1 // SPDX-License-Identifier: GPL-2.0-only
2 // Copyright (C) 2015-2021 ARM Limited.
3 // Original author: Dave Martin <Dave.Martin@arm.com>
4 //
5 // Utility functions for assembly code.
6
7 #include <asm/unistd.h>
8 #include "assembler.h"
9
10 // Print a single character x0 to stdout
11 // Clobbers x0-x2,x8
12 function putc
13 str x0, [sp, #-16]!
14
15 mov x0, #1 // STDOUT_FILENO
16 mov x1, sp
17 mov x2, #1
18 mov x8, #__NR_write
19 svc #0
20
21 add sp, sp, #16
22 ret
23 endfunction
24 .globl putc
25
26 // Print a NUL-terminated string starting at address x0 to stdout
27 // Clobbers x0-x3,x8
28 function puts
29 mov x1, x0
30
31 mov x2, #0
32 0: ldrb w3, [x0], #1
33 cbz w3, 1f
34 add x2, x2, #1
35 b 0b
36
37 1: mov w0, #1 // STDOUT_FILENO
38 mov x8, #__NR_write
39 svc #0
40
41 ret
42 endfunction
43 .globl puts
44
45 // Print an unsigned decimal number x0 to stdout
46 // Clobbers x0-x4,x8
47 function putdec
48 mov x1, sp
49 str x30, [sp, #-32]! // Result can't be > 20 digits
50
51 mov x2, #0
52 strb w2, [x1, #-1]! // Write the NUL terminator
53
54 mov x2, #10
55 0: udiv x3, x0, x2 // div-mod loop to generate the digits
56 msub x0, x3, x2, x0
57 add w0, w0, #'0'
58 strb w0, [x1, #-1]!
59 mov x0, x3
60 cbnz x3, 0b
61
62 ldrb w0, [x1]
63 cbnz w0, 1f
64 mov w0, #'0' // Print "0" for 0, not ""
65 strb w0, [x1, #-1]!
66
67 1: mov x0, x1
68 bl puts
69
70 ldr x30, [sp], #32
71 ret
72 endfunction
73 .globl putdec
74
75 // Print an unsigned decimal number x0 to stdout, followed by a newline
76 // Clobbers x0-x5,x8
77 function putdecn
78 mov x5, x30
79
80 bl putdec
81 mov x0, #'\n'
82 bl putc
83
84 ret x5
85 endfunction
86 .globl putdecn
87
88 // Clobbers x0-x3,x8
89 function puthexb
90 str x30, [sp, #-0x10]!
91
92 mov w3, w0
93 lsr w0, w0, #4
94 bl puthexnibble
95 mov w0, w3
96
97 ldr x30, [sp], #0x10
98 // fall through to puthexnibble
99 endfunction
100 .globl puthexb
101
102 // Clobbers x0-x2,x8
103 function puthexnibble
104 and w0, w0, #0xf
105 cmp w0, #10
106 blo 1f
107 add w0, w0, #'a' - ('9' + 1)
108 1: add w0, w0, #'0'
109 b putc
110 endfunction
111 .globl puthexnibble
112
113 // x0=data in, x1=size in, clobbers x0-x5,x8
114 function dumphex
115 str x30, [sp, #-0x10]!
116
117 mov x4, x0
118 mov x5, x1
119
120 0: subs x5, x5, #1
121 b.lo 1f
122 ldrb w0, [x4], #1
123 bl puthexb
124 b 0b
125
126 1: ldr x30, [sp], #0x10
127 ret
128 endfunction
129 .globl dumphex
130
131 // Trivial memory copy: copy x2 bytes, starting at address x1, to address x0.
132 // Clobbers x0-x3
133 function memcpy
134 cmp x2, #0
135 b.eq 1f
136 0: ldrb w3, [x1], #1
137 strb w3, [x0], #1
138 subs x2, x2, #1
139 b.ne 0b
140 1: ret
141 endfunction
142 .globl memcpy
143
144 // Fill x1 bytes starting at x0 with 0xae (for canary purposes)
145 // Clobbers x1, x2.
146 function memfill_ae
147 mov w2, #0xae
148 b memfill
149 endfunction
150 .globl memfill_ae
151
152 // Fill x1 bytes starting at x0 with 0.
153 // Clobbers x1, x2.
154 function memclr
155 mov w2, #0
156 endfunction
157 .globl memclr
158 // fall through to memfill
159
160 // Trivial memory fill: fill x1 bytes starting at address x0 with byte w2
161 // Clobbers x1
162 function memfill
163 cmp x1, #0
164 b.eq 1f
165
166 0: strb w2, [x0], #1
167 subs x1, x1, #1
168 b.ne 0b
169
170 1: ret
171 endfunction
172 .globl memfill
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