/* ARM assembly Raspberry PI */ /* program defqueue.s */ /* Constantes */ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall .equ NBMAXIELEMENTS, 100 /*******************************************/ /* Structures */ /********************************************/ /* example structure for value of item */ .struct 0 value_ident: @ ident .struct value_ident + 4 value_value1: @ value 1 .struct value_value1 + 4 value_value2: @ value 2 .struct value_value2 + 4 value_fin: /* example structure for queue */ .struct 0 queue_ptdeb: @ begin pointer of item .struct queue_ptdeb + 4 queue_ptfin: @ end pointer of item .struct queue_ptfin + 4 queue_stvalue: @ structure of value item .struct queue_stvalue + (value_fin * NBMAXIELEMENTS) queue_fin: /*********************************/ /* Initialized data */ /*********************************/ .data szMessEmpty: .asciz "Empty queue. \n" szMessNotEmpty: .asciz "Not empty queue. \n" szMessError: .asciz "Error detected !!!!. \n" szMessResult: .ascii "Ident :" @ message result sMessIdent: .fill 11, 1, ' ' .ascii " value 1 :" sMessValue1: .fill 11, 1, ' ' .ascii " value 2 :" sMessValue2: .fill 11, 1, ' ' .asciz "\n" szCarriageReturn: .asciz "\n" /*********************************/ /* UnInitialized data */ /*********************************/ .bss .align 4 Queue1: .skip queue_fin @ queue memory place stItem: .skip value_fin @ value item memory place /*********************************/ /* code section */ /*********************************/ .text .global main main: @ entry of program ldr r0,iAdrQueue1 @ queue structure address bl isEmpty cmp r0,#0 beq 1f ldr r0,iAdrszMessEmpty bl affichageMess @ display message empty b 2f 1: ldr r0,iAdrszMessNotEmpty bl affichageMess @ display message not empty 2: @ init item 1 ldr r0,iAdrstItem mov r1,#1 str r1,[r0,#value_ident] mov r1,#11 str r1,[r0,#value_value1] mov r1,#12 str r1,[r0,#value_value2] ldr r0,iAdrQueue1 @ queue structure address ldr r1,iAdrstItem bl pushQueue @ add item in queue cmp r0,#-1 @ error ? beq 99f @ init item 2 ldr r0,iAdrstItem mov r1,#2 str r1,[r0,#value_ident] mov r1,#21 str r1,[r0,#value_value1] mov r1,#22 str r1,[r0,#value_value2] ldr r0,iAdrQueue1 @ queue structure address ldr r1,iAdrstItem bl pushQueue @ add item in queue cmp r0,#-1 beq 99f ldr r0,iAdrQueue1 @ queue structure address bl isEmpty cmp r0,#0 @ not empty beq 3f ldr r0,iAdrszMessEmpty bl affichageMess @ display message empty b 4f 3: ldr r0,iAdrszMessNotEmpty bl affichageMess @ display message not empty 4: ldr r0,iAdrQueue1 @ queue structure address bl popQueue @ return address item cmp r0,#-1 @ error ? beq 99f mov r2,r0 @ save item pointer ldr r0,[r2,#value_ident] ldr r1,iAdrsMessIdent @ display ident bl conversion10 @ decimal conversion ldr r0,[r2,#value_value1] ldr r1,iAdrsMessValue1 @ display value 1 bl conversion10 @ decimal conversion ldr r0,[r2,#value_value2] ldr r1,iAdrsMessValue2 @ display value 2 bl conversion10 @ decimal conversion ldr r0,iAdrszMessResult bl affichageMess @ display message b 4b @ loop 99: @ error ldr r0,iAdrszMessError bl affichageMess 100: @ standard end of the program mov r0, #0 @ return code mov r7, #EXIT @ request to exit program svc #0 @ perform the system call iAdrQueue1: .int Queue1 iAdrstItem: .int stItem iAdrszMessError: .int szMessError iAdrszMessEmpty: .int szMessEmpty iAdrszMessNotEmpty: .int szMessNotEmpty iAdrszMessResult: .int szMessResult iAdrszCarriageReturn: .int szCarriageReturn iAdrsMessIdent: .int sMessIdent iAdrsMessValue1: .int sMessValue1 iAdrsMessValue2: .int sMessValue2 /******************************************************************/ /* test if queue empty */ /******************************************************************/ /* r0 contains the address of queue structure */ isEmpty: push {r1,r2,lr} @ save registres ldr r1,[r0,#queue_ptdeb] @ begin pointer ldr r2,[r0,#queue_ptfin] @ begin pointer cmp r1,r2 moveq r0,#1 @ empty queue movne r0,#0 @ not empty pop {r1,r2,lr} @ restaur registers bx lr @ return /******************************************************************/ /* add item in queue */ /******************************************************************/ /* r0 contains the address of queue structure */ /* r1 contains the address of item */ pushQueue: push {r1-r4,lr} @ save registres add r2,r0,#queue_stvalue @ address of values structure ldr r3,[r0,#queue_ptfin] @ end pointer add r2,r3 @ free address of queue ldr r4,[r1,#value_ident] @ load ident item str r4,[r2,#value_ident] @ and store in queue ldr r4,[r1,#value_value1] @ idem str r4,[r2,#value_value1] ldr r4,[r1,#value_value2] str r4,[r2,#value_value2] add r3,#value_fin cmp r3,#value_fin * NBMAXIELEMENTS moveq r0,#-1 @ error beq 100f str r3,[r0,#queue_ptfin] @ store new end pointer 100: pop {r1-r4,lr} @ restaur registers bx lr @ return /******************************************************************/ /* pop queue */ /******************************************************************/ /* r0 contains the address of queue structure */ popQueue: push {r1,r2,lr} @ save registres mov r1,r0 @ control if empty queue bl isEmpty cmp r0,#1 @ yes -> error moveq r0,#-1 beq 100f mov r0,r1 ldr r1,[r0,#queue_ptdeb] @ begin pointer add r2,r0,#queue_stvalue @ address of begin values item add r2,r1 @ address of item add r1,#value_fin str r1,[r0,#queue_ptdeb] @ store nex begin pointer mov r0,r2 @ return pointer item 100: pop {r1,r2,lr} @ restaur registers bx lr @ return /******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess: push {r0,r1,r2,r7,lr} @ save registres 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" svc #0 @ call systeme pop {r0,r1,r2,r7,lr} @ restaur registers */ bx lr @ return /******************************************************************/ /* Converting a register to a decimal */ /******************************************************************/ /* r0 contains value and r1 address area */ .equ LGZONECAL, 10 conversion10: push {r1-r4,lr} @ save registers mov r3,r1 mov r2,#LGZONECAL 1: @ start loop bl divisionpar10 @ r0 <- dividende. quotient ->r0 reste -> r1 add r1,#48 @ digit strb r1,[r3,r2] @ store digit on area cmp r0,#0 @ stop if quotient = 0 subne r2,#1 @ previous position bne 1b @ else loop @ end replaces digit in front of area mov r4,#0 2: ldrb r1,[r3,r2] strb r1,[r3,r4] @ store in area begin add r4,#1 add r2,#1 @ previous position cmp r2,#LGZONECAL @ end ble 2b @ loop mov r1,#' ' 3: strb r1,[r3,r4] add r4,#1 cmp r4,#LGZONECAL @ end ble 3b 100: pop {r1-r4,lr} @ restaur registres bx lr @return /***************************************************/ /* division par 10 signé */ /* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/* /* and http://www.hackersdelight.org/ */ /***************************************************/ /* r0 dividende */ /* r0 quotient */ /* r1 remainder */ divisionpar10: /* r0 contains the argument to be divided by 10 */ push {r2-r4} @ save registers */ mov r4,r0 mov r3,#0x6667 @ r3 <- magic_number lower movt r3,#0x6666 @ r3 <- magic_number upper 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 @ return