| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | */ |
| 24 | ENTRY(_find_first_zero_bit_le) |
| 25 | teq r1, #0 |
| 26 | beq 3f |
| 27 | mov r2, #0 |
| 28 | 1: ldrb r3, [r0, r2, lsr #3] |
| 29 | eors r3, r3, #0xff @ invert bits |
| 30 | bne .found @ any now set - found zero bit |
| 31 | add r2, r2, #8 @ next bit pointer |
| 32 | 2: cmp r2, r1 @ any more? |
| 33 | blo 1b |
| 34 | 3: mov r0, r1 @ no free bits |
| 35 | RETINSTR(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 | */ |
| 41 | ENTRY(_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 .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 | */ |
| 58 | ENTRY(_find_first_bit_le) |
| 59 | teq r1, #0 |
| 60 | beq 3f |
| 61 | mov r2, #0 |
| 62 | 1: ldrb r3, [r0, r2, lsr #3] |
| 63 | movs r3, r3 |
| 64 | bne .found @ any now set - found zero bit |
| 65 | add r2, r2, #8 @ next bit pointer |
| 66 | 2: cmp r2, r1 @ any more? |
| 67 | blo 1b |
| 68 | 3: mov r0, r1 @ no free bits |
| 69 | RETINSTR(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 | */ |
| 75 | ENTRY(_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 .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 | |
| 89 | ENTRY(_find_first_zero_bit_be) |
| 90 | teq r1, #0 |
| 91 | beq 3f |
| 92 | mov r2, #0 |
| 93 | 1: eor r3, r2, #0x18 @ big endian byte ordering |
| 94 | ldrb r3, [r0, r3, lsr #3] |
| 95 | eors r3, r3, #0xff @ invert bits |
| 96 | bne .found @ any now set - found zero bit |
| 97 | add r2, r2, #8 @ next bit pointer |
| 98 | 2: cmp r2, r1 @ any more? |
| 99 | blo 1b |
| 100 | 3: mov r0, r1 @ no free bits |
| 101 | RETINSTR(mov,pc,lr) |
| 102 | |
| 103 | ENTRY(_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 .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 | |
| 117 | ENTRY(_find_first_bit_be) |
| 118 | teq r1, #0 |
| 119 | beq 3f |
| 120 | mov r2, #0 |
| 121 | 1: eor r3, r2, #0x18 @ big endian byte ordering |
| 122 | ldrb r3, [r0, r3, lsr #3] |
| 123 | movs r3, r3 |
| 124 | bne .found @ any now set - found zero bit |
| 125 | add r2, r2, #8 @ next bit pointer |
| 126 | 2: cmp r2, r1 @ any more? |
| 127 | blo 1b |
| 128 | 3: mov r0, r1 @ no free bits |
| 129 | RETINSTR(mov,pc,lr) |
| 130 | |
| 131 | ENTRY(_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 .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 | .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 | RETINSTR(mov,pc,lr) |
| 168 | |