1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * linux/arch/arm/lib/findbit.S 4 * 5 * Copyright (C) 1995-2000 Russell King 6 * 7 * 16th March 2001 - John Ripley <jripley@sonicblue.com> 8 * Fixed so that "size" is an exclusive not an inclusive quantity. 9 * All users of these functions expect exclusive sizes, and may 10 * also call with zero size. 11 * Reworked by rmk. 12 */ 13 #include <linux/linkage.h> 14 #include <asm/assembler.h> 15 #include <asm/unwind.h> 16 .text 17 18 #ifdef __ARMEB__ 19 #define SWAB_ENDIAN le 20 #else 21 #define SWAB_ENDIAN be 22 #endif 23 24 .macro find_first, endian, set, name 25 ENTRY(_find_first_\name\()bit_\endian) 26 UNWIND( .fnstart) 27 teq r1, #0 28 beq 3f 29 mov r2, #0 30 1: ldr r3, [r0], #4 31 .ifeq \set 32 mvns r3, r3 @ invert/test bits 33 .else 34 movs r3, r3 @ test bits 35 .endif 36 .ifc \endian, SWAB_ENDIAN 37 bne .L_found_swab 38 .else 39 bne .L_found @ found the bit? 40 .endif 41 add r2, r2, #32 @ next index 42 2: cmp r2, r1 @ any more? 43 blo 1b 44 3: mov r0, r1 @ no more bits 45 ret lr 46 UNWIND( .fnend) 47 ENDPROC(_find_first_\name\()bit_\endian) 48 .endm 49 50 .macro find_next, endian, set, name 51 ENTRY(_find_next_\name\()bit_\endian) 52 UNWIND( .fnstart) 53 cmp r2, r1 54 bhs 3b 55 mov ip, r2, lsr #5 @ word index 56 add r0, r0, ip, lsl #2 57 ands ip, r2, #31 @ bit position 58 beq 1b 59 ldr r3, [r0], #4 60 .ifeq \set 61 mvn r3, r3 @ invert bits 62 .endif 63 .ifc \endian, SWAB_ENDIAN 64 rev_l r3, ip 65 .if .Lrev_l_uses_tmp 66 @ we need to recompute ip because rev_l will have overwritten 67 @ it. 68 and ip, r2, #31 @ bit position 69 .endif 70 .endif 71 movs r3, r3, lsr ip @ shift off unused bits 72 bne .L_found 73 orr r2, r2, #31 @ no zero bits 74 add r2, r2, #1 @ align bit pointer 75 b 2b @ loop for next bit 76 UNWIND( .fnend) 77 ENDPROC(_find_next_\name\()bit_\endian) 78 .endm 79 80 .macro find_bit, endian, set, name 81 find_first \endian, \set, \name 82 find_next \endian, \set, \name 83 .endm 84 85 /* _find_first_zero_bit_le and _find_next_zero_bit_le */ 86 find_bit le, 0, zero_ 87 88 /* _find_first_bit_le and _find_next_bit_le */ 89 find_bit le, 1 90 91 #ifdef __ARMEB__ 92 93 /* _find_first_zero_bit_be and _find_next_zero_bit_be */ 94 find_bit be, 0, zero_ 95 96 /* _find_first_bit_be and _find_next_bit_be */ 97 find_bit be, 1 98 99 #endif 100 101 /* 102 * One or more bits in the LSB of r3 are assumed to be set. 103 */ 104 .L_found_swab: 105 UNWIND( .fnstart) 106 rev_l r3, ip 107 .L_found: 108 #if __LINUX_ARM_ARCH__ >= 7 109 rbit r3, r3 @ reverse bits 110 clz r3, r3 @ count high zero bits 111 add r0, r2, r3 @ add offset of first set bit 112 #elif __LINUX_ARM_ARCH__ >= 5 113 rsb r0, r3, #0 114 and r3, r3, r0 @ mask out lowest bit set 115 clz r3, r3 @ count high zero bits 116 rsb r3, r3, #31 @ offset of first set bit 117 add r0, r2, r3 @ add offset of first set bit 118 #else 119 mov ip, #~0 120 tst r3, ip, lsr #16 @ test bits 0-15 121 addeq r2, r2, #16 122 moveq r3, r3, lsr #16 123 tst r3, #0x00ff 124 addeq r2, r2, #8 125 moveq r3, r3, lsr #8 126 tst r3, #0x000f 127 addeq r2, r2, #4 128 moveq r3, r3, lsr #4 129 tst r3, #0x0003 130 addeq r2, r2, #2 131 moveq r3, r3, lsr #2 132 tst r3, #0x0001 133 addeq r2, r2, #1 134 mov r0, r2 135 #endif 136 cmp r1, r0 @ Clamp to maxbit 137 movlo r0, r1 138 ret lr 139 UNWIND( .fnend) 140