commit d03baf1697443dd71b01aeeb6b7ef5b1ac070cf5
Author: FRIGN <[email protected]>
AuthorDate: Sun Oct 25 23:26:49 2015 +0100
Commit: sin <[email protected]>
CommitDate: Mon Oct 26 11:55:41 2015 +0000
Add -e and -E flags to od(1) and properly handle endianness
The -e and -E flags allow the user to override the host endianness
and force od(1) to handle input according to a little (-e) or big (-E)
endian environment.
The previous handling was broken as bitshifts alone are already
endian-independent.
diff --git a/od.1 b/od.1
index c453b09..bd74ad4 100644
--- a/od.1
+++ b/od.1
@@ -1,4 +1,4 @@
-.Dd 2015-10-09
+.Dd 2015-10-25
.Dt OD 1
.Os sbase
.Sh NAME
@@ -7,6 +7,7 @@
.Sh SYNOPSIS
.Nm
.Op Fl A Ar addrformat
+.Op Fl E | e
.Op Fl t Ar outputformat...
.Op Fl v
.Op Ar file ...
@@ -26,6 +27,12 @@ reads from stdin.
is one of d|o|x|n and sets the address to be
either in \fId\fRecimal, \fIo\fRctal, he\fIx\fRadecimal or \fIn\fRot
printed at all. The default is octal.
+.It Fl E | e
+Force Little Endian
+.Fl ( e )
+or Big Endian
+.Fl ( E )
+system-independently.
.It Fl t Ar outputformat
.Ar outputformat
is a list of a|c|d|o|u|x followed by a digit or C|S|I|L and sets
@@ -49,3 +56,7 @@ The
flag is enabled by default and the 'd' parameter for the
.Op Fl t
flag is interpreted as 'u'.
+.Pp
+The
+.Op Ee
+flags are an extension to that specification.
diff --git a/od.c b/od.c
index 4c9f02a..8061c86 100644
--- a/od.c
+++ b/od.c
@@ -1,5 +1,4 @@
/* See LICENSE file for copyright and license details. */
-#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
@@ -8,6 +7,8 @@
#include "queue.h"
#include "util.h"
+#define HOST_BIG_ENDIAN (*(uint16_t *)"\0\xff" == 0xff)
+
struct type {
unsigned char format;
unsigned int len;
@@ -19,6 +20,7 @@ static unsigned char addr_format = 'o';
static off_t skip = 0;
static off_t max = -1;
static size_t linelen = 1;
+static int big_endian;
static void
printaddress(off_t addr)
@@ -37,7 +39,7 @@ static void
printchunk(unsigned char *s, unsigned char format, size_t len) {
long long res, basefac;
size_t i;
- char fmt[] = " %0*ll#";
+ char fmt[] = " %#*ll#";
const char *namedict[] = {
"nul", "soh", "stx", "etx", "eot", "enq", "ack",
@@ -70,17 +72,18 @@ printchunk(unsigned char *s, unsigned char format, size_t
len) {
}
break;
default:
- res = 0;
- basefac = 1;
-#if __BYTE_ORDER == __BIG_ENDIAN
- for (i = len; i; i--) {
- res += s[i - 1] * basefac;
-#else
- for (i = 0; i < len; i++) {
- res += s[i] * basefac;
-#endif
- basefac <<= 8;
+ if (big_endian == HOST_BIG_ENDIAN) {
+ for (res = 0, basefac = 1, i = 0; i < len; i++) {
+ res += s[i] * basefac;
+ basefac <<= 8;
+ }
+ } else {
+ for (res = 0, basefac = 1, i = len; i; i--) {
+ res += s[i - 1] * basefac;
+ basefac <<= 8;
+ }
}
+ fmt[2] = big_endian ? '-' : '+';
fmt[6] = format;
printf(fmt, (int)(3 * len + len - 1), res);
}
@@ -165,7 +168,7 @@ lcm(unsigned int a, unsigned int b)
static void
usage(void)
{
- eprintf("usage: %s [-A addressformat] [-t outputformat] "
+ eprintf("usage: %s [-A addressformat] [-E | -e] [-t outputformat] "
"[-v] [file ...]\n", argv0);
}
@@ -177,6 +180,8 @@ main(int argc, char *argv[])
int ret = 0;
char *s;
+ big_endian = HOST_BIG_ENDIAN;
+
ARGBEGIN {
case 'A':
s = EARGF(usage());
@@ -184,6 +189,10 @@ main(int argc, char *argv[])
usage();
addr_format = s[0];
break;
+ case 'E':
+ case 'e':
+ big_endian = (ARGC() == 'E');
+ break;
case 'j':
if ((skip = parseoffset(EARGF(usage()))) < 0)
usage();
