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Check-in [3e3feb2dda]

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Overview
Comment:Another minor performance enhancement on sbs diff.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 3e3feb2dda2c95070e0d34dc7d5ec4304a914bf6
User & Date: drh 2012-02-07 20:04:29.842
Context
2012-02-08
00:34
Fix issues with the --brief option to the diff command. ... (check-in: fbaa7ca99f user: drh tags: trunk)
2012-02-07
20:04
Another minor performance enhancement on sbs diff. ... (check-in: 3e3feb2dda user: drh tags: trunk)
18:58
Performance optimization for the alignment calculation on side-by-side diffs. Noticably faster. ... (check-in: 87f867018b user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/diff.c.
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  while( nB>0 && fossil_isspace(zB[0]) ){ nB--; zB++; }
  while( nB>0 && fossil_isspace(zB[nB-1]) ){ nB--; }
  if( nA>250 ) nA = 250;
  if( nB>250 ) nB = 250;
  avg = (nA+nB)/2;
  if( avg==0 ) return 0;
  memset(aFirst, 0, sizeof(aFirst));
  memset(aNext, 0, nB);
  zA--; zB--;   /* Make both zA[] and zB[] 1-indexed */
  for(i=nB; i>0; i--){
    c = (unsigned char)zB[i];
    aNext[i] = aFirst[c];
    aFirst[c] = i;
  }
  best = 0;
  for(i=1; i<=nA; i++){
    c = (unsigned char)zA[i];
    for(j=aFirst[c]; j>0; j = aNext[j]){
      int limit = minInt(nA-i, nB-j)+1;
      for(k=1; k<limit && zA[k+i]==zB[k+j]; k++){}
      if( k>best ) best = k;
    }
  }
  score = (best>avg) ? 0 : (avg - best)*100/avg;

#if 0
  fprintf(stderr, "A: [%.*s]\nB: [%.*s]\nbest=%d avg=%d score=%d\n",








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  while( nB>0 && fossil_isspace(zB[0]) ){ nB--; zB++; }
  while( nB>0 && fossil_isspace(zB[nB-1]) ){ nB--; }
  if( nA>250 ) nA = 250;
  if( nB>250 ) nB = 250;
  avg = (nA+nB)/2;
  if( avg==0 ) return 0;
  memset(aFirst, 0, sizeof(aFirst));

  zA--; zB--;   /* Make both zA[] and zB[] 1-indexed */
  for(i=nB; i>0; i--){
    c = (unsigned char)zB[i];
    aNext[i] = aFirst[c];
    aFirst[c] = i;
  }
  best = 0;
  for(i=1; i<=nA-best; i++){
    c = (unsigned char)zA[i];
    for(j=aFirst[c]; j>0 && j<nB-best; j = aNext[j]){
      int limit = minInt(nA-i, nB-j);
      for(k=1; k<=limit && zA[k+i]==zB[k+j]; k++){}
      if( k>best ) best = k;
    }
  }
  score = (best>avg) ? 0 : (avg - best)*100/avg;

#if 0
  fprintf(stderr, "A: [%.*s]\nB: [%.*s]\nbest=%d avg=%d score=%d\n",
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