[PATCH v2 05/10] ARM: update findbit.S from Linux
Sascha Hauer
s.hauer at pengutronix.de
Thu Sep 26 04:17:07 PDT 2024
This updates findbit.S from Linux-6.10
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)
--
2.39.5
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