qos_l_other.h File Reference

Composite operations on signed long integers for non-i386 architectures. More...

#include <linux/types.h>

Go to the source code of this file.

Defines
#define	l_shl_div(num, SHF, den)   ((__s32) ((((__s64) ((__s32)(num))) << (SHF)) / ((__s32)(den))))
	Computes '(num << SHF) / den' as __s32.
#define	l_mul_div(x, num, den)   ((__s32) (((__s64) ((__s32)(x))) * ((__s32)(num)) / ((__s32)(den))))
	Computes '(x * num) / den' as __s32 (32 bits).
#define	l_mul_shr(x, y, SHF)   ((__s32) ((((__s64) ((__s32)(x))) * ((__s32)(y))) >> (SHF)))
	Computes '(x * y) >> SHF' as __s32 (32 bits).

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Detailed Description

Composite operations on signed long integers for non-i386 architectures.

Definition in file qos_l_other.h.

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Define Documentation

#define l_mul_div	(	x,
		num,
		den		)	((__s32) (((__s64) ((__s32)(x))) * ((__s32)(num)) / ((__s32)(den))))

Computes '(x * num) / den' as __s32 (32 bits).

Computation is carried on with intermediate result (x * num) on 64 bits.

Parameters:

	x	an __s32 integer (32 bits)
	num	an __s32 integer (32 bits)
	den	an __s32 integer (32 bits)

Returns:

the result as an __s32 integer (32 bits)

Note:

No overflow check is made after the division.

Todo:

Investigate on volatiles, that do not allow optimizations. They should not be required, but without them bw2Q(), which uses l_mul_shr, outputs zero instead of the correct value.

Definition at line 55 of file qos_l_other.h.

#define l_mul_shr	(	x,
		y,
		SHF		)	((__s32) ((((__s64) ((__s32)(x))) * ((__s32)(y))) >> (SHF)))

Computes '(x * y) >> SHF' as __s32 (32 bits).

The computation is carried on with intermediate result (x*y) on 64 bits.

This macro is useful for multiplying two integers where one of them represents a real in fixed precision with SHF decimal bits (i.e. 1.0 is represented as 1ul<<SHF).

Parameters:

	x	an __s32 integer (32 bits)
	y	an __s32 integer (32 bits)
	SHF	a macro which evaluates to an integer within 1 and 31

Returns:

the result as an __s32 integer (32 bits)

Note:

No overflow check is made after the shift.

Todo:

Investigate on volatiles, that do not allow optimizations. They should not be required, but without them bw2Q(), which uses l_mul_shr, outputs zero instead of the correct value.

Definition at line 83 of file qos_l_other.h.

#define l_shl_div	(	num,
		SHF,
		den		)	((__s32) ((((__s64) ((__s32)(num))) << (SHF)) / ((__s32)(den))))

Computes '(num << SHF) / den' as __s32.

Computation is carried on with intermediate result (num << SHF) on 64 bits. This macro is useful for representing the result of the division num/dev as a real in fixed precision with SHF decimal bits (i.e. 1.0 is represented as 1ul<<SHF).

Parameters:

	num	an __s32 integer (32 bits)
	SHF	a macro which evaluates to an integer within 1 and 31
	den	an __s32 integer (32 bits)

Returns:

the result as an __s32 integer (32 bits)

Note:

No overflow check is made after the division.

Todo:

Investigate on volatiles, that do not allow optimizations. They should not be required, but without them bw2Q(), which uses l_mul_shr, outputs zero instead of the correct value.

Definition at line 30 of file qos_l_other.h.