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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/unicore32/lib/findbit.S
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/*

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 * linux/arch/unicore32/lib/findbit.S

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 *

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 * Code specific to PKUnity SoC and UniCore ISA

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 *

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 * Copyright (C) 2001-2010 GUAN Xue-tao

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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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#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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__uc32_find_first_zero_bit:

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		cxor.a	r1, #0

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		beq	3f

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		mov	r2, #0

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1:		ldb	r3, [r0+], r2 >> #3

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		xor.a	r3, r3, #0xff		@ invert bits

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		bne	.L_found		@ any now set - found zero bit

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		add	r2, r2, #8		@ next bit pointer

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2:		csub.a	r2, r1			@ any more?

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		bub	1b

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3:		mov	r0, r1			@ no free bits

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		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

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 *		(void *addr, unsigned int maxbit, int offset)

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 */

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ENTRY(__uc32_find_next_zero_bit)

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		cxor.a	r1, #0

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		beq	3b

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		and.a	ip, r2, #7

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		beq	1b			@ If new byte, goto old routine

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		ldb	r3, [r0+], r2 >> #3

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		xor	r3, r3, #0xff		@ now looking for a 1 bit

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		mov.a	r3, r3 >> ip		@ shift off unused bits

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		bne	.L_found

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		or	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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ENDPROC(__uc32_find_next_zero_bit)

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/*

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 * Purpose  : Find a 'one' bit

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 * Prototype: int find_first_bit

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 *		(const unsigned long *addr, unsigned int maxbit);

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 */

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__uc32_find_first_bit:

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		cxor.a	r1, #0

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		beq	3f

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		mov	r2, #0

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1:		ldb	r3, [r0+], r2 >> #3

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		mov.a	r3, r3

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		bne	.L_found		@ any now set - found zero bit

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		add	r2, r2, #8		@ next bit pointer

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2:		csub.a	r2, r1			@ any more?

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		bub	1b

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3:		mov	r0, r1			@ no free bits

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		mov	pc, lr

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/*

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 * Purpose  : Find next 'one' bit

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 * Prototype: int find_next_zero_bit

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 *		(void *addr, unsigned int maxbit, int offset)

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 */

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ENTRY(__uc32_find_next_bit)

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		cxor.a	r1, #0

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		beq	3b

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		and.a	ip, r2, #7

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		beq	1b			@ If new byte, goto old routine

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		ldb	r3, [r0+], r2 >> #3

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		mov.a	r3, r3 >> ip		@ shift off unused bits

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		bne	.L_found

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		or	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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ENDPROC(__uc32_find_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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.L_found:

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		rsub	r1, r3, #0

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		and	r3, r3, r1

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		cntlz	r3, r3

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		rsub	r3, r3, #31

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		add	r0, r2, r3

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		mov	pc, lr

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