> From: Morten Brørup [mailto:m...@smartsharesystems.com] > Sent: Friday, 17 June 2022 10.45 > > With this patch, the checksum can be calculated on an unligned part of > a packet buffer. > I.e. the buf parameter is no longer required to be 16 bit aligned. > > The DPDK invariant that packet buffers must be 16 bit aligned remains > unchanged. > This invariant also defines how to calculate the 16 bit checksum on an > unaligned part of a packet buffer. > > Bugzilla ID: 1035 > Cc: sta...@dpdk.org > > Signed-off-by: Morten Brørup <m...@smartsharesystems.com> > --- > lib/net/rte_ip.h | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h > index b502481670..8e301d9c26 100644 > --- a/lib/net/rte_ip.h > +++ b/lib/net/rte_ip.h > @@ -162,9 +162,22 @@ __rte_raw_cksum(const void *buf, size_t len, > uint32_t sum) > { > /* extend strict-aliasing rules */ > typedef uint16_t __attribute__((__may_alias__)) u16_p; > - const u16_p *u16_buf = (const u16_p *)buf; > - const u16_p *end = u16_buf + len / sizeof(*u16_buf); > + const u16_p *u16_buf; > + const u16_p *end; > + > + /* if buffer is unaligned, keeping it byte order independent */ > + if (unlikely((uintptr_t)buf & 1)) { > + uint16_t first = 0; > + if (unlikely(len == 0)) > + return 0; > + ((unsigned char *)&first)[1] = *(const unsigned char *)buf; > + sum += first; > + buf = (const void *)((uintptr_t)buf + 1); > + len--; > + } > > + u16_buf = (const u16_p *)buf; > + end = u16_buf + len / sizeof(*u16_buf); > for (; u16_buf != end; ++u16_buf) > sum += *u16_buf; > > -- > 2.17.1
@Emil, can you please test this patch with an unaligned buffer on your application to confirm that it produces the expected result.
