[PATCH 05/10] ARM: update findbit.S from Linux
Ahmad Fatoum
a.fatoum at pengutronix.de
Wed Sep 25 09:03:39 PDT 2024
On 25.09.24 15:55, Sascha Hauer wrote:
> This updates findbit.S from Linux
Please mention version.
>
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> ---
> 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 <jripley at sonicblue.com>
> * 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)
>
--
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