cmake/ClipMode.cmake

include (CheckCSourceRuns)
include (CMakePushCheckState)

macro (CLIP_MODE)
	if ((NOT DEFINED CPU_CLIPS_NEGATIVE) AND (NOT DEFINED CPU_CLIPS_POSITIVE))
		set (CLIP_MODE_POSITIVE_MESSAGE "Target processor clips on positive float to int conversion")
		set (CLIP_MODE_NEGATIVE_MESSAGE "Target processor clips on negative float to int conversion")

		message (STATUS "Checking processor clipping capabilities...")

		if (CMAKE_CROSSCOMPILING)

			set (CLIP_MSG "disabled")
			set (CPU_CLIPS_POSITIVE FALSE CACHE BOOL ${CLIP_MODE_POSITIVE_MESSAGE})
			set (CPU_CLIPS_NEGATIVE FALSE CACHE BOOL ${CLIP_MODE_NEGATIVE_MESSAGE})

		else (NOT CMAKE_CROSSCOMPILING)

			cmake_push_check_state ()
			
			set (CMAKE_REQUIRED_QUIET TRUE)
			if (LIBM_REQUIRED)
				set (CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} ${M_LIBRARY})
			endif ()
			
			check_c_source_runs (
			"
			#define	_ISOC9X_SOURCE	1
			#define _ISOC99_SOURCE	1
			#define	__USE_ISOC99	1
			#define __USE_ISOC9X	1
			#include <math.h>
			int main (void)
			{	double	fval ;
				int k, ival ;

				fval = 1.0 * 0x7FFFFFFF ;
				for (k = 0 ; k < 100 ; k++)
				{	ival = (lrint (fval)) >> 24 ;
					if (ival != 127)
						return 1 ;
				
					fval *= 1.2499999 ;
					} ;
				
					return 0 ;
				}
			"
			CPU_CLIPS_POSITIVE)
			
			check_c_source_runs (
			"
			#define	_ISOC9X_SOURCE	1
			#define _ISOC99_SOURCE	1
			#define	__USE_ISOC99	1
			#define __USE_ISOC9X	1
			#include <math.h>
			int main (void)
			{	double	fval ;
				int k, ival ;

				fval = -8.0 * 0x10000000 ;
				for (k = 0 ; k < 100 ; k++)
				{	ival = (lrint (fval)) >> 24 ;
					if (ival != -128)
						return 1 ;
				
					fval *= 1.2499999 ;
					} ;
				
					return 0 ;
				}
			"
			CPU_CLIPS_NEGATIVE)

			cmake_pop_check_state ()

			if (CPU_CLIPS_POSITIVE AND (NOT CPU_CLIPS_NEGATIVE))
				set (CLIP_MSG "positive")
			elseif (CPU_CLIPS_NEGATIVE AND (NOT CPU_CLIPS_POSITIVE))
				set (CLIP_MSG "negative")
			elseif (CPU_CLIPS_POSITIVE AND CPU_CLIPS_NEGATIVE)
				set (CLIP_MSG "both")
			else ()
				set (CLIP_MSG "none")
			endif ()

		endif (CMAKE_CROSSCOMPILING)

		message (STATUS "Checking processor clipping capabilities... ${CLIP_MSG}")
	endif ()
endmacro (CLIP_MODE)