Use function for 16/24/32-bit BE conversion

Use functions for 16/24/32-bit big endian conversion to save ROM.
diff --git a/library/platform_util.c b/library/platform_util.c
index 756e226..f901769 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -134,3 +134,54 @@
 #endif /* _WIN32 && !EFIX64 && !EFI32 */
 }
 #endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
+
+unsigned char * mbedtls_platform_put_uint32_be( unsigned char *buf,
+                                                unsigned long num)
+{
+    *buf++ = (unsigned char) ( num >> 24 );
+    *buf++ = (unsigned char) ( num >> 16 );
+    *buf++ = (unsigned char) ( num >> 8  );
+    *buf++ = (unsigned char) ( num       );
+
+    return buf;
+}
+
+unsigned char * mbedtls_platform_put_uint24_be( unsigned char *buf,
+                                                unsigned long num )
+{
+    *buf++ = (unsigned char) ( num >> 16 );
+    *buf++ = (unsigned char) ( num >> 8  );
+    *buf++ = (unsigned char) ( num       );
+
+    return buf;
+}
+
+unsigned char * mbedtls_platform_put_uint16_be( unsigned char *buf,
+                                                unsigned long num )
+{
+    *buf++ = (unsigned char) ( num >> 8 );
+    *buf++ = (unsigned char) ( num      );
+
+    return buf;
+}
+
+unsigned int mbedtls_platform_get_uint32_be( const unsigned char *buf )
+{
+    return ( ( (unsigned int) buf[0] << 24 ) |
+             ( (unsigned int) buf[1] << 16 ) |
+             ( (unsigned int) buf[2] <<  8 ) |
+             ( (unsigned int) buf[3]       ) );
+}
+
+unsigned int mbedtls_platform_get_uint24_be( const unsigned char *buf )
+{
+    return ( ( buf[0] << 16 ) |
+             ( buf[1] <<  8)  |
+             ( buf[2]      ) );
+}
+
+unsigned short mbedtls_platform_get_uint16_be( const unsigned char *buf )
+{
+    return ( ( buf[0] << 8 )  |
+             ( buf[1]      ) );
+}
diff --git a/library/sha256.c b/library/sha256.c
index c576a03..1c1df02 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -49,40 +49,12 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
-    !defined(inline) && !defined(__cplusplus)
-#define inline __inline
-#endif
-
 #define SHA256_VALIDATE_RET(cond)                           \
     MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_SHA256_BAD_INPUT_DATA )
 #define SHA256_VALIDATE(cond)  MBEDTLS_INTERNAL_VALIDATE( cond )
 
 #if !defined(MBEDTLS_SHA256_ALT)
 
-/*
- * 32-bit integer manipulation (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-do {                                                    \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-} while( 0 )
-#endif
-
-static inline void sha256_put_uint32_be( uint32_t n,
-                                         unsigned char *b,
-                                         uint8_t i )
-{
-    b[i    ] = (unsigned char) ( n >> 24 );
-    b[i + 1] = (unsigned char) ( n >> 16 );
-    b[i + 2] = (unsigned char) ( n >>  8 );
-    b[i + 3] = (unsigned char) ( n       );
-}
-
 void mbedtls_sha256_init( mbedtls_sha256_context *ctx )
 {
     SHA256_VALIDATE( ctx != NULL );
@@ -227,7 +199,7 @@
     for( i = 0; i < 64; i++ )
     {
         if( i < 16 )
-            GET_UINT32_BE( W[i], data, 4 * i );
+            W[i] = mbedtls_platform_get_uint32_be( &data[4 * i] );
         else
             R( i );
 
@@ -238,7 +210,7 @@
     }
 #else /* MBEDTLS_SHA256_SMALLER */
     for( i = 0; i < 16; i++ )
-        GET_UINT32_BE( W[i], data, 4 * i );
+        W[i] = mbedtls_platform_get_uint32_be( &data[4 * i] );
 
     for( i = 0; i < 16; i += 8 )
     {
@@ -385,8 +357,8 @@
          | ( ctx->total[1] <<  3 );
     low  = ( ctx->total[0] <<  3 );
 
-    sha256_put_uint32_be( high, ctx->buffer, 56 );
-    sha256_put_uint32_be( low,  ctx->buffer, 60 );
+    mbedtls_platform_put_uint32_be( ctx->buffer + 56, high );
+    mbedtls_platform_put_uint32_be( ctx->buffer + 60, low );
 
     if( ( ret = mbedtls_internal_sha256_process( ctx, ctx->buffer ) ) != 0 )
         return( ret );
@@ -394,18 +366,16 @@
     /*
      * Output final state
      */
-    sha256_put_uint32_be( ctx->state[0], output,  0 );
-    sha256_put_uint32_be( ctx->state[1], output,  4 );
-    sha256_put_uint32_be( ctx->state[2], output,  8 );
-    sha256_put_uint32_be( ctx->state[3], output, 12 );
-    sha256_put_uint32_be( ctx->state[4], output, 16 );
-    sha256_put_uint32_be( ctx->state[5], output, 20 );
-    sha256_put_uint32_be( ctx->state[6], output, 24 );
+
+    for ( int s_pos = 0, o_pos = 0; s_pos < 7; s_pos++, o_pos += 4 )
+    {
+        mbedtls_platform_put_uint32_be( &output[o_pos], ctx->state[s_pos] );
+    }
 
 #if !defined(MBEDTLS_SHA256_NO_SHA224)
     if( ctx->is224 == 0 )
 #endif
-        sha256_put_uint32_be( ctx->state[7], output, 28 );
+        mbedtls_platform_put_uint32_be( &output[28], ctx->state[7] );
 
     return( 0 );
 }
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 5c2d870..6a9523e 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -102,18 +102,14 @@
      * } ServerNameList;
      *
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
 
-    *p++ = (unsigned char)( ( (hostname_len + 5) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 5)      ) & 0xFF );
-
-    *p++ = (unsigned char)( ( (hostname_len + 3) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 3)      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SERVERNAME );
+    p = mbedtls_platform_put_uint16_be( p, hostname_len + 5 );
+    p = mbedtls_platform_put_uint16_be( p, hostname_len + 3 );
 
     *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len      ) & 0xFF );
+
+    p = mbedtls_platform_put_uint16_be( p, hostname_len );
 
     memcpy( p, ssl->hostname, hostname_len );
 
@@ -148,8 +144,7 @@
     /*
      * Secure renegotiation
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
     *p++ = 0x00;
     *p++ = ( ssl->verify_data_len + 1 ) & 0xFF;
@@ -237,15 +232,10 @@
      * SignatureAndHashAlgorithm
      *   supported_signature_algorithms<2..2^16-2>;
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG      ) & 0xFF );
 
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 )      ) & 0xFF );
-
-    *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SIG_ALG );
+    p = mbedtls_platform_put_uint16_be( p, ( sig_alg_len + 2 ) );
+    p = mbedtls_platform_put_uint16_be( p, sig_alg_len );
     *olen = 6 + sig_alg_len;
 }
 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 &&
@@ -290,18 +280,13 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      ) & 0xFF );
-
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 )      ) & 0xFF );
-
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     )      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
+    p = mbedtls_platform_put_uint16_be( p,  ( elliptic_curve_len + 2 ) );
+    p = mbedtls_platform_put_uint16_be( p,  ( elliptic_curve_len ) );
 
     MBEDTLS_SSL_BEGIN_FOR_EACH_SUPPORTED_EC_TLS_ID( tls_id )
-    *p++ = tls_id >> 8;
-    *p++ = tls_id & 0xFF;
+    p = mbedtls_platform_put_uint16_be( p, tls_id );
+
     MBEDTLS_SSL_END_FOR_EACH_SUPPORTED_EC_TLS_ID
 
     *olen = 6 + elliptic_curve_len;
@@ -324,8 +309,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -362,8 +346,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     /*
      * We may need to send ClientHello multiple times for Hello verification.
@@ -410,8 +393,7 @@
         memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, kkpp_len );
 
     *olen = kkpp_len + 4;
 }
@@ -452,11 +434,10 @@
     }
 
     /* Add extension ID + size */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+
+    p = mbedtls_platform_put_uint16_be( p, ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -487,8 +468,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -521,8 +501,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_TRUNCATED_HMAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -556,8 +535,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -592,8 +570,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -625,11 +602,8 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
-
-    *p++ = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( tlen      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SESSION_TICKET );
+    p = mbedtls_platform_put_uint16_be( p, tlen );
 
     *olen = 4;
 
@@ -673,8 +647,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_ALPN );
 
     /*
      * opaque ProtocolName<1..2^8-1>;
@@ -697,12 +670,9 @@
     *olen = p - buf;
 
     /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
-
+    mbedtls_platform_put_uint16_be( &buf[4], ( *olen - 6 ) );
     /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    mbedtls_platform_put_uint16_be( &buf[2], ( *olen - 4 ) );
 }
 #endif /* MBEDTLS_SSL_ALPN */
 
@@ -730,11 +700,7 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     t = mbedtls_time( NULL );
-    *p++ = (unsigned char)( t >> 24 );
-    *p++ = (unsigned char)( t >> 16 );
-    *p++ = (unsigned char)( t >>  8 );
-    *p++ = (unsigned char)( t       );
-
+    p = mbedtls_platform_put_uint32_be( p, t );
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, current time: %lu", t ) );
 #else
     if( ( ret = mbedtls_ssl_conf_get_frng( ssl->conf )
@@ -1012,8 +978,7 @@
     if( ssl->conf->fallback == MBEDTLS_SSL_IS_FALLBACK )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding FALLBACK_SCSV" ) );
-        *p++ = (unsigned char)( MBEDTLS_SSL_FALLBACK_SCSV_VALUE >> 8 );
-        *p++ = (unsigned char)( MBEDTLS_SSL_FALLBACK_SCSV_VALUE      );
+        p = mbedtls_platform_put_uint16_be( p, MBEDTLS_SSL_FALLBACK_SCSV_VALUE );
         n++;
     }
 #endif
@@ -1141,8 +1106,7 @@
 
     if( ext_len > 0 )
     {
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        p = mbedtls_platform_put_uint16_be( p, ext_len );
         p += ext_len;
     }
 
@@ -1497,7 +1461,7 @@
         return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
     }
 
-    list_len = ( buf[0] << 8 ) | buf[1];
+    list_len = mbedtls_platform_get_uint16_be( buf );
     if( list_len != len - 2 )
     {
         mbedtls_ssl_pend_fatal_alert( ssl,
@@ -1743,11 +1707,7 @@
 #endif /* !MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
     }
 
-    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu",
-                           ( (uint32_t) buf[2] << 24 ) |
-                           ( (uint32_t) buf[3] << 16 ) |
-                           ( (uint32_t) buf[4] <<  8 ) |
-                           ( (uint32_t) buf[5]       ) ) );
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu", mbedtls_platform_get_uint32_be(&buf[2])) );
 
     memcpy( ssl->handshake->randbytes + 32, buf + 2, 32 );
 
@@ -1790,7 +1750,7 @@
     }
 
     /* ciphersuite (used later) */
-    i = ( buf[35 + n] << 8 ) | buf[36 + n];
+    i = mbedtls_platform_get_uint16_be( &buf[ 35 + n ] );
 
     /*
      * Read and check compression
@@ -2462,8 +2422,7 @@
     defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if( len_bytes == 2 )
     {
-        out[0] = (unsigned char)( *olen >> 8 );
-        out[1] = (unsigned char)( *olen      );
+        mbedtls_platform_put_uint16_be( out, *olen );
         *olen += 2;
     }
 #endif
@@ -2977,7 +2936,8 @@
                                           MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
             return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
         }
-        sig_len = ( p[0] << 8 ) | p[1];
+
+        sig_len = mbedtls_platform_get_uint16_be( p );
         p += 2;
 
         if( p != end - sig_len )
@@ -3573,9 +3533,7 @@
         if( (size_t)( end - p ) < n + 2 )
             return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
 
-        p[0] = (unsigned char)( n >> 8 );
-        p[1] = (unsigned char)( n      );
-        p += 2;
+        p = mbedtls_platform_put_uint16_be( p, n );
 
         ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
                            (int) mbedtls_mpi_size( &ssl->handshake->dhm_ctx.P ),
@@ -3690,9 +3648,7 @@
             return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
         }
 
-        p[0] = (unsigned char)( n >> 8 );
-        p[1] = (unsigned char)( n      );
-        p += 2;
+        p = mbedtls_platform_put_uint16_be( p, n );
 
         memcpy( p, ssl->conf->psk_identity, n );
         p += ssl->conf->psk_identity_len;
@@ -3736,9 +3692,7 @@
                 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
             }
 
-            p[0] = (unsigned char)( n >> 8 );
-            p[1] = (unsigned char)( n      );
-            p += 2;
+            p = mbedtls_platform_put_uint16_be( p, n );
 
             ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
                            (int) mbedtls_mpi_size( &ssl->handshake->dhm_ctx.P ),
@@ -4036,8 +3990,7 @@
         return( ret );
     }
 
-    ssl->out_msg[4 + offset] = (unsigned char)( n >> 8 );
-    ssl->out_msg[5 + offset] = (unsigned char)( n      );
+    mbedtls_platform_put_uint16_be( &ssl->out_msg[4 + offset], n );
 
     ssl->out_msglen  = 6 + n + offset;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
@@ -4103,10 +4056,9 @@
 
     msg = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );
 
-    lifetime = ( ((uint32_t) msg[0]) << 24 ) | ( msg[1] << 16 ) |
-               ( msg[2] << 8 ) | ( msg[3] );
+    lifetime = mbedtls_platform_get_uint32_be( msg );
 
-    ticket_len = ( msg[4] << 8 ) | ( msg[5] );
+    ticket_len = mbedtls_platform_get_uint16_be( &msg[4] );
 
     if( ticket_len + 6 + mbedtls_ssl_hs_hdr_len( ssl ) != ssl->in_hslen )
     {
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index 6f0be8a..a06cc3c 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -172,12 +172,7 @@
 #else
     t = ctx->serial++;
 #endif
-
-    (*p)[0] = (unsigned char)( t >> 24 );
-    (*p)[1] = (unsigned char)( t >> 16 );
-    (*p)[2] = (unsigned char)( t >>  8 );
-    (*p)[3] = (unsigned char)( t       );
-    *p += 4;
+    *p = mbedtls_platform_put_uint32_be( *p, t );
 
 #if defined(MBEDTLS_THREADING_C)
     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
@@ -243,10 +238,7 @@
     cur_time = ctx->serial;
 #endif
 
-    cookie_time = ( (unsigned long) cookie[0] << 24 ) |
-                  ( (unsigned long) cookie[1] << 16 ) |
-                  ( (unsigned long) cookie[2] <<  8 ) |
-                  ( (unsigned long) cookie[3]       );
+    cookie_time = mbedtls_platform_get_uint32_be( cookie );
 
     if( ctx->timeout != 0 && cur_time - cookie_time > ctx->timeout )
         return( -1 );
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index fd1ece0..4fa92fe 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -98,7 +98,8 @@
                                       MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
-    servername_list_size = ( ( buf[0] << 8 ) | ( buf[1] ) );
+    servername_list_size = mbedtls_platform_get_uint16_be( buf );
+
     if( servername_list_size + 2 != len )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
@@ -110,7 +111,7 @@
     p = buf + 2;
     while( servername_list_size > 2 )
     {
-        hostname_len = ( ( p[1] << 8 ) | p[2] );
+        hostname_len = mbedtls_platform_get_uint16_be( &p[1] );
         if( hostname_len + 3 > servername_list_size )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
@@ -218,7 +219,9 @@
                                       MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
-    sig_alg_list_size = ( ( buf[0] << 8 ) | ( buf[1] ) );
+
+    sig_alg_list_size = mbedtls_platform_get_uint16_be( buf );
+
     if( sig_alg_list_size + 2 != len ||
         sig_alg_list_size % 2 != 0 )
     {
@@ -293,7 +296,8 @@
                                       MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
-    list_size = ( ( buf[0] << 8 ) | ( buf[1] ) );
+
+    list_size = mbedtls_platform_get_uint16_be( buf );
     if( list_size + 2 != len ||
         list_size % 2 != 0 )
     {
@@ -658,6 +662,7 @@
     }
 
     list_len = ( buf[0] << 8 ) | buf[1];
+
     if( list_len != len - 2 )
     {
         mbedtls_ssl_pend_fatal_alert( ssl,
@@ -751,8 +756,7 @@
 
     while( ec_tls_ids_len-- != 0 )
     {
-        uint16_t const cur_tls_id =
-            ( acceptable_ec_tls_ids[0] << 8 ) | acceptable_ec_tls_ids[1];
+        uint16_t const cur_tls_id = mbedtls_platform_get_uint16_be( acceptable_ec_tls_ids );
 
         if( cur_tls_id == tls_id )
             return( 0 );
@@ -1102,7 +1106,7 @@
         return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
     }
 
-    n = ( ( buf[0] << 8 ) | buf[1] ) & 0x7FFF;
+    n = mbedtls_platform_get_uint16_be( buf );
 
     if( n < 17 || n > 512 )
     {
@@ -1162,9 +1166,9 @@
      */
     MBEDTLS_SSL_DEBUG_BUF( 4, "record contents", buf, n );
 
-    ciph_len = ( buf[0] << 8 ) | buf[1];
-    sess_len = ( buf[2] << 8 ) | buf[3];
-    chal_len = ( buf[4] << 8 ) | buf[5];
+    ciph_len = mbedtls_platform_get_uint16_be( &buf[0] );
+    sess_len = mbedtls_platform_get_uint16_be( &buf[2] );
+    chal_len = mbedtls_platform_get_uint16_be( &buf[4] );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "ciph_len: %d, sess_len: %d, chal_len: %d",
                    ciph_len, sess_len, chal_len ) );
@@ -1489,7 +1493,7 @@
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
-    msg_len = ( ssl->in_len[0] << 8 ) | ssl->in_len[1];
+    msg_len = mbedtls_platform_get_uint16_be( ssl->in_len );
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
     if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
@@ -1578,8 +1582,7 @@
         if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
         {
             /* This couldn't be done in ssl_prepare_handshake_record() */
-            unsigned int cli_msg_seq = ( ssl->in_msg[4] << 8 ) |
-                                         ssl->in_msg[5];
+            unsigned int cli_msg_seq = mbedtls_platform_get_uint16_be( &ssl->in_msg[4] );
 
             if( cli_msg_seq != ssl->handshake->in_msg_seq )
             {
@@ -1594,8 +1597,8 @@
         else
 #endif
         {
-            unsigned int cli_msg_seq = ( ssl->in_msg[4] << 8 ) |
-                                         ssl->in_msg[5];
+            unsigned int cli_msg_seq = mbedtls_platform_get_uint16_be( &ssl->in_msg[4] );
+
             ssl->handshake->out_msg_seq = cli_msg_seq;
             ssl->handshake->in_msg_seq  = cli_msg_seq + 1;
         }
@@ -1783,8 +1786,8 @@
     }
 #endif /* MBEDTLS_SSL_PROTO_TLS */
 
-    ciph_len = ( buf[ciph_offset + 0] << 8 )
-             | ( buf[ciph_offset + 1]      );
+
+    ciph_len = mbedtls_platform_get_uint16_be( &buf[ciph_offset + 0] );
 
     if( ciph_len < 2 ||
         ciph_len + 2 + ciph_offset + 1 > msg_len || /* 1 for comp. alg. len */
@@ -2323,9 +2326,7 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding truncated hmac extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_TRUNCATED_HMAC );
     *p++ = 0x00;
     *p++ = 0x00;
 
@@ -2367,13 +2368,9 @@
      *      opaque cid<0..2^8-1>;
      *   } ConnectionId;
     */
-
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, ext_len );
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
 
@@ -2423,9 +2420,7 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding encrypt then mac extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
     *p++ = 0x00;
     *p++ = 0x00;
 
@@ -2451,8 +2446,7 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding extended master secret "
                         "extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      ) & 0xFF );
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2476,9 +2470,7 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding session ticket extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_SESSION_TICKET );
     *p++ = 0x00;
     *p++ = 0x00;
 
@@ -2541,9 +2533,7 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, max_fragment_length extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
     *p++ = 0x00;
     *p++ = 1;
 
@@ -2626,9 +2616,7 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
-
+    p = mbedtls_platform_put_uint16_be( p, kkpp_len );
     *olen = kkpp_len + 4;
 }
 #endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
@@ -2652,16 +2640,11 @@
      * 6 . 6    protocol name length
      * 7 . 7+n  protocol name
      */
-    buf[0] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    buf[1] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    mbedtls_platform_put_uint16_be( &buf[0], MBEDTLS_TLS_EXT_ALPN );
 
     *olen = 7 + strlen( ssl->alpn_chosen );
-
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
-
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    mbedtls_platform_put_uint16_be( &buf[2], ( *olen - 4 ) );
+    mbedtls_platform_put_uint16_be( &buf[4], ( *olen - 6 ) );
 
     buf[6] = (unsigned char)( ( ( *olen - 7 )      ) & 0xFF );
 
@@ -2791,10 +2774,7 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     t = mbedtls_time( NULL );
-    *p++ = (unsigned char)( t >> 24 );
-    *p++ = (unsigned char)( t >> 16 );
-    *p++ = (unsigned char)( t >>  8 );
-    *p++ = (unsigned char)( t       );
+    p = mbedtls_platform_put_uint32_be( p, t );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu", t ) );
 #else
@@ -3121,8 +3101,7 @@
         }
         MBEDTLS_SSL_END_FOR_EACH_SIG_HASH_TLS
 
-        p[0] = (unsigned char)( sa_len >> 8 );
-        p[1] = (unsigned char)( sa_len      );
+        mbedtls_platform_put_uint16_be( p, sa_len );
         sa_len += 2;
         p += sa_len;
     }
@@ -3167,8 +3146,7 @@
                 break;
             }
 
-            *p++ = (unsigned char)( dn_size >> 8 );
-            *p++ = (unsigned char)( dn_size      );
+            p = mbedtls_platform_put_uint16_be( p, dn_size );
             memcpy( p, frame->subject_raw.p, dn_size );
             p += dn_size;
 
@@ -3185,8 +3163,7 @@
     ssl->out_msglen  = p - buf;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
     ssl->out_msg[0]  = MBEDTLS_SSL_HS_CERTIFICATE_REQUEST;
-    ssl->out_msg[4 + ct_len + sa_len] = (unsigned char)( total_dn_size  >> 8 );
-    ssl->out_msg[5 + ct_len + sa_len] = (unsigned char)( total_dn_size       );
+    mbedtls_platform_put_uint16_be( &ssl->out_msg[4 + ct_len + sa_len], total_dn_size );
 
     ret = mbedtls_ssl_write_handshake_msg( ssl );
 
@@ -3740,8 +3717,8 @@
 #if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
     if( signature_len != 0 )
     {
-        ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len >> 8 );
-        ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len      );
+        mbedtls_platform_put_uint16_be( &ssl->out_msg[ssl->out_msglen], signature_len );
+        ssl->out_msglen += 2;
 
         MBEDTLS_SSL_DEBUG_BUF( 3, "my signature",
                                ssl->out_msg + ssl->out_msglen,
@@ -4610,7 +4587,7 @@
         goto exit;
     }
 
-    sig_len = ( ssl->in_msg[i] << 8 ) | ssl->in_msg[i+1];
+    sig_len = mbedtls_platform_get_uint16_be( &ssl->in_msg[i] );
     i += 2;
 
     if( i + sig_len != ssl->in_hslen )
@@ -4682,15 +4659,9 @@
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_ticket_write", ret );
         tlen = 0;
     }
+    mbedtls_platform_put_uint32_be( &ssl->out_msg[4], lifetime );
 
-    ssl->out_msg[4] = ( lifetime >> 24 ) & 0xFF;
-    ssl->out_msg[5] = ( lifetime >> 16 ) & 0xFF;
-    ssl->out_msg[6] = ( lifetime >>  8 ) & 0xFF;
-    ssl->out_msg[7] = ( lifetime       ) & 0xFF;
-
-    ssl->out_msg[8] = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    ssl->out_msg[9] = (unsigned char)( ( tlen      ) & 0xFF );
-
+    mbedtls_platform_put_uint16_be( &ssl->out_msg[8], tlen );
     ssl->out_msglen = 10 + tlen;
 
     /*
diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c
index 5fe693c..eeaeb52 100644
--- a/library/ssl_ticket.c
+++ b/library/ssl_ticket.c
@@ -221,8 +221,8 @@
     {
          goto cleanup;
     }
-    state_len_bytes[0] = ( clear_len >> 8 ) & 0xff;
-    state_len_bytes[1] = ( clear_len      ) & 0xff;
+
+    mbedtls_platform_put_uint16_be( state_len_bytes, clear_len );
 
     /* Encrypt and authenticate */
     tag = state + clear_len;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index e47c456..25351ae 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2102,8 +2102,7 @@
         if( end - p < 2 )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-        *(p++) = (unsigned char)( psk_len >> 8 );
-        *(p++) = (unsigned char)( psk_len      );
+        p = mbedtls_platform_put_uint16_be( p, psk_len );
 
         if( end < p || (size_t)( end - p ) < psk_len )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -2144,8 +2143,7 @@
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
             return( ret );
         }
-        *(p++) = (unsigned char)( len >> 8 );
-        *(p++) = (unsigned char)( len );
+        p = mbedtls_platform_put_uint16_be( p, len );
         p += len;
 
         MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K  );
@@ -2185,8 +2183,7 @@
                                 MBEDTLS_DEBUG_ECDH_Z );
 #endif /* MBEDTLS_USE_TINYCRYPT */
 
-        *(p++) = (unsigned char)( zlen >> 8 );
-        *(p++) = (unsigned char)( zlen      );
+        p = mbedtls_platform_put_uint16_be( p, zlen );
         p += zlen;
 
     }
@@ -2201,8 +2198,7 @@
     if( end - p < 2 )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    *(p++) = (unsigned char)( psk_len >> 8 );
-    *(p++) = (unsigned char)( psk_len      );
+    p = mbedtls_platform_put_uint16_be( p, psk_len );
 
     if( end < p || (size_t)( end - p ) < psk_len )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -2241,8 +2237,7 @@
 
     memcpy( header, ctr, 8 );
     header[ 8] = (unsigned char)  type;
-    header[ 9] = (unsigned char)( len >> 8 );
-    header[10] = (unsigned char)( len      );
+    mbedtls_platform_put_uint16_be( &header[9], len );
 
     memset( padding, 0x36, padlen );
     mbedtls_md_starts( md_ctx );
@@ -2394,15 +2389,13 @@
     {
         memcpy( add_data + 11, rec->cid, rec->cid_len );
         add_data[11 + rec->cid_len + 0] = rec->cid_len;
-        add_data[11 + rec->cid_len + 1] = ( rec->data_len >> 8 ) & 0xFF;
-        add_data[11 + rec->cid_len + 2] = ( rec->data_len >> 0 ) & 0xFF;
+        mbedtls_platform_put_uint16_be( &add_data[11 + rec->cid_len + 1], rec->data_len );
         *add_data_len = 13 + 1 + rec->cid_len;
     }
     else
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
     {
-        add_data[11 + 0] = ( rec->data_len >> 8 ) & 0xFF;
-        add_data[11 + 1] = ( rec->data_len >> 0 ) & 0xFF;
+        mbedtls_platform_put_uint16_be( &add_data[11], rec->data_len );
         *add_data_len = 13;
     }
 }
@@ -4150,13 +4143,8 @@
              * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
             memcpy( ssl->out_msg, cur->p, 6 );
 
-            ssl->out_msg[6] = ( ( frag_off >> 16 ) & 0xff );
-            ssl->out_msg[7] = ( ( frag_off >>  8 ) & 0xff );
-            ssl->out_msg[8] = ( ( frag_off       ) & 0xff );
-
-            ssl->out_msg[ 9] = ( ( cur_hs_frag_len >> 16 ) & 0xff );
-            ssl->out_msg[10] = ( ( cur_hs_frag_len >>  8 ) & 0xff );
-            ssl->out_msg[11] = ( ( cur_hs_frag_len       ) & 0xff );
+            mbedtls_platform_put_uint24_be( &ssl->out_msg[6], frag_off );
+            mbedtls_platform_put_uint24_be( &ssl->out_msg[9], cur_hs_frag_len );
 
             MBEDTLS_SSL_DEBUG_BUF( 3, "handshake header", ssl->out_msg, 12 );
 
@@ -4353,9 +4341,7 @@
      */
     if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
     {
-        ssl->out_msg[1] = (unsigned char)( hs_len >> 16 );
-        ssl->out_msg[2] = (unsigned char)( hs_len >>  8 );
-        ssl->out_msg[3] = (unsigned char)( hs_len       );
+        mbedtls_platform_put_uint24_be( &ssl->out_msg[1], hs_len );
 
         /*
          * DTLS has additional fields in the Handshake layer,
@@ -4383,8 +4369,7 @@
             /* Write message_seq and update it, except for HelloRequest */
             if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
             {
-                ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
-                ssl->out_msg[5] = ( ssl->handshake->out_msg_seq      ) & 0xFF;
+                mbedtls_platform_put_uint16_be( &ssl->out_msg[4], ssl->handshake->out_msg_seq );
                 ++( ssl->handshake->out_msg_seq );
             }
             else
@@ -4495,8 +4480,7 @@
                                    ssl->conf->transport, ssl->out_hdr + 1 );
 
         memcpy( ssl->out_ctr, ssl->cur_out_ctr, 8 );
-        ssl->out_len[0] = (unsigned char)( len >> 8 );
-        ssl->out_len[1] = (unsigned char)( len      );
+        mbedtls_platform_put_uint16_be( ssl->out_len, len );
 
         if( ssl->transform_out != NULL )
         {
@@ -4539,8 +4523,7 @@
             memcpy( ssl->out_cid, rec.cid, rec.cid_len );
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
             ssl->out_msglen = len = rec.data_len;
-            ssl->out_len[0] = (unsigned char)( rec.data_len >> 8 );
-            ssl->out_len[1] = (unsigned char)( rec.data_len      );
+            mbedtls_platform_put_uint16_be( ssl->out_len, rec.data_len );
         }
 
         protected_record_size = len + mbedtls_ssl_out_hdr_len( ssl );
@@ -4641,16 +4624,12 @@
 
 static uint32_t ssl_get_hs_frag_len( mbedtls_ssl_context const *ssl )
 {
-    return( ( ssl->in_msg[9] << 16  ) |
-            ( ssl->in_msg[10] << 8  ) |
-              ssl->in_msg[11] );
+    return mbedtls_platform_get_uint24_be( &ssl->in_msg[9] );
 }
 
 static uint32_t ssl_get_hs_frag_off( mbedtls_ssl_context const *ssl )
 {
-    return( ( ssl->in_msg[6] << 16 ) |
-            ( ssl->in_msg[7] << 8  ) |
-              ssl->in_msg[8] );
+    return mbedtls_platform_get_uint24_be( &ssl->in_msg[6] );
 }
 
 static int ssl_check_hs_header( mbedtls_ssl_context const *ssl )
@@ -4753,9 +4732,7 @@
 
 static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl )
 {
-    return( ( ssl->in_msg[1] << 16 ) |
-            ( ssl->in_msg[2] << 8  ) |
-              ssl->in_msg[3] );
+    return mbedtls_platform_get_uint24_be( &ssl->in_msg[1] );
 }
 
 int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
@@ -4777,7 +4754,7 @@
     if( MBEDTLS_SSL_TRANSPORT_IS_DTLS( ssl->conf->transport ) )
     {
         int ret;
-        unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
+        unsigned int recv_msg_seq = mbedtls_platform_get_uint16_be( &ssl->in_msg[4] );
 
         if( ssl_check_hs_header( ssl ) != 0 )
         {
@@ -5104,12 +5081,12 @@
     /* Go back and fill length fields */
     obuf[27] = (unsigned char)( *olen - 28 );
 
-    obuf[14] = obuf[22] = (unsigned char)( ( *olen - 25 ) >> 16 );
-    obuf[15] = obuf[23] = (unsigned char)( ( *olen - 25 ) >>  8 );
-    obuf[16] = obuf[24] = (unsigned char)( ( *olen - 25 )       );
+    mbedtls_platform_put_uint24_be( &obuf[14], ( *olen - 25 ) );
+    obuf[22] = obuf[14];
+    obuf[23] = obuf[15];
+    obuf[24] = obuf[16];
 
-    obuf[11] = (unsigned char)( ( *olen - 13 ) >>  8 );
-    obuf[12] = (unsigned char)( ( *olen - 13 )       );
+    mbedtls_platform_put_uint16_be( &obuf[11], ( *olen - 13 ) );
 
     return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
 }
@@ -5371,8 +5348,7 @@
      */
 
     rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len;
-    rec->data_len    = ( (size_t) buf[ rec_hdr_len_offset + 0 ] << 8 ) |
-                       ( (size_t) buf[ rec_hdr_len_offset + 1 ] << 0 );
+    rec->data_len = mbedtls_platform_get_uint16_be(  &buf[rec_hdr_len_offset] );
     MBEDTLS_SSL_DEBUG_BUF( 4, "input record header", buf, rec->data_offset );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "input record: msgtype = %d, "
@@ -5451,7 +5427,7 @@
 #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
 static int ssl_check_client_reconnect( mbedtls_ssl_context *ssl )
 {
-    unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
+    unsigned int rec_epoch = mbedtls_platform_get_uint16_be( &ssl->in_ctr[0] );
 
     /*
      * Check for an epoch 0 ClientHello. We can't use in_msg here to
@@ -5798,9 +5774,7 @@
     if( ( hs_buf->is_valid == 1 ) && ( hs_buf->is_complete == 1 ) )
     {
         /* Synthesize a record containing the buffered HS message. */
-        size_t msg_len = ( hs_buf->data[1] << 16 ) |
-                         ( hs_buf->data[2] << 8  ) |
-                           hs_buf->data[3];
+        size_t msg_len = mbedtls_platform_get_uint24_be( &hs_buf->data[1] );
 
         /* Double-check that we haven't accidentally buffered
          * a message that doesn't fit into the input buffer. */
@@ -5899,7 +5873,8 @@
         case MBEDTLS_SSL_MSG_HANDSHAKE:
         {
             unsigned recv_msg_seq_offset;
-            unsigned recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
+            unsigned recv_msg_seq = mbedtls_platform_get_uint16_be( &ssl->in_msg[4] );
+
             mbedtls_ssl_hs_buffer *hs_buf;
             size_t msg_len = ssl->in_hslen - 12;
 
@@ -6497,8 +6472,7 @@
     ssl->in_hdr[0] = rec.type;
     ssl->in_msg    = rec.buf + rec.data_offset;
     ssl->in_msglen = rec.data_len;
-    ssl->in_len[0] = (unsigned char)( rec.data_len >> 8 );
-    ssl->in_len[1] = (unsigned char)( rec.data_len      );
+    mbedtls_platform_put_uint16_be( ssl->in_len, rec.data_len );
 
     return( 0 );
 }
@@ -6830,17 +6804,13 @@
             return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE );
         }
 
-        ssl->out_msg[i    ] = (unsigned char)( n >> 16 );
-        ssl->out_msg[i + 1] = (unsigned char)( n >>  8 );
-        ssl->out_msg[i + 2] = (unsigned char)( n       );
+        mbedtls_platform_put_uint24_be( &ssl->out_msg[i], n );
 
         i += 3; memcpy( ssl->out_msg + i, crt->raw.p, n );
         i += n; crt = crt->next;
     }
 
-    ssl->out_msg[4]  = (unsigned char)( ( i - 7 ) >> 16 );
-    ssl->out_msg[5]  = (unsigned char)( ( i - 7 ) >>  8 );
-    ssl->out_msg[6]  = (unsigned char)( ( i - 7 )       );
+    mbedtls_platform_put_uint24_be( &ssl->out_msg[4], ( i - 7 ) );
 
     ssl->out_msglen  = i;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
@@ -6947,7 +6917,7 @@
     /*
      * Same message structure as in mbedtls_ssl_write_certificate()
      */
-    n = ( ssl->in_msg[i+1] << 8 ) | ssl->in_msg[i+2];
+    n = mbedtls_platform_get_uint16_be( &ssl->in_msg[i + 1] );
 
     if( ssl->in_msg[i] != 0 ||
         ssl->in_hslen != n + 3 + mbedtls_ssl_hs_hdr_len( ssl ) )
@@ -6982,8 +6952,7 @@
         }
 
         /* Read length of the next CRT in the chain. */
-        n = ( (unsigned int) ssl->in_msg[i + 1] << 8 )
-            | (unsigned int) ssl->in_msg[i + 2];
+        n = mbedtls_platform_get_uint16_be( &ssl->in_msg[i + 1] );
         i += 3;
 
         if( n < 128 || i + n > ssl->in_hslen )
@@ -9789,8 +9758,7 @@
     {
         const int ciphersuite =
             mbedtls_ssl_session_get_ciphersuite( session );
-        *p++ = (unsigned char)( ( ciphersuite >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ciphersuite      ) & 0xFF );
+        p = mbedtls_platform_put_uint16_be( p, ciphersuite );
 
 #if defined(MBEDTLS_ZLIB_SUPPORT)
         *p++ = (unsigned char)(
@@ -9803,11 +9771,7 @@
 
         memcpy( p, session->master, 48 );
         p += 48;
-
-        *p++ = (unsigned char)( ( session->verify_result >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result       ) & 0xFF );
+        p = mbedtls_platform_put_uint32_be( p, session->verify_result );
     }
 
     /*
@@ -9824,9 +9788,7 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( cert_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len       ) & 0xFF );
+        p = mbedtls_platform_put_uint24_be( p, cert_len );
 
         if( session->peer_cert != NULL )
         {
@@ -9869,9 +9831,7 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session->ticket_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len       ) & 0xFF );
+        p = mbedtls_platform_put_uint24_be( p, session->ticket_len );
 
         if( session->ticket != NULL )
         {
@@ -9879,10 +9839,7 @@
             p += session->ticket_len;
         }
 
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime       ) & 0xFF );
+        p = mbedtls_platform_put_uint32_be( p, session->ticket_lifetime );
     }
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
@@ -10017,7 +9974,7 @@
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
     }
 
-    ciphersuite = ( p[0] << 8 ) | p[1];
+    ciphersuite = mbedtls_platform_get_uint16_be( p );
     p += 2;
 
 #if !defined(MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE)
@@ -10041,10 +9998,7 @@
     memcpy( session->master, p, 48 );
     p += 48;
 
-    session->verify_result = ( (uint32_t) p[0] << 24 ) |
-                             ( (uint32_t) p[1] << 16 ) |
-                             ( (uint32_t) p[2] <<  8 ) |
-                             ( (uint32_t) p[3]       );
+    session->verify_result = mbedtls_platform_get_uint32_be( p );
     p += 4;
 
     /* Immediately clear invalid pointer values that have been read, in case
@@ -10068,7 +10022,8 @@
     if( 3 > (size_t)( end - p ) )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2];
+    cert_len = mbedtls_platform_get_uint24_be( &p[0] );
+
     p += 3;
 
     if( cert_len == 0 )
@@ -10139,7 +10094,7 @@
     if( 3 > (size_t)( end - p ) )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    session->ticket_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2];
+    session->ticket_len = mbedtls_platform_get_uint24_be( &p[0] );
     p += 3;
 
     if( session->ticket_len != 0 )
@@ -10158,10 +10113,7 @@
     if( 4 > (size_t)( end - p ) )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    session->ticket_lifetime = ( (uint32_t) p[0] << 24 ) |
-                               ( (uint32_t) p[1] << 16 ) |
-                               ( (uint32_t) p[2] <<  8 ) |
-                               ( (uint32_t) p[3]       );
+    session->ticket_lifetime = mbedtls_platform_get_uint32_be( p );
     p += 4;
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
@@ -11267,10 +11219,7 @@
     used += 4 + session_len;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session_len >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len       ) & 0xFF );
+        p = mbedtls_platform_put_uint32_be( p, session_len );
 
         ret = ssl_session_save( ssl->session, 1,
                                 p, session_len, &session_len );
@@ -11312,10 +11261,7 @@
     used += 4;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen       ) & 0xFF );
+        p = mbedtls_platform_put_uint32_be( p, ssl->badmac_seen );
     }
 #endif /* MBEDTLS_SSL_DTLS_BADMAC_LIMIT */
 
@@ -11362,8 +11308,7 @@
     used += 2;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->mtu >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->mtu       ) & 0xFF );
+        p = mbedtls_platform_put_uint16_be( p, ssl->mtu );
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
@@ -11466,10 +11411,7 @@
     if( (size_t)( end - p ) < 4 )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    session_len = ( (size_t) p[0] << 24 ) |
-                  ( (size_t) p[1] << 16 ) |
-                  ( (size_t) p[2] <<  8 ) |
-                  ( (size_t) p[3]       );
+    session_len = mbedtls_platform_get_uint32_be( p );
     p += 4;
 
     /* This has been allocated by ssl_handshake_init(), called by
@@ -11558,10 +11500,7 @@
     if( (size_t)( end - p ) < 4 )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    ssl->badmac_seen = ( (uint32_t) p[0] << 24 ) |
-                       ( (uint32_t) p[1] << 16 ) |
-                       ( (uint32_t) p[2] <<  8 ) |
-                       ( (uint32_t) p[3]       );
+    ssl->badmac_seen = mbedtls_platform_get_uint32_be( p );
     p += 4;
 #endif /* MBEDTLS_SSL_DTLS_BADMAC_LIMIT */
 
@@ -11607,7 +11546,7 @@
     if( (size_t)( end - p ) < 2 )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    ssl->mtu = ( p[0] << 8 ) | p[1];
+    ssl->mtu = mbedtls_platform_get_uint16_be( p );
     p += 2;
 #endif /* MBEDTLS_SSL_PROTO_DTLS */