*/
typedef struct DLine DLine;
struct DLine {
  const char *z;        /* The text of the line */
  unsigned int h;       /* Hash of the line */
  unsigned int iNext;   /* 1+(Index of next line with same the same hash) */

  /* an array of DLine elements serves two purposes.  The fields
  ** above are one per line of input text.  But each entry is also
  ** a bucket in a hash table, as follows: */
  unsigned int iHash;   /* 1+(first entry in the hash chain) */
};

/*
** Length of a dline

    blob_append(pOut, "        ", 8);
  }
  if( html ) blob_append(pOut, "</span>", -1);
}


/*
** Given a raw diff p[] in which the p->aEdit[] array has been filled
** in, compute a context diff into pOut.
*/
static void contextDiff(
  DContext *p,      /* The difference */
  Blob *pOut,       /* Output a context diff to here */
  int nContext,     /* Number of lines of context */
  int showLn,       /* Show line numbers */

  /* A single chunk of text inserted on the right */
  if( nPrefix+nSuffix==nLeft ){
    sbsWriteLineno(p, lnLeft);
    p->iStart2 = p->iEnd2 = 0;
    p->iStart = p->iEnd = -1;
    sbsWriteText(p, pLeft, SBS_PAD);
    sbsWrite(p, nLeft==nRight ? "   " : " | ", 3);
    sbsWriteLineno(p, lnRight);
    p->iStart = nPrefix;
    p->iEnd = nRight - nSuffix;
    p->zStart = zClassAdd;
    sbsWriteText(p, pRight, SBS_NEWLINE);
    return;
  }

  i = (nRight+1)*(nLeft+1) - k;
  memmove(aM, &aM[k], i);

  /* Return the result */
  fossil_free(pToFree);
  return aM;
}

/*
** R[] is an array of six integer, two COPY/DELETE/INSERT triples for a
** pair of adjacent differences.  Return true if the gap between these
** two differences is so small that they should be rendered as a single
** edit.
*/
static int smallGap(int *R){
  return R[3]<=2 || R[3]<=(R[1]+R[2]+R[4]+R[5])/8;
}

/*
** Given a diff context in which the aEdit[] array has been filled
** in, compute a side-by-side diff into pOut.
*/
static void sbsDiff(
  DContext *p,       /* The computed diff */

    b += m;

    /* Show the differences */
    for(i=0; i<nr; i++){
      unsigned char *alignment;
      ma = R[r+i*3+1];   /* Lines on left but not on right */
      mb = R[r+i*3+2];   /* Lines on right but not on left */

      /* If the gap between the current diff and then next diff within the
      ** same block is not too great, then render them as if they are a 
      ** single diff. */
      while( i<nr-1 && smallGap(&R[r+i*3]) ){
        i++;
        m = R[r+i*3];
        ma += R[r+i*3+1] + m;
        mb += R[r+i*3+2] + m;
      }

      alignment = sbsAlignment(&A[a], ma, &B[b], mb);
      for(j=0; ma+mb>0; j++){
        if( alignment[j]==1 ){
          s.n = 0;
          sbsWriteLineno(&s, a);
          s.iStart = 0;
          s.zStart = "<span class=\"diffrm\">";

     target="testwindow">Large diff of sqlite3.c</a>.  This diff was very
     slow prior to the preformance enhancement change [9e15437e97].

External:

  *  <a href="http://www.sqlite.org/src/fdiff?v1=aafcb21a74e41f9a&v2=a6d127dd05daf0f9#chunk3" target="testwindow">
     Code indentation change.</a>
  *  <a href="http://www.sqlite.org/src/fdiff?v1=ab90126ee0163539&v2=a867cafae0235324#chunk1" target="testwindow">
     A more difficult code indentation change.</a>