Clean up endian temporary compatibility macro

[skliper]

Is your feature request related to a problem? Please describe.
Missing an else (likely error) case (or !defined(__BYTE_ORDER))

osal/src/os/inc/common_types.h

Lines 145 to 171 in ead5723

	/*
	* TEMPORARY COMPATIBILITY MACRO
	*
	* Any code that depends on this macro should be fixed so as to not need it.
	* The value for this had been set by the BSP makefiles but this is not reliable,
	* especially on processors that support both big- and little- endian modes e.g.
	* ARM and MIPS.
	*
	* This is deprecated and only here to bridge the gap until code that depends
	* on this can be fixed. Do not write any new code that uses this macro.
	*
	* If using an older makefile that defines one of the BIT_ORDER macros already,
	* then this entire section is skipped and the macro is used as-is.
	*/
	#if !defined(SOFTWARE_BIG_BIT_ORDER) && !defined(SOFTWARE_LITTLE_BIT_ORDER)
	#if defined(__BYTE_ORDER) && __BYTE_ORDER == __BIG_ENDIAN || defined(__BIG_ENDIAN__) || defined(__ARMEB__) || \
	defined(__THUMBEB__) || defined(__AARCH64EB__) || defined(_MIBSEB) || defined(__MIBSEB) || defined(__MIBSEB__)
	/* It is a big-endian target architecture */
	#define SOFTWARE_BIG_BIT_ORDER
	#elif defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN || defined(__LITTLE_ENDIAN__) || defined(__ARMEL__) || \
	defined(__THUMBEL__) || defined(__AARCH64EL__) || defined(_MIPSEL) || defined(__MIPSEL) || defined(__MIPSEL__)
	/* It is a little-endian target architecture */
	#define SOFTWARE_LITTLE_BIT_ORDER
	#endif
	#endif /* !defined(SOFTWARE_BIG_BIT_ORDER) && !defined(SOFTWARE_LITTLE_BIT_ORDER) */

It's also a misnomer (BYTE not BIT), and one of many various patterns (see nasa/cFE#1209)

Describe the solution you'd like
At minimum add the error case, ideally clean/remove/consolidate.

Describe alternatives you've considered
None

Additional context
nasa/cFE#1209

Requester Info
Jacob Hageman - NASA/GSFC, OSAL code review

[jphickey]

Here's the conundrum with this one:

• CFS Developers should be discouraged from writing any endian-specific code.
• So while these macros are defined via some commonly-used C library macros, none of the symbols checked are standardized in any way, nothing is guaranteed to work.
• These BIG/LITTLE macros are only there for backward compatibility. We don't actually want anyone to use them. Nothing in OSAL itself uses these at all, either.

SO - at the end of the day - we shouldn't be puting an #error in a file that is used everywhere in the event that a (nonstandardized) test was inconclusive as to how to define a macro that we actively discourage you from using.

My recommendation would be to take this out of OSAL completely, and only put it into the CFE file that defines CFE_MAKE_BIG16/32 and then we can just punt the problem to CFE to discourage developers from writing endian -specific code.

[jphickey]

Submitted nasa/cFE#1217 to stop CFE from depending on this, after which it can be removed from OSAL.