CoCalc -- asm-utils.S

GitHub Repository: torvalds/linux
Path: blob/master/tools/testing/selftests/arm64/fp/asm-utils.S
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// SPDX-License-Identifier: GPL-2.0-only
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// Copyright (C) 2015-2021 ARM Limited.
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// Original author: Dave Martin <Dave.Martin@arm.com>
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//
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// Utility functions for assembly code.
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#include <asm/unistd.h>
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#include "assembler.h"
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// Print a single character x0 to stdout
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// Clobbers x0-x2,x8
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function putc
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	str	x0, [sp, #-16]!
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	mov	x0, #1			// STDOUT_FILENO
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	mov	x1, sp
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	mov	x2, #1
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	mov	x8, #__NR_write
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	svc	#0
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	add	sp, sp, #16
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	ret
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endfunction
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.globl	putc
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// Print a NUL-terminated string starting at address x0 to stdout
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// Clobbers x0-x3,x8
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function puts
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	mov	x1, x0
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	mov	x2, #0
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0:	ldrb	w3, [x0], #1
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	cbz	w3, 1f
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	add	x2, x2, #1
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	b	0b
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1:	mov	w0, #1			// STDOUT_FILENO
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	mov	x8, #__NR_write
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	svc	#0
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	ret
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endfunction
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.globl	puts
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// Print an unsigned decimal number x0 to stdout
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// Clobbers x0-x4,x8
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function putdec
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	mov	x1, sp
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	str	x30, [sp, #-32]!	// Result can't be > 20 digits
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	mov	x2, #0
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	strb	w2, [x1, #-1]!		// Write the NUL terminator
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	mov	x2, #10
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0:	udiv	x3, x0, x2		// div-mod loop to generate the digits
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	msub	x0, x3, x2, x0
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	add	w0, w0, #'0'
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	strb	w0, [x1, #-1]!
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	mov	x0, x3
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	cbnz	x3, 0b
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	ldrb	w0, [x1]
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	cbnz	w0, 1f
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	mov	w0, #'0'		// Print "0" for 0, not ""
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	strb	w0, [x1, #-1]!
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1:	mov	x0, x1
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	bl	puts
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	ldr	x30, [sp], #32
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	ret
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endfunction
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.globl	putdec
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// Print an unsigned decimal number x0 to stdout, followed by a newline
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// Clobbers x0-x5,x8
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function putdecn
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	mov	x5, x30
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	bl	putdec
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	mov	x0, #'\n'
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	bl	putc
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	ret	x5
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endfunction
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.globl	putdecn
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// Clobbers x0-x3,x8
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function puthexb
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	str	x30, [sp, #-0x10]!
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	mov	w3, w0
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	lsr	w0, w0, #4
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	bl	puthexnibble
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	mov	w0, w3
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	ldr	x30, [sp], #0x10
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	// fall through to puthexnibble
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endfunction
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.globl	puthexb
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// Clobbers x0-x2,x8
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function puthexnibble
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	and	w0, w0, #0xf
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	cmp	w0, #10
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	blo	1f
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	add	w0, w0, #'a' - ('9' + 1)
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1:	add	w0, w0, #'0'
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	b	putc
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endfunction
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.globl	puthexnibble
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// x0=data in, x1=size in, clobbers x0-x5,x8
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function dumphex
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	str	x30, [sp, #-0x10]!
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	mov	x4, x0
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	mov	x5, x1
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0:	subs	x5, x5, #1
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	b.lo	1f
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	ldrb	w0, [x4], #1
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	bl	puthexb
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	b	0b
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1:	ldr	x30, [sp], #0x10
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	ret
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endfunction
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.globl	dumphex
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	// Trivial memory copy: copy x2 bytes, starting at address x1, to address x0.
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// Clobbers x0-x3
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function memcpy
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	cmp	x2, #0
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	b.eq	1f
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0:	ldrb	w3, [x1], #1
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	strb	w3, [x0], #1
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	subs	x2, x2, #1
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	b.ne	0b
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1:	ret
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endfunction
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.globl	memcpy
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// Fill x1 bytes starting at x0 with 0xae (for canary purposes)
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// Clobbers x1, x2.
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function memfill_ae
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	mov	w2, #0xae
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	b	memfill
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endfunction
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.globl	memfill_ae
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// Fill x1 bytes starting at x0 with 0.
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// Clobbers x1, x2.
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function memclr
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	mov	w2, #0
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endfunction
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.globl	memclr
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	// fall through to memfill
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// Trivial memory fill: fill x1 bytes starting at address x0 with byte w2
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// Clobbers x1
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function memfill
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	cmp	x1, #0
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	b.eq	1f
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0:	strb	w2, [x0], #1
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	subs	x1, x1, #1
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	b.ne	0b
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1:	ret
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endfunction
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.globl	memfill
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