Commit 2511d032 authored by Russell King (Oracle)'s avatar Russell King (Oracle)
Browse files

ARM: findbit: operate by words 



Convert the implementations to operate on words rather than bytes
which makes bitmap searching faster.

Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
parent 2953a3e1

arch/arm/include/asm/assembler.h

+6 −0
Original line number Diff line number Diff line
@@ -761,6 +761,12 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) 
	.endif

	.endm



	.if		__LINUX_ARM_ARCH__ < 6

	.set		.Lrev_l_uses_tmp, 1

	.else

	.set		.Lrev_l_uses_tmp, 0

	.endif



	/*

	 * bl_r - branch and link to register

	 *

arch/arm/lib/findbit.S

+44 −34
Original line number Diff line number Diff line
@@ -14,32 +14,32 @@ 
#include <asm/assembler.h>

                .text



#ifdef __ARMEB__

#define SWAB_ENDIAN le

#else

#define SWAB_ENDIAN be

#endif



		.macro	find_first, endian, set, name

ENTRY(_find_first_\name\()bit_\endian)

		teq	r1, #0

		beq	3f

		mov	r2, #0

1:

		.ifc	\endian, be

		eor	r3, r2, #0x18

 ARM(		ldrb	r3, [r0, r3, lsr #3]	)

 THUMB(		lsr	r3, #3			)

 THUMB(		ldrb	r3, [r0, r3]		)

1:		ldr	r3, [r0], #4

		.ifeq \set

		mvns	r3, r3			@ invert/test bits

		.else

 ARM(		ldrb	r3, [r0, r2, lsr #3]	)

 THUMB(		lsr	r3, r2, #3		)

 THUMB(		ldrb	r3, [r0, r3]		)

		movs	r3, r3			@ test bits

		.endif

		.ifeq	\set

		eors	r3, r3, #0xff		@ invert bits

		.ifc \endian, SWAB_ENDIAN

		bne	.L_found_swab

		.else

		movs	r3, r3

		bne	.L_found		@ found the bit?

		.endif

		bne	.L_found		@ any now set - found zero bit

		add	r2, r2, #8		@ next bit pointer

		add	r2, r2, #32		@ next index

2:		cmp	r2, r1			@ any more?

		blo	1b

3:		mov	r0, r1			@ no free bits

3:		mov	r0, r1			@ no more bits

		ret	lr

ENDPROC(_find_first_\name\()bit_\endian)

		.endm
@@ -48,24 +48,25 @@ ENDPROC(_find_first_\name\()bit_\endian) 
ENTRY(_find_next_\name\()bit_\endian)

		cmp	r2, r1

		bhs	3b

		ands	ip, r2, #7

		beq	1b			@ If new byte, goto old routine

		.ifc	\endian, be

		eor	r3, r2, #0x18

 ARM(		ldrb	r3, [r0, r3, lsr #3]	)

 THUMB(		lsr	r3, #3			)

 THUMB(		ldrb	r3, [r0, r3]		)

		.else

 ARM(		ldrb	r3, [r0, r2, lsr #3]	)

 THUMB(		lsr	r3, r2, #3		)

 THUMB(		ldrb	r3, [r0, r3]		)

		.endif

		mov	ip, r2, lsr #5		@ word index

		add	r0, r0, ip, lsl #2

		ands	ip, r2, #31		@ bit position

		beq	1b

		ldr	r3, [r0], #4

		.ifeq \set

		eor	r3, r3, #0xff		@ now looking for a 1 bit

		mvn	r3, r3			@ invert bits

		.endif

		.ifc \endian, SWAB_ENDIAN

		rev_l	r3, ip

		.if	.Lrev_l_uses_tmp

		@ we need to recompute ip because rev_l will have overwritten

		@ it.

		and	ip, r2, #31		@ bit position

		.endif

		.endif

		movs	r3, r3, lsr ip		@ shift off unused bits

		bne	.L_found

		orr	r2, r2, #7		@ if zero, then no bits here

		orr	r2, r2, #31		@ no zero bits

		add	r2, r2, #1		@ align bit pointer

		b	2b			@ loop for next bit

ENDPROC(_find_next_\name\()bit_\endian)
@@ -95,6 +96,8 @@ ENDPROC(_find_next_\name\()bit_\endian) 
/*

 * One or more bits in the LSB of r3 are assumed to be set.

 */

.L_found_swab:

		rev_l	r3, ip

.L_found:

#if __LINUX_ARM_ARCH__ >= 7

		rbit	r3, r3			@ reverse bits
@@ -107,13 +110,20 @@ ENDPROC(_find_next_\name\()bit_\endian) 
		rsb	r3, r3, #31		@ offset of first set bit

		add	r0, r2, r3		@ add offset of first set bit

#else

		tst	r3, #0x0f

		mov	ip, #~0

		tst	r3, ip, lsr #16		@ test bits 0-15

		addeq	r2, r2, #16

		moveq	r3, r3, lsr #16

		tst	r3, #0x00ff

		addeq	r2, r2, #8

		moveq	r3, r3, lsr #8

		tst	r3, #0x000f

		addeq	r2, r2, #4

		movne	r3, r3, lsl #4

		tst	r3, #0x30

		moveq	r3, r3, lsr #4

		tst	r3, #0x0003

		addeq	r2, r2, #2

		movne	r3, r3, lsl #2

		tst	r3, #0x40

		moveq	r3, r3, lsr #2

		tst	r3, #0x0001

		addeq	r2, r2, #1

		mov	r0, r2

#endif