1/* SPDX-License-Identifier: GPL-2.0 */
2// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/linkage.h>
5#include "sysdep.h"
6
7ENTRY(memcmp)
8	/* Test if len less than 4 bytes.  */
9	mov	r3, r0
10	movi	r0, 0
11	mov	r12, r4
12	cmplti	r2, 4
13	bt	.L_compare_by_byte
14
15	andi	r13, r0, 3
16	movi	r19, 4
17
18	/* Test if s1 is not 4 bytes aligned.  */
19	bnez	r13, .L_s1_not_aligned
20
21	LABLE_ALIGN
22.L_s1_aligned:
23	/* If dest is aligned, then copy.  */
24	zext	r18, r2, 31, 4
25	/* Test if len less than 16 bytes.  */
26	bez	r18, .L_compare_by_word
27
28.L_compare_by_4word:
29	/* If aligned, load word each time.  */
30	ldw	r20, (r3, 0)
31	ldw	r21, (r1, 0)
32	/* If s1[i] != s2[i], goto .L_byte_check.  */
33	cmpne	r20, r21
34	bt	.L_byte_check
35
36	ldw	r20, (r3, 4)
37	ldw	r21, (r1, 4)
38	cmpne	r20, r21
39	bt	.L_byte_check
40
41	ldw	r20, (r3, 8)
42	ldw	r21, (r1, 8)
43	cmpne	r20, r21
44	bt	.L_byte_check
45
46	ldw	r20, (r3, 12)
47	ldw	r21, (r1, 12)
48	cmpne	r20, r21
49	bt	.L_byte_check
50
51	PRE_BNEZAD (r18)
52	addi	a3, 16
53	addi	a1, 16
54
55	BNEZAD (r18, .L_compare_by_4word)
56
57.L_compare_by_word:
58	zext	r18, r2, 3, 2
59	bez	r18, .L_compare_by_byte
60.L_compare_by_word_loop:
61	ldw	r20, (r3, 0)
62	ldw	r21, (r1, 0)
63	addi	r3, 4
64	PRE_BNEZAD (r18)
65	cmpne	r20, r21
66	addi    r1, 4
67	bt	.L_byte_check
68	BNEZAD (r18, .L_compare_by_word_loop)
69
70.L_compare_by_byte:
71        zext    r18, r2, 1, 0
72        bez     r18, .L_return
73.L_compare_by_byte_loop:
74        ldb     r0, (r3, 0)
75        ldb     r4, (r1, 0)
76        addi    r3, 1
77        subu    r0, r4
78        PRE_BNEZAD (r18)
79        addi    r1, 1
80        bnez    r0, .L_return
81        BNEZAD (r18, .L_compare_by_byte_loop)
82
83.L_return:
84        mov     r4, r12
85        rts
86
87# ifdef __CSKYBE__
88/* d[i] != s[i] in word, so we check byte 0.  */
89.L_byte_check:
90        xtrb0   r0, r20
91        xtrb0   r2, r21
92        subu    r0, r2
93        bnez    r0, .L_return
94
95        /* check byte 1 */
96        xtrb1   r0, r20
97        xtrb1   r2, r21
98        subu    r0, r2
99        bnez    r0, .L_return
100
101        /* check byte 2 */
102        xtrb2   r0, r20
103        xtrb2   r2, r21
104        subu    r0, r2
105        bnez    r0, .L_return
106
107        /* check byte 3 */
108        xtrb3   r0, r20
109        xtrb3   r2, r21
110        subu    r0, r2
111# else
112/* s1[i] != s2[i] in word, so we check byte 3.  */
113.L_byte_check:
114	xtrb3	r0, r20
115	xtrb3	r2, r21
116        subu    r0, r2
117        bnez    r0, .L_return
118
119	/* check byte 2 */
120	xtrb2	r0, r20
121	xtrb2	r2, r21
122        subu    r0, r2
123        bnez    r0, .L_return
124
125	/* check byte 1 */
126	xtrb1	r0, r20
127	xtrb1	r2, r21
128	subu	r0, r2
129	bnez    r0, .L_return
130
131	/* check byte 0 */
132	xtrb0	r0, r20
133	xtrb0	r2, r21
134	subu	r0, r2
135	br	.L_return
136# endif /* !__CSKYBE__ */
137
138/* Compare when s1 is not aligned.  */
139.L_s1_not_aligned:
140	sub	r13, r19, r13
141	sub	r2, r13
142.L_s1_not_aligned_loop:
143	ldb	r0, (r3, 0)
144	ldb	r4, (r1, 0)
145	addi	r3, 1
146	subu	r0, r4
147	PRE_BNEZAD (r13)
148	addi	r1, 1
149	bnez	r0, .L_return
150	BNEZAD (r13, .L_s1_not_aligned_loop)
151	br	.L_s1_aligned
152ENDPROC(memcmp)
153