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 .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 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 */ 41ENTRY(_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