On 25.09.24 15:55, Sascha Hauer wrote: > This updates findbit.S from Linux
Please mention version. > > Signed-off-by: Sascha Hauer <[email protected]> > --- > arch/arm/lib32/findbit.S | 243 > ++++++++++++++++++----------------------------- > 1 file changed, 94 insertions(+), 149 deletions(-) > > diff --git a/arch/arm/lib32/findbit.S b/arch/arm/lib32/findbit.S > index 82a0f34dc2..b7ac2d3c07 100644 > --- a/arch/arm/lib32/findbit.S > +++ b/arch/arm/lib32/findbit.S > @@ -1,9 +1,8 @@ > /* SPDX-License-Identifier: GPL-2.0-only */ > -/* SPDX-FileCopyrightText: 1995-2000 Russell King */ > - > /* > - * Originally from Linux kernel > - * arch/arm/lib/findbit.S > + * linux/arch/arm/lib/findbit.S > + * > + * Copyright (C) 1995-2000 Russell King > * > * 16th March 2001 - John Ripley <[email protected]> > * Fixed so that "size" is an exclusive not an inclusive quantity. > @@ -13,182 +12,128 @@ > */ > #include <linux/linkage.h> > #include <asm/assembler.h> > +#include <asm/unwind.h> > .text > > -/* > - * Purpose : Find a 'zero' bit > - * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); > - */ > -ENTRY(_find_first_zero_bit_le) > - teq r1, #0 > - beq 3f > - mov r2, #0 > -1: > - ARM( ldrb r3, [r0, r2, lsr #3] ) > - THUMB( lsr r3, r2, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - eors r3, r3, #0xff @ invert bits > - bne .L_found @ any now set - found zero bit > - add r2, r2, #8 @ next bit pointer > -2: cmp r2, r1 @ any more? > - blo 1b > -3: mov r0, r1 @ no free bits > - mov pc, lr > -ENDPROC(_find_first_zero_bit_le) > - > -/* > - * Purpose : Find next 'zero' bit > - * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int > offset) > - */ > -ENTRY(_find_next_zero_bit_le) > - teq r1, #0 > - beq 3b > - ands ip, r2, #7 > - beq 1b @ If new byte, goto old routine > - ARM( ldrb r3, [r0, r2, lsr #3] ) > - THUMB( lsr r3, r2, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - eor r3, r3, #0xff @ now looking for a 1 bit > - movs r3, r3, lsr ip @ shift off unused bits > - bne .L_found > - orr r2, r2, #7 @ if zero, then no bits here > - add r2, r2, #1 @ align bit pointer > - b 2b @ loop for next bit > -ENDPROC(_find_next_zero_bit_le) > +#ifdef __ARMEB__ > +#define SWAB_ENDIAN le > +#else > +#define SWAB_ENDIAN be > +#endif > > -/* > - * Purpose : Find a 'one' bit > - * Prototype: int find_first_bit(const unsigned long *addr, unsigned int > maxbit); > - */ > -ENTRY(_find_first_bit_le) > + .macro find_first, endian, set, name > +ENTRY(_find_first_\name\()bit_\endian) > + UNWIND( .fnstart) > teq r1, #0 > beq 3f > mov r2, #0 > -1: > - ARM( ldrb r3, [r0, r2, lsr #3] ) > - THUMB( lsr r3, r2, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - movs r3, r3 > - bne .L_found @ any now set - found zero bit > - add r2, r2, #8 @ next bit pointer > +1: ldr r3, [r0], #4 > + .ifeq \set > + mvns r3, r3 @ invert/test bits > + .else > + movs r3, r3 @ test bits > + .endif > + .ifc \endian, SWAB_ENDIAN > + bne .L_found_swab > + .else > + bne .L_found @ found the bit? > + .endif > + add r2, r2, #32 @ next index > 2: cmp r2, r1 @ any more? > blo 1b > -3: mov r0, r1 @ no free bits > - mov pc, lr > -ENDPROC(_find_first_bit_le) > +3: mov r0, r1 @ no more bits > + ret lr > + UNWIND( .fnend) > +ENDPROC(_find_first_\name\()bit_\endian) > + .endm > > -/* > - * Purpose : Find next 'one' bit > - * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int > offset) > - */ > -ENTRY(_find_next_bit_le) > - teq r1, #0 > - beq 3b > - ands ip, r2, #7 > - beq 1b @ If new byte, goto old routine > - ARM( ldrb r3, [r0, r2, lsr #3] ) > - THUMB( lsr r3, r2, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > + .macro find_next, endian, set, name > +ENTRY(_find_next_\name\()bit_\endian) > + UNWIND( .fnstart) > + cmp r2, r1 > + bhs 3b > + 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 > + 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_bit_le) > + UNWIND( .fnend) > +ENDPROC(_find_next_\name\()bit_\endian) > + .endm > > -#ifdef __ARMEB__ > + .macro find_bit, endian, set, name > + find_first \endian, \set, \name > + find_next \endian, \set, \name > + .endm > > -ENTRY(_find_first_zero_bit_be) > - teq r1, #0 > - beq 3f > - mov r2, #0 > -1: eor r3, r2, #0x18 @ big endian byte ordering > - ARM( ldrb r3, [r0, r3, lsr #3] ) > - THUMB( lsr r3, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - eors r3, r3, #0xff @ invert bits > - bne .L_found @ any now set - found zero bit > - add r2, r2, #8 @ next bit pointer > -2: cmp r2, r1 @ any more? > - blo 1b > -3: mov r0, r1 @ no free bits > - mov pc, lr > -ENDPROC(_find_first_zero_bit_be) > +/* _find_first_zero_bit_le and _find_next_zero_bit_le */ > + find_bit le, 0, zero_ > > -ENTRY(_find_next_zero_bit_be) > - teq r1, #0 > - beq 3b > - ands ip, r2, #7 > - beq 1b @ If new byte, goto old routine > - eor r3, r2, #0x18 @ big endian byte ordering > - ARM( ldrb r3, [r0, r3, lsr #3] ) > - THUMB( lsr r3, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - eor r3, r3, #0xff @ now looking for a 1 bit > - movs r3, r3, lsr ip @ shift off unused bits > - bne .L_found > - orr r2, r2, #7 @ if zero, then no bits here > - add r2, r2, #1 @ align bit pointer > - b 2b @ loop for next bit > -ENDPROC(_find_next_zero_bit_be) > +/* _find_first_bit_le and _find_next_bit_le */ > + find_bit le, 1 > > -ENTRY(_find_first_bit_be) > - teq r1, #0 > - beq 3f > - mov r2, #0 > -1: eor r3, r2, #0x18 @ big endian byte ordering > - ARM( ldrb r3, [r0, r3, lsr #3] ) > - THUMB( lsr r3, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - movs r3, r3 > - bne .L_found @ any now set - found zero bit > - add r2, r2, #8 @ next bit pointer > -2: cmp r2, r1 @ any more? > - blo 1b > -3: mov r0, r1 @ no free bits > - mov pc, lr > -ENDPROC(_find_first_bit_be) > +#ifdef __ARMEB__ > > -ENTRY(_find_next_bit_be) > - teq r1, #0 > - beq 3b > - ands ip, r2, #7 > - beq 1b @ If new byte, goto old routine > - eor r3, r2, #0x18 @ big endian byte ordering > - ARM( ldrb r3, [r0, r3, lsr #3] ) > - THUMB( lsr r3, #3 ) > - THUMB( ldrb r3, [r0, r3] ) > - movs r3, r3, lsr ip @ shift off unused bits > - bne .L_found > - orr r2, r2, #7 @ if zero, then no bits here > - add r2, r2, #1 @ align bit pointer > - b 2b @ loop for next bit > -ENDPROC(_find_next_bit_be) > +/* _find_first_zero_bit_be and _find_next_zero_bit_be */ > + find_bit be, 0, zero_ > + > +/* _find_first_bit_be and _find_next_bit_be */ > + find_bit be, 1 > > #endif > > /* > * One or more bits in the LSB of r3 are assumed to be set. > */ > +.L_found_swab: > + UNWIND( .fnstart) > + rev_l r3, ip > .L_found: > -#if __LINUX_ARM_ARCH__ >= 5 > +#if __LINUX_ARM_ARCH__ >= 7 > + rbit r3, r3 @ reverse bits > + clz r3, r3 @ count high zero bits > + add r0, r2, r3 @ add offset of first set bit > +#elif __LINUX_ARM_ARCH__ >= 5 > rsb r0, r3, #0 > - and r3, r3, r0 > - clz r3, r3 > - rsb r3, r3, #31 > - add r0, r2, r3 > + and r3, r3, r0 @ mask out lowest bit set > + clz r3, r3 @ count high zero bits > + 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 > cmp r1, r0 @ Clamp to maxbit > movlo r0, r1 > - mov pc, lr > - > + ret lr > + UNWIND( .fnend) > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
