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-rw-r--r--libc/unistd/Makefile2
-rw-r--r--libc/unistd/swab.c18
2 files changed, 19 insertions, 1 deletions
diff --git a/libc/unistd/Makefile b/libc/unistd/Makefile
index c325eae3a..97cd21c49 100644
--- a/libc/unistd/Makefile
+++ b/libc/unistd/Makefile
@@ -27,7 +27,7 @@ DIRS:=
CSRC=execl.c execlp.c execv.c execvep.c execvp.c execle.c getcwd.c \
sleep.c usleep.c getpass.c sysconf_src.c getlogin.c \
- fpathconf.c confstr.c pathconf.c
+ fpathconf.c confstr.c pathconf.c swab.c
ifeq ($(strip $(HAS_MMU)),true)
CSRC+=daemon.c
endif
diff --git a/libc/unistd/swab.c b/libc/unistd/swab.c
new file mode 100644
index 000000000..c63ca7284
--- /dev/null
+++ b/libc/unistd/swab.c
@@ -0,0 +1,18 @@
+#include <unistd.h>
+#include <sys/types.h>
+
+/* swab() swaps the position of two adjacent bytes, every two bytes.
+ * Contributed by Kensuke Otake <kensuke@phreaker.net> */
+
+void swab(const void *source, void *dest, ssize_t count) {
+ const char *from = (const char *)source;
+ char *to = (char *)dest;
+
+ count &= ~((ssize_t)1);
+
+ while (count > 1) {
+ const char b0 = from[--count], b1 = from[--count];
+ to[count] = b0;
+ to[count + 1] = b1;
+ }
+}