cctools/as/frags.h

   1 #ifndef _FRAGS_H_
   2 #define _FRAGS_H_
   3 /* frags.h - Header file for the frag concept.
   4    Copyright (C) 1987 Free Software Foundation, Inc.
   5
   6 This file is part of GAS, the GNU Assembler.
   7
   8 GAS is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 1, or (at your option)
  11 any later version.
  12
  13 GAS is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GAS; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  21
  22 #import "as.h"
  23 #import "relax.h"
  24 #import "struc-symbol.h"
  25
  26 /*
  27  * A code fragment (frag) is some known number of chars, followed by some
  28  * unknown number of chars. Typically the unknown number of chars is an
  29  * instruction address whose size is yet unknown. We always know the greatest
  30  * possible size the unknown number of chars may become, and reserve that
  31  * much room at the end of the frag.
  32  * Once created, frags do not change address during assembly.
  33  * We chain the frags in (a) forward-linked list(s). The object-file address
  34  * of the 1st char of a frag is generally not known until after relax().
  35  * Many things at assembly time describe an address by {object-file-address
  36  * of a particular frag}+offset.
  37
  38  BUG: it may be smarter to have a single pointer off to various different
  39 notes for different frag kinds. See how code pans out.
  40
  41  */
  42 struct frag                     /* a code fragment */
  43 {
  44     uint64_t fr_address;        /* Object file address. */
  45     uint64_t last_fr_address;   /* When relaxing multiple times, remember the */
  46                                 /* address the frag had in the last relax pass*/
  47     struct frag *fr_next;       /* Chain forward; ascending address order. */
  48                                 /* Rooted in frch_root. */
  49
  50     int32_t fr_fix;             /* (Fixed) number of chars we know we have. */
  51                                 /* May be 0. */
  52     int32_t fr_var;             /* (Variable) number of chars after above. */
  53                                 /* May be 0. */
  54     struct symbol *fr_symbol;   /* For variable-length tail. */
  55     int32_t fr_offset;          /* For variable-length tail. */
  56     char *fr_opcode;            /* ->opcode low addr byte,for relax()ation*/
  57     relax_stateT fr_type;       /* What state is my tail in? */
  58     relax_substateT fr_subtype; /* Used to index in to md_relax_table for */
  59                                 /*  fr_type == rs_machine_dependent frags. */
  60 #ifdef ARM
  61     /* Where the frag was created, or where it became a variant frag.  */
  62     char *fr_file;
  63     unsigned int fr_line;
  64     /* Flipped each relax pass so we can easily determine whether
  65        fr_address has been adjusted.  */
  66     unsigned int relax_marker:1,
  67                  pad:31;
  68 #endif /* ARM */
  69     char fr_literal[1];         /* Chars begin here. */
  70                                 /* One day we will compile fr_literal[0]. */
  71 };
  72
  73 /* We want to say fr_literal[0] below */
  74 #define SIZEOF_STRUCT_FRAG \
  75  ((uintptr_t)zero_address_frag.fr_literal - (uintptr_t)&zero_address_frag)
  76
  77 /*
  78  * frag_now points at the current frag we are building. This frag is incomplete.
  79  * It is, however, included in frchain_now. Frag_now->fr_fix is not the total
  80  * bytes in use for the frag.  For that use:
  81  * frag_now->fr_fix + obstack_next_free(&frags) - frag_now->fr_literal.
  82  */
  83 extern fragS *frag_now;
  84 extern addressT frag_now_fix (void);
  85 extern addressT frag_now_fix_octets (void);
  86
  87 /*
  88  * Frags ONLY live in this obstack.  We use obstack_next_free() macro
  89  * so please don't put any other objects on this stack!
  90  */
  91 extern struct obstack frags;
  92
  93 /* For foreign-segment symbol fixups. */
  94 extern fragS zero_address_frag;
  95
  96 void frag_grow (unsigned int nchars);
  97 extern void frag_new(
  98     int old_frags_var_max_size);
  99 extern char * frag_more(
 100     int nchars);
 101 extern char *frag_var(
 102     relax_stateT type,
 103     int max_chars,
 104     int var,
 105     relax_substateT subtype,
 106     symbolS *symbol,
 107     int32_t offset,
 108     char *opcode);
 109 extern void frag_wane(
 110     fragS *fragP);
 111 extern void frag_align(
 112     int power_of_2_alignment,
 113     char *fill,
 114     int fill_size,
 115     int max_bytes_to_fill);
 116
 117 /*
 118  * A macro to speed up appending exactly 1 char
 119  * to current frag.
 120  */
 121 /* JF changed < 1 to <= 1 to avoid a race conditon */
 122 #define FRAG_APPEND_1_CHAR(datum)       \
 123 {                                       \
 124         if (obstack_room( &frags ) <= 1) {\
 125                 frag_wane (frag_now);   \
 126                 frag_new (0);           \
 127         }                               \
 128         (void)obstack_1grow( &frags, datum );   \
 129 }
 130 #endif /* _FRAGS_H_ */