From 17eb38a5f2bc6e26634314dd7070ae4407924518 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rich@annexia.org>
Date: Tue, 14 May 2013 15:56:07 +0000
Subject: [PATCH] Add functions: is_zeroes_bitstring, is_ones_bitstring.

---
 aclocal.m4                      |  6 +++---
 bitstring.ml                    | 36 ++++++++++++++++++++++++++++++++++++
 bitstring.mli                   |  6 ++++++
 tests/test_36_is_zeroes_ones.ml | 29 +++++++++++++++++++++++++++++
 4 files changed, 74 insertions(+), 3 deletions(-)
 create mode 100644 tests/test_36_is_zeroes_ones.ml

diff --git a/aclocal.m4 b/aclocal.m4
index f4de067..36c9013 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1,7 +1,7 @@
-# generated automatically by aclocal 1.11 -*- Autoconf -*-
+# generated automatically by aclocal 1.12.2 -*- Autoconf -*-
+
+# Copyright (C) 1996-2012 Free Software Foundation, Inc.
 
-# Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
-# 2005, 2006, 2007, 2008, 2009  Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
diff --git a/bitstring.ml b/bitstring.ml
index efac383..1c51a73 100644
--- a/bitstring.ml
+++ b/bitstring.ml
@@ -1101,6 +1101,42 @@ let equals ((_, _, len1) as bs1) ((_, _, len2) as bs2) =
   else if bs1 = bs2 then true
   else 0 = compare bs1 bs2
 
+let is_zeroes_bitstring ((data, off, len) as bits) =
+  if off land 7 = 0 && len land 7 = 0 then (
+    let off = off lsr 3 and len = len lsr 3 in
+    let rec loop i =
+      if i < len then (
+        if String.unsafe_get data (off + i) <> '\000' then false
+        else loop (i+1)
+      ) else true
+    in
+    loop 0
+  )
+  else (
+    (* Slow/unaligned case. *)
+    let len = bitstring_length bits in
+    let zeroes = zeroes_bitstring len in
+    0 = compare bits zeroes
+  )
+
+let is_ones_bitstring ((data, off, len) as bits) =
+  if off land 7 = 0 && len land 7 = 0 then (
+    let off = off lsr 3 and len = len lsr 3 in
+    let rec loop i =
+      if i < len then (
+        if String.unsafe_get data (off + i) <> '\xff' then false
+        else loop (i+1)
+      ) else true
+    in
+    loop 0
+  )
+  else (
+    (* Slow/unaligned case. *)
+    let len = bitstring_length bits in
+    let ones = ones_bitstring len in
+    0 = compare bits ones
+  )
+
 (*----------------------------------------------------------------------*)
 (* Bit get/set functions. *)
 
diff --git a/bitstring.mli b/bitstring.mli
index a29cb03..33f85f4 100644
--- a/bitstring.mli
+++ b/bitstring.mli
@@ -707,6 +707,12 @@ val equals : bitstring -> bitstring -> bool
     semantically equal.  It is the same as calling [compare] and
     testing if the result is [0], but usually more efficient. *)
 
+val is_zeroes_bitstring : bitstring -> bool
+(** Tests if the bitstring is all zero bits (cf. {!zeroes_bitstring}) *)
+
+val is_ones_bitstring : bitstring -> bool
+(** Tests if the bitstring is all one bits (cf. {!ones_bitstring}). *)
+
 (** {3 Bitstring manipulation} *)
 
 val bitstring_length : bitstring -> int
diff --git a/tests/test_36_is_zeroes_ones.ml b/tests/test_36_is_zeroes_ones.ml
new file mode 100644
index 0000000..59ab38f
--- /dev/null
+++ b/tests/test_36_is_zeroes_ones.ml
@@ -0,0 +1,29 @@
+(* Test if bitstrings are all zeroes or all ones.
+ * $Id$
+ *)
+
+open Printf
+
+let () =
+  for i = 0 to 33 do
+    let bits = Bitstring.zeroes_bitstring i in
+    if not (Bitstring.is_zeroes_bitstring bits) then (
+      eprintf "is_zeros_bitstring failed %d\n" i;
+      exit 1
+    );
+    if i > 0 && Bitstring.is_ones_bitstring bits then (
+      eprintf "false match is_ones_bitstring %d\n" i;
+      exit 1
+    )
+  done;
+  for i = 0 to 33 do
+    let bits = Bitstring.ones_bitstring i in
+    if not (Bitstring.is_ones_bitstring bits) then (
+      eprintf "is_ones_bitstring failed %d\n" i;
+      exit 1
+    );
+    if i > 0 && Bitstring.is_zeroes_bitstring bits then (
+      eprintf "false match is_zeroes_bitstring %d\n" i;
+      exit 1
+    )
+  done
-- 
1.8.3.1