];
 104 };
 105
 106 #define SIZEOF_STRUCT_FRAG \
 107 ((char *) zero_address_frag.fr_literal - (char *) &zero_address_frag)
 108 /* We want to say fr_literal[0] above.  */
 109
 110 /* Current frag we are building.  This frag is incomplete.  It is,
 111    however, included in frchain_now.  The fr_fix field is bogus;
 112    instead, use frag_now_fix ().  */
 113 COMMON fragS *frag_now;
 114 extern addressT frag_now_fix (void);
 115 extern addressT frag_now_fix_octets (void);
 116
 117 /* For foreign-segment symbol fixups.  */
 118 COMMON fragS zero_address_frag;
 119 /* For local common (N_BSS segment) fixups.  */
 120 COMMON fragS bss_address_frag;
 121
 122 #if 0
 123 /* A macro to speed up appending exactly 1 char to current frag.  */
 124 /* JF changed < 1 to <= 1 to avoid a race condition.  */
 125 #define FRAG_APPEND_1_CHAR(datum)                       \
 126 {                                                       \
 127   if (obstack_room (&frags) <= 1)                       \
 128     {                                                   \
 129       frag_wane (frag_now);                             \
 130       frag_new (0);                                     \
 131     }                                                   \
 132   obstack_1grow (&frags, datum);                        \
 133 }
 134 #else
 135 extern void frag_append_1_char (int);
 136 #define FRAG_APPEND_1_CHAR(X) frag_append_1_char (X)
 137 #endif
 138
 139 void frag_init (void);
 140 fragS *frag_alloc (struct obstack *);
 141 void frag_grow (unsigned int nchars);
 142 char *frag_more (int nchars);
 143 void frag_align (int alignment, int fill_character, int max);
 144 void frag_align_pattern (int alignment, const char *fill_pattern,
 145                          int n_fill, int max);
 146 void frag_align_code (int alignment, int max);
 147 void frag_new (int old_frags_var_max_size);
 148 void frag_wane (fragS * fragP);
 149 int frag_room (void);
 150
 151 char *frag_variant (relax_stateT type,
 152                     int max_chars,
 153                     int var,
 154                     relax_substateT subtype,
 155                     symbolS * symbol,
 156                     offsetT offset,
 157                     char *opcode);
 158
 159 char *frag_var (relax_stateT type,
 160                 int max_chars,
 161                 int var,
 162                 relax_substateT subtype,
 163                 symbolS * symbol,
 164                 offsetT offset,
 165                 char *opcode);
 166
 167 #endif /* FRAGS_H */