From fe25510fc23031f1a3c1b42edd37067d1989a9f6 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Sat, 17 Dec 2016 20:58:36 -0800 Subject: altos/arm: Align data so that gcc 5.4 doesn't do byte-accesses. Add -Wcast-align Gcc 5.4.1 tracks alignment of data through assignments, so that a uint32_t pointer which comes from byte-aligned uint8_t data: extern uint8_t foo[]; uint32_t *q = (void *) foo; Fetches and stores through this pointer are done bytewise. This is slow (meh), but if q references a device register, things to bad very quickly. This patch works around this bug in the compiler by adding __attribute__((aligned(4))) tags to some variables, or changing them from uint8_t to uint32_t. Places doing this will now be caught as I've added -Wcast-align to the compiler flags. That required adding (void *) casts, after the relevant code was checked to make sure the compiler could tell that the addresses were aligned. Signed-off-by: Keith Packard --- src/stm/ao_eeprom_stm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/stm/ao_eeprom_stm.c') diff --git a/src/stm/ao_eeprom_stm.c b/src/stm/ao_eeprom_stm.c index 05f880b8..4f477122 100644 --- a/src/stm/ao_eeprom_stm.c +++ b/src/stm/ao_eeprom_stm.c @@ -83,7 +83,7 @@ ao_intflash_write32(uint16_t pos, uint32_t w) { volatile uint32_t *addr; - addr = (uint32_t *) (stm_eeprom + pos); + addr = (uint32_t *) (void *) (stm_eeprom + pos); /* Write a word to a valid address in the data EEPROM */ *addr = w; @@ -96,7 +96,7 @@ ao_intflash_write8(uint16_t pos, uint8_t d) uint32_t w, *addr, mask; uint8_t shift; - addr = (uint32_t *) (stm_eeprom + (pos & ~3)); + addr = (uint32_t *) (void *) (stm_eeprom + (pos & ~3)); /* Compute word to be written */ shift = (pos & 3) << 3; -- cgit v1.2.3