Substring
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/* ===============================
This program uses codes from Rosetta Code.
See: https://rosettacode.org/wiki/Substring
This code follows Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.
=============================== */
/* ARM assembly AARCH64 Raspberry PI 3B */
/* program substring.s */
/*******************************************/
/* Constantes file */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
/*******************************************/
/* Initialized data */
/*******************************************/
.data
szMessString: .asciz "Result : "
szString1: .asciz "abcdefghijklmnopqrstuvwxyz"
szStringStart: .asciz "abcdefg"
szCarriageReturn: .asciz "\n"
/*******************************************/
/* UnInitialized data */
/*******************************************/
.bss
szSubString: .skip 500 // buffer result
/*******************************************/
/* code section */
/*******************************************/
.text
.global main
main:
ldr x0,qAdrszString1 // address input string
ldr x1,qAdrszSubString // address output string
mov x2,22 // location
mov x3,4 // length
bl subStringNbChar // starting from n characters in and of m length
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszSubString // display substring result
bl affichageMess
ldr x0,qAdrszCarriageReturn // display line return
bl affichageMess
//
ldr x0,qAdrszString1
ldr x1,qAdrszSubString
mov x2,15 // location
bl subStringEnd //starting from n characters in, up to the end of the string
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszSubString
bl affichageMess
ldr x0,qAdrszCarriageReturn // display line return
bl affichageMess
//
ldr x0,qAdrszString1
ldr x1,qAdrszSubString
bl subStringMinus // whole string minus last character
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszSubString
bl affichageMess
ldr x0,qAdrszCarriageReturn // display line return
bl affichageMess
//
ldr x0,qAdrszString1
ldr x1,qAdrszSubString
mov x2,'c' // start character
mov x3,5 // length
bl subStringStChar //starting from a known character within the string and of m length
cmp x0,-1 // error ?
beq 2f
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszSubString
bl affichageMess
ldr x0,qAdrszCarriageReturn // display line return
bl affichageMess
//
2:
ldr x0,qAdrszString1
ldr x1,qAdrszSubString
ldr x2,qAdrszStringStart // sub string to start
mov x3,10 // length
bl subStringStString // starting from a known substring within the string and of m length
cmp x0,-1 // error ?
beq 3f
ldr x0,qAdrszMessString // display message
bl affichageMess
ldr x0,qAdrszSubString
bl affichageMess
ldr x0,qAdrszCarriageReturn // display line return
bl affichageMess
3:
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
qAdrszString1: .quad szString1
qAdrszSubString: .quad szSubString
qAdrszStringStart: .quad szStringStart
qAdrszCarriageReturn: .quad szCarriageReturn
/******************************************************************/
/* sub strings index start number of characters */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of the output string */
/* x2 contains the start index */
/* x3 contains numbers of characters to extract */
/* x0 returns number of characters or -1 if error */
subStringNbChar:
stp x1,lr,[sp,-16]! // save registers
mov x14,#0 // counter byte output string
1:
ldrb w15,[x0,x2] // load byte string input
cbz x15,2f // zero final ?
strb w15,[x1,x14] // store byte output string
add x2,x2,1 // increment counter
add x14,x14,1
cmp x14,x3 // end ?
blt 1b // no -> loop
2:
strb wzr,[x1,x14] // store final zero byte string 2
mov x0,x14
100:
ldp x1,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/******************************************************************/
/* sub strings index start at end of string */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of the output string */
/* x2 contains the start index */
/* x0 returns number of characters or -1 if error */
subStringEnd:
stp x2,lr,[sp,-16]! // save registers
mov x14,0 // counter byte output string
1:
ldrb w15,[x0,x2] // load byte string 1
cbz x15,2f // zero final ?
strb w15,[x1,x14]
add x2,x2,1
add x14,x14,1
b 1b // loop
2:
strb wzr,[x1,x14] // store final zero byte string 2
mov x0,x14
100:
ldp x2,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/******************************************************************/
/* whole string minus last character */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of the output string */
/* x0 returns number of characters or -1 if error */
subStringMinus:
stp x1,lr,[sp,-16]! // save registers
mov x12,0 // counter byte input string
mov x14,0 // counter byte output string
1:
ldrb w15,[x0,x12] // load byte string
cbz x15,2f // zero final ?
strb w15,[x1,x14]
add x12,x12,1
add x14,x14,1
b 1b // loop
2:
sub x14,x14,1
strb wzr,[x1,x14] // store final zero byte string 2
mov x0,x14
100:
ldp x1,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/******************************************************************/
/* starting from a known character within the string and of m length */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of the output string */
/* x2 contains the character */
/* x3 contains the length
/* x0 returns number of characters or -1 if error */
subStringStChar:
stp x1,lr,[sp,-16]! // save registers
mov x16,0 // counter byte input string
mov x14,0 // counter byte output string
1:
ldrb w15,[x0,x16] // load byte string
cbz x15,4f // zero final ?
cmp x15,x2 // character find ?
beq 2f // yes
add x16,x16,1 // no -> increment indice
b 1b // loop
2:
strb w15,[x1,x14]
add x16,x16,1
add x14,x14,1
cmp x14,x3
bge 3f
ldrb w15,[x0,x16] // load byte string
cbnz x15,2b // loop if no zero final
3:
strb wzr,[x1,x14] // store final zero byte string 2
mov x0,x14
b 100f
4:
strb w15,[x1,x14]
mov x0,#-1
100:
ldp x1,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/******************************************************************/
/* starting from a known substring within the string and of m length */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of the output string */
/* x2 contains the address of string to start */
/* x3 contains the length
/* x0 returns number of characters or -1 if error */
subStringStString:
stp x1,lr,[sp,-16]! // save registers
stp x20,x21,[sp,-16]! // save registers
mov x20,x0 // save address
mov x21,x1 // save address output string
mov x1,x2
bl searchSubString
cmp x0,-1 // not found ?
beq 100f
mov x16,x0 // counter byte input string
mov x14,0
1:
ldrb w15,[x20,x16] // load byte string
strb w15,[x21,x14]
cmp x15,#0 // zero final ?
csel x0,x14,x0,eq
beq 100f
add x14,x14,1
cmp x14,x3
add x15,x16,1
csel x16,x15,x16,lt
blt 1b // loop
strb wzr,[x21,x14]
mov x0,x14 // return indice
100:
ldp x20,x21,[sp],16 // restaur 2 registers
ldp x1,lr,[sp],16 // restaur 2 registers
ret // return to address lr x30
/******************************************************************/
/* search a substring in the string */
/******************************************************************/
/* x0 contains the address of the input string */
/* x1 contains the address of substring */
/* x0 returns index of substring in string or -1 if not found */
searchSubString:
stp x1,lr,[sp,-16]! // save registers
mov x12,0 // counter byte input string
mov x13,0 // counter byte string
mov x16,-1 // index found
ldrb w14,[x1,x13]
1:
ldrb w15,[x0,x12] // load byte string
cbz x15,4f // zero final ?
cmp x15,x14 // compare character
beq 2f
mov x16,-1 // no equals - > raz index
mov x13,0 // and raz counter byte
add x12,x12,1 // and increment counter byte
b 1b // and loop
2: // characters equals
cmp x16,-1 // first characters equals ?
csel x16,x12,x16,eq
// moveq x6,x2 // yes -> index begin in x6
add x13,x13,1 // increment counter substring
ldrb w14,[x1,x13] // and load next byte
cbz x14,3f // zero final ? yes -> end search
add x12,x12,1 // else increment counter string
b 1b // and loop
3:
mov x0,x16 // return indice
b 100f
4:
mov x0,#-1 // yes returns error
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"
