tree 50f30795fce75982af2d0793feba69d825e24eff
parent 9a0e0affef2277dc3417ed9f8b14891c9dda57c6
author Gilles Peskine <Gilles.Peskine@arm.com> 1637083906 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> 1637085409 +0100

mbedtls_ssl_config: Replace bit-fields by separate bytes

This slightly increases the RAM consumption per context, but saves code
size on architectures with an instruction for direct byte access (which is
most of them).

Although this is technically an API break, in practice, a realistic
application won't break: it would have had to bypass API functions and rely
on the field size (e.g. relying on -1 == 1 in a 1-bit field).

Results (arm-none-eabi-gcc 7.3.1, build_arm_none_eabi_gcc_m0plus build):
library/ssl_cli.o: 19952 -> 19900 (diff: 52)
library/ssl_msg.o: 25810 -> 25798 (diff: 12)
library/ssl_srv.o: 22371 -> 22299 (diff: 72)
library/ssl_tls.o: 23274 -> 23038 (diff: 236)

Results (same architecture, config-suite-b.h + MBEDTLS_ECDH_LEGACY_CONTEXT +
MBEDTLS_ECP_RESTARTABLE):
library/ssl_cli.o: 2868 -> 2848 (diff: 20)
library/ssl_msg.o: 2916 -> 2924 (diff: -8)
library/ssl_srv.o: 3204 -> 3184 (diff: 20)
library/ssl_tls.o: 5860 -> 5756 (diff: 104)

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>