Bignum: Apply naming conventions

Numbers:

- A, B for mbedtls_mpi_uint* operands
- a, b for mbedtls_mpi_uint operands
- X or x for result
- HAC references where applicable

Lengths:

- Reserve size or length for length/size in bytes or byte buffers.
- For length of mbedtls_mpi_uint* buffers use limbs
- Length parameters are qualified if possible (eg. input_length or
  a_limbs)

Setup functions:

- The parameters match the corresponding structure member's name
- The structure to set up is a standard lower case name even if in other
  functions different naming conventions would apply

Scope of changes/conventions:

- bignum_core
- bignum_mod
- bignum_mod_raw

Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c
index 334965d..0a3f3a0 100644
--- a/library/bignum_mod_raw.c
+++ b/library/bignum_mod_raw.c
@@ -43,18 +43,20 @@
 
 int mbedtls_mpi_mod_raw_read( mbedtls_mpi_uint *X,
                               const mbedtls_mpi_mod_modulus *m,
-                              const unsigned char *buf,
-                              size_t buflen )
+                              const unsigned char *input,
+                              size_t input_lentgth )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     switch( m->ext_rep )
     {
         case MBEDTLS_MPI_MOD_EXT_REP_LE:
-            ret = mbedtls_mpi_core_read_le( X, m->limbs, buf, buflen );
+            ret = mbedtls_mpi_core_read_le( X, m->limbs,
+                                            input, input_lentgth );
             break;
         case MBEDTLS_MPI_MOD_EXT_REP_BE:
-            ret = mbedtls_mpi_core_read_be( X, m->limbs, buf, buflen );
+            ret = mbedtls_mpi_core_read_be( X, m->limbs,
+                                            input, input_lentgth );
             break;
         default:
             return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
@@ -74,17 +76,19 @@
     return( ret );
 }
 
-int mbedtls_mpi_mod_raw_write( const mbedtls_mpi_uint *X,
+int mbedtls_mpi_mod_raw_write( const mbedtls_mpi_uint *A,
                                const mbedtls_mpi_mod_modulus *m,
-                               unsigned char *buf,
-                               size_t buflen )
+                               unsigned char *output,
+                               size_t output_length )
 {
     switch( m->ext_rep )
     {
         case MBEDTLS_MPI_MOD_EXT_REP_LE:
-            return( mbedtls_mpi_core_write_le( X, m->limbs, buf, buflen ) );
+            return( mbedtls_mpi_core_write_le( A, m->limbs,
+                                               output, output_length ) );
         case MBEDTLS_MPI_MOD_EXT_REP_BE:
-            return( mbedtls_mpi_core_write_be( X, m->limbs, buf, buflen ) );
+            return( mbedtls_mpi_core_write_be( A, m->limbs,
+                                               output, output_length ) );
         default:
             return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
     }