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Add a non-NEON variant of mbedtls_xor

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Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-06-15 18:43:24 +01:00
parent b055f75c3d
commit 03bb526c24
1 changed files with 36 additions and 0 deletions
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36
library/common.h
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@ -154,6 +154,42 @@ inline void mbedtls_xor(unsigned char *r, const unsigned char *a, const unsigned
}
}
/**
* Perform a fast block XOR operation, such that
* r[i] = a[i] ^ b[i] where 0 <= i < n
*
* In some situations, this can perform better than mbedtls_xor (e.g., it's about 5%
* better in AES-CBC).
*
* \param r Pointer to result (buffer of at least \p n bytes). \p r
* may be equal to either \p a or \p b, but behaviour when
* it overlaps in other ways is undefined.
* \param a Pointer to input (buffer of at least \p n bytes)
* \param b Pointer to input (buffer of at least \p n bytes)
* \param n Number of bytes to process.
*/
static inline void mbedtls_xor_no_simd(unsigned char *r, const unsigned char *a, const unsigned char *b, size_t n)
{
size_t i = 0;
#if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
#if defined(__amd64__) || defined(__x86_64__) || defined(__aarch64__)
/* This codepath probably only makes sense on architectures with 64-bit registers */
for (; (i + 8) <= n; i += 8) {
uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
mbedtls_put_unaligned_uint64(r + i, x);
}
#else
for (; (i + 4) <= n; i += 4) {
uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
mbedtls_put_unaligned_uint32(r + i, x);
}
#endif
#endif
for (; i < n; i++) {
r[i] = a[i] ^ b[i];
}
}
/* Fix MSVC C99 compatible issue
* MSVC support __func__ from visual studio 2015( 1900 )
* Use MSVC predefine macro to avoid name check fail.