| 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 2b |
| 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 | * One or more bits in the LSB of r3 are assumed to be set. |
| 56 | */ |
| 57 | .found: tst r3, #0x0f |
| 58 | addeq r2, r2, #4 |
| 59 | movne r3, r3, lsl #4 |
| 60 | tst r3, #0x30 |
| 61 | addeq r2, r2, #2 |
| 62 | movne r3, r3, lsl #2 |
| 63 | tst r3, #0x40 |
| 64 | addeq r2, r2, #1 |
| 65 | mov r0, r2 |
| 66 | RETINSTR(mov,pc,lr) |
| 67 | |