84 lines
2.7 KiB
Plaintext
84 lines
2.7 KiB
Plaintext
/* ARM assembly Raspberry PI */
|
|
/* program strEmpty.s */
|
|
|
|
/* Constantes */
|
|
.equ STDOUT, 1 @ Linux output console
|
|
.equ EXIT, 1 @ Linux syscall
|
|
.equ WRITE, 4 @ Linux syscall
|
|
/* Initialized data */
|
|
.data
|
|
szNotEmptyString: .asciz "String is not empty. \n"
|
|
szEmptyString: .asciz "String is empty. \n"
|
|
@ empty string
|
|
szString: .asciz "" @ with zero final
|
|
szString1: .asciz "A" @ with zero final
|
|
|
|
/* UnInitialized data */
|
|
.bss
|
|
|
|
/* code section */
|
|
.text
|
|
.global main
|
|
main: /* entry of program */
|
|
push {fp,lr} /* saves 2 registers */
|
|
|
|
@ load string
|
|
ldr r1,iAdrszString
|
|
ldrb r0,[r1] @ load first byte of string
|
|
cmp r0,#0 @ compar with zero ?
|
|
bne 1f
|
|
ldr r0,iAdrszEmptyString
|
|
bl affichageMess
|
|
b 2f
|
|
1:
|
|
|
|
ldr r0,iAdrszNotEmptyString
|
|
bl affichageMess
|
|
/* second string */
|
|
2:
|
|
@ load string 1
|
|
ldr r1,iAdrszString1
|
|
ldrb r0,[r1] @ load first byte of string
|
|
cmp r0,#0 @ compar with zero ?
|
|
bne 3f
|
|
ldr r0,iAdrszEmptyString
|
|
bl affichageMess
|
|
b 100f
|
|
3:
|
|
ldr r0,iAdrszNotEmptyString
|
|
bl affichageMess
|
|
b 100f
|
|
|
|
100: /* standard end of the program */
|
|
mov r0, #0 @ return code
|
|
pop {fp,lr} @restaur 2 registers
|
|
mov r7, #EXIT @ request to exit program
|
|
swi 0 @ perform the system call
|
|
iAdrszString: .int szString
|
|
iAdrszString1: .int szString1
|
|
iAdrszNotEmptyString: .int szNotEmptyString
|
|
iAdrszEmptyString: .int szEmptyString
|
|
|
|
/******************************************************************/
|
|
/* display text with size calculation */
|
|
/******************************************************************/
|
|
/* r0 contains the address of the message */
|
|
affichageMess:
|
|
push {fp,lr} /* save registres */
|
|
push {r0,r1,r2,r7} /* save others registers */
|
|
mov r2,#0 /* counter length */
|
|
1: /* loop length calculation */
|
|
ldrb r1,[r0,r2] /* read octet start position + index */
|
|
cmp r1,#0 /* if 0 its over */
|
|
addne r2,r2,#1 /* else add 1 in the length */
|
|
bne 1b /* and loop */
|
|
/* so here r2 contains the length of the message */
|
|
mov r1,r0 /* address message in r1 */
|
|
mov r0,#STDOUT /* code to write to the standard output Linux */
|
|
mov r7, #WRITE /* code call system "write" */
|
|
swi #0 /* call systeme */
|
|
pop {r0,r1,r2,r7} /* restaur others registers */
|
|
pop {fp,lr} /* restaur des 2 registres */
|
|
bx lr /* return */
|
|
|