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String prepend: Difference between revisions
add task to ARM64 assembly Raspberry Pi
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To illustrate the operation, show the content of the variable.
<br><br>
=={{header|AArch64 Assembly}}==
{{works with|as|Raspberry Pi 3B version Buster 64 bits}}
<lang AArch64 Assembly>
/* ARM assembly AARCH64 Raspberry PI 3B */
/* program appendstr64.s */
/*******************************************/
/* Constantes file */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
/*******************************************/
/* Initialized data */
/*******************************************/
.data
szMessString: .asciz "British Museum.\n"
szComplement: .skip 80
szStringStart: .asciz "The rosetta stone is at "
szCarriageReturn: .asciz "\n"
/*******************************************/
/* UnInitialized data */
/*******************************************/
.bss
/*******************************************/
/* code section */
/*******************************************/
.text
.global main
main:
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszMessString
ldr x1,qAdrszStringStart
bl prepend // append sting2 to string1
ldr x0,qAdrszMessString
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
100: // standard end of the program
mov x0,0 // return code
mov x8,EXIT // request to exit program
svc 0 // perform system call
qAdrszMessString: .quad szMessString
qAdrszStringStart: .quad szStringStart
qAdrszCarriageReturn: .quad szCarriageReturn
/**************************************************/
/* append two strings */
/**************************************************/
/* x0 contains the address of the string1 */
/* x1 contains the address of the string2 */
prepend:
stp x1,lr,[sp,-16]! // save registers
mov x3,#0 // length counter
1: // compute length of string 1
ldrb w4,[x0,x3]
cmp w4,#0
cinc x3,x3,ne // increment to one if not equal
bne 1b // loop if not equal
mov x5,#0 // length counter insertion string
2: // compute length of insertion string
ldrb w4,[x1,x5]
cmp x4,#0
cinc x5,x5,ne // increment to one if not equal
bne 2b
cmp x5,#0
beq 99f // string empty -> error
add x3,x3,x5 // add 2 length
add x3,x3,#1 // +1 for final zero
mov x6,x0 // save address string 1
mov x0,#0 // allocation place heap
mov x8,BRK // call system 'brk'
svc #0
mov x5,x0 // save address heap for output string
add x0,x0,x3 // reservation place x3 length
mov x8,BRK // call system 'brk'
svc #0
cmp x0,#-1 // allocation error
beq 99f
mov x4,#0 // counter byte string 2
3:
ldrb w3,[x1,x4] // load byte string 2
cbz x3,4f // zero final ?
strb w3,[x5,x4] // store byte string 2 in heap
add x4,x4,1 // increment counter 1
b 3b // no -> loop
4:
mov x2,#0 // counter byte string 1
5:
ldrb w3,[x6,x2] // load byte string 1
strb w3,[x5,x4] // store byte string in heap
cbz x3,6f // zero final ?
add x2,x2,1 // no -> increment counter 1
add x4,x4,1 // no -> increment counter 2
b 5b // no -> loop
6: // recopie heap in string 1
mov x2,#0 // counter byte string
7:
ldrb w3,[x5,x2] // load byte string in heap
strb w3,[x6,x2] // store byte string 1
cbz x3,100f // zero final ?
add x2,x2,1 // no -> increment counter 1
b 7b // no -> loop
100:
ldp x1,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/********************************************************/
/* File Include fonctions */
/********************************************************/
/* for this file see task include a file in language AArch64 assembly */
.include "../includeARM64.inc"
</lang>
{{Output}}
<pre>
British Museum.
The rosetta stone is at British Museum.
</pre>
=={{header|Ada}}==
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