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