171 lines
6.4 KiB
Plaintext
171 lines
6.4 KiB
Plaintext
/* ARM assembly Raspberry PI */
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/* program concAreaString.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 NBMAXITEMS, 20 @
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/* Initialized data */
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.data
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szMessLenArea: .ascii "The length of area 3 is : "
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sZoneconv: .fill 12,1,' '
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szCarriageReturn: .asciz "\n"
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/* areas strings */
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szString1: .asciz "Apples"
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szString2: .asciz "Oranges"
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szString3: .asciz "Pommes"
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szString4: .asciz "Raisins"
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szString5: .asciz "Abricots"
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/* pointer items area 1*/
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tablesPoi1:
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pt1_1: .int szString1
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pt1_2: .int szString2
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ptVoid_1: .int 0
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/* pointer items area 2*/
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tablesPoi2:
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pt2_1: .int szString3
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pt2_2: .int szString4
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pt2_3: .int szString5
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ptVoid_2: .int 0
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/* UnInitialized data */
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.bss
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tablesPoi3: .skip 4 * NBMAXITEMS
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/* code section */
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.text
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.global main
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main: /* entry of program */
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push {fp,lr} /* saves 2 registers */
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@ copy area 1 -> area 3
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ldr r1,iAdrtablesPoi1 @ begin pointer area 1
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ldr r3,iAdrtablesPoi3 @ begin pointer area 3
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mov r0,#0 @ counter
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1:
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ldr r2,[r1,r0,lsl #2] @ read string pointer address item r0 (4 bytes by pointer)
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cmp r2,#0 @ is null ?
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strne r2,[r3,r0,lsl #2] @ no store pointer in area 3
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addne r0,#1 @ increment counter
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bne 1b @ and loop
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@ copy area 2 -> area 3
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ldr r1,iAdrtablesPoi2 @ begin pointer area 2
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ldr r3,iAdrtablesPoi3 @ begin pointer area 3
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mov r4,#0 @ counter area 2
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2: @ r0 contains the first void item in area 3
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ldr r2,[r1,r4,lsl #2] @ read string pointer address item r0 (4 bytes by pointer)
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cmp r2,#0 @ is null ?
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strne r2,[r3,r0,lsl #2] @ no store pointer in area 3
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addne r0,#1 @ increment counter
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addne r4,#1 @ increment counter
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bne 2b @ and loop
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@ count items number in area 3
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ldr r1,iAdrtablesPoi3 @ begin pointer table
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mov r0,#0 @ counter
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3: @ begin loop
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ldr r2,[r1,r0,lsl #2] @ read string pointer address item r0 (4 bytes by pointer)
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cmp r2,#0 @ is null ?
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addne r0,#1 @ no increment counter
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bne 3b @ and loop
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ldr r1,iAdrsZoneconv @ conversion decimal
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bl conversion10S
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ldr r0,iAdrszMessLenArea
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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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pop {fp,lr} @restaur 2 registers
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mov r7, #EXIT @ request to exit program
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swi 0 @ perform the system call
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iAdrtablesPoi1: .int tablesPoi1
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iAdrtablesPoi2: .int tablesPoi2
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iAdrtablesPoi3: .int tablesPoi3
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iAdrszMessLenArea: .int szMessLenArea
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iAdrsZoneconv: .int sZoneconv
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iAdrszCarriageReturn: .int szCarriageReturn
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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 {fp,lr} /* save registres */
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push {r0,r1,r2,r7} /* save others 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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swi #0 /* call systeme */
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pop {r0,r1,r2,r7} /* restaur others registers */
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pop {fp,lr} /* restaur des 2 registres */
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bx lr /* return */
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/***************************************************/
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/* conversion register signed décimal */
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/***************************************************/
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/* r0 contient le registre */
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/* r1 contient l adresse de la zone de conversion */
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conversion10S:
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push {r0-r5,lr} /* save des registres */
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mov r2,r1 /* debut zone stockage */
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mov r5,#'+' /* par defaut le signe est + */
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cmp r0,#0 /* nombre négatif ? */
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movlt r5,#'-' /* oui le signe est - */
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mvnlt r0,r0 /* et inversion en valeur positive */
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addlt r0,#1
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mov r4,#10 /* longueur de la zone */
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1: /* debut de boucle de conversion */
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bl divisionpar10 /* division */
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add r1,#48 /* ajout de 48 au reste pour conversion ascii */
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strb r1,[r2,r4] /* stockage du byte en début de zone r5 + la position r4 */
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sub r4,r4,#1 /* position précedente */
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cmp r0,#0
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bne 1b /* boucle si quotient different de zéro */
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strb r5,[r2,r4] /* stockage du signe à la position courante */
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subs r4,r4,#1 /* position précedente */
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blt 100f /* si r4 < 0 fin */
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/* sinon il faut completer le debut de la zone avec des blancs */
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mov r3,#' ' /* caractere espace */
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2:
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strb r3,[r2,r4] /* stockage du byte */
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subs r4,r4,#1 /* position précedente */
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bge 2b /* boucle si r4 plus grand ou egal a zero */
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100: /* fin standard de la fonction */
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pop {r0-r5,lr} /*restaur desregistres */
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bx lr
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/***************************************************/
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/* division par 10 signé */
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/* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/*
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/* and http://www.hackersdelight.org/ */
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/***************************************************/
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/* r0 contient le dividende */
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/* r0 retourne le quotient */
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/* r1 retourne le reste */
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divisionpar10:
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/* r0 contains the argument to be divided by 10 */
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push {r2-r4} /* save registers */
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mov r4,r0
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ldr r3, .Ls_magic_number_10 /* r1 <- magic_number */
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smull r1, r2, r3, r0 /* r1 <- Lower32Bits(r1*r0). r2 <- Upper32Bits(r1*r0) */
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mov r2, r2, ASR #2 /* r2 <- r2 >> 2 */
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mov r1, r0, LSR #31 /* r1 <- r0 >> 31 */
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add r0, r2, r1 /* r0 <- r2 + r1 */
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add r2,r0,r0, lsl #2 /* r2 <- r0 * 5 */
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sub r1,r4,r2, lsl #1 /* r1 <- r4 - (r2 * 2) = r4 - (r0 * 10) */
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pop {r2-r4}
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bx lr /* leave function */
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bx lr /* leave function */
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.Ls_magic_number_10: .word 0x66666667
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