commit ad1115a3fd7be77d8725f401fc4966880a1a8572
author Joe Subbiani <joe.subbiani@arm.com> Fri Jul 16 14:27:50 2021 +0100
committer Joe Subbiani <joe.subbiani@arm.com> Tue Aug 03 14:08:33 2021 +0100
tree e6ae64b72c8fa190103d06ac9db1c92927d757a5
parent 1bd5d7da82d1480762e0a8f5f750ea80dcc7ec68

Use byte reading macros in places not using a byte mask

byte shifting opertations throughout library/ were only replaced with
the byte reading macros when an 0xff mask was being used.
The byte reading macros are now more widley used, however they have not
been used in all cases of a byte shift operation, as it detracted from
the immediate readability or otherwise did not seem appropriate.

Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>

library/chachapoly.c

diff --git a/library/chachapoly.c b/library/chachapoly.c
index 77d5477..696d97b 100644
--- a/library/chachapoly.c
+++ b/library/chachapoly.c
@@ -263,22 +263,22 @@
     /* The lengths of the AAD and ciphertext are processed by
      * Poly1305 as the final 128-bit block, encoded as little-endian integers.
      */
-    len_block[ 0] = (unsigned char)( ctx->aad_len       );
-    len_block[ 1] = (unsigned char)( ctx->aad_len >>  8 );
-    len_block[ 2] = (unsigned char)( ctx->aad_len >> 16 );
-    len_block[ 3] = (unsigned char)( ctx->aad_len >> 24 );
-    len_block[ 4] = (unsigned char)( ctx->aad_len >> 32 );
-    len_block[ 5] = (unsigned char)( ctx->aad_len >> 40 );
-    len_block[ 6] = (unsigned char)( ctx->aad_len >> 48 );
-    len_block[ 7] = (unsigned char)( ctx->aad_len >> 56 );
-    len_block[ 8] = (unsigned char)( ctx->ciphertext_len       );
-    len_block[ 9] = (unsigned char)( ctx->ciphertext_len >>  8 );
-    len_block[10] = (unsigned char)( ctx->ciphertext_len >> 16 );
-    len_block[11] = (unsigned char)( ctx->ciphertext_len >> 24 );
-    len_block[12] = (unsigned char)( ctx->ciphertext_len >> 32 );
-    len_block[13] = (unsigned char)( ctx->ciphertext_len >> 40 );
-    len_block[14] = (unsigned char)( ctx->ciphertext_len >> 48 );
-    len_block[15] = (unsigned char)( ctx->ciphertext_len >> 56 );
+    len_block[ 0] = MBEDTLS_BYTE_0( ctx->aad_len );
+    len_block[ 1] = MBEDTLS_BYTE_1( ctx->aad_len );
+    len_block[ 2] = MBEDTLS_BYTE_2( ctx->aad_len );
+    len_block[ 3] = MBEDTLS_BYTE_3( ctx->aad_len );
+    len_block[ 4] = MBEDTLS_BYTE_4( ctx->aad_len );
+    len_block[ 5] = MBEDTLS_BYTE_5( ctx->aad_len );
+    len_block[ 6] = MBEDTLS_BYTE_6( ctx->aad_len );
+    len_block[ 7] = MBEDTLS_BYTE_7( ctx->aad_len );
+    len_block[ 8] = MBEDTLS_BYTE_0( ctx->ciphertext_len );
+    len_block[ 9] = MBEDTLS_BYTE_1( ctx->ciphertext_len );
+    len_block[10] = MBEDTLS_BYTE_2( ctx->ciphertext_len );
+    len_block[11] = MBEDTLS_BYTE_3( ctx->ciphertext_len );
+    len_block[12] = MBEDTLS_BYTE_4( ctx->ciphertext_len );
+    len_block[13] = MBEDTLS_BYTE_5( ctx->ciphertext_len );
+    len_block[14] = MBEDTLS_BYTE_6( ctx->ciphertext_len );
+    len_block[15] = MBEDTLS_BYTE_7( ctx->ciphertext_len );
 
     ret = mbedtls_poly1305_update( &ctx->poly1305_ctx, len_block, 16U );
     if( ret != 0 )