mbedtls/library/alignment.h

8  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
33  * https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=msvc-170#alignment
34  * specifies that on Windows-on-Arm64, unaligned access is safe (except for uncached
47  * https://www.iar.com/knowledge/support/technical-notes/compiler/accessing-unaligned-data
48  * This results in a single load / store instruction (if unaligned access is supported).
58  * gcc may generate a branch to memcpy for calls like `memcpy(dest, src, 4)` rather than
61  * This is architecture dependent: x86-64 seems fine even with old gcc; 32-bit Arm
65  * For gcc < 6.3.0, this issue happens at -O0
68  * For gcc 4.x, this implementation will generate byte-by-byte loads even if unaligned access is
71  * For performance (and code size, in some cases), we want to avoid the branch and just generate
72  * some inline load/store instructions since the access is small and constant-size.
77  * https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc/Variable-Attributes.html
123     r = p16->x;  in mbedtls_get_unaligned_uint16()
149     p16->x = x;  in mbedtls_put_unaligned_uint16()
175     r = p32->x;  in mbedtls_get_unaligned_uint32()
201     p32->x = x;  in mbedtls_put_unaligned_uint32()
227     r = p64->x;  in mbedtls_get_unaligned_uint64()
253     p64->x = x;  in mbedtls_put_unaligned_uint64()
265  * Given a multi-byte integer \p x, MBEDTLS_BYTE_n retrieves the n-th
278  * Detect GCC built-in byteswap routines
291  * Detect Clang built-in byteswap routines
306  * Detect MSVC built-in byteswap routines
320 /* Detect armcc built-in byteswap routine */
322 #if defined(__ARM_ACLE)  /* ARM Compiler 6 - earlier versions don't need a header */
328 /* Detect IAR built-in byteswap routine */
339  * Where compiler built-ins are not present, fall back to C code that the
405  * big-endian order (MSB first).
419  * Put in memory a 32 bits unsigned integer in big-endian order.
441  * little-endian order (LSB first).
456  * Put in memory a 32 bits unsigned integer in little-endian order.
478  * little-endian order (LSB first).
492  * Put in memory a 16 bits unsigned integer in little-endian order.
514  * big-endian order (MSB first).
528  * Put in memory a 16 bits unsigned integer in big-endian order.
550  * big-endian order (MSB first).
565  * Put in memory a 24 bits unsigned integer in big-endian order.
582  * little-endian order (LSB first).
597  * Put in memory a 24 bits unsigned integer in little-endian order.
614  * big-endian order (MSB first).
628  * Put in memory a 64 bits unsigned integer in big-endian order.
650  * little-endian order (LSB first).
664  * Put in memory a 64 bits unsigned integer in little-endian order.