96 lines
4.1 KiB
Plaintext
96 lines
4.1 KiB
Plaintext
/* ARM assembly Raspberry PI */
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/* program appendstr.s */
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/* Constantes */
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.equ STDOUT, 1 @ Linux output console
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.equ EXIT, 1 @ Linux syscall
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.equ WRITE, 4 @ Linux syscall
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.equ BUFFERSIZE, 100
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/* Initialized data */
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.data
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szMessString: .asciz "String :\n"
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szString1: .asciz "Alphabet : "
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sComplement: .fill BUFFERSIZE,1,0
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szString2: .asciz "abcdefghijklmnopqrstuvwxyz"
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szCarriageReturn: .asciz "\n"
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/* UnInitialized data */
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.bss
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/* code section */
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.text
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.global main
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main:
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszString1 @ display begin string
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bl affichageMess
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ldr r0,iAdrszCarriageReturn @ display line return
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bl affichageMess
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ldr r0,iAdrszString1
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ldr r1,iAdrszString2
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bl append @ append sting2 to string1
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ldr r0,iAdrszMessString
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bl affichageMess
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ldr r0,iAdrszString1 @ display string
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bl affichageMess
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ldr r0,iAdrszCarriageReturn
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bl affichageMess
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100: @ standard end of the program
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mov r0, #0 @ return code
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mov r7, #EXIT @ request to exit program
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svc 0 @ perform system call
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iAdrszMessString: .int szMessString
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iAdrszString1: .int szString1
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iAdrszString2: .int szString2
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iAdrszCarriageReturn: .int szCarriageReturn
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/******************************************************************/
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/* append two strings */
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/******************************************************************/
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/* r0 contains the address of the string1 */
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/* r1 contains the address of the string2 */
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append:
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push {r0,r1,r2,r7,lr} @ save registers
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mov r2,#0 @ counter byte string 1
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1:
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ldrb r3,[r0,r2] @ load byte string 1
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cmp r3,#0 @ zero final ?
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addne r2,#1
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bne 1b @ no -> loop
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mov r4,#0 @ counter byte string 2
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2:
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ldrb r3,[r1,r4] @ load byte string 2
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strb r3,[r0,r2] @ store byte string 1
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cmp r3,#0 @ zero final ?
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addne r2,#1 @ no -> increment counter 1
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addne r4,#1 @ no -> increment counter 2
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bne 2b @ no -> loop
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100:
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pop {r0,r1,r2,r7,lr} @ restaur registers
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bx lr @ return
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/******************************************************************/
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/* display text with size calculation */
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/******************************************************************/
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/* r0 contains the address of the message */
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affichageMess:
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push {r0,r1,r2,r7,lr} @ save registers
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mov r2,#0 @ counter length */
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1: @ loop length calculation
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ldrb r1,[r0,r2] @ read octet start position + index
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cmp r1,#0 @ if 0 its over
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addne r2,r2,#1 @ else add 1 in the length
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bne 1b @ and loop
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@ so here r2 contains the length of the message
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mov r1,r0 @ address message in r1
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mov r0,#STDOUT @ code to write to the standard output Linux
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mov r7, #WRITE @ code call system "write"
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svc #0 @ call system
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pop {r0,r1,r2,r7,lr} @ restaur registers
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bx lr @ return
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