From 547636c1f1e5c060cef0fb45aed42f6a0afd7d73 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emanuel=20Kom=C3=ADnek?= <kominek@avast.com>
Date: Sat, 15 Sep 2018 19:54:22 +0200
Subject: [PATCH 1/2] Merging control records having zero in their first
 triplet with the previous record (original bsdiff produces records having
 both the first and second item zeroes, i.e. representing only a seek in the
 old file).

---
 bsdiff.c | 40 +++++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/bsdiff.c b/bsdiff.c
index 628f1c1..8992214 100644
--- a/bsdiff.c
+++ b/bsdiff.c
@@ -222,6 +222,7 @@ 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 ctrlcur[3],ctrlnext[3];
 	int64_t oldscore,scsc;
 	int64_t s,Sf,lenf,Sb,lenb;
 	int64_t overlap,Ss,lens;
@@ -240,6 +241,7 @@ 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;
+	ctrlcur[0]=0;ctrlcur[1]=0;ctrlcur[2]=0;
 	while(scan<req.newsize) {
 		oldscore=0;
 
@@ -292,13 +294,27 @@ 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;
+			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;
+				};
+				ctrlcur[0]=ctrlnext[0];
+				ctrlcur[1]=ctrlnext[1];
+				ctrlcur[2]=ctrlnext[2];
+			} else {
+				ctrlcur[1]+=ctrlnext[1];
+				ctrlcur[2]+=ctrlnext[2];
+			};
 
 			/* Write diff data */
 			for(i=0;i<lenf;i++)
@@ -318,6 +334,16 @@ static int bsdiff_internal(const struct bsdiff_request req)
 		};
 	};
 
+	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;
+	};
+
 	return 0;
 }
 

From b2b0eed77a7fe75be17a2619ce936a677a10640c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emanuel=20Kom=C3=ADnek?= <drake127@planescape.cz>
Date: Tue, 15 Sep 2020 20:00:51 +0200
Subject: [PATCH 2/2] Reintroduced optimizations.

These optimizations work for both original and endsley's formats.
---
 bsdiff.c | 44 ++++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/bsdiff.c b/bsdiff.c
index 8992214..1cb58d4 100644
--- a/bsdiff.c
+++ b/bsdiff.c
@@ -221,8 +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 ctrlcur[3],ctrlnext[3];
+	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;
@@ -240,7 +240,7 @@ 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;
@@ -307,6 +307,21 @@ static int bsdiff_internal(const struct bsdiff_request req)
 					/* 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];
@@ -316,17 +331,6 @@ static int bsdiff_internal(const struct bsdiff_request req)
 				ctrlcur[2]+=ctrlnext[2];
 			};
 
-			/* 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;
-
-			/* 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;
@@ -342,6 +346,18 @@ static int bsdiff_internal(const struct bsdiff_request req)
 		/* 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;