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Define variables closer to their use

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Make variables const where possible.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2022-11-16 20:04:00 +01:00 committed by Janos Follath
parent 7af166b827
commit cf979b0fc1
1 changed files with 16 additions and 15 deletions
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31
library/bignum_core.c
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@ -607,18 +607,9 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* heap allocated memory pool */ /* heap allocated memory pool */
mbedtls_mpi_uint *mempool = NULL; mbedtls_mpi_uint *mempool = NULL;
/* pointers to temporaries within memory pool */
mbedtls_mpi_uint *Wtable, *Wselect, *temp;
/* pointers to table entries */
mbedtls_mpi_uint *Wcur, *Wlast, *W1;
size_t wsize, welem; const size_t wsize = exp_mod_get_window_size( E_limbs * biL );
mbedtls_mpi_uint one = 1, mm; const size_t welem = ( (size_t) 1 ) << wsize;
mm = mbedtls_mpi_core_montmul_init( N ); /* Compute Montgomery constant */
wsize = exp_mod_get_window_size( E_limbs * biL );
welem = ( (size_t) 1 ) << wsize;
/* Allocate memory pool and set pointers to parts of it */ /* Allocate memory pool and set pointers to parts of it */
const size_t table_limbs = welem * AN_limbs; const size_t table_limbs = welem * AN_limbs;
@ -633,14 +624,20 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
goto cleanup; goto cleanup;
} }
Wtable = mempool; /* pointers to temporaries within memory pool */
Wselect = Wtable + table_limbs; mbedtls_mpi_uint *const Wtable = mempool;
temp = Wselect + select_limbs; mbedtls_mpi_uint *const Wselect = Wtable + table_limbs;
mbedtls_mpi_uint *const temp = Wselect + select_limbs;
/* /*
* Window precomputation * Window precomputation
*/ */
const mbedtls_mpi_uint mm = mbedtls_mpi_core_montmul_init( N );
/* pointers to table entries */
mbedtls_mpi_uint *Wcur, *Wlast, *W1;
/* W[0] = 1 (in Montgomery presentation) */ /* W[0] = 1 (in Montgomery presentation) */
memset( Wtable, 0, AN_limbs * ciL ); memset( Wtable, 0, AN_limbs * ciL );
Wtable[0] = 1; Wtable[0] = 1;
@ -667,8 +664,11 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
E += E_limbs; E += E_limbs;
size_t limb_bits_remaining = 0; size_t limb_bits_remaining = 0;
mbedtls_mpi_uint cur_limb, window = 0; mbedtls_mpi_uint window = 0;
size_t window_bits = 0; size_t window_bits = 0;
/* Will be initialized properly in the first loop iteration */
mbedtls_mpi_uint cur_limb = 0;
while( 1 ) while( 1 )
{ {
size_t window_bits_missing = wsize - window_bits; size_t window_bits_missing = wsize - window_bits;
@ -711,6 +711,7 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
} }
/* Convert X back to normal presentation */ /* Convert X back to normal presentation */
const mbedtls_mpi_uint one = 1;
mbedtls_mpi_core_montmul( X, X, &one, 1, N, AN_limbs, mm, temp ); mbedtls_mpi_core_montmul( X, X, &one, 1, N, AN_limbs, mm, temp );
ret = 0; ret = 0;