mirror of https://gitee.com/openkylin/linux.git
68 lines
1.7 KiB
ArmAsm
68 lines
1.7 KiB
ArmAsm
/*
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* linux/arch/arm/lib/findbit.S
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*
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* Copyright (C) 1995-2000 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* 16th March 2001 - John Ripley <jripley@sonicblue.com>
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* Fixed so that "size" is an exclusive not an inclusive quantity.
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* All users of these functions expect exclusive sizes, and may
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* also call with zero size.
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* Reworked by rmk.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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.text
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/*
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* Purpose : Find a 'zero' bit
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* Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
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*/
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ENTRY(_find_first_zero_bit_le)
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teq r1, #0
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beq 3f
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mov r2, #0
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1: ldrb r3, [r0, r2, lsr #3]
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eors r3, r3, #0xff @ invert bits
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bne .found @ any now set - found zero bit
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add r2, r2, #8 @ next bit pointer
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2: cmp r2, r1 @ any more?
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blo 1b
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3: mov r0, r1 @ no free bits
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RETINSTR(mov,pc,lr)
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/*
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* Purpose : Find next 'zero' bit
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* Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
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*/
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ENTRY(_find_next_zero_bit_le)
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teq r1, #0
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beq 2b
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ands ip, r2, #7
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beq 1b @ If new byte, goto old routine
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ldrb r3, [r0, r2, lsr #3]
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eor r3, r3, #0xff @ now looking for a 1 bit
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movs r3, r3, lsr ip @ shift off unused bits
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bne .found
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orr r2, r2, #7 @ if zero, then no bits here
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add r2, r2, #1 @ align bit pointer
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b 2b @ loop for next bit
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/*
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* One or more bits in the LSB of r3 are assumed to be set.
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*/
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.found: tst r3, #0x0f
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addeq r2, r2, #4
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movne r3, r3, lsl #4
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tst r3, #0x30
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addeq r2, r2, #2
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movne r3, r3, lsl #2
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tst r3, #0x40
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addeq r2, r2, #1
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mov r0, r2
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RETINSTR(mov,pc,lr)
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