/* ARM assembly Raspberry PI */ /* program areaString.s */ /* Constantes */ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall /* Initialized data */ .data szMessStringsch: .ascii "The string is at item : " sZoneconv: .fill 12,1,' ' szCarriageReturn: .asciz "\n" szMessStringNfound: .asciz "The string is not found in this area.\n" /* areas strings */ szString1: .asciz "Apples" szString2: .asciz "Oranges" szString3: .asciz "Pommes" szString4: .asciz "Raisins" szString5: .asciz "Abricots" /* pointer items area 1*/ tablesPoi1: pt1_1: .int szString1 pt1_2: .int szString2 pt1_3: .int szString3 pt1_4: .int szString4 ptVoid_1: .int 0 ptVoid_2: .int 0 ptVoid_3: .int 0 ptVoid_4: .int 0 ptVoid_5: .int 0 szStringSch: .asciz "Raisins" szStringSch1: .asciz "Ananas" /* UnInitialized data */ .bss /* code section */ .text .global main main: /* entry of program */ push {fp,lr} /* saves 2 registers */ @@@@@@@@@@@@@@@@@@@@@@@@ @ add string 5 to area @@@@@@@@@@@@@@@@@@@@@@@@ ldr r1,iAdrtablesPoi1 @ begin pointer area 1 mov r0,#0 @ counter 1: @ search first void pointer ldr r2,[r1,r0,lsl #2] @ read string pointer address item r0 (4 bytes by pointer) cmp r2,#0 @ is null ? addne r0,#1 @ no increment counter bne 1b @ and loop @ store pointer string 5 in area at position r0 ldr r2,iAdrszString5 @ address string 5 str r2,[r1,r0,lsl #2] @ store address @@@@@@@@@@@@@@@@@@@@@@@@ @ display string at item 3 @@@@@@@@@@@@@@@@@@@@@@@@ mov r2,#2 @ pointers begin in position 0 ldr r1,iAdrtablesPoi1 @ begin pointer area 1 ldr r0,[r1,r2,lsl #2] bl affichageMess ldr r0,iAdrszCarriageReturn bl affichageMess @@@@@@@@@@@@@@@@@@@@@@@@ @ search string in area @@@@@@@@@@@@@@@@@@@@@@@@ ldr r1,iAdrszStringSch //ldr r1,iAdrszStringSch1 @ uncomment for other search : not found !! ldr r2,iAdrtablesPoi1 @ begin pointer area 1 mov r3,#0 2: @ search ldr r0,[r2,r3,lsl #2] @ read string pointer address item r0 (4 bytes by pointer) cmp r0,#0 @ is null ? beq 3f @ end search bl comparaison cmp r0,#0 @ string = ? addne r3,#1 @ no increment counter bne 2b @ and loop mov r0,r3 @ position item string ldr r1,iAdrsZoneconv @ conversion decimal bl conversion10S ldr r0,iAdrszMessStringsch bl affichageMess b 100f 3: @ end search string not found ldr r0,iAdrszMessStringNfound bl affichageMess 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 iAdrtablesPoi1: .int tablesPoi1 iAdrszMessStringsch: .int szMessStringsch iAdrszString5: .int szString5 iAdrszStringSch: .int szStringSch iAdrszStringSch1: .int szStringSch1 iAdrsZoneconv: .int sZoneconv iAdrszMessStringNfound: .int szMessStringNfound iAdrszCarriageReturn: .int szCarriageReturn /******************************************************************/ /* 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 */ /***************************************************/ /* conversion register signed décimal */ /***************************************************/ /* r0 contient le registre */ /* r1 contient l adresse de la zone de conversion */ conversion10S: push {r0-r5,lr} /* save des registres */ mov r2,r1 /* debut zone stockage */ mov r5,#'+' /* par defaut le signe est + */ cmp r0,#0 /* nombre négatif ? */ movlt r5,#'-' /* oui le signe est - */ mvnlt r0,r0 /* et inversion en valeur positive */ addlt r0,#1 mov r4,#10 /* longueur de la zone */ 1: /* debut de boucle de conversion */ bl divisionpar10 /* division */ add r1,#48 /* ajout de 48 au reste pour conversion ascii */ strb r1,[r2,r4] /* stockage du byte en début de zone r5 + la position r4 */ sub r4,r4,#1 /* position précedente */ cmp r0,#0 bne 1b /* boucle si quotient different de zéro */ strb r5,[r2,r4] /* stockage du signe à la position courante */ subs r4,r4,#1 /* position précedente */ blt 100f /* si r4 < 0 fin */ /* sinon il faut completer le debut de la zone avec des blancs */ mov r3,#' ' /* caractere espace */ 2: strb r3,[r2,r4] /* stockage du byte */ subs r4,r4,#1 /* position précedente */ bge 2b /* boucle si r4 plus grand ou egal a zero */ 100: /* fin standard de la fonction */ pop {r0-r5,lr} /*restaur desregistres */ bx lr /***************************************************/ /* division par 10 signé */ /* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/* /* and http://www.hackersdelight.org/ */ /***************************************************/ /* r0 contient le dividende */ /* r0 retourne le quotient */ /* r1 retourne le reste */ divisionpar10: /* r0 contains the argument to be divided by 10 */ push {r2-r4} /* save registers */ mov r4,r0 ldr r3, .Ls_magic_number_10 /* r1 <- magic_number */ smull r1, r2, r3, r0 /* r1 <- Lower32Bits(r1*r0). r2 <- Upper32Bits(r1*r0) */ mov r2, r2, ASR #2 /* r2 <- r2 >> 2 */ mov r1, r0, LSR #31 /* r1 <- r0 >> 31 */ add r0, r2, r1 /* r0 <- r2 + r1 */ add r2,r0,r0, lsl #2 /* r2 <- r0 * 5 */ sub r1,r4,r2, lsl #1 /* r1 <- r4 - (r2 * 2) = r4 - (r0 * 10) */ pop {r2-r4} bx lr /* leave function */ bx lr /* leave function */ .Ls_magic_number_10: .word 0x66666667