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Merge pull request #8049 from daverodgman/bignum_codesize_misc

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Bignum codesize misc
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Dave Rodgman 2023-08-10 10:58:13 +01:00 committed by GitHub
commit e5fbd93eaf
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 41 additions and 19 deletions
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42
library/bignum.c
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@ -258,6 +258,10 @@ static inline mbedtls_mpi_uint mpi_sint_abs(mbedtls_mpi_sint z)
return (mbedtls_mpi_uint) 0 - (mbedtls_mpi_uint) z;
}
/* Convert x to a sign, i.e. to 1, if x is positive, or -1, if x is negative.
* This looks awkward but generates smaller code than (x < 0 ? -1 : 1) */
#define TO_SIGN(x) ((((mbedtls_mpi_uint) x) >> (biL - 1)) * -2 + 1)
/*
* Set value from integer
*/
@ -270,7 +274,7 @@ int mbedtls_mpi_lset(mbedtls_mpi *X, mbedtls_mpi_sint z)
memset(X->p, 0, X->n * ciL);
X->p[0] = mpi_sint_abs(z);
X->s = (z < 0) ? -1 : 1;
X->s = TO_SIGN(z);
cleanup:
@ -326,16 +330,35 @@ cleanup:
*/
size_t mbedtls_mpi_lsb(const mbedtls_mpi *X)
{
size_t i, j, count = 0;
size_t i;
MBEDTLS_INTERNAL_VALIDATE_RET(X != NULL, 0);
#if defined(__has_builtin)
#if (MBEDTLS_MPI_UINT_MAX == UINT_MAX) && __has_builtin(__builtin_ctz)
#define mbedtls_mpi_uint_ctz __builtin_ctz
#elif (MBEDTLS_MPI_UINT_MAX == ULONG_MAX) && __has_builtin(__builtin_ctzl)
#define mbedtls_mpi_uint_ctz __builtin_ctzl
#elif (MBEDTLS_MPI_UINT_MAX == ULLONG_MAX) && __has_builtin(__builtin_ctzll)
#define mbedtls_mpi_uint_ctz __builtin_ctzll
#endif
#endif
#if defined(mbedtls_mpi_uint_ctz)
for (i = 0; i < X->n; i++) {
for (j = 0; j < biL; j++, count++) {
if (X->p[i] != 0) {
return i * biL + mbedtls_mpi_uint_ctz(X->p[i]);
}
}
#else
size_t count = 0;
for (i = 0; i < X->n; i++) {
for (size_t j = 0; j < biL; j++, count++) {
if (((X->p[i] >> j) & 1) != 0) {
return count;
}
}
}
#endif
return 0;
}
@ -796,9 +819,8 @@ int mbedtls_mpi_cmp_abs(const mbedtls_mpi *X, const mbedtls_mpi *Y)
}
}
if (i == 0 && j == 0) {
return 0;
}
/* If i == j == 0, i.e. abs(X) == abs(Y),
* we end up returning 0 at the end of the function. */
if (i > j) {
return 1;
@ -880,7 +902,7 @@ int mbedtls_mpi_cmp_int(const mbedtls_mpi *X, mbedtls_mpi_sint z)
MPI_VALIDATE_RET(X != NULL);
*p = mpi_sint_abs(z);
Y.s = (z < 0) ? -1 : 1;
Y.s = TO_SIGN(z);
Y.n = 1;
Y.p = p;
@ -1068,7 +1090,7 @@ int mbedtls_mpi_add_int(mbedtls_mpi *X, const mbedtls_mpi *A, mbedtls_mpi_sint b
MPI_VALIDATE_RET(A != NULL);
p[0] = mpi_sint_abs(b);
B.s = (b < 0) ? -1 : 1;
B.s = TO_SIGN(b);
B.n = 1;
B.p = p;
@ -1086,7 +1108,7 @@ int mbedtls_mpi_sub_int(mbedtls_mpi *X, const mbedtls_mpi *A, mbedtls_mpi_sint b
MPI_VALIDATE_RET(A != NULL);
p[0] = mpi_sint_abs(b);
B.s = (b < 0) ? -1 : 1;
B.s = TO_SIGN(b);
B.n = 1;
B.p = p;
@ -1436,7 +1458,7 @@ int mbedtls_mpi_div_int(mbedtls_mpi *Q, mbedtls_mpi *R,
MPI_VALIDATE_RET(A != NULL);
p[0] = mpi_sint_abs(b);
B.s = (b < 0) ? -1 : 1;
B.s = TO_SIGN(b);
B.n = 1;
B.p = p;

18
library/bignum_core.c
View file

@ -686,16 +686,16 @@ cleanup:
static size_t exp_mod_get_window_size(size_t Ebits)
{
size_t wsize = (Ebits > 671) ? 6 : (Ebits > 239) ? 5 :
(Ebits > 79) ? 4 : 1;
#if (MBEDTLS_MPI_WINDOW_SIZE < 6)
if (wsize > MBEDTLS_MPI_WINDOW_SIZE) {
wsize = MBEDTLS_MPI_WINDOW_SIZE;
}
#if MBEDTLS_MPI_WINDOW_SIZE >= 6
return (Ebits > 671) ? 6 : (Ebits > 239) ? 5 : (Ebits > 79) ? 4 : 1;
#elif MBEDTLS_MPI_WINDOW_SIZE == 5
return (Ebits > 239) ? 5 : (Ebits > 79) ? 4 : 1;
#elif MBEDTLS_MPI_WINDOW_SIZE > 1
return (Ebits > 79) ? MBEDTLS_MPI_WINDOW_SIZE : 1;
#else
(void) Ebits;
return 1;
#endif
return wsize;
}
size_t mbedtls_mpi_core_exp_mod_working_limbs(size_t AN_limbs, size_t E_limbs)