On 06/16/2017 08:40 AM, Shreyansh Jain wrote:
From: Hemant Agrawal <hemant.agra...@nxp.com> Bit Swap and LE<=>BE conversions for 23, 40 and 48 bit width Signed-off-by: Hemant Agrawal <hemant.agra...@nxp.com> --- .../common/include/generic/rte_byteorder.h | 78 ++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/lib/librte_eal/common/include/generic/rte_byteorder.h b/lib/librte_eal/common/include/generic/rte_byteorder.h index e00bccb..8903ff6 100644 --- a/lib/librte_eal/common/include/generic/rte_byteorder.h +++ b/lib/librte_eal/common/include/generic/rte_byteorder.h @@ -122,6 +122,84 @@ rte_constant_bswap64(uint64_t x) ((x & 0xff00000000000000ULL) >> 56); }+/*+ * An internal function to swap bytes of a 48-bit value. + */ +static inline uint64_t +rte_constant_bswap48(uint64_t x) +{ + return ((x & 0x0000000000ffULL) << 40) | + ((x & 0x00000000ff00ULL) << 24) | + ((x & 0x000000ff0000ULL) << 8) | + ((x & 0x0000ff000000ULL) >> 8) | + ((x & 0x00ff00000000ULL) >> 24) | + ((x & 0xff0000000000ULL) >> 40); +} +
Won't something like bswap64(x << 16) be much more efficient? Two instructions for the non-constant case, compared to 15-20 here.
