common/cpt: fix bit shift operation for KASUMI

Using the rte_bsf32 function to find last set bit. This avoids
the for loop and hence the bad bit shift operation.

Coverity issue: 323477
Fixes: 351fbee21986 ("common/cpt: support hash")

Signed-off-by: Ankur Dwivedi <ankur.dwivedi@caviumnetworks.com>
Signed-off-by: Anoob Joseph <anoob.joseph@caviumnetworks.com>

diff --git a/drivers/common/cpt/cpt_ucode.h b/drivers/common/cpt/cpt_ucode.h
index c5a9f34..5933ea7 100644 (file)
--- a/drivers/common/cpt/cpt_ucode.h
+++ b/drivers/common/cpt/cpt_ucode.h
@@ -3449,32 +3449,27 @@ find_kasumif9_direction_and_length(uint8_t *src,
                                   uint8_t *addr_direction)
 {
        uint8_t found = 0;
+       uint32_t pos;
+       uint8_t last_byte;
        while (!found && counter_num_bytes > 0) {
                counter_num_bytes--;
                if (src[counter_num_bytes] == 0x00)
                        continue;
-               if (src[counter_num_bytes] == 0x80) {
-                       *addr_direction  =  src[counter_num_bytes - 1] & 0x1;
-                       *addr_length_in_bits = counter_num_bytes * 8  - 1;
-                       found = 1;
-               } else {
-                       int i = 0;
-                       uint8_t last_byte = src[counter_num_bytes];
-                       for (i = 0; i < 8 && found == 0; i++) {
-                               if (last_byte & (1 << i)) {
-                                       *addr_direction = (last_byte >> (i+1))
-                                                         & 0x1;
-                                       if (i != 6)
-                                               *addr_length_in_bits =
-                                                       counter_num_bytes * 8
-                                                       + (8 - (i + 2));
-                                       else
-                                               *addr_length_in_bits =
-                                                       counter_num_bytes * 8;
-                                       found = 1;
-                                       }
-                               }
+               pos = rte_bsf32(src[counter_num_bytes]);
+               if (pos == 7) {
+                       if (likely(counter_num_bytes > 0)) {
+                               last_byte = src[counter_num_bytes - 1];
+                               *addr_direction  =  last_byte & 0x1;
+                               *addr_length_in_bits = counter_num_bytes * 8
+                                                       - 1;
                        }
+               } else {
+                       last_byte = src[counter_num_bytes];
+                       *addr_direction = (last_byte >> (pos + 1)) & 0x1;
+                       *addr_length_in_bits = counter_num_bytes * 8
+                                               + (8 - (pos + 2));
+               }
+               found = 1;
        }
 }