1/*
2 * linux/arch/unicore32/lib/findbit.S
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Copyright (C) 2001-2010 GUAN Xue-tao
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12#include <linux/linkage.h>
13#include <asm/assembler.h>
14                .text
15
16/*
17 * Purpose  : Find a 'zero' bit
18 * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
19 */
20ENTRY(find_first_zero_bit)
21		cxor.a	r1, #0
22		beq	3f
23		mov	r2, #0
241:		ldb	r3, [r0+], r2 >> #3
25		xor.a	r3, r3, #0xff		@ invert bits
26		bne	.L_found		@ any now set - found zero bit
27		add	r2, r2, #8		@ next bit pointer
282:		csub.a	r2, r1			@ any more?
29		bub	1b
303:		mov	r0, r1			@ no free bits
31		mov	pc, lr
32ENDPROC(find_first_zero_bit)
33
34/*
35 * Purpose  : Find next 'zero' bit
36 * Prototype: int find_next_zero_bit
37 *		(void *addr, unsigned int maxbit, int offset)
38 */
39ENTRY(find_next_zero_bit)
40		cxor.a	r1, #0
41		beq	3b
42		and.a	ip, r2, #7
43		beq	1b			@ If new byte, goto old routine
44		ldb	r3, [r0+], r2 >> #3
45		xor	r3, r3, #0xff		@ now looking for a 1 bit
46		mov.a	r3, r3 >> ip		@ shift off unused bits
47		bne	.L_found
48		or	r2, r2, #7		@ if zero, then no bits here
49		add	r2, r2, #1		@ align bit pointer
50		b	2b			@ loop for next bit
51ENDPROC(find_next_zero_bit)
52
53/*
54 * Purpose  : Find a 'one' bit
55 * Prototype: int find_first_bit
56 *		(const unsigned long *addr, unsigned int maxbit);
57 */
58ENTRY(find_first_bit)
59		cxor.a	r1, #0
60		beq	3f
61		mov	r2, #0
621:		ldb	r3, [r0+], r2 >> #3
63		mov.a	r3, r3
64		bne	.L_found		@ any now set - found zero bit
65		add	r2, r2, #8		@ next bit pointer
662:		csub.a	r2, r1			@ any more?
67		bub	1b
683:		mov	r0, r1			@ no free bits
69		mov	pc, lr
70ENDPROC(find_first_bit)
71
72/*
73 * Purpose  : Find next 'one' bit
74 * Prototype: int find_next_zero_bit
75 *		(void *addr, unsigned int maxbit, int offset)
76 */
77ENTRY(find_next_bit)
78		cxor.a	r1, #0
79		beq	3b
80		and.a	ip, r2, #7
81		beq	1b			@ If new byte, goto old routine
82		ldb	r3, [r0+], r2 >> #3
83		mov.a	r3, r3 >> ip		@ shift off unused bits
84		bne	.L_found
85		or	r2, r2, #7		@ if zero, then no bits here
86		add	r2, r2, #1		@ align bit pointer
87		b	2b			@ loop for next bit
88ENDPROC(find_next_bit)
89
90/*
91 * One or more bits in the LSB of r3 are assumed to be set.
92 */
93.L_found:
94		rsub	r1, r3, #0
95		and	r3, r3, r1
96		cntlz	r3, r3
97		rsub	r3, r3, #31
98		add	r0, r2, r3
99		mov	pc, lr
100
101