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Small optimization resulting in smaller patch files #21

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Small optimization resulting in smaller patch files #21

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547636c
Merging control records having zero in their first triplet with the p…
Sep 15, 2018
b2b0eed
Reintroduced optimizations.
drake127 Sep 15, 2020
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82 changes: 62 additions & 20 deletions bsdiff.c
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Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,8 @@ static int bsdiff_internal(const struct bsdiff_request req)
{
int64_t *I,*V;
int64_t scan,pos,len;
int64_t lastscan,lastpos,lastoffset;
int64_t lastscan,lastpos,lastoffset,lastwrittenscan,lastwrittenpos;
int64_t ctrlcur[3], ctrlnext[3];
int64_t oldscore,scsc;
int64_t s,Sf,lenf,Sb,lenb;
int64_t overlap,Ss,lens;
Expand All @@ -239,7 +240,8 @@ static int bsdiff_internal(const struct bsdiff_request req)

/* Compute the differences, writing ctrl as we go */
scan=0;len=0;pos=0;
lastscan=0;lastpos=0;lastoffset=0;
lastscan=0;lastpos=0;lastoffset=lastwrittenscan=lastwrittenpos=0;
ctrlcur[0]=0;ctrlcur[1]=0;ctrlcur[2]=0;
while(scan<req.newsize) {
oldscore=0;

Expand Down Expand Up @@ -292,32 +294,72 @@ static int bsdiff_internal(const struct bsdiff_request req)
lenb-=lens;
};

offtout(lenf,buf);
offtout((scan-lenb)-(lastscan+lenf),buf+8);
offtout((pos-lenb)-(lastpos+lenf),buf+16);

/* Write control data */
if (writedata(req.stream, buf, sizeof(buf)))
return -1;

/* Write diff data */
for(i=0;i<lenf;i++)
buffer[i]=req.new[lastscan+i]-req.old[lastpos+i];
if (writedata(req.stream, buffer, lenf))
return -1;
ctrlnext[0]=lenf;
ctrlnext[1]=(scan-lenb)-(lastscan+lenf);
ctrlnext[2]=(pos-lenb)-(lastpos+lenf);

if (ctrlnext[0]) {
if (ctrlcur[0]||ctrlcur[1]||ctrlcur[2]) {
offtout(ctrlcur[0],buf);
offtout(ctrlcur[1],buf+8);
offtout(ctrlcur[2],buf+16);

/* Write control data */
if (writedata(req.stream, buf, sizeof(buf)))
return -1;

/* Write diff data */
for(i=0;i<ctrlcur[0];i++)
buffer[i]=req.new[lastwrittenscan+i]-req.old[lastwrittenpos+i];
if (writedata(req.stream, buffer, ctrlcur[0]))
return -1;

/* Write extra data */
for(i=0;i<ctrlcur[1];i++)
buffer[i]=req.new[lastwrittenscan+ctrlcur[0]+i];
if (writedata(req.stream, buffer, ctrlcur[1]))
return -1;

lastwrittenscan=lastscan;
lastwrittenpos=lastpos;
};
ctrlcur[0]=ctrlnext[0];
ctrlcur[1]=ctrlnext[1];
ctrlcur[2]=ctrlnext[2];
} else {
ctrlcur[1]+=ctrlnext[1];
ctrlcur[2]+=ctrlnext[2];
};

/* Write extra data */
for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
buffer[i]=req.new[lastscan+lenf+i];
if (writedata(req.stream, buffer, (scan-lenb)-(lastscan+lenf)))
return -1;

lastscan=scan-lenb;
lastpos=pos-lenb;
lastoffset=pos-scan;
};
};

if (ctrlcur[0]||ctrlcur[1]) {
offtout(ctrlcur[0],buf);
offtout(ctrlcur[1],buf+8);
offtout(ctrlcur[2],buf+16);

/* Write control data */
if (writedata(req.stream, buf, sizeof(buf)))
return -1;

/* Write diff data */
for(i=0;i<ctrlcur[0];i++)
buffer[i]=req.new[lastwrittenscan+i]-req.old[lastwrittenpos+i];
if (writedata(req.stream, buffer, ctrlcur[0]))
return -1;

/* Write extra data */
for(i=0;i<ctrlcur[1];i++)
buffer[i]=req.new[lastwrittenscan+ctrlcur[0]+i];
if (writedata(req.stream, buffer, ctrlcur[1]))
return -1;
};

return 0;
}

Expand Down