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
 12function 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
 23endfunction
 24.globl	putc
 25	
 26// Print a NUL-terminated string starting at address x0 to stdout
 27// Clobbers x0-x3,x8
 28function puts
 29	mov	x1, x0
 30
 31	mov	x2, #0
 320:	ldrb	w3, [x0], #1
 33	cbz	w3, 1f
 34	add	x2, x2, #1
 35	b	0b
 36
 371:	mov	w0, #1			// STDOUT_FILENO
 38	mov	x8, #__NR_write
 39	svc	#0
 40
 41	ret
 42endfunction
 43.globl	puts
 44
 45// Print an unsigned decimal number x0 to stdout
 46// Clobbers x0-x4,x8
 47function 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
 550:	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
 671:	mov	x0, x1
 68	bl	puts
 69
 70	ldr	x30, [sp], #32
 71	ret
 72endfunction
 73.globl	putdec
 74
 75// Print an unsigned decimal number x0 to stdout, followed by a newline
 76// Clobbers x0-x5,x8
 77function putdecn
 78	mov	x5, x30
 79
 80	bl	putdec
 81	mov	x0, #'\n'
 82	bl	putc
 83
 84	ret	x5
 85endfunction
 86.globl	putdecn
 87
 88// Clobbers x0-x3,x8
 89function 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
 99endfunction
100.globl	puthexb
101
102// Clobbers x0-x2,x8
103function puthexnibble
104	and	w0, w0, #0xf
105	cmp	w0, #10
106	blo	1f
107	add	w0, w0, #'a' - ('9' + 1)
1081:	add	w0, w0, #'0'
109	b	putc
110endfunction
111.globl	puthexnibble
112
113// x0=data in, x1=size in, clobbers x0-x5,x8
114function dumphex
115	str	x30, [sp, #-0x10]!
116
117	mov	x4, x0
118	mov	x5, x1
119
1200:	subs	x5, x5, #1
121	b.lo	1f
122	ldrb	w0, [x4], #1
123	bl	puthexb
124	b	0b
125
1261:	ldr	x30, [sp], #0x10
127	ret
128endfunction
129.globl	dumphex
130
131	// Trivial memory copy: copy x2 bytes, starting at address x1, to address x0.
132// Clobbers x0-x3
133function memcpy
134	cmp	x2, #0
135	b.eq	1f
1360:	ldrb	w3, [x1], #1
137	strb	w3, [x0], #1
138	subs	x2, x2, #1
139	b.ne	0b
1401:	ret
141endfunction
142.globl	memcpy
143
144// Fill x1 bytes starting at x0 with 0xae (for canary purposes)
145// Clobbers x1, x2.
146function memfill_ae
147	mov	w2, #0xae
148	b	memfill
149endfunction
150.globl	memfill_ae
151	
152// Fill x1 bytes starting at x0 with 0.
153// Clobbers x1, x2.
154function memclr
155	mov	w2, #0
156endfunction
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
162function memfill
163	cmp	x1, #0
164	b.eq	1f
165
1660:	strb	w2, [x0], #1
167	subs	x1, x1, #1
168	b.ne	0b
169
1701:	ret
171endfunction
172.globl	memfill