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bignum_core: Aligned xxx_core_shift_l to xxx_core_shift_r

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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>
This commit is contained in:
Minos Galanakis
2023-04-20 14:22:16 +01:00
parent ad808dd5f1
commit ec09e25251
2 changed files with 32 additions and 37 deletions
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50
library/bignum_core.c
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@ -353,52 +353,44 @@ void mbedtls_mpi_core_shift_r(mbedtls_mpi_uint *X, size_t limbs,
}
}
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,