Create macro to do ntoh for 3 bytes

use it in NSSAI parsing function

openair3/NAS/NR_UE/nr_nas_msg_sim.c

@@ -52,6 +52,7 @@
 #include <openair1/SIMULATION/ETH_TRANSPORT/proto.h>
 #include "openair2/SDAP/nr_sdap/nr_sdap.h"
 #include "openair3/SECU/nas_stream_eia2.h"
+#include "openair3/UTILS/conversions.h"
 
 uint8_t  *registration_request_buf;
 uint32_t  registration_request_len;
@@ -937,14 +938,14 @@ static void parse_allowed_nssai(nr_nas_msg_snssai_t nssaiList[8], const uint8_t
 
       case 4:
         nssai->sst = *buf++;
-        nssai->sd = 0xffffff & (buf[2] | buf[1] << 8 | buf[0] << 16);
+        nssai->sd = 0xffffff & ntoh_int24_buf(buf);
         buf += 3;
         nssai_cnt++;
         break;
 
       case 5:
         nssai->sst = *buf++;
-        nssai->sd = 0xffffff & (buf[2] | buf[1] << 8 | buf[0] << 16);
+        nssai->sd = 0xffffff & ntoh_int24_buf(buf);
         buf += 3;
         nssai->hplmn_sst = *buf++;
         nssai_cnt++;
@@ -952,10 +953,10 @@ static void parse_allowed_nssai(nr_nas_msg_snssai_t nssaiList[8], const uint8_t
 
       case 8:
         nssai->sst = *buf++;
-        nssai->sd = 0xffffff & (buf[2] | buf[1] << 8 | buf[0] << 16);
+        nssai->sd = 0xffffff & ntoh_int24_buf(buf);
         buf += 3;
         nssai->hplmn_sst = *buf++;
-        nssai->hplmn_sd = 0xffffff & (buf[2] | buf[1] << 8 | buf[0] << 16);
+        nssai->hplmn_sd = 0xffffff & ntoh_int24_buf(buf);
         buf += 3;
         nssai_cnt++;
         break;

openair3/UTILS/conversions.h

@@ -41,6 +41,9 @@
 # define hton_int16(x) (x)
 #endif
 
+#define ntoh_int24_buf(bUF) \
+  ((*bUF << 16) | ((*(bUF + 1)) << 8) | (*(bUF + 2)))
+
 #define IN_ADDR_TO_BUFFER(X,bUFF) INT32_TO_BUFFER((X).s_addr,(char*)bUFF)
 
 #define IN6_ADDR_TO_BUFFER(X,bUFF)                     \