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#ifndef _CPUSUPPORT_H_
#define _CPUSUPPORT_H_
/*
* To enable support for non-portable CPU features at compile time, one or
* more CPUSUPPORT_ARCH_FEATURE macros should be defined. This can be done
* directly on the compiler command line via -D CPUSUPPORT_ARCH_FEATURE or
* -D CPUSUPPORT_ARCH_FEATURE=1; or a file can be created with the
* necessary #define lines and then -D CPUSUPPORT_CONFIG_FILE=cpuconfig.h
* (or similar) can be provided to include that file here.
*/
#ifdef CPUSUPPORT_CONFIG_FILE
#include CPUSUPPORT_CONFIG_FILE
#endif
/**
* The CPUSUPPORT_FEATURE macro declares the necessary variables and
* functions for detecting CPU feature support at run time. The function
* defined in the macro acts to cache the result of the ..._detect function
* using the ..._present and ..._init variables. The _detect function and the
* _present and _init variables are turn defined by CPUSUPPORT_FEATURE_DECL in
* appropriate cpusupport_foo_bar.c file.
*
* In order to allow CPUSUPPORT_FEATURE to be used for features which do not
* have corresponding CPUSUPPORT_FEATURE_DECL blocks in another source file,
* we abuse the C preprocessor: If CPUSUPPORT_${enabler} is defined to 1, then
* we access _present_1, _init_1, and _detect_1; but if it is not defined, we
* access _present_CPUSUPPORT_${enabler} etc., which we define as static, thus
* preventing the compiler from emitting a reference to an external symbol.
*
* In this way, it becomes possible to issue CPUSUPPORT_FEATURE invocations
* for nonexistent features without running afoul of the requirement that
* "If an identifier declared with external linkage is used... in the entire
* program there shall be exactly one external definition" (C99 standard, 6.9
* paragraph 5). In practice, this means that users of the cpusupport code
* can omit build and runtime detection files without changing the framework
* code.
*/
#define CPUSUPPORT_FEATURE__(arch_feature, enabler, enabled) \
static int cpusupport_ ## arch_feature ## _present ## _CPUSUPPORT_ ## enabler; \
static int cpusupport_ ## arch_feature ## _init ## _CPUSUPPORT_ ## enabler; \
static inline int cpusupport_ ## arch_feature ## _detect ## _CPUSUPPORT_ ## enabler(void) { return (0); } \
extern int cpusupport_ ## arch_feature ## _present_ ## enabled; \
extern int cpusupport_ ## arch_feature ## _init_ ## enabled; \
int cpusupport_ ## arch_feature ## _detect_ ## enabled(void); \
\
static inline int \
cpusupport_ ## arch_feature(void) \
{ \
\
if (cpusupport_ ## arch_feature ## _present_ ## enabled) \
return (1); \
else if (cpusupport_ ## arch_feature ## _init_ ## enabled) \
return (0); \
cpusupport_ ## arch_feature ## _present_ ## enabled = \
cpusupport_ ## arch_feature ## _detect_ ## enabled(); \
cpusupport_ ## arch_feature ## _init_ ## enabled = 1; \
return (cpusupport_ ## arch_feature ## _present_ ## enabled); \
} \
static void (* cpusupport_ ## arch_feature ## _dummyptr)(void); \
static inline void \
cpusupport_ ## arch_feature ## _dummyfunc(void) \
{ \
\
(void)cpusupport_ ## arch_feature ## _present ## _CPUSUPPORT_ ## enabler; \
(void)cpusupport_ ## arch_feature ## _init ## _CPUSUPPORT_ ## enabler; \
(void)cpusupport_ ## arch_feature ## _detect ## _CPUSUPPORT_ ## enabler; \
(void)cpusupport_ ## arch_feature ## _present_ ## enabled; \
(void)cpusupport_ ## arch_feature ## _init_ ## enabled; \
(void)cpusupport_ ## arch_feature ## _detect_ ## enabled; \
(void)cpusupport_ ## arch_feature ## _dummyptr; \
} \
static void (* cpusupport_ ## arch_feature ## _dummyptr)(void) = cpusupport_ ## arch_feature ## _dummyfunc; \
struct cpusupport_ ## arch_feature ## _dummy
#define CPUSUPPORT_FEATURE_(arch_feature, enabler, enabled) \
CPUSUPPORT_FEATURE__(arch_feature, enabler, enabled)
#define CPUSUPPORT_FEATURE(arch, feature, enabler) \
CPUSUPPORT_FEATURE_(arch ## _ ## feature, enabler, CPUSUPPORT_ ## enabler)
/*
* CPUSUPPORT_FEATURE_DECL(arch, feature):
* Macro which defines variables and provides a function declaration for
* detecting the presence of "feature" on the "arch" architecture. The
* function body following this macro expansion must return nonzero if the
* feature is present, or zero if the feature is not present or the detection
* fails for any reason.
*/
#define CPUSUPPORT_FEATURE_DECL(arch, feature) \
int cpusupport_ ## arch ## _ ## feature ## _present_1 = 0; \
int cpusupport_ ## arch ## _ ## feature ## _init_1 = 0; \
int cpusupport_ ## arch ## _ ## feature ## _detect_1(void); \
int \
cpusupport_ ## arch ## _ ## feature ## _detect_1(void)
/*
* List of features. If a feature here is not enabled by the appropriate
* CPUSUPPORT_ARCH_FEATURE macro being defined, it has no effect; but if the
* relevant macro may be defined (e.g., by Build/cpusupport.sh successfully
* compiling Build/cpusupport-ARCH-FEATURE.c) then the C file containing the
* corresponding run-time detection code (cpusupport_arch_feature.c) must be
* compiled and linked in.
*/
CPUSUPPORT_FEATURE(x86, aesni, X86_AESNI);
CPUSUPPORT_FEATURE(x86, sse2, X86_SSE2);
#endif /* !_CPUSUPPORT_H_ */
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