309 lines
12 KiB
Plaintext
309 lines
12 KiB
Plaintext
/* ARM assembly Raspberry PI */
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/* program substring.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 "Result : "
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szString1: .asciz "abcdefghijklmnopqrstuvwxyz"
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szStringStart: .asciz "abcdefg"
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szCarriageReturn: .asciz "\n"
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/* UnInitialized data */
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.bss
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szSubString: .skip 500 @ buffer result
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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,iAdrszString1 @ address input string
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ldr r1,iAdrszSubString @ address output string
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mov r2,#22 @ location
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mov r3,#4 @ length
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bl subStringNbChar @ starting from n characters in and of m length
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszSubString @ display substring result
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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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@
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ldr r0,iAdrszString1
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ldr r1,iAdrszSubString
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mov r2,#15 @ location
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bl subStringEnd @starting from n characters in, up to the end of the string
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszSubString
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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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@
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ldr r0,iAdrszString1
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ldr r1,iAdrszSubString
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bl subStringMinus @ whole string minus last character
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszSubString
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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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@
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ldr r0,iAdrszString1
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ldr r1,iAdrszSubString
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mov r2,#'c' @ start character
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mov r3,#5 @ length
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bl subStringStChar @starting from a known character within the string and of m length
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cmp r0,#-1 @ error ?
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beq 2f
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszSubString
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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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@
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2:
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ldr r0,iAdrszString1
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ldr r1,iAdrszSubString
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ldr r2,iAdrszStringStart @ sub string to start
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mov r3,#10 @ length
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bl subStringStString @ starting from a known substring within the string and of m length
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cmp r0,#-1 @ error ?
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beq 3f
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ldr r0,iAdrszMessString @ display message
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bl affichageMess
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ldr r0,iAdrszSubString
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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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3:
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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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iAdrszSubString: .int szSubString
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iAdrszStringStart: .int szStringStart
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iAdrszCarriageReturn: .int szCarriageReturn
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/******************************************************************/
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/* sub strings index start number of characters */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of the output string */
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/* r2 contains the start index */
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/* r3 contains numbers of characters to extract */
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/* r0 returns number of characters or -1 if error */
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subStringNbChar:
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push {r1-r5,lr} @ save registers
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mov r4,#0 @ counter byte output string
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1:
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ldrb r5,[r0,r2] @ load byte string input
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cmp r5,#0 @ zero final ?
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beq 2f
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strb r5,[r1,r4] @ store byte output string
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add r2,#1 @ increment counter
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add r4,#1
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cmp r4,r3 @ end ?
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blt 1b @ no -> loop
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2:
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mov r5,#0
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strb r5,[r1,r4] @ load byte string 2
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mov r0,r4
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100:
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pop {r1-r5,lr} @ restaur registers
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bx lr @ return
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/******************************************************************/
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/* sub strings index start at end of string */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of the output string */
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/* r2 contains the start index */
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/* r0 returns number of characters or -1 if error */
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subStringEnd:
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push {r1-r5,lr} @ save registers
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mov r4,#0 @ counter byte output string
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1:
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ldrb r5,[r0,r2] @ load byte string 1
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cmp r5,#0 @ zero final ?
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beq 2f
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strb r5,[r1,r4]
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add r2,#1
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add r4,#1
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b 1b @ loop
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2:
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mov r5,#0
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strb r5,[r1,r4] @ load byte string 2
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mov r0,r4
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100:
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pop {r1-r5,lr} @ restaur registers
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bx lr
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/******************************************************************/
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/* whole string minus last character */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of the output string */
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/* r0 returns number of characters or -1 if error */
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subStringMinus:
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push {r1-r5,lr} @ save registers
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mov r2,#0 @ counter byte input string
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mov r4,#0 @ counter byte output string
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1:
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ldrb r5,[r0,r2] @ load byte string
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cmp r5,#0 @ zero final ?
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beq 2f
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strb r5,[r1,r4]
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add r2,#1
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add r4,#1
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b 1b @ loop
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2:
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sub r4,#1
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mov r5,#0
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strb r5,[r1,r4] @ load byte string 2
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mov r0,r4
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100:
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pop {r1-r5,lr} @ restaur registers
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bx lr
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/******************************************************************/
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/* starting from a known character within the string and of m length */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of the output string */
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/* r2 contains the character */
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/* r3 contains the length
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/* r0 returns number of characters or -1 if error */
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subStringStChar:
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push {r1-r5,lr} @ save registers
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mov r6,#0 @ counter byte input string
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mov r4,#0 @ counter byte output string
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1:
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ldrb r5,[r0,r6] @ load byte string
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cmp r5,#0 @ zero final ?
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streqb r5,[r1,r4]
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moveq r0,#-1
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beq 100f
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cmp r5,r2
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beq 2f
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add r6,#1
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b 1b @ loop
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2:
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strb r5,[r1,r4]
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add r6,#1
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add r4,#1
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cmp r4,r3
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bge 3f
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ldrb r5,[r0,r6] @ load byte string
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cmp r5,#0
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bne 2b
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3:
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mov r5,#0
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strb r5,[r1,r4] @ load byte string 2
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mov r0,r4
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100:
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pop {r1-r5,lr} @ restaur registers
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bx lr
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/******************************************************************/
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/* starting from a known substring within the string and of m length */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of the output string */
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/* r2 contains the address of string to start */
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/* r3 contains the length
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/* r0 returns number of characters or -1 if error */
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subStringStString:
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push {r1-r8,lr} @ save registers
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mov r7,r0 @ save address
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mov r8,r1 @ counter byte string
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mov r1,r2
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bl searchSubString
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cmp r0,#-1
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beq 100f
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mov r6,r0 @ counter byte input string
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mov r4,#0
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1:
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ldrb r5,[r7,r6] @ load byte string
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strb r5,[r8,r4]
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cmp r5,#0 @ zero final ?
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moveq r0,r4
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beq 100f
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add r4,#1
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cmp r4,r3
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addlt r6,#1
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blt 1b @ loop
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mov r5,#0
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strb r5,[r8,r4]
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mov r0,r4
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100:
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pop {r1-r8,lr} @ restaur registers
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bx lr
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/******************************************************************/
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/* search a substring in the string */
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/******************************************************************/
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/* r0 contains the address of the input string */
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/* r1 contains the address of substring */
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/* r0 returns index of substring in string or -1 if not found */
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searchSubString:
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push {r1-r6,lr} @ save registers
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mov r2,#0 @ counter byte input string
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mov r3,#0 @ counter byte string
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mov r6,#-1 @ index found
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ldrb r4,[r1,r3]
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1:
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ldrb r5,[r0,r2] @ load byte string
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cmp r5,#0 @ zero final ?
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moveq r0,#-1 @ yes returns error
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beq 100f
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cmp r5,r4 @ compare character
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beq 2f
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mov r6,#-1 @ no equals - > raz index
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mov r3,#0 @ and raz counter byte
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add r2,#1 @ and increment counter byte
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b 1b @ and loop
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2: @ characters equals
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cmp r6,#-1 @ first characters equals ?
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moveq r6,r2 @ yes -> index begin in r6
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add r3,#1 @ increment counter substring
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ldrb r4,[r1,r3] @ and load next byte
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cmp r4,#0 @ zero final ?
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beq 3f @ yes -> end search
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add r2,#1 @ else increment counter string
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b 1b @ and loop
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3:
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mov r0,r6
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100:
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pop {r1-r6,lr} @ restaur registers
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bx lr
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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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