RosettaCodeData/Task/Environment-variables/AArch64-Assembly/environment-variables.aarch64

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/* ARM assembly AARCH64 Raspberry PI 3B */
/* program varenvir64.s */
/***********************/
/* Constantes */
/***********************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
/*******************************************/
/* Macros */
/*******************************************/
//.include "../../ficmacros64.inc" @ for developer debugging
/***********************/
/* Initialized data */
/***********************/
.data
szMessDebutPgm: .asciz "Program 64 bits start. \n"
szMessFinOK: .asciz "Program normal end. \n"
szCarriageReturn: .asciz "\n"
szmessresUser: .asciz "result for USER :"
szmessresHome: .asciz "result for HOME :"
szmessresPath: .asciz "result for PATH :"
szVarRech: .asciz "USER="
.equ LGVARRECH, . - szVarRech - 1 // car zero final
szVarRech1: .asciz "HOME="
.equ LGVARRECH1, . - szVarRech1 - 1 // car zero final
szVarRech2: .asciz "PATH="
.equ LGVARRECH2, . - szVarRech2 - 1 // car zero final
/***********************/
/* UnInitialized data */
/***********************/
.bss
.align 4
/***********************/
/* code section */
/***********************/
.text
.global main
main: // entry of program
ldr x0,qAdrszMessDebutPgm
bl affichageMess
mov fp,sp // fp <- start address
mov x0,fp
// variable search USER
ldr x2,[fp] // number param
add x2,x2,#2
ldr x1,qAdrszVarRech
1:
ldr x0,[fp,x2,lsl #3] // load variable address
cmp x0,#0 // end ?
beq 2f
mov x4,x0
bl searchSubBeginString // search variable name
cmp x0,#-1 // no find ?
cinc x2,x2,eq
beq 1b
ldr x0,qAdrszmessresUser
bl affichageMess
add x0,x4,#LGVARRECH
bl affichageMess // display result
ldr x0,qAdrszCarriageReturn
bl affichageMess
2:
ldr x2,[fp] // search variable HOME
add x2,x2,#2
ldr x1,qAdrszVarRech1
3:
ldr x0,[fp,x2,lsl #3]
cmp x0,#0
beq 4f
mov x4,x0
bl searchSubBeginString
cmp x0,#-1
cinc x2,x2,eq
beq 3b
ldr x0,qAdrszmessresHome
bl affichageMess
add x0,x4,#LGVARRECH
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
4:
ldr x2,[fp] // search variable PATH
add x2,x2,#2
ldr x1,qAdrszVarRech2
5:
ldr x0,[fp,x2,lsl #3]
cmp x0,#0
beq 6f
mov x4,x0
bl searchSubBeginString
cmp x0,#-1
cinc x2,x2,eq
beq 5b
ldr x0,qAdrszmessresPath
bl affichageMess
add x0,x4,#LGVARRECH
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
6:
ldr x0,qAdrszMessFinOK
bl affichageMess
100: // standard end of the program
mov x0, #0 // return code
mov x8,EXIT
svc 0 // perform the system call
qAdrszMessDebutPgm: .quad szMessDebutPgm
qAdrszMessFinOK: .quad szMessFinOK
qAdrszCarriageReturn: .quad szCarriageReturn
qAdrszVarRech: .quad szVarRech
qAdrszVarRech1: .quad szVarRech1
qAdrszVarRech2: .quad szVarRech2
qAdrszmessresUser: .quad szmessresUser
qAdrszmessresPath: .quad szmessresPath
qAdrszmessresHome: .quad szmessresHome
/******************************************************************/
/* search a substring at the string beguining */
/******************************************************************/
/* r0 contains the address of the input string */
/* r1 contains the address of substring */
/* r0 returns index of substring in string or -1 if not found */
searchSubBeginString:
stp x1,lr,[sp,-16]! // save registers
stp x2,x3,[sp,-16]!
stp x4,x5,[sp,-16]!
mov x2,#0 // counter byte input string
mov x3,#0 // counter byte string
1:
ldrb w4,[x1,x3]
ldrb w5,[x0,x2] // load byte string
cmp x5,#0
beq 3f
cmp x4,#0 // zero final ?
csel x0,xzr,x0,eq // yes string find in position 0
beq 100f
cmp x5,x4 // compare character
beq 2f
mov x0,#-1 // no return no find
b 100f
2:
add x2,x2,#1 // and increment counter byte
add x3,x3,#1 // and increment
b 1b // and loop
3:
mov x2,-1 //
cmp x4,#0
mov x0,#-1 // yes returns no find
bne 100f
mov x0,#0 // string find in position 0
100:
ldp x4,x5,[sp],16
ldp x2,x3,[sp],16
ldp x1,lr,[sp],16 // restaur registers
ret
/***************************************************/
/* ROUTINES INCLUDE */
/***************************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeARM64.inc"