From d617ec87eec19efe7f2a854c437da882348d459e Mon Sep 17 00:00:00 2001
From: darkjames <darkjames@f5534014-38df-0310-8fa8-9805f1628bb7>
Date: Tue, 17 May 2011 22:20:14 +0000
Subject: [PATCH] Add generic tvb_get_bits_buf() which accepts any no_of_bits.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@37217 f5534014-38df-0310-8fa8-9805f1628bb7
---
 epan/libwireshark.def |  2 ++
 epan/tvbuff.c         | 53 +++++++++++++++++++++++++++++++++++++++++++
 epan/tvbuff.h         |  3 +++
 3 files changed, 58 insertions(+)

diff --git a/epan/libwireshark.def b/epan/libwireshark.def
index 1bad5dea64..142bf7bf4a 100644
--- a/epan/libwireshark.def
+++ b/epan/libwireshark.def
@@ -387,6 +387,7 @@ ep_strdup_printf
 ep_strdup_vprintf
 ep_strndup
 ep_strsplit
+ep_tvb_get_bits
 ep_tvb_memdup
 epan_base64_decode
 epan_cleanup
@@ -1069,6 +1070,7 @@ tvb_find_line_end_unquoted
 tvb_format_text
 tvb_format_text_wsp
 tvb_free
+tvb_get_bits_buf
 tvb_get_bits8
 tvb_get_bits16
 tvb_get_bits32
diff --git a/epan/tvbuff.c b/epan/tvbuff.c
index 83fffe827c..d7a16ebd35 100644
--- a/epan/tvbuff.c
+++ b/epan/tvbuff.c
@@ -1656,6 +1656,59 @@ tvb_get_bits8(tvbuff_t *tvb, gint bit_offset, const gint no_of_bits)
 	return (guint8)value;
 }
 
+void
+tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf)
+{
+	/* Byte align offset */
+	gint offset = bit_offset >> 3;
+	bit_offset = bit_offset & 0x7;
+
+	if (G_LIKELY(bit_offset != 0)) {
+		/* XXX, this can be optimized */
+		while (no_of_bits >= 8) {
+			guint16 value = (tvb_get_ntohs(tvb, offset) & bit_mask16[bit_offset]) >> (8 - bit_offset);
+
+			*buf++ = (guint8) value;
+			offset++;
+			no_of_bits -= 8;
+		}
+
+		/* something left? */
+		if (no_of_bits > 0)
+			*buf = tvb_get_bits8(tvb, offset * 8 + bit_offset, no_of_bits);
+
+	} else {
+		/* fast code path for bit_offset == 0 */
+		while (no_of_bits >= 8) {
+			*buf++ = tvb_get_guint8(tvb, offset);
+			offset++;
+			no_of_bits -= 8;
+		}
+
+		/* something left? */
+		if (no_of_bits > 0)
+			*buf = tvb_get_guint8(tvb, offset) >> (8-no_of_bits);
+	}
+}
+
+guint8 *
+ep_tvb_get_bits(tvbuff_t *tvb, gint bit_offset, gint no_of_bits)
+{
+	gint no_of_bytes;
+	guint8 *buf;
+
+	/* XXX, no_of_bits == -1 -> to end of tvb? */
+
+	if (no_of_bits < 0 || bit_offset < 0) {
+		DISSECTOR_ASSERT_NOT_REACHED();
+	}
+
+	no_of_bytes = (no_of_bits >> 3) + ((no_of_bits & 0x7) != 0);	/* ceil(no_of_bits / 8.0) */
+	buf = ep_alloc(no_of_bytes);
+	tvb_get_bits_buf(tvb, bit_offset, no_of_bits, buf);
+	return buf;
+}
+
 /* Get 9 - 16 bits */
 /* Bit offset mask for number of bits = 16 - 32 */
 static const guint32 bit_mask32[] = {
diff --git a/epan/tvbuff.h b/epan/tvbuff.h
index 4763d14683..2d66967560 100644
--- a/epan/tvbuff.h
+++ b/epan/tvbuff.h
@@ -363,6 +363,9 @@ extern guint64 tvb_get_bits64(tvbuff_t *tvb, gint bit_offset, const gint no_of_b
  */
 extern guint32 tvb_get_bits(tvbuff_t *tvb, const gint bit_offset, const gint no_of_bits, const gboolean little_endian);
 
+void tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf);
+guint8 *ep_tvb_get_bits(tvbuff_t *tvb, gint bit_offset, gint no_of_bits);
+
 /** Returns target for convenience. Does not suffer from possible
  * expense of tvb_get_ptr(), since this routine is smart enough
  * to copy data in chunks if the request range actually exists in
-- 
2.34.1