bignum_core: Aligned `xxx_core_shift_l` to `xxx_core_shift_r`
This patch modifies the left-shift implementation to closely
align in interface and behaviour to the existing right-shift
method.
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/library/bignum_core.c b/library/bignum_core.c
index 26aff15..92a9d55 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -353,52 +353,44 @@
}
}
-int mbedtls_mpi_shift_l( mbedtls_mpi *X, size_t count )
+void mbedtls_mpi_core_shift_l(mbedtls_mpi_uint *X, size_t limbs,
+ size_t count)
{
- int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
- size_t i, v0, t1;
+ size_t i, v0, v1;
mbedtls_mpi_uint r0 = 0, r1;
- MPI_VALIDATE_RET( X != NULL );
- v0 = count / (biL );
- t1 = count & (biL - 1);
+ v0 = count / (biL);
+ v1 = count & (biL - 1);
- i = mbedtls_mpi_bitlen( X ) + count;
-
- if( X->n * biL < i )
- MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, BITS_TO_LIMBS( i ) ) );
-
- ret = 0;
+ if (v0 > limbs || (v0 == limbs && v1 > 0)) {
+ memset(X, 0, limbs * ciL);
+ return;
+ }
/*
* shift by count / limb_size
*/
- if( v0 > 0 )
- {
- for( i = X->n; i > v0; i-- )
- X->p[i - 1] = X->p[i - v0 - 1];
+ if (v0 > 0) {
+ for (i = limbs; i > v0; i--) {
+ X[i - 1] = X[i - v0 - 1];
+ }
- for( ; i > 0; i-- )
- X->p[i - 1] = 0;
+ for (; i > 0; i--) {
+ X[i - 1] = 0;
+ }
}
/*
* shift by count % limb_size
*/
- if( t1 > 0 )
- {
- for( i = v0; i < X->n; i++ )
- {
- r1 = X->p[i] >> (biL - t1);
- X->p[i] <<= t1;
- X->p[i] |= r0;
+ if (v1 > 0) {
+ for (i = v0; i < limbs; i++) {
+ r1 = X[i] >> (biL - v1);
+ X[i] <<= v1;
+ X[i] |= r0;
r0 = r1;
}
}
-
-cleanup:
-
- return( ret );
}
mbedtls_mpi_uint mbedtls_mpi_core_add(mbedtls_mpi_uint *X,