[U-Boot] [PATCH v3 1/5] CONFIG_SYS_[ID]CACHE_OFF: unify the 'any' case

Tom Rini trini at konsulko.com
Sun May 19 20:44:22 UTC 2019


On Fri, May 03, 2019 at 09:40:56AM -0400, Trevor Woerner wrote:

> According to De Morgan's Law[1]:
> 	!(A && B) = !A || !B
> 	!(A || B) = !A && !B
> 
> There are 5 places in the code where we find:
> 	#if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
> and 4 places in the code where we find:
> 	#if (!defined(CONFIG_SYS_ICACHE_OFF) || !defined(CONFIG_SYS_DCACHE_OFF))
> 
> In words, the construct:
> 	!defined(CONFIG_SYS_[DI]CACHE_OFF)
> means:
> 	"is the [DI]CACHE on?"
> and the construct:
> 	defined(CONFIG_SYS_[DI]CACHE_OFF)
> means:
> 	"is the [DI]CACHE off?"
> 
> Therefore
> 	!(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
> means:
> 	"the opposite of 'are they both off?'"
> in other words:
> 	"are either or both on?"
> and:
> 	(!defined(CONFIG_SYS_ICACHE_OFF) || !defined(CONFIG_SYS_DCACHE_OFF)
> means:
> 	"are either or both on?"
> 
> As a result, I've converted the 4 instances of '(!A || !B)' to '!(A && B)' for
> consistency.
> 
> [1] https://en.wikipedia.org/wiki/De_Morgan%27s_laws
> 
> Signed-off-by: Trevor Woerner <trevor at toganlabs.com>

Applied to u-boot/master, thanks!

-- 
Tom
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