diff options
| -rw-r--r-- | epan/tvbuff.c | 52 | ||||
| -rw-r--r-- | epan/tvbuff.h | 4 |
2 files changed, 43 insertions, 13 deletions
diff --git a/epan/tvbuff.c b/epan/tvbuff.c index d7a16ebd35..197ba7e754 100644 --- a/epan/tvbuff.c +++ b/epan/tvbuff.c @@ -1657,25 +1657,51 @@ tvb_get_bits8(tvbuff_t *tvb, gint bit_offset, const gint no_of_bits) } void -tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf) +tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf, gboolean lsb0) { + guint8 bit_mask, bit_shift; /* Byte align offset */ gint offset = bit_offset >> 3; bit_offset = bit_offset & 0x7; + bit_mask = (lsb0) ? 0xff : bit_mask8[bit_offset]; + bit_shift = (lsb0) ? bit_offset : (8 - bit_offset); + 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); + guint16 value = (guint16) tvb_get_guint8(tvb, offset); - *buf++ = (guint8) value; + while (no_of_bits >= 8) { offset++; + value = ((value & bit_mask) << 8) | tvb_get_guint8(tvb, offset); + + *buf++ = (guint8) (value >> bit_shift); no_of_bits -= 8; } /* something left? */ - if (no_of_bits > 0) - *buf = tvb_get_bits8(tvb, offset * 8 + bit_offset, no_of_bits); + if (no_of_bits > 0) { + guint8 tot_no_bits = bit_offset+no_of_bits; + + /* Overlaps with next byte? Get next byte */ + if (tot_no_bits > 8) { + offset++; + value = ((value & bit_mask) << 8) | tvb_get_guint8(tvb, offset); + } + + if (lsb0) { + value = (value >> bit_offset) & (bit_mask8[8-no_of_bits]); + + /* value = (value & ((1 << tot_no_bits)-1)) >> bit_offset; */ + + + } else { + if (tot_no_bits > 8) + value = value >> (16 - tot_no_bits); + else + value = (value & bit_mask) >> (8-tot_no_bits); + } + *buf = (guint8) value; + } } else { /* fast code path for bit_offset == 0 */ @@ -1686,13 +1712,17 @@ tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf) } /* something left? */ - if (no_of_bits > 0) - *buf = tvb_get_guint8(tvb, offset) >> (8-no_of_bits); + if (no_of_bits > 0) { + if (lsb0) + *buf = tvb_get_guint8(tvb, offset) & bit_mask8[8-no_of_bits]; /* read: ((1 << no_of_bits)-1) */ + else + *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) +ep_tvb_get_bits(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, gboolean lsb0) { gint no_of_bytes; guint8 *buf; @@ -1705,7 +1735,7 @@ ep_tvb_get_bits(tvbuff_t *tvb, gint bit_offset, gint no_of_bits) 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); + tvb_get_bits_buf(tvb, bit_offset, no_of_bits, buf, lsb0); return buf; } diff --git a/epan/tvbuff.h b/epan/tvbuff.h index 2d66967560..1c2acbe765 100644 --- a/epan/tvbuff.h +++ b/epan/tvbuff.h @@ -363,8 +363,8 @@ 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); +void tvb_get_bits_buf(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, guint8 *buf, gboolean lsb0); +guint8 *ep_tvb_get_bits(tvbuff_t *tvb, gint bit_offset, gint no_of_bits, gboolean lsb0); /** Returns target for convenience. Does not suffer from possible * expense of tvb_get_ptr(), since this routine is smart enough |