commit 01e3847b7e6ff87f72a34a42cd98425e569250f6
from: Russ Cox <rsc@swtch.com>
date: Mon Mar 11 21:26:11 2013 UTC

xd: accept -S for 8-byte swap

R=rsc
https://codereview.appspot.com/7565045

commit - 36bb28dc638bb3091e05996156b5fbecbc67dcd5
commit + 01e3847b7e6ff87f72a34a42cd98425e569250f6
blob - 10307aa0b2c95df072b080987a3a7e950b6d2d11
blob + 9d43a750822b54900fac724b8eebb4cbc41fd8b0
--- man/man1/xd.1
+++ man/man1/xd.1
@@ -75,6 +75,9 @@ Print file addresses in the given style (and size 4).
 .B -s
 Reverse (swab) the order of bytes in each group of 4 before printing.
 .TP
+.B -S
+Reverse the order of bytes in each group of 8 before printing.
+.TP
 .B -r
 Print repeating groups of identical 16-byte sequences as the first group
 followed by an asterisk.
blob - 3e8ba5d334b0351950d296a4a1946b7aa3c66bd7
blob + 7be55b21043263e339b9b74ded227dadf57afc3e
--- src/cmd/xd.c
+++ src/cmd/xd.c
@@ -8,6 +8,7 @@ int		ndata;
 unsigned long	addr;
 int		repeats;
 int		swizzle;
+int		swizzle8;
 int		flush;
 int		abase=2;
 int		xd(char *, int);
@@ -83,6 +84,12 @@ main(int argc, char *argv[])
 				goto Usage;
 			continue;
 		}
+		if(argv[0][0] == 'S'){
+			swizzle8 = 1;
+			if(argv[0][1])
+				goto Usage;
+			continue;
+		}
 		if(argv[0][0] == 'u'){
 			flush = 1;
 			if(argv[0][1])
@@ -215,6 +222,8 @@ xd(char *name, int title)
 				data[i] = 0;
 		if(swizzle)
 			swizz();
+		if(swizzle8)
+			swizz8();
 		if(ndata==16 && repeats){
 			if(addr>0 && data[0]==odata[0]){
 				for(i=1; i<16; i++)
@@ -273,6 +282,33 @@ swizz(void)
 		p[3] = q[0];
 		p += 4;
 		q += 4;
+	}
+}
+
+void
+swizz8(void)
+{
+	uchar *p, *q;
+	int i;
+	uchar swdata[16];
+
+	p = data;
+	q = swdata;
+	for(i=0; i<16; i++)
+		*q++ = *p++;
+	p = data;
+	q = swdata;
+	for(i=0; i<8; i++){
+		p[0] = q[7];
+		p[1] = q[6];
+		p[2] = q[5];
+		p[3] = q[4];
+		p[4] = q[3];
+		p[5] = q[2];
+		p[6] = q[1];
+		p[7] = q[0];
+		p += 8;
+		q += 8;
 	}
 }