1/* 2 * linux/arch/arm/lib/findbit.S 3 * 4 * Copyright (C) 1995-2000 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * 16th March 2001 - John Ripley <jripley@sonicblue.com> 11 * Fixed so that "size" is an exclusive not an inclusive quantity. 12 * All users of these functions expect exclusive sizes, and may 13 * also call with zero size. 14 * Reworked by rmk. 15 */ 16#include <linux/linkage.h> 17#include <asm/assembler.h> 18 .text 19 20/* 21 * Purpose : Find a 'zero' bit 22 * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit); 23 */ 24ENTRY(_find_first_zero_bit_le) 25 teq r1, #0 26 beq 3f 27 mov r2, #0 281: ldrb r3, [r0, r2, lsr #3] 29 eors r3, r3, #0xff @ invert bits 30 bne .L_found @ any now set - found zero bit 31 add r2, r2, #8 @ next bit pointer 322: cmp r2, r1 @ any more? 33 blo 1b 343: mov r0, r1 @ no free bits 35 mov pc, lr 36 37/* 38 * Purpose : Find next 'zero' bit 39 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) 40 */ 41ENTRY(_find_next_zero_bit_le) 42 teq r1, #0 43 beq 3b 44 ands ip, r2, #7 45 beq 1b @ If new byte, goto old routine 46 ldrb r3, [r0, r2, lsr #3] 47 eor r3, r3, #0xff @ now looking for a 1 bit 48 movs r3, r3, lsr ip @ shift off unused bits 49 bne .L_found 50 orr r2, r2, #7 @ if zero, then no bits here 51 add r2, r2, #1 @ align bit pointer 52 b 2b @ loop for next bit 53 54/* 55 * Purpose : Find a 'one' bit 56 * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit); 57 */ 58ENTRY(_find_first_bit_le) 59 teq r1, #0 60 beq 3f 61 mov r2, #0 621: ldrb r3, [r0, r2, lsr #3] 63 movs r3, r3 64 bne .L_found @ any now set - found zero bit 65 add r2, r2, #8 @ next bit pointer 662: cmp r2, r1 @ any more? 67 blo 1b 683: mov r0, r1 @ no free bits 69 mov pc, lr 70 71/* 72 * Purpose : Find next 'one' bit 73 * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset) 74 */ 75ENTRY(_find_next_bit_le) 76 teq r1, #0 77 beq 3b 78 ands ip, r2, #7 79 beq 1b @ If new byte, goto old routine 80 ldrb r3, [r0, r2, lsr #3] 81 movs r3, r3, lsr ip @ shift off unused bits 82 bne .L_found 83 orr r2, r2, #7 @ if zero, then no bits here 84 add r2, r2, #1 @ align bit pointer 85 b 2b @ loop for next bit 86 87#ifdef __ARMEB__ 88 89ENTRY(_find_first_zero_bit_be) 90 teq r1, #0 91 beq 3f 92 mov r2, #0 931: eor r3, r2, #0x18 @ big endian byte ordering 94 ldrb r3, [r0, r3, lsr #3] 95 eors r3, r3, #0xff @ invert bits 96 bne .L_found @ any now set - found zero bit 97 add r2, r2, #8 @ next bit pointer 982: cmp r2, r1 @ any more? 99 blo 1b 1003: mov r0, r1 @ no free bits 101 mov pc, lr 102 103ENTRY(_find_next_zero_bit_be) 104 teq r1, #0 105 beq 3b 106 ands ip, r2, #7 107 beq 1b @ If new byte, goto old routine 108 eor r3, r2, #0x18 @ big endian byte ordering 109 ldrb r3, [r0, r3, lsr #3] 110 eor r3, r3, #0xff @ now looking for a 1 bit 111 movs r3, r3, lsr ip @ shift off unused bits 112 bne .L_found 113 orr r2, r2, #7 @ if zero, then no bits here 114 add r2, r2, #1 @ align bit pointer 115 b 2b @ loop for next bit 116 117ENTRY(_find_first_bit_be) 118 teq r1, #0 119 beq 3f 120 mov r2, #0 1211: eor r3, r2, #0x18 @ big endian byte ordering 122 ldrb r3, [r0, r3, lsr #3] 123 movs r3, r3 124 bne .L_found @ any now set - found zero bit 125 add r2, r2, #8 @ next bit pointer 1262: cmp r2, r1 @ any more? 127 blo 1b 1283: mov r0, r1 @ no free bits 129 mov pc, lr 130 131ENTRY(_find_next_bit_be) 132 teq r1, #0 133 beq 3b 134 ands ip, r2, #7 135 beq 1b @ If new byte, goto old routine 136 eor r3, r2, #0x18 @ big endian byte ordering 137 ldrb r3, [r0, r3, lsr #3] 138 movs r3, r3, lsr ip @ shift off unused bits 139 bne .L_found 140 orr r2, r2, #7 @ if zero, then no bits here 141 add r2, r2, #1 @ align bit pointer 142 b 2b @ loop for next bit 143 144#endif 145 146/* 147 * One or more bits in the LSB of r3 are assumed to be set. 148 */ 149.L_found: 150#if __LINUX_ARM_ARCH__ >= 5 151 rsb r1, r3, #0 152 and r3, r3, r1 153 clz r3, r3 154 rsb r3, r3, #31 155 add r0, r2, r3 156#else 157 tst r3, #0x0f 158 addeq r2, r2, #4 159 movne r3, r3, lsl #4 160 tst r3, #0x30 161 addeq r2, r2, #2 162 movne r3, r3, lsl #2 163 tst r3, #0x40 164 addeq r2, r2, #1 165 mov r0, r2 166#endif 167 mov pc, lr 168 169