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cell-binutils  2.17cvs20070401
Classes | Functions
merge.c File Reference
#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "hashtab.h"
#include "libiberty.h"

Go to the source code of this file.

Classes

struct  sec_merge_hash_entry
struct  sec_merge_hash
struct  sec_merge_info
struct  sec_merge_sec_info
union  sec_merge_hash_entry.u

Functions

static struct bfd_hash_entrysec_merge_hash_newfunc (struct bfd_hash_entry *entry, struct bfd_hash_table *table, const char *string)
static struct
sec_merge_hash_entry
sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string, unsigned int alignment, bfd_boolean create)
static struct sec_merge_hashsec_merge_init (unsigned int entsize, bfd_boolean strings)
static struct
sec_merge_hash_entry
sec_merge_add (struct sec_merge_hash *tab, const char *str, unsigned int alignment, struct sec_merge_sec_info *secinfo)
static bfd_boolean sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
bfd_boolean _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec, void **psecinfo)
static bfd_boolean record_section (struct sec_merge_info *sinfo, struct sec_merge_sec_info *secinfo)
static int strrevcmp (const void *a, const void *b)
static int strrevcmp_align (const void *a, const void *b)
static int is_suffix (const struct sec_merge_hash_entry *A, const struct sec_merge_hash_entry *B)
static void merge_strings (struct sec_merge_info *sinfo)
bfd_boolean _bfd_merge_sections (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_link_info *info ATTRIBUTE_UNUSED, void *xsinfo, void(*remove_hook)(bfd *, asection *))
bfd_boolean _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
bfd_vma _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec, void *psecinfo, bfd_vma offset)

Class Documentation

struct sec_merge_hash_entry

Definition at line 35 of file merge.c.

Collaboration diagram for sec_merge_hash_entry:
Class Members
unsigned int alignment
unsigned int len
struct sec_merge_hash_entry * next
struct sec_merge_sec_info * secinfo
union sec_merge_hash_entry u
struct sec_merge_hash

Definition at line 58 of file merge.c.

Collaboration diagram for sec_merge_hash:
Class Members
unsigned int entsize
struct sec_merge_hash_entry * first
struct sec_merge_hash_entry * last
bfd_size_type size
bfd_boolean strings
struct sec_merge_info

Definition at line 73 of file merge.c.

Collaboration diagram for sec_merge_info:
Class Members
struct sec_merge_sec_info * chain
struct sec_merge_hash * htab
struct sec_merge_info * next
struct sec_merge_sec_info

Definition at line 83 of file merge.c.

Collaboration diagram for sec_merge_sec_info:
Class Members
unsigned char contents
struct sec_merge_hash_entry * first_str
struct sec_merge_hash * htab
struct sec_merge_sec_info * next
void ** psecinfo
asection * sec
union sec_merge_hash_entry.u

Definition at line 43 of file merge.c.

Class Members
bfd_size_type index
struct sec_merge_hash_entry * suffix

Function Documentation

bfd_boolean _bfd_add_merge_section ( bfd abfd,
void **  psinfo,
asection sec,
void **  psecinfo 
)

Definition at line 346 of file merge.c.

{
  struct sec_merge_info *sinfo;
  struct sec_merge_sec_info *secinfo;
  unsigned int align;
  bfd_size_type amt;

  if ((abfd->flags & DYNAMIC) != 0
      || (sec->flags & SEC_MERGE) == 0)
    abort ();

  if (sec->size == 0
      || (sec->flags & SEC_EXCLUDE) != 0
      || sec->entsize == 0)
    return TRUE;

  if ((sec->flags & SEC_RELOC) != 0)
    {
      /* We aren't prepared to handle relocations in merged sections.  */
      return TRUE;
    }

  align = sec->alignment_power;
  if ((sec->entsize < (unsigned) 1 << align
       && ((sec->entsize & (sec->entsize - 1))
          || !(sec->flags & SEC_STRINGS)))
      || (sec->entsize > (unsigned) 1 << align
         && (sec->entsize & (((unsigned) 1 << align) - 1))))
    {
      /* Sanity check.  If string character size is smaller than
        alignment, then we require character size to be a power
        of 2, otherwise character size must be integer multiple
        of alignment.  For non-string constants, alignment must
        be smaller than or equal to entity size and entity size
        must be integer multiple of alignment.  */
      return TRUE;
    }

  for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
    if ((secinfo = sinfo->chain)
       && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
       && secinfo->sec->entsize == sec->entsize
       && secinfo->sec->alignment_power == sec->alignment_power
       && secinfo->sec->output_section == sec->output_section)
      break;

  if (sinfo == NULL)
    {
      /* Initialize the information we need to keep track of.  */
      sinfo = bfd_alloc (abfd, sizeof (struct sec_merge_info));
      if (sinfo == NULL)
       goto error_return;
      sinfo->next = (struct sec_merge_info *) *psinfo;
      sinfo->chain = NULL;
      *psinfo = sinfo;
      sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
      if (sinfo->htab == NULL)
       goto error_return;
    }

  /* Read the section from abfd.  */

  amt = sizeof (struct sec_merge_sec_info) + sec->size - 1;
  *psecinfo = bfd_alloc (abfd, amt);
  if (*psecinfo == NULL)
    goto error_return;

  secinfo = (struct sec_merge_sec_info *) *psecinfo;
  if (sinfo->chain)
    {
      secinfo->next = sinfo->chain->next;
      sinfo->chain->next = secinfo;
    }
  else
    secinfo->next = secinfo;
  sinfo->chain = secinfo;
  secinfo->sec = sec;
  secinfo->psecinfo = psecinfo;
  secinfo->htab = sinfo->htab;
  secinfo->first_str = NULL;

  sec->rawsize = sec->size;
  if (! bfd_get_section_contents (sec->owner, sec, secinfo->contents,
                              0, sec->size))
    goto error_return;

  return TRUE;

 error_return:
  *psecinfo = NULL;
  return FALSE;
}

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bfd_boolean _bfd_merge_sections ( bfd *abfd  ATTRIBUTE_UNUSED,
struct bfd_link_info *info  ATTRIBUTE_UNUSED,
void *  xsinfo,
void(*)(bfd *, asection *)  remove_hook 
)

Definition at line 701 of file merge.c.

{
  struct sec_merge_info *sinfo;

  for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
    {
      struct sec_merge_sec_info * secinfo;

      if (! sinfo->chain)
       continue;

      /* Move sinfo->chain to head of the chain, terminate it.  */
      secinfo = sinfo->chain;
      sinfo->chain = secinfo->next;
      secinfo->next = NULL;

      /* Record the sections into the hash table.  */
      for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
       if (secinfo->sec->flags & SEC_EXCLUDE)
         {
           *secinfo->psecinfo = NULL;
           if (remove_hook)
             (*remove_hook) (abfd, secinfo->sec);
         }
       else if (! record_section (sinfo, secinfo))
         break;

      if (secinfo)
       continue;

      if (sinfo->htab->first == NULL)
       continue;

      if (sinfo->htab->strings)
       merge_strings (sinfo);
      else
       {
         struct sec_merge_hash_entry *e;
         bfd_size_type size = 0;

         /* Things are much simpler for non-strings.
            Just assign them slots in the section.  */
         secinfo = NULL;
         for (e = sinfo->htab->first; e; e = e->next)
           {
             if (e->secinfo->first_str == NULL)
              {
                if (secinfo)
                  secinfo->sec->size = size;
                e->secinfo->first_str = e;
                size = 0;
              }
             size = (size + e->alignment - 1)
                   & ~((bfd_vma) e->alignment - 1);
             e->u.index = size;
             size += e->len;
             secinfo = e->secinfo;
           }
         secinfo->sec->size = size;
       }

       /* Finally remove all input sections which have not made it into
          the hash table at all.  */
       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
         if (secinfo->first_str == NULL)
           secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
    }

  return TRUE;
}

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bfd_vma _bfd_merged_section_offset ( bfd *output_bfd  ATTRIBUTE_UNUSED,
asection **  psec,
void *  psecinfo,
bfd_vma  offset 
)

Definition at line 803 of file merge.c.

{
  struct sec_merge_sec_info *secinfo;
  struct sec_merge_hash_entry *entry;
  unsigned char *p;
  asection *sec = *psec;

  secinfo = (struct sec_merge_sec_info *) psecinfo;

  if (offset >= sec->rawsize)
    {
      if (offset > sec->rawsize)
       {
         (*_bfd_error_handler)
           (_("%s: access beyond end of merged section (%ld)"),
            bfd_get_filename (sec->owner), (long) offset);
       }
      return secinfo->first_str ? sec->size : 0;
    }

  if (secinfo->htab->strings)
    {
      if (sec->entsize == 1)
       {
         p = secinfo->contents + offset - 1;
         while (p >= secinfo->contents && *p)
           --p;
         ++p;
       }
      else
       {
         p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
         p -= sec->entsize;
         while (p >= secinfo->contents)
           {
             unsigned int i;

             for (i = 0; i < sec->entsize; ++i)
              if (p[i] != '\0')
                break;
             if (i == sec->entsize)
              break;
             p -= sec->entsize;
           }
         p += sec->entsize;
       }
    }
  else
    {
      p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
    }
  entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
  if (!entry)
    {
      if (! secinfo->htab->strings)
       abort ();
      /* This should only happen if somebody points into the padding
        after a NUL character but before next entity.  */
      if (*p)
       abort ();
      if (! secinfo->htab->first)
       abort ();
      entry = secinfo->htab->first;
      p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
          - entry->len);
    }

  *psec = entry->secinfo->sec;
  return entry->u.index + (secinfo->contents + offset - p);
}

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bfd_boolean _bfd_write_merged_section ( bfd output_bfd,
asection sec,
void *  psecinfo 
)

Definition at line 778 of file merge.c.

{
  struct sec_merge_sec_info *secinfo;
  file_ptr pos;

  secinfo = (struct sec_merge_sec_info *) psecinfo;

  if (secinfo->first_str == NULL)
    return TRUE;

  pos = sec->output_section->filepos + sec->output_offset;
  if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
    return FALSE;

  if (! sec_merge_emit (output_bfd, secinfo->first_str))
    return FALSE;

  return TRUE;
}

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static int is_suffix ( const struct sec_merge_hash_entry A,
const struct sec_merge_hash_entry B 
) [inline, static]

Definition at line 576 of file merge.c.

{
  if (A->len <= B->len)
    /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
       not to be equal by the hash table.  */
    return 0;

  return memcmp (A->root.string + (A->len - B->len),
               B->root.string, B->len) == 0;
}

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static void merge_strings ( struct sec_merge_info sinfo) [static]

Definition at line 591 of file merge.c.

{
  struct sec_merge_hash_entry **array, **a, *e;
  struct sec_merge_sec_info *secinfo;
  bfd_size_type size, amt;
  unsigned int alignment = 0;

  /* Now sort the strings */
  amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
  array = bfd_malloc (amt);
  if (array == NULL)
    goto alloc_failure;

  for (e = sinfo->htab->first, a = array; e; e = e->next)
    if (e->alignment)
      {
       *a++ = e;
       /* Adjust the length to not include the zero terminator.  */
       e->len -= sinfo->htab->entsize;
       if (alignment != e->alignment)
         {
           if (alignment == 0)
             alignment = e->alignment;
           else
             alignment = (unsigned) -1;
         }
      }

  sinfo->htab->size = a - array;
  if (sinfo->htab->size != 0)
    {
      qsort (array, (size_t) sinfo->htab->size,
            sizeof (struct sec_merge_hash_entry *),
            (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
             ? strrevcmp_align : strrevcmp));

      /* Loop over the sorted array and merge suffixes */
      e = *--a;
      e->len += sinfo->htab->entsize;
      while (--a >= array)
       {
         struct sec_merge_hash_entry *cmp = *a;

         cmp->len += sinfo->htab->entsize;
         if (e->alignment >= cmp->alignment
             && !((e->len - cmp->len) & (cmp->alignment - 1))
             && is_suffix (e, cmp))
           {
             cmp->u.suffix = e;
             cmp->alignment = 0;
           }
         else
           e = cmp;
       }
    }

alloc_failure:
  if (array)
    free (array);

  /* Now assign positions to the strings we want to keep.  */
  size = 0;
  secinfo = sinfo->htab->first->secinfo;
  for (e = sinfo->htab->first; e; e = e->next)
    {
      if (e->secinfo != secinfo)
       {
         secinfo->sec->size = size;
         secinfo = e->secinfo;
       }
      if (e->alignment)
       {
         if (e->secinfo->first_str == NULL)
           {
             e->secinfo->first_str = e;
             size = 0;
           }
         size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
         e->u.index = size;
         size += e->len;
       }
    }
  secinfo->sec->size = size;
  if (secinfo->sec->alignment_power != 0)
    {
      bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
      secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
    }

  /* And now adjust the rest, removing them from the chain (but not hashtable)
     at the same time.  */
  for (a = &sinfo->htab->first, e = *a; e; e = e->next)
    if (e->alignment)
      a = &e->next;
    else
      {
       *a = e->next;
       if (e->len)
         {
           e->secinfo = e->u.suffix->secinfo;
           e->alignment = e->u.suffix->alignment;
           e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
         }
      }
}

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static bfd_boolean record_section ( struct sec_merge_info sinfo,
struct sec_merge_sec_info secinfo 
) [static]

Definition at line 442 of file merge.c.

{
  asection *sec = secinfo->sec;
  struct sec_merge_hash_entry *entry;
  bfd_boolean nul;
  unsigned char *p, *end;
  bfd_vma mask, eltalign;
  unsigned int align, i;

  align = sec->alignment_power;
  end = secinfo->contents + sec->size;
  nul = FALSE;
  mask = ((bfd_vma) 1 << align) - 1;
  if (sec->flags & SEC_STRINGS)
    {
      for (p = secinfo->contents; p < end; )
       {
         eltalign = p - secinfo->contents;
         eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
         if (!eltalign || eltalign > mask)
           eltalign = mask + 1;
         entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
                             secinfo);
         if (! entry)
           goto error_return;
         p += entry->len;
         if (sec->entsize == 1)
           {
             while (p < end && *p == 0)
              {
                if (!nul && !((p - secinfo->contents) & mask))
                  {
                    nul = TRUE;
                    entry = sec_merge_add (sinfo->htab, "",
                                        (unsigned) mask + 1, secinfo);
                    if (! entry)
                     goto error_return;
                  }
                p++;
              }
           }
         else
           {
             while (p < end)
              {
                for (i = 0; i < sec->entsize; i++)
                  if (p[i] != '\0')
                    break;
                if (i != sec->entsize)
                  break;
                if (!nul && !((p - secinfo->contents) & mask))
                  {
                    nul = TRUE;
                    entry = sec_merge_add (sinfo->htab, (char *) p,
                                        (unsigned) mask + 1, secinfo);
                    if (! entry)
                     goto error_return;
                  }
                p += sec->entsize;
              }
           }
       }
    }
  else
    {
      for (p = secinfo->contents; p < end; p += sec->entsize)
       {
         entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
         if (! entry)
           goto error_return;
       }
    }

  return TRUE;

error_return:
  for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
    *secinfo->psecinfo = NULL;
  return FALSE;
}

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static struct sec_merge_hash_entry* sec_merge_add ( struct sec_merge_hash tab,
const char *  str,
unsigned int  alignment,
struct sec_merge_sec_info secinfo 
) [static, read]

Definition at line 265 of file merge.c.

{
  register struct sec_merge_hash_entry *entry;

  entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
  if (entry == NULL)
    return NULL;

  if (entry->secinfo == NULL)
    {
      tab->size++;
      entry->secinfo = secinfo;
      if (tab->first == NULL)
       tab->first = entry;
      else
       tab->last->next = entry;
      tab->last = entry;
    }

  return entry;
}

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static bfd_boolean sec_merge_emit ( bfd abfd,
struct sec_merge_hash_entry entry 
) [static]

Definition at line 289 of file merge.c.

{
  struct sec_merge_sec_info *secinfo = entry->secinfo;
  asection *sec = secinfo->sec;
  char *pad = NULL;
  bfd_size_type off = 0;
  int alignment_power = sec->output_section->alignment_power;

  if (alignment_power)
    {
      pad = bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
      if (pad == NULL)
       return FALSE;
    }

  for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
    {
      const char *str;
      bfd_size_type len;

      len = -off & (entry->alignment - 1);
      if (len != 0)
       {
         if (bfd_bwrite (pad, len, abfd) != len)
           goto err;
         off += len;
       }

      str = entry->root.string;
      len = entry->len;

      if (bfd_bwrite (str, len, abfd) != len)
       goto err;

      off += len;
    }

  /* Trailing alignment needed?  */
  off = sec->size - off;
  if (off != 0
      && bfd_bwrite (pad, off, abfd) != off)
    goto err;

  if (pad != NULL)
    free (pad);
  return TRUE;

 err:
  if (pad != NULL)
    free (pad);
  return FALSE;
}

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static struct sec_merge_hash_entry* sec_merge_hash_lookup ( struct sec_merge_hash table,
const char *  string,
unsigned int  alignment,
bfd_boolean  create 
) [static, read]

Definition at line 133 of file merge.c.

{
  register const unsigned char *s;
  register unsigned long hash;
  register unsigned int c;
  struct sec_merge_hash_entry *hashp;
  unsigned int len, i;
  unsigned int index;

  hash = 0;
  len = 0;
  s = (const unsigned char *) string;
  if (table->strings)
    {
      if (table->entsize == 1)
       {
         while ((c = *s++) != '\0')
           {
             hash += c + (c << 17);
             hash ^= hash >> 2;
             ++len;
           }
         hash += len + (len << 17);
       }
      else
       {
         for (;;)
           {
             for (i = 0; i < table->entsize; ++i)
              if (s[i] != '\0')
                break;
             if (i == table->entsize)
              break;
             for (i = 0; i < table->entsize; ++i)
              {
                c = *s++;
                hash += c + (c << 17);
                hash ^= hash >> 2;
              }
             ++len;
           }
         hash += len + (len << 17);
         len *= table->entsize;
       }
      hash ^= hash >> 2;
      len += table->entsize;
    }
  else
    {
      for (i = 0; i < table->entsize; ++i)
       {
         c = *s++;
         hash += c + (c << 17);
         hash ^= hash >> 2;
       }
      len = table->entsize;
    }

  index = hash % table->table.size;
  for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
       hashp != NULL;
       hashp = (struct sec_merge_hash_entry *) hashp->root.next)
    {
      if (hashp->root.hash == hash
         && len == hashp->len
         && memcmp (hashp->root.string, string, len) == 0)
       {
         /* If the string we found does not have at least the required
            alignment, we need to insert another copy.  */
         if (hashp->alignment < alignment)
           {
             if (create)
              {
                /*  Mark the less aligned copy as deleted.  */
                hashp->len = 0;
                hashp->alignment = 0;
              }
             break;
           }
         return hashp;
       }
    }

  if (! create)
    return NULL;

  hashp = ((struct sec_merge_hash_entry *)
          sec_merge_hash_newfunc (NULL, &table->table, string));
  if (hashp == NULL)
    return NULL;
  hashp->root.string = string;
  hashp->root.hash = hash;
  hashp->len = len;
  hashp->alignment = alignment;
  hashp->root.next = table->table.table[index];
  table->table.table[index] = (struct bfd_hash_entry *) hashp;

  return hashp;
}

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static struct bfd_hash_entry* sec_merge_hash_newfunc ( struct bfd_hash_entry entry,
struct bfd_hash_table table,
const char *  string 
) [static, read]

Definition at line 103 of file merge.c.

{
  /* Allocate the structure if it has not already been allocated by a
     subclass.  */
  if (entry == NULL)
    entry = bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
  if (entry == NULL)
    return NULL;

  /* Call the allocation method of the superclass.  */
  entry = bfd_hash_newfunc (entry, table, string);

  if (entry != NULL)
    {
      /* Initialize the local fields.  */
      struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;

      ret->u.suffix = NULL;
      ret->alignment = 0;
      ret->secinfo = NULL;
      ret->next = NULL;
    }

  return entry;
}

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static struct sec_merge_hash* sec_merge_init ( unsigned int  entsize,
bfd_boolean  strings 
) [static, read]

Definition at line 237 of file merge.c.

{
  struct sec_merge_hash *table;

  table = bfd_malloc (sizeof (struct sec_merge_hash));
  if (table == NULL)
    return NULL;

  if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
                            sizeof (struct sec_merge_hash_entry), 16699))
    {
      free (table);
      return NULL;
    }

  table->size = 0;
  table->first = NULL;
  table->last = NULL;
  table->entsize = entsize;
  table->strings = strings;

  return table;
}

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static int strrevcmp ( const void *  a,
const void *  b 
) [static]

Definition at line 525 of file merge.c.

{
  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  unsigned int lenA = A->len;
  unsigned int lenB = B->len;
  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  int l = lenA < lenB ? lenA : lenB;

  while (l)
    {
      if (*s != *t)
       return (int) *s - (int) *t;
      s--;
      t--;
      l--;
    }
  return lenA - lenB;
}

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static int strrevcmp_align ( const void *  a,
const void *  b 
) [static]

Definition at line 550 of file merge.c.

{
  struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  unsigned int lenA = A->len;
  unsigned int lenB = B->len;
  const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  int l = lenA < lenB ? lenA : lenB;
  int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));

  if (tail_align != 0)
    return tail_align;

  while (l)
    {
      if (*s != *t)
       return (int) *s - (int) *t;
      s--;
      t--;
      l--;
    }
  return lenA - lenB;
}

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