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outbin.c

/* outbin.c output routines for the Netwide Assembler to produce
 *    flat-form binary files
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 */

/* This is the extended version of NASM's original binary output
 * format.  It is backward compatible with the original BIN format,
 * and contains support for multiple sections and advanced section
 * ordering.
 *
 * Feature summary:
 *
 * - Users can create an arbitrary number of sections; they are not
 *   limited to just ".text", ".data", and ".bss".
 *
 * - Sections can be either progbits or nobits type.
 *
 * - You can specify that they be aligned at a certian boundary
 *   following the previous section ("align="), or positioned at an
 *   arbitrary byte-granular location ("start=").
 *
 * - You can specify a "virtual" start address for a section, which
 *   will be used for the calculation for all address references
 *   with respect to that section ("vstart=").
 *
 * - The ORG directive, as well as the section/segment directive
 *   arguments ("align=", "start=", "vstart="), can take a critical
 *   expression as their value.  For example: "align=(1 << 12)".
 *
 * - You can generate map files using the 'map' directive.
 *
 */

/* Uncomment the following define if you want sections to adapt
 * their progbits/nobits state depending on what type of
 * instructions are issued, rather than defaulting to progbits.
 * Note that this behavior violates the specification.

#define ABIN_SMART_ADAPT

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "nasm.h"
#include "nasmlib.h"
#include "labels.h"
#include "eval.h"
#include "outform.h"

#ifdef OF_BIN

struct ofmt *bin_get_ofmt(); /* Prototype goes here since no header file. */

static FILE *fp, *rf = NULL;
static efunc error;

/* Section flags keep track of which attributes the user has defined. */
#define START_DEFINED       0x001
#define ALIGN_DEFINED       0x002
#define FOLLOWS_DEFINED     0x004
#define VSTART_DEFINED      0x008
#define VALIGN_DEFINED      0x010
#define VFOLLOWS_DEFINED    0x020
#define TYPE_DEFINED        0x040
#define TYPE_PROGBITS       0x080
#define TYPE_NOBITS         0x100

/* This struct is used to keep track of symbols for map-file generation. */
static struct bin_label
{  char * name;
   struct bin_label *next;
} *no_seg_labels, **nsl_tail;

static struct Section
{  char *name;
   struct SAA * contents;
   long length;          /* section length in bytes */

/* Section attributes */
   int flags;            /* see flag definitions above */
   unsigned long align;  /* section alignment */
   unsigned long valign; /* notional section alignment */
   unsigned long start;  /* section start address */
   unsigned long vstart; /* section virtual start address */
   char *follows;        /* the section that this one will follow */
   char *vfollows;       /* the section that this one will notionally follow */
   long start_index;     /* NASM section id for non-relocated version */
   long vstart_index;    /* the NASM section id */

   struct bin_label *labels;  /* linked-list of label handles for map output. */
   struct bin_label **labels_end;  /* Holds address of end of labels list. */
   struct Section *ifollows;  /* Points to previous section (implicit follows). */
   struct Section *next;  /* This links sections with a defined start address. */

/* The extended bin format allows for sections to have a "virtual"
 * start address.  This is accomplished by creating two sections:
 * one beginning at the Load Memory Address and the other beginning
 * at the Virtual Memory Address.  The LMA section is only used to
 * define the section.<section_name>.start label, but there isn't
 * any other good way for us to handle that label.
 */

} *sections, *last_section;

static struct Reloc {
    struct Reloc *next;
    long posn;
    long bytes;
    long secref;
    long secrel;
    struct Section *target;
} *relocs, **reloctail;

extern char *stdscan_bufptr;
extern int lookup_label (char *label, long *segment, long *offset);

static unsigned char format_mode;  /* 0 = original bin, 1 = extended bin */
static long current_section;       /* only really needed if format_mode = 0 */
static unsigned long origin;
static int origin_defined;

/* Stuff we need for map-file generation. */
#define MAP_ORIGIN       1
#define MAP_SUMMARY      2
#define MAP_SECTIONS     4
#define MAP_SYMBOLS      8
static int map_control = 0;
static char *infile, *outfile;

static const char *bin_stdmac[] = {
   "%define __SECT__ [section .text]",
   "%imacro org 1+.nolist",
   "[org %1]",
   "%endmacro",
   "%macro __NASM_CDecl__ 1",
   "%endmacro",
   NULL
};

static void add_reloc(struct Section *s, long bytes, long secref, long secrel)
{   struct Reloc *r;

    r = *reloctail = nasm_malloc(sizeof(struct Reloc));
    reloctail = &r->next;
    r->next = NULL;
    r->posn = s->length;
    r->bytes = bytes;
    r->secref = secref;
    r->secrel = secrel;
    r->target = s;
}

static struct Section *find_section_by_name(const char *name)
{  struct Section *s;

   for (s = sections; s; s = s->next)
      if (!strcmp(s->name,name)) break;
   return s;
}

static struct Section *find_section_by_index(long index)
{  struct Section *s;

   for (s = sections; s; s = s->next)
      if ((index == s->vstart_index) || (index == s->start_index))
        break;
   return s;
}

static struct Section * create_section(char *name)
{  /* Create a new section. */
   last_section->next = nasm_malloc(sizeof(struct Section));
   last_section->next->ifollows = last_section;
   last_section = last_section->next;
   last_section->labels = NULL;
   last_section->labels_end = &(last_section->labels);

   /* Initialize section attributes. */
   last_section->name = nasm_strdup(name);
   last_section->contents = saa_init(1L);
   last_section->follows = last_section->vfollows = 0;
   last_section->length = 0;
   last_section->flags = 0;
   last_section->next = NULL;

   /* Register our sections with NASM. */
   last_section->vstart_index = seg_alloc();
   last_section->start_index  = seg_alloc();
   return last_section;
}

static void bin_cleanup (int debuginfo)
{  struct Section *g, **gp;
   struct Section *gs = NULL, **gsp;
   struct Section *s, **sp;
   struct Section *nobits = NULL, **nt;
   struct Section * last_progbits;
   struct bin_label *l;
   struct Reloc *r;
   unsigned long pend;
   int h;

#ifdef DEBUG
   fprintf(stdout, "bin_cleanup: Sections were initially referenced in this order:\n");
   for (h = 0, s = sections; s; h++, s = s->next)
      fprintf(stdout, "%i. %s\n", h, s->name);
#endif

   /* Assembly has completed, so now we need to generate the output file.
    * Step 1: Separate progbits and nobits sections into separate lists.
    * Step 2: Sort the progbits sections into their output order.
    * Step 3: Compute start addresses for all progbits sections.
    * Step 4: Compute vstart addresses for all sections.
    * Step 5: Apply relocations.
    * Step 6: Write the sections' data to the output file.
    * Step 7: Generate the map file.
    * Step 8: Release all allocated memory.
    */

   /* To do: Smart section-type adaptation could leave some empty sections
    * without a defined type (progbits/nobits).  Won't fix now since this
    * feature will be disabled.  */


   /* Step 1: Split progbits and nobits sections into separate lists. */

   nt = &nobits;
   /* Move nobits sections into a separate list.  Also pre-process nobits
    * sections' attributes. */
   for (sp = &sections->next, s = sections->next; s; s = *sp)
   {  /* Skip progbits sections. */
      if (s->flags & TYPE_PROGBITS)
      {  sp = &s->next; continue;
      }
      /* Do some special pre-processing on nobits sections' attributes. */
      if (s->flags & (START_DEFINED | ALIGN_DEFINED | FOLLOWS_DEFINED))
      {  /* Check for a mixture of real and virtual section attributes. */
         if (s->flags & (VSTART_DEFINED | VALIGN_DEFINED | VFOLLOWS_DEFINED))
            error(ERR_FATAL, "cannot mix real and virtual attributes"
               " in nobits section (%s)", s->name);
         /* Real and virtual attributes mean the same thing for nobits sections. */
         if (s->flags & START_DEFINED)
         {  s->vstart = s->start; s->flags |= VSTART_DEFINED;
         }
         if (s->flags & ALIGN_DEFINED)
         {  s->valign = s->align; s->flags |= VALIGN_DEFINED;
         }
         if (s->flags & FOLLOWS_DEFINED)
         {  s->vfollows = s->follows; s->flags |= VFOLLOWS_DEFINED;
            s->flags &= ~FOLLOWS_DEFINED;
         }
      }
      /* Every section must have a start address. */
      if (s->flags & VSTART_DEFINED)
      {  s->start = s->vstart; s->flags |= START_DEFINED;
      }
      /* Move the section into the nobits list. */
      *sp = s->next; s->next = NULL;
      *nt = s; nt = &s->next;
   }

   /* Step 2: Sort the progbits sections into their output order. */

   /* In Step 2 we move around sections in groups.  A group
    * begins with a section (group leader) that has a user-
    * defined start address or follows section.  The remainder
    * of the group is made up of the sections that implicitly
    * follow the group leader (i.e., they were defined after
    * the group leader and were not given an explicit start
    * address or follows section by the user). */

   /* For anyone attempting to read this code:
    * g (group) points to a group of sections, the first one of which has
    *   a user-defined start address or follows section.
    * gp (g previous) holds the location of the pointer to g.
    * gs (g scan) is a temp variable that we use to scan to the end of the group.
    * gsp (gs previous) holds the location of the pointer to gs.
    * nt (nobits tail) points to the nobits section-list tail.
    */

   /* Link all 'follows' groups to their proper position.  To do
    * this we need to know three things: the start of the group
    * to relocate (g), the section it is following (s), and the
    * end of the group we're relocating (gs). */
   for (gp = &sections, g = sections; g; g = gs)
   {  /* Find the next follows group that is out of place (g). */
      if (!(g->flags & FOLLOWS_DEFINED))
      {  while (g->next)
         {  if ((g->next->flags & FOLLOWS_DEFINED) &&
               strcmp(g->name, g->next->follows)) break;
            g = g->next;
         }
         if (!g->next) break;
         gp = &g->next; g = g->next;
      }
      /* Find the section that this group follows (s). */
      for (sp = &sections, s = sections;
         s && strcmp(s->name, g->follows);
         sp = &s->next, s = s->next);
      if (!s) error(ERR_FATAL, "section %s follows an invalid or"
         " unknown section (%s)", g->name, g->follows);
      if (s->next && (s->next->flags & FOLLOWS_DEFINED) &&
         !strcmp(s->name, s->next->follows))
         error(ERR_FATAL, "sections %s and %s can't both follow"
            " section %s", g->name, s->next->name, s->name);
      /* Find the end of the current follows group (gs). */
      for (gsp = &g->next, gs = g->next;
         gs && (gs != s) && !(gs->flags & START_DEFINED);
         gsp = &gs->next, gs = gs->next)
      {  if (gs->next && (gs->next->flags & FOLLOWS_DEFINED) &&
            strcmp(gs->name, gs->next->follows))
         {  gsp = &gs->next; gs = gs->next; break;
         }
      }
      /* Re-link the group after its follows section. */
      *gsp = s->next; s->next = g;
      *gp = gs;
   }

   /* Link all 'start' groups to their proper position.  Once
    * again we need to know g, s, and gs (see above).  The main
    * difference is we already know g since we sort by moving
    * groups from the 'unsorted' list into a 'sorted' list (g
    * will always be the first section in the unsorted list). */
   for (g = sections, sections = NULL; g; g = gs)
   {  /* Find the section that we will insert this group before (s). */
      for (sp = &sections, s = sections; s; sp = &s->next, s = s->next)
         if ((s->flags & START_DEFINED) && (g->start < s->start)) break;
      /* Find the end of the group (gs). */
      for (gs = g->next, gsp = &g->next;
         gs && !(gs->flags & START_DEFINED);
         gsp = &gs->next, gs = gs->next);
      /* Re-link the group before the target section. */
         *sp = g; *gsp = s;
   }


   /* Step 3: Compute start addresses for all progbits sections. */

   /* Make sure we have an origin and a start address for the first section. */
   if (origin_defined)
      switch (sections->flags & (START_DEFINED | ALIGN_DEFINED))
      {  case START_DEFINED | ALIGN_DEFINED:
         case START_DEFINED:
            /* Make sure this section doesn't begin before the origin. */
            if (sections->start < origin) error(ERR_FATAL, "section %s begins"
               " before program origin", sections->name);
            break;
         case ALIGN_DEFINED:
            sections->start = ((origin + sections->align - 1) &
               ~(sections->align - 1)); break;
         case 0:
            sections->start = origin;
      }
   else
   {  if (!(sections->flags & START_DEFINED))
         sections->start = 0;
      origin = sections->start;
   }
   sections->flags |= START_DEFINED;

   /* Make sure each section has an explicit start address.  If it
    * doesn't, then compute one based its alignment and the end of
    * the previous section. */
   for (pend = sections->start, g = s = sections; g; g = g->next)
   {  /* Find the next section that could cause an overlap situation
       * (has a defined start address, and is not zero length). */
      if (g == s)
         for (s = g->next;
           s && ((s->length == 0) || !(s->flags & START_DEFINED));
           s = s->next);
      /* Compute the start address of this section, if necessary. */
      if (!(g->flags & START_DEFINED))
      {  /* Default to an alignment of 4 if unspecified. */
         if (!(g->flags & ALIGN_DEFINED))
         {  g->align = 4; g->flags |= ALIGN_DEFINED;
         }
         /* Set the section start address. */
         g->start = (pend + g->align - 1) & ~(g->align - 1);
         g->flags |= START_DEFINED;
      }
      /* Ugly special case for progbits sections' virtual attributes:
       *   If there is a defined valign, but no vstart and no vfollows, then
       *   we valign after the previous progbits section.  This case doesn't
       *   really make much sense for progbits sections with a defined start
       *   address, but it is possible and we must do *something*.
       * Not-so-ugly special case:
       *   If a progbits section has no virtual attributes, we set the
       *   vstart equal to the start address.  */
      if (!(g->flags & (VSTART_DEFINED | VFOLLOWS_DEFINED)))
      {  if (g->flags & VALIGN_DEFINED)
            g->vstart = (pend + g->valign - 1) & ~(g->valign - 1);
         else g->vstart = g->start;
         g->flags |= VSTART_DEFINED;
      }
      /* Ignore zero-length sections. */
      if (g->start < pend) continue;
      /* Compute the span of this section. */
      pend = g->start + g->length;
      /* Check for section overlap. */
      if (s)
      {  if (g->start > s->start)
            error(ERR_FATAL, "sections %s ~ %s and %s overlap!",
               gs->name, g->name, s->name);
         if (pend > s->start)
            error(ERR_FATAL, "sections %s and %s overlap!",
               g->name, s->name);
      }
      /* Remember this section as the latest >0 length section. */
      gs = g;
   }

   /* Step 4: Compute vstart addresses for all sections. */

   /* Attach the nobits sections to the end of the progbits sections. */
   for (s = sections; s->next; s = s->next); s->next = nobits;
   last_progbits = s;
   /* Scan for sections that don't have a vstart address.  If we find one we'll
    * attempt to compute its vstart.  If we can't compute the vstart, we leave
    * it alone and come back to it in a subsequent scan.  We continue scanning
    * and re-scanning until we've gone one full cycle without computing any
    * vstarts. */
   do
   {  /* Do one full scan of the sections list. */
      for (h = 0, g = sections; g; g = g->next)
      {  if (g->flags & VSTART_DEFINED) continue;
         /* Find the section that this one virtually follows.  */
         if (g->flags & VFOLLOWS_DEFINED)
         {  for (s = sections; s && strcmp(g->vfollows, s->name); s = s->next);
            if (!s) error(ERR_FATAL, "section %s vfollows unknown section (%s)",
               g->name, g->vfollows);
         }
         else if (g->ifollows != NULL)
            for (s = sections; s && (s != g->ifollows); s = s->next);
         /* The .bss section is the only one with ifollows = NULL.  In this case we
          * implicitly follow the last progbits section.  */
         else s = last_progbits;

         /* If the section we're following has a vstart, we can proceed. */
         if (s->flags & VSTART_DEFINED)
         {  /* Default to virtual alignment of four. */
            if (!(g->flags & VALIGN_DEFINED))
            {  g->valign = 4; g->flags |= VALIGN_DEFINED;
            }
            /* Compute the vstart address. */
            g->vstart = (s->vstart + s->length + g->valign - 1) & ~(g->valign - 1);
            g->flags |= VSTART_DEFINED; h++;
            /* Start and vstart mean the same thing for nobits sections. */
            if (g->flags & TYPE_NOBITS) g->start = g->vstart;
         }
      }
   } while (h);

   /* Now check for any circular vfollows references, which will manifest
    * themselves as sections without a defined vstart. */
   for (h = 0, s = sections; s; s = s->next)
   {  if (!(s->flags & VSTART_DEFINED))
      {  /* Non-fatal errors after assembly has completed are generally a
          * no-no, but we'll throw a fatal one eventually so it's ok.  */
         error(ERR_NONFATAL, "cannot compute vstart for section %s", s->name);
         h++;
      }
   }
   if (h) error(ERR_FATAL, "circular vfollows path detected");

#ifdef DEBUG
   fprintf(stdout, "bin_cleanup: Confirm final section order for output file:\n");
   for (h = 0, s = sections; s && (s->flags & TYPE_PROGBITS); h++, s = s->next)
      fprintf(stdout, "%i. %s\n", h, s->name);
#endif


   /* Step 5: Apply relocations. */

   /* Prepare the sections for relocating. */
   for (s = sections; s; s = s->next) saa_rewind(s->contents);
   /* Apply relocations. */
   for (r = relocs; r; r = r->next)
   {  unsigned char *p, *q, mydata[4];
      long l;

      saa_fread (r->target->contents, r->posn, mydata, r->bytes);
      p = q = mydata;
      l = *p++;

      if (r->bytes > 1)
      {  l += ((long)*p++) << 8;
         if (r->bytes == 4)
         {  l += ((long)*p++) << 16;
            l += ((long)*p++) << 24;
         }
      }

      s = find_section_by_index(r->secref);
      if (s)
      {  if (r->secref == s->start_index) l += s->start;
         else l += s->vstart;
      }
      s = find_section_by_index(r->secrel);
      if (s)
      {  if (r->secrel == s->start_index) l -= s->start;
         else l -= s->vstart;
      }

      if (r->bytes == 4) WRITELONG(q, l);
      else if (r->bytes == 2) WRITESHORT(q, l);
      else *q++ = (unsigned char) (l & 0xFF);
      saa_fwrite(r->target->contents, r->posn, mydata, r->bytes);
   }


   /* Step 6: Write the section data to the output file. */

   /* Write the progbits sections to the output file. */
   for(pend = origin, s = sections; s && (s->flags & TYPE_PROGBITS); s = s->next)
   {  /* Skip zero-length sections. */
      if (s->length == 0) continue;
      /* Pad the space between sections. */
      for (h = s->start - pend; h; h--)
         fputc('\0', fp);
      /* Write the section to the output file. */
      if (s->length > 0) saa_fpwrite(s->contents, fp);
      pend = s->start + s->length;
   }
   /* Done writing the file, so close it. */
   fclose(fp);


   /* Step 7: Generate the map file. */

   if (map_control)
   {  const char *not_defined = { "not defined" };

      /* Display input and output file names. */
      fprintf(rf, "\n- NASM Map file ");
      for (h = 63; h; h--) fputc('-', rf);
      fprintf(rf, "\n\nSource file:  %s\nOutput file:  %s\n\n",
         infile, outfile);

      if (map_control & MAP_ORIGIN)
      {  /* Display program origin. */
        fprintf(rf, "-- Program origin ");
        for (h = 61; h; h--) fputc('-', rf);
        fprintf(rf, "\n\n%08lX\n\n", origin);
      }
      /* Display sections summary. */
      if (map_control & MAP_SUMMARY)
      {  fprintf(rf, "-- Sections (summary) ");
         for (h = 57; h; h--) fputc('-', rf);
         fprintf(rf, "\n\nVstart    Start     Stop      "
            "Length    Class     Name\n");
         for (s = sections; s; s = s->next)
         {  fprintf(rf, "%08lX  %08lX  %08lX  %08lX  ",
               s->vstart, s->start, s->start + s->length, s->length);
            if (s->flags & TYPE_PROGBITS) fprintf(rf, "progbits  ");
            else fprintf(rf, "nobits    ");
            fprintf(rf, "%s\n", s->name);
         }
         fprintf(rf, "\n");
      }
      /* Display detailed section information. */
      if (map_control & MAP_SECTIONS)
      {  fprintf(rf, "-- Sections (detailed) ");
         for (h = 56; h; h--) fputc('-', rf);
         fprintf(rf, "\n\n");
         for (s = sections; s; s = s->next)
         {  fprintf(rf, "---- Section %s ", s->name);
            for (h = 65 - strlen(s->name); h; h--) fputc('-', rf);
            fprintf(rf, "\n\nclass:     ");
            if (s->flags & TYPE_PROGBITS) fprintf(rf, "progbits");
            else fprintf(rf, "nobits");
            fprintf(rf, "\nlength:    %08lX\nstart:     %08lX"
               "\nalign:     ", s->length, s->start);
            if (s->flags & ALIGN_DEFINED) fprintf(rf, "%08lX", s->align);
            else fprintf(rf, not_defined);
            fprintf(rf, "\nfollows:   ");
            if (s->flags & FOLLOWS_DEFINED) fprintf(rf, "%s", s->follows);
            else fprintf(rf, not_defined);
            fprintf(rf, "\nvstart:    %08lX\nvalign:    ", s->vstart);
            if (s->flags & VALIGN_DEFINED) fprintf(rf, "%08lX", s->valign);
            else fprintf(rf, not_defined);
            fprintf(rf, "\nvfollows:  ");
            if (s->flags & VFOLLOWS_DEFINED) fprintf(rf, "%s", s->vfollows);
            else fprintf(rf, not_defined);
            fprintf(rf, "\n\n");
         }
      }
      /* Display symbols information. */
      if (map_control & MAP_SYMBOLS)
      {  long segment, offset;

         fprintf(rf, "-- Symbols ");
         for (h = 68; h; h--) fputc('-', rf);
         fprintf(rf, "\n\n");
         if (no_seg_labels)
         {  fprintf(rf, "---- No Section ");
            for (h = 63; h; h--) fputc('-', rf);
            fprintf(rf, "\n\nValue     Name\n");
            for (l = no_seg_labels; l; l = l->next)
            {  lookup_label(l->name, &segment, &offset);
               fprintf(rf, "%08lX  %s\n", offset, l->name);
            }
            fprintf(rf, "\n\n");
         }
         for (s = sections; s; s = s->next)
         {  if (s->labels)
            {  fprintf(rf, "---- Section %s ", s->name);
               for (h = 65 - strlen(s->name); h; h--) fputc('-', rf);
               fprintf(rf, "\n\nReal      Virtual   Name\n");
               for (l = s->labels; l; l = l->next)
               {  lookup_label(l->name, &segment, &offset);
                  fprintf(rf, "%08lX  %08lX  %s\n", s->start + offset,
                     s->vstart + offset, l->name);
               }
               fprintf(rf, "\n");
            }
         }
      }
   }

   /* Close the report file. */
   if (map_control && (rf != stdout) && (rf != stderr))
      fclose(rf);


   /* Step 8: Release all allocated memory. */

   /* Free sections, label pointer structs, etc.. */
   while (sections)
   {  s = sections; sections = s->next;
      saa_free(s->contents);
      nasm_free(s->name);
      if (s->flags & FOLLOWS_DEFINED) nasm_free(s->follows);
      if (s->flags & VFOLLOWS_DEFINED) nasm_free(s->vfollows);
      while (s->labels)
      {  l = s->labels; s->labels = l->next;
         nasm_free(l);
      }
      nasm_free(s);
   }

   /* Free no-section labels. */
   while (no_seg_labels)
   {  l = no_seg_labels; no_seg_labels = l->next;
      nasm_free(l);
   }

   /* Free relocation structures. */
   while (relocs)
   {  r = relocs->next;
      nasm_free(relocs);
      relocs = r;
   }
}

static void bin_out (long segto, const void *data, unsigned long type,
           long segment, long wrt)
{  unsigned char *p, mydata[4];
   struct Section *s;
   long realbytes;

   if (wrt != NO_SEG)
   {  wrt = NO_SEG;        /* continue to do _something_ */
      error (ERR_NONFATAL,
         "WRT not supported by binary output format");
   }

   /* Handle absolute-assembly (structure definitions). */
   if (segto == NO_SEG)
   {  if ((type & OUT_TYPMASK) != OUT_RESERVE)
         error (ERR_NONFATAL, "attempt to assemble code in"
            " [ABSOLUTE] space");
      return;
   }

   /* Find the segment we are targeting. */
   s = find_section_by_index(segto);
   if (!s)
      error (ERR_PANIC, "code directed to nonexistent segment?");

   /* "Smart" section-type adaptation code. */
   if (!(s->flags & TYPE_DEFINED))
   {  if ((type & OUT_TYPMASK) == OUT_RESERVE)
         s->flags |= TYPE_DEFINED | TYPE_NOBITS;
      else s->flags |= TYPE_DEFINED | TYPE_PROGBITS;
   }

   if ((s->flags & TYPE_NOBITS) && ((type & OUT_TYPMASK) != OUT_RESERVE))
      error(ERR_WARNING, "attempt to initialise memory in a"
         " nobits section: ignored");

   if ((type & OUT_TYPMASK) == OUT_ADDRESS)
   {  if (segment != NO_SEG && !find_section_by_index(segment))
      {  if (segment % 2)
            error(ERR_NONFATAL, "binary output format does not support"
               " segment base references");
         else
            error(ERR_NONFATAL, "binary output format does not support"
               " external references");
         segment = NO_SEG;
      }
      if (s->flags & TYPE_PROGBITS)
      {  if (segment != NO_SEG)
            add_reloc(s, type & OUT_SIZMASK, segment, -1L);
         p = mydata;
         if ((type & OUT_SIZMASK) == 4)
            WRITELONG(p, *(long *)data);
         else
            WRITESHORT(p, *(long *)data);
         saa_wbytes(s->contents, mydata, type & OUT_SIZMASK);
      }
      s->length += type & OUT_SIZMASK;
   }
   else if ((type & OUT_TYPMASK) == OUT_RAWDATA)
   {  type &= OUT_SIZMASK;
      if (s->flags & TYPE_PROGBITS) saa_wbytes(s->contents, data, type);
      s->length += type;
   }
   else if ((type & OUT_TYPMASK) == OUT_RESERVE)
   {  type &= OUT_SIZMASK;
      if (s->flags & TYPE_PROGBITS)
      {  error(ERR_WARNING, "uninitialised space declared in"
            " %s section: zeroing", s->name);
         saa_wbytes (s->contents, NULL, type);
      }
      s->length += type;
   }
   else if ((type & OUT_TYPMASK) == OUT_REL2ADR ||
      (type & OUT_TYPMASK) == OUT_REL4ADR)
   {  realbytes = ((type & OUT_TYPMASK) == OUT_REL4ADR ? 4 : 2);
      if (segment != NO_SEG && !find_section_by_index(segment))
      {  if (segment % 2)
            error(ERR_NONFATAL, "binary output format does not support"
               " segment base references");
         else
            error(ERR_NONFATAL, "binary output format does not support"
               " external references");
         segment = NO_SEG;
      }
      if (s->flags & TYPE_PROGBITS)
      {  add_reloc(s, realbytes, segment, segto);
         p = mydata;
         if (realbytes == 4)
            WRITELONG(p, *(long*)data - realbytes - s->length);
         else
            WRITESHORT(p, *(long*)data - realbytes - s->length);
         saa_wbytes(s->contents, mydata, realbytes);
      }
      s->length += realbytes;
   }
}

static void bin_deflabel (char *name, long segment, long offset,
           int is_global, char *special)
{  (void) segment;   /* Don't warn that this parameter is unused */
   (void) offset;    /* Don't warn that this parameter is unused */

   if (special)
      error (ERR_NONFATAL, "binary format does not support any"
         " special symbol types");
   else if (name[0] == '.' && name[1] == '.' && name[2] != '@')
      error (ERR_NONFATAL, "unrecognised special symbol `%s'", name);
   else if (is_global == 2)
      error (ERR_NONFATAL, "binary output format does not support common"
         " variables");
   else
   {  struct Section *s;
      struct bin_label ***ltp;

      /* Remember label definition so we can look it up later when
       * creating the map file. */
      s = find_section_by_index(segment);
      if (s) ltp = &(s->labels_end);
      else ltp = &nsl_tail;
      (**ltp) = nasm_malloc(sizeof(struct bin_label));
      (**ltp)->name = name;
      (**ltp)->next = NULL;
      *ltp = &((**ltp)->next);
   }

}

/* These constants and the following function are used
 * by bin_secname() to parse attribute assignments. */

enum { ATTRIB_START, ATTRIB_ALIGN, ATTRIB_FOLLOWS,
       ATTRIB_VSTART, ATTRIB_VALIGN, ATTRIB_VFOLLOWS,
       ATTRIB_NOBITS, ATTRIB_PROGBITS };

static int bin_read_attribute(char **line, int *attribute, unsigned long *value)
{  expr *e;
   int attrib_name_size;
   struct tokenval tokval;
   char *exp;

   /* Skip whitespace. */
   while (**line && isspace(**line)) (*line)++;
   if (!**line) return 0;

   /* Figure out what attribute we're reading. */
   if (!nasm_strnicmp(*line,"align=", 6))
   {  *attribute = ATTRIB_ALIGN;
      attrib_name_size = 6;
   }
   else if (format_mode)
   {  if (!nasm_strnicmp(*line,"start=", 6))
      {  *attribute = ATTRIB_START;
         attrib_name_size = 6;
      }
      else if (!nasm_strnicmp(*line,"follows=", 8))
      {  *attribute = ATTRIB_FOLLOWS;
         *line += 8; return 1;
      }
      else if (!nasm_strnicmp(*line,"vstart=", 7))
      {  *attribute = ATTRIB_VSTART;
         attrib_name_size = 7;
      }
      else if (!nasm_strnicmp(*line,"valign=", 7))
      {  *attribute = ATTRIB_VALIGN;
         attrib_name_size = 7;
      }
      else if (!nasm_strnicmp(*line,"vfollows=", 9))
      {  *attribute = ATTRIB_VFOLLOWS;
         *line += 9; return 1;
      }
      else if (!nasm_strnicmp(*line,"nobits", 6) &&
         (isspace((*line)[6]) || ((*line)[6] == '\0')))
      {  *attribute = ATTRIB_NOBITS;
         *line += 6; return 1;
      }
      else if (!nasm_strnicmp(*line,"progbits", 8) &&
         (isspace((*line)[8]) || ((*line)[8] == '\0')))
      {  *attribute = ATTRIB_PROGBITS;
         *line += 8; return 1;
      }
      else return 0;
   }
   else return 0;

   /* Find the end of the expression. */
   if ((*line)[attrib_name_size] != '(')
   {
      /* Single term (no parenthesis). */
      exp = *line += attrib_name_size;
      while (**line && !isspace(**line)) (*line)++;
      if (**line)
      {  **line = '\0'; (*line)++;
      }
   }
   else
   {  char c;
      int pcount = 1;

      /* Full expression (delimited by parenthesis) */
      exp = *line += attrib_name_size + 1;
      while (1)
      {  (*line) += strcspn(*line, "()'\"");
         if (**line == '(')
         {  ++(*line); ++pcount;
         }
         if (**line == ')')
         {  ++(*line); --pcount;
            if (!pcount) break;
         }
         if ((**line == '"') || (**line == '\''))
         {  c = **line;
            while (**line)
            {  ++(*line);
               if (**line == c) break;
            }
            if (!**line)
            {  error(ERR_NONFATAL, "invalid syntax in `section' directive");
               return -1;
            }
            ++(*line);
         }
         if (!**line)
         {  error(ERR_NONFATAL, "expecting `)'");
            return -1;
         }
      }
      *(*line - 1) = '\0';  /* Terminate the expression. */
   }

   /* Check for no value given. */
   if (!*exp)
   {  error(ERR_WARNING, "No value given to attribute in"
         " `section' directive");
      return -1;
   }

   /* Read and evaluate the expression. */
   stdscan_reset();
   stdscan_bufptr = exp;
   tokval.t_type = TOKEN_INVALID;
   e = evaluate(stdscan, NULL, &tokval, NULL, 1, error, NULL);
   if (e)
   {  if (!is_really_simple(e))
      {  error(ERR_NONFATAL, "section attribute value must be"
            " a critical expression");
         return -1;
      }
   }
   else
   {  error(ERR_NONFATAL, "Invalid attribute value"
         " specified in `section' directive.");
      return -1;
   }
   *value = (unsigned long) reloc_value(e);
   return 1;
}

static void bin_assign_attributes(struct Section *sec, char *astring)
{  int attribute, check;
   unsigned long value;
   char *p;

   while (1)
   {  /* Get the next attribute. */
      check = bin_read_attribute(&astring, &attribute, &value);
      /* Skip bad attribute. */
      if (check == -1) continue;
      /* Unknown section attribute, so skip it and warn the user. */
      if (!check)
      {  if (!*astring) break;  /* End of line. */
         else
         {  p = astring; while (*astring && !isspace(*astring)) astring++;
            if (*astring)
            {  *astring = '\0'; astring++;
            }
            error(ERR_WARNING, "ignoring unknown section attribute:"
               " \"%s\"", p);
         }
      continue;
      }

      switch (attribute)
      {  /* Handle nobits attribute. */
         case ATTRIB_NOBITS:
            if ((sec->flags & TYPE_DEFINED) && (sec->flags & TYPE_PROGBITS))
               error(ERR_NONFATAL, "attempt to change section type"
                  " from progbits to nobits");
            else sec->flags |= TYPE_DEFINED | TYPE_NOBITS;
            continue;

         /* Handle progbits attribute. */
         case ATTRIB_PROGBITS:
            if ((sec->flags & TYPE_DEFINED) && (sec->flags & TYPE_NOBITS))
               error(ERR_NONFATAL, "attempt to change section type"
                  " from nobits to progbits");
            else sec->flags |= TYPE_DEFINED | TYPE_PROGBITS;
            continue;

         /* Handle align attribute. */
         case ATTRIB_ALIGN:
            if (!format_mode && (!strcmp(sec->name, ".text")))
               error(ERR_NONFATAL, "cannot specify an alignment"
                  " to the .text section");
            else
            {  if (!value || ((value - 1) & value))
                  error(ERR_NONFATAL, "argument to `align' is not a"
                  " power of two");
               else
               {  /* Alignment is already satisfied if the previous
                   * align value is greater. */
                  if ((sec->flags & ALIGN_DEFINED) && (value < sec->align))
                     value = sec->align;

                  /* Don't allow a conflicting align value. */
                  if ((sec->flags & START_DEFINED) && (sec->start & (value - 1)))
                     error(ERR_NONFATAL, "`align' value conflicts "
                     "with section start address");
                  else
                  {  sec->align = value; sec->flags |= ALIGN_DEFINED;
                  }
               }
            }
            continue;

         /* Handle valign attribute. */
         case ATTRIB_VALIGN:
            if (!value || ((value - 1) & value))
               error(ERR_NONFATAL, "argument to `valign' is not a"
                  " power of two");
            else
            {  /* Alignment is already satisfied if the previous
                * align value is greater. */
               if ((sec->flags & VALIGN_DEFINED) && (value < sec->valign))
                  value = sec->valign;

               /* Don't allow a conflicting valign value. */
               if ((sec->flags & VSTART_DEFINED) && (sec->vstart & (value - 1)))
                  error(ERR_NONFATAL, "`valign' value conflicts "
                     "with `vstart' address");
               else
               {  sec->valign = value; sec->flags |= VALIGN_DEFINED;
               }
            }
            continue;

         /* Handle start attribute. */
         case ATTRIB_START:
            if (sec->flags & FOLLOWS_DEFINED)
               error(ERR_NONFATAL, "cannot combine `start' and `follows'"
                  " section attributes");
            else if (value < 0)
               error(ERR_NONFATAL, "attempt to specify a negative"
                  " section start address");
            else if ((sec->flags & START_DEFINED) && (value != sec->start))
               error(ERR_NONFATAL, "section start address redefined");
            else
            {  sec->start = value; sec->flags |= START_DEFINED;
               if (sec->flags & ALIGN_DEFINED)
               {  if (sec->start & (sec->align - 1))
                     error (ERR_NONFATAL, "`start' address conflicts"
                        " with section alignment");
                  sec->flags ^= ALIGN_DEFINED;
               }
            }
            continue;

         /* Handle vstart attribute. */
         case ATTRIB_VSTART:
            if (sec->flags & VFOLLOWS_DEFINED)
               error(ERR_NONFATAL, "cannot combine `vstart' and `vfollows'"
                  " section attributes");
            else if ((sec->flags & VSTART_DEFINED) && (value != sec->vstart))
               error(ERR_NONFATAL, "section virtual start address"
                  " (vstart) redefined");
            else
            {  sec->vstart = value; sec->flags |= VSTART_DEFINED;
               if (sec->flags & VALIGN_DEFINED)
               {  if (sec->vstart & (sec->valign - 1))
                     error (ERR_NONFATAL, "`vstart' address conflicts"
                        " with `valign' value");
                  sec->flags ^= VALIGN_DEFINED;
               }
            }
            continue;

         /* Handle follows attribute. */
         case ATTRIB_FOLLOWS:
            p = astring; astring += strcspn(astring, " \t");
            if (astring == p)
               error(ERR_NONFATAL, "expecting section name for `follows'"
                  " attribute");
            else
            {  *(astring++) = '\0';
               if (sec->flags & START_DEFINED)
                  error(ERR_NONFATAL, "cannot combine `start' and `follows'"
                     " section attributes");
               sec->follows = nasm_strdup(p);
               sec->flags |= FOLLOWS_DEFINED;
            }
            continue;

         /* Handle vfollows attribute. */
         case ATTRIB_VFOLLOWS:
            if (sec->flags & VSTART_DEFINED)
               error(ERR_NONFATAL, "cannot combine `vstart' and `vfollows'"
                  " section attributes");
            else
            {  p = astring; astring += strcspn(astring, " \t");
               if (astring == p)
                  error(ERR_NONFATAL, "expecting section name for `vfollows'"
                     " attribute");
               else
               {  *(astring++) = '\0';
                  sec->vfollows = nasm_strdup(p);
                  sec->flags |= VFOLLOWS_DEFINED;
               }
            }
            continue;
      }
   }
}

static void bin_define_section_labels()
{  static int labels_defined = 0;
   struct Section * sec;
   char * label_name;
   size_t base_len;

   if (labels_defined) return;
   for (sec = sections; sec; sec = sec->next)
   {  base_len = strlen(sec->name) + 8;
      label_name = nasm_malloc(base_len + 8);
      strcpy(label_name, "section.");
      strcpy(label_name + 8, sec->name);

      /* section.<name>.start */
      strcpy(label_name + base_len, ".start");
      define_label(label_name, sec->start_index, 0L,
         NULL, 0, 0, bin_get_ofmt(), error);

      /* section.<name>.vstart */
      strcpy(label_name + base_len, ".vstart");
      define_label(label_name, sec->vstart_index, 0L,
         NULL, 0, 0, bin_get_ofmt(), error);

      nasm_free(label_name);
   }
   labels_defined = 1;
}

static long bin_secname(char *name, int pass, int *bits)
{  char *p;
   struct Section *sec;

   /* bin_secname is called with *name = NULL at the start of each
    * pass.  Use this opportunity to establish the default section
    * (default is BITS-16 ".text" segment).
    */
   if (!name)
   {  /* Reset ORG and section attributes at the start of each pass. */
      origin_defined = 0;
      for (sec = sections; sec; sec = sec->next)
         sec->flags &= ~(START_DEFINED | VSTART_DEFINED |
            ALIGN_DEFINED | VALIGN_DEFINED);

      /* Define section start and vstart labels. */
      if (format_mode && (pass != 1)) bin_define_section_labels();

      /* Establish the default (.text) section. */
      *bits = 16;
      sec = find_section_by_name(".text");
      sec->flags |= TYPE_DEFINED | TYPE_PROGBITS;
      current_section = sec->vstart_index;
      return current_section;
   }

   /* Attempt to find the requested section.  If it does not
    * exist, create it. */
   p = name;
   while (*p && !isspace(*p)) p++;
   if (*p) *p++ = '\0';
   sec = find_section_by_name(name);
   if(!sec)
   {  sec = create_section(name);
      if (!strcmp(name, ".data"))
         sec->flags |= TYPE_DEFINED | TYPE_PROGBITS;
      else if (!strcmp(name, ".bss"))
      {  sec->flags |= TYPE_DEFINED | TYPE_NOBITS;
         sec->ifollows = NULL;
      }
      else if (!format_mode)
      {  error(ERR_NONFATAL, "section name must be "
            ".text, .data, or .bss");
         return current_section;
      }
   }

   /* Handle attribute assignments. */
   if (pass != 1) bin_assign_attributes(sec, p);

#ifndef ABIN_SMART_ADAPT
   /* The following line disables smart adaptation of
    * PROGBITS/NOBITS section types (it forces sections to
    * default to PROGBITS). */
   if ((pass != 1) && !(sec->flags & TYPE_DEFINED))
      sec->flags |= TYPE_DEFINED | TYPE_PROGBITS;
#endif

   /* Set the current section and return. */
   current_section = sec->vstart_index;
   return current_section;
}

static int bin_directive (char *directive, char *args, int pass)
{
   /* Handle ORG directive */
   if (!nasm_stricmp(directive, "org"))
   {  struct tokenval tokval;
      unsigned long value;
      expr *e;

      stdscan_reset();
      stdscan_bufptr = args;
      tokval.t_type = TOKEN_INVALID;
      e = evaluate(stdscan, NULL, &tokval, NULL, 1, error, NULL);
      if (e)
      {  if (!is_really_simple(e))
            error(ERR_NONFATAL, "org value must be a critical"
               " expression");
         else
         {  value = reloc_value(e);
            /* Check for ORG redefinition. */
            if (origin_defined && (value != origin))
               error(ERR_NONFATAL, "program origin redefined");
            else
            {  origin = value;
               origin_defined = 1;
            }
         }
      }
      else
         error(ERR_NONFATAL, "No or invalid offset specified"
            " in ORG directive.");
      return 1;
   }

   /* The 'map' directive allows the user to generate section
    * and symbol information to stdout, stderr, or to a file. */
   else if (format_mode && !nasm_stricmp(directive, "map"))
   {  char *p;

      if (pass != 1) return 1;
      args += strspn(args, " \t");
      while (*args)
      {  p = args; args += strcspn(args, " \t");
         if (*args != '\0') *(args++) = '\0';
         if (!nasm_stricmp(p, "all"))
            map_control |= MAP_ORIGIN | MAP_SUMMARY | MAP_SECTIONS | MAP_SYMBOLS;
         else if (!nasm_stricmp(p, "brief"))
            map_control |= MAP_ORIGIN | MAP_SUMMARY;
         else if (!nasm_stricmp(p, "sections"))
            map_control |= MAP_ORIGIN | MAP_SUMMARY | MAP_SECTIONS;
         else if (!nasm_stricmp(p, "segments"))
            map_control |= MAP_ORIGIN | MAP_SUMMARY | MAP_SECTIONS;
         else if (!nasm_stricmp(p, "symbols"))
            map_control |= MAP_SYMBOLS;
         else if (!rf)
         {  if (!nasm_stricmp(p, "stdout"))
               rf = stdout;
            else if (!nasm_stricmp(p, "stderr"))
               rf = stderr;
            else
            {  /* Must be a filename. */
               rf = fopen(p, "wt");
               if (!rf)
               {  error(ERR_WARNING, "unable to open map file `%s'", p);
                  map_control = 0;
                  return 1;
                 }
            }
         }
         else error(ERR_WARNING, "map file already specified");
      }
      if (map_control == 0) map_control |= MAP_ORIGIN | MAP_SUMMARY;
      if (!rf) rf = stdout;
      return 1;
   }
   return 0;
}

static void bin_filename (char *inname, char *outname, efunc error)
{  standard_extension(inname, outname, "", error);
   infile = inname; outfile = outname;
}

static long bin_segbase (long segment)
{    return segment;
}

static int bin_set_info(enum geninfo type, char **val)
{  return 0;
}

static void bin_init (FILE *afp, efunc errfunc, ldfunc ldef, evalfunc eval)
{   fp = afp;
    error = errfunc;

    (void) eval;   /* Don't warn that this parameter is unused. */
    (void) ldef;   /* Placate optimizers. */

    relocs          = NULL;
    reloctail       = &relocs;
    origin_defined  = 0;
    no_seg_labels   = NULL;
    nsl_tail        = &no_seg_labels;
    format_mode     = 1; /* Extended bin format
                          * (set this to zero for old bin format). */

   /* Create default section (.text). */
   sections = last_section = nasm_malloc(sizeof(struct Section));
   last_section->next = NULL;
   last_section->name = nasm_strdup(".text");
   last_section->contents = saa_init(1L);
   last_section->follows = last_section->vfollows = 0;
   last_section->ifollows = NULL;
   last_section->length = 0;
   last_section->flags = TYPE_DEFINED | TYPE_PROGBITS;
   last_section->labels = NULL;
   last_section->labels_end = &(last_section->labels);
   last_section->start_index  = seg_alloc();
   last_section->vstart_index = current_section = seg_alloc();
}

struct ofmt of_bin = {
    "flat-form binary files (e.g. DOS .COM, .SYS)",
    "bin",
    NULL,
    null_debug_arr,
    &null_debug_form,
    bin_stdmac,
    bin_init,
    bin_set_info,
    bin_out,
    bin_deflabel,
    bin_secname,
    bin_segbase,
    bin_directive,
    bin_filename,
    bin_cleanup
};

/* This is needed for bin_define_section_labels() */
struct ofmt *bin_get_ofmt()
{  return &of_bin;
}

#endif   /* #ifdef OF_BIN */

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