Low-level integer routines with gcc - Revision history

Roux at 13:45, 28 June 2012

2012-06-28T13:45:29Z

← Older revision		Revision as of 15:45, 28 June 2012
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	Ref : [http://gcc.gnu.org/onlinedocs/gccint.pdf From Gnu Compiler Collection Internals]		Ref : [http://gcc.gnu.org/onlinedocs/gccint.pdf From Gnu Compiler Collection Internals]

	An alternative is to dig directly into the /include/ directory of gcc and find some useful routines: for example		An alternative is to dig directly into the /include/ directory of gcc and find some useful routines: for example in smmintrin.h, one finds a popcount for longs:
	<source lang="cpp">		<source lang="cpp">
	~~#include <smmintrin.h>~~
	long word = 1028464683;		long word = 1028464683;
	cout << __builtin_popcountll(word) << endl;		cout << __builtin_popcountll(word) << endl;
	</source>		</source>

Roux at 13:44, 28 June 2012

2012-06-28T13:44:45Z

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 int __popcountti2 (long long a ) //These functions return the number of bits set in a.
 int64_t __bswapdi2 (int64 t a )  //These functions return the a byteswapped.
 </source>

Roux at 15:31, 11 April 2012

2012-04-11T15:31:12Z

← Older revision		Revision as of 17:31, 11 April 2012
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	Gcc supports low-level integer routines similar to the FORTRAN routines POPCOUNT, ISHIFT...		Gcc supports low-level integer routines similar to the FORTRAN routines POPCOUNT, ISHIFT...

			The examples below are given for ''long long'', the routines name changes for ''long'' and ''int''
	<source lang="cpp">		<source lang="cpp">
	long long __ashlti3 (long long a, int b ) //These functions return the result of shifting a left by b bits.		long long __ashlti3 (long long a, int b ) //These functions return the result of shifting a left by b bits.

Roux at 15:30, 11 April 2012

2012-04-11T15:30:21Z

← Older revision		Revision as of 17:30, 11 April 2012
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	long long __divti3 (long long a, long long b ) //These functions return the quotient of the signed division of a and b.		long long __divti3 (long long a, long long b ) //These functions return the quotient of the signed division of a and b.
	long long __lshrti3 (long long a, int b ) //These functions return the result of logically shifting a right by b bits.		long long __lshrti3 (long long a, int b ) //These functions return the result of logically shifting a right by b bits.
	int __clzti2 (long long a ) //These functions return the number of leading 0-bits in a, starting at the most significant bit position. If a is zero, the result is undefined.		int __clzti2 (long long a ) //These functions return the number of leading 0-bits in a, starting at the most significant bit position.
	int __ctzti2 (long long a ) //These functions return the number of trailing 0-bits in a, starting at the least significant bit position. If a is zero, the result is undefined.		//If a is zero, the result is undefined.
	int __ffsti2 (long long a ) //These functions return the index of the least significant 1-bit in a, or the value zero if a is zero. The least significant bit is index one.		int __ctzti2 (long long a ) //These functions return the number of trailing 0-bits in a, starting at the least significant bit position.
			//If a is zero, the result is undefined.
			int __ffsti2 (long long a ) //These functions return the index of the least significant 1-bit in a, or the value zero if a is zero.
			// The least significant bit is index one.
	int __parityti2 (long long a ) //These functions return the value zero if the number of bits set in a is even, and the value one otherwise.		int __parityti2 (long long a ) //These functions return the value zero if the number of bits set in a is even, and the value one otherwise.
	int __popcountti2 (long long a ) //These functions return the number of bits set in a.		int __popcountti2 (long long a ) //These functions return the number of bits set in a.
	int64_t __bswapdi2 (int64 t a ) //These functions return the a byteswapped.		int64_t __bswapdi2 (int64 t a ) //These functions return the a byteswapped.
	</source>		</source>

Roux: Created page with "Gcc supports low-level integer routines similar to the FORTRAN routines POPCOUNT, ISHIFT... long long __ashlti3 (long long a, int b ) //These functio..."

2012-04-11T15:29:30Z

Created page with "Gcc supports low-level integer routines similar to the FORTRAN routines POPCOUNT, ISHIFT... <source lang="cpp"> long long __ashlti3 (long long a, int b ) //These functio..."

New page

Gcc supports low-level integer routines similar to the FORTRAN routines POPCOUNT, ISHIFT...
<source lang="cpp">
long long __ashlti3 (long long a, int b ) //These functions return the result of shifting a left by b bits.
long long __ashrti3 (long long a, int b ) //These functions return the result of arithmetically shifting a right by b bits.
long long __divti3 (long long a, long long b ) //These functions return the quotient of the signed division of a and b.
long long __lshrti3 (long long a, int b ) //These functions return the result of logically shifting a right by b bits.
int __clzti2 (long long a ) //These functions return the number of leading 0-bits in a, starting at the most significant bit position. If a is zero, the result is undefined.
int __ctzti2 (long long a ) //These functions return the number of trailing 0-bits in a, starting at the least significant bit position. If a is zero, the result is undefined.
int __ffsti2 (long long a ) //These functions return the index of the least significant 1-bit in a, or the value zero if a is zero. The least significant bit is index one.
int __parityti2 (long long a ) //These functions return the value zero if the number of bits set in a is even, and the value one otherwise.
int __popcountti2 (long long a ) //These functions return the number of bits set in a.
int64_t __bswapdi2 (int64 t a ) //These functions return the a byteswapped.
</source>