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Using Inline Assembly in C/C++

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14 Oct 2006CPOL5 min read 843.2K   3.5K   73  
This article describes using inline assembly code in your C/C++ program... was it ever difficult for you, it will never be any more!
#include <stdio.h>

float sinx( float degree ) {
	float result, two_right_angles = 180.0f ;
	__asm__ __volatile__ ( "fld %1;"
							"fld %2;"
							"fldpi;"
							"fmul;"
							"fdiv;"
							"fsin;"
							"fstp %0;" : "=g" (result) : "g"(two_right_angles), "g" (degree)
	) ;
	return result ;
}

float cosx( float degree ) {
	float result, two_right_angles = 180.0f, radians ;
	__asm__ __volatile__ ( "fld %1;"
							"fld %2;"
							"fldpi;"
							"fmul;"
							"fdiv;"
							"fstp %0;" : "=g" (radians) : "g"(two_right_angles), "g" (degree)
	) ;
	__asm__ __volatile__ ( "fld %1;"
							"fcos;"
							"fstp %0;" : "=g" (result) : "g" (radians)
	) ;
	return result ;
}

float square_root( float val ) {
	float result ;
	__asm__ __volatile__ ( "fld %1;"
							"fsqrt;"
							"fstp %0;" : "=g" (result) : "g" (val)
	) ;
	return result ;
}

int main() {
	float theta ;
	printf( "Enter theta in degrees : " ) ;
	scanf( "%f", &theta ) ;

	printf( "sinx(%f) = %f\n", theta, sinx( theta ) );
	printf( "cosx(%f) = %f\n", theta, cosx( theta ) );
	printf( "square_root(%f) = %f\n", theta, square_root( theta ) ) ;

	return 0 ;
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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