222 lines
11 KiB
Plaintext
222 lines
11 KiB
Plaintext
/* ARM assembly Raspberry PI */
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/* program kprime.s */
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/************************************/
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/* Constantes */
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/************************************/
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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 MAXI, 10
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.equ MAXIK, 5
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/*********************************/
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/* Initialized data */
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/*********************************/
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.data
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sMessDeb: .ascii "k="
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sMessValeurDeb: .fill 11, 1, ' ' @ size => 11
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sMessResult: .ascii " "
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sMessValeur: .fill 11, 1, ' ' @ size => 11
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szCarriageReturn: .asciz "\n"
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/*********************************/
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/* UnInitialized data */
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/*********************************/
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.bss
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/*********************************/
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/* code section */
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/*********************************/
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.text
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.global main
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main: @ entry of program
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mov r3,#1 @ k
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1: @ start loop k
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mov r0,r3
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ldr r1,iAdrsMessValeurDeb
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bl conversion10 @ call conversion decimal
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ldr r0,iAdrsMessValeurDeb
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mov r1,#':'
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strb r1,[r0,#2] @ write : after k value
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mov r1,#0
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strb r1,[r0,#3] @ final zéro
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ldr r0,iAdrsMessDeb
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bl affichageMess @ display message
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mov r4,#2 @ n
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mov r5,#0 @ result counter
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2: @ start loop n
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mov r0,r4
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mov r1,r3
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bl kprime @ is kprine ?
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cmp r0,#0
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beq 3f @ no
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mov r0,r4
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ldr r1,iAdrsMessValeur
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bl conversion10 @ call conversion decimal
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ldr r0,iAdrsMessValeur
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mov r1,#0
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strb r1,[r0,#4] @ final zéro
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ldr r0,iAdrsMessResult
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bl affichageMess @ display message
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add r5,#1 @ increment counter
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3:
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add r4,#1 @ increment n
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cmp r5,#MAXI @ maxi ?
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blt 2b @ no -> loop
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ldr r0,iAdrszCarriageReturn
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bl affichageMess @ display carriage return
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add r3,#1 @ increment k
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cmp r3,#MAXIK @ maxi ?
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ble 1b @ no -> loop
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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 the system call
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iAdrsMessValeur: .int sMessValeur
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iAdrszCarriageReturn: .int szCarriageReturn
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iAdrsMessResult: .int sMessResult
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iAdrsMessValeurDeb: .int sMessValeurDeb
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iAdrsMessDeb: .int sMessDeb
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/******************************************************************/
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/* compute kprime (n,k) */
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/******************************************************************/
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/* r0 contains n */
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/* r1 contains k */
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kprime:
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push {r1-r7,lr} @ save registers
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mov r5,r0 @ save n
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mov r7,r1 @ save k
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mov r4,#0 @ counter product
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mov r1,#2 @ divisor
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1: @ start loop
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cmp r4,r7 @ counter >= k
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bge 4f @ yes -> end
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mul r6,r1,r1 @ compute product
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cmp r6,r5 @ > n
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bgt 4f @ yes -> end
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2: @ start loop division
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mov r0,r5 @ dividende
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bl division @ by r1
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cmp r3,#0 @ remainder = 0 ?
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bne 3f @ no
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mov r5,r2 @ yes -> n = n / r1
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add r4,#1 @ increment counter
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b 2b @ and loop
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3:
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add r1,#1 @ increment divisor
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b 1b @ and loop
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4: @ end compute
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cmp r5,#1 @ n > 1
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addgt r4,#1 @ yes increment counter
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cmp r4,r7 @ counter = k ?
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movne r0,#0 @ no -> no kprime
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moveq r0,#1 @ yes -> kprime
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100:
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pop {r1-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 registres
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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 systeme
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pop {r0,r1,r2,r7,lr} @ restaur des 2 registres */
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bx lr @ return
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/******************************************************************/
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/* Converting a register to a decimal unsigned */
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/******************************************************************/
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/* r0 contains value and r1 address area */
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/* r0 return size of result (no zero final in area) */
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/* area size => 11 bytes */
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.equ LGZONECAL, 10
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conversion10:
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push {r1-r4,lr} @ save registers
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mov r3,r1
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mov r2,#LGZONECAL
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1: @ start loop
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bl divisionpar10U @ unsigned r0 <- dividende. quotient ->r0 reste -> r1
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add r1,#48 @ digit
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strb r1,[r3,r2] @ store digit on area
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cmp r0,#0 @ stop if quotient = 0
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subne r2,#1 @ else previous position
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bne 1b @ and loop
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@ and move digit from left of area
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mov r4,#0
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2:
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ldrb r1,[r3,r2]
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strb r1,[r3,r4]
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add r2,#1
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add r4,#1
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cmp r2,#LGZONECAL
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ble 2b
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@ and move spaces in end on area
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mov r0,r4 @ result length
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mov r1,#' ' @ space
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3:
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strb r1,[r3,r4] @ store space in area
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add r4,#1 @ next position
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cmp r4,#LGZONECAL
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ble 3b @ loop if r4 <= area size
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100:
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pop {r1-r4,lr} @ restaur registres
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bx lr @return
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/***************************************************/
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/* division par 10 unsigned */
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/***************************************************/
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/* r0 dividende */
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/* r0 quotient */
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/* r1 remainder */
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divisionpar10U:
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push {r2,r3,r4, lr}
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mov r4,r0 @ save value
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ldr r3,iMagicNumber @ r3 <- magic_number raspberry 1 2
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umull r1, r2, r3, r0 @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
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mov r0, r2, LSR #3 @ r2 <- r2 >> shift 3
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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,r3,r4,lr}
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bx lr @ leave function
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iMagicNumber: .int 0xCCCCCCCD
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/***************************************************/
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/* integer division unsigned */
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/***************************************************/
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division:
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/* r0 contains dividend */
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/* r1 contains divisor */
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/* r2 returns quotient */
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/* r3 returns remainder */
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push {r4, lr}
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mov r2, #0 @ init quotient
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mov r3, #0 @ init remainder
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mov r4, #32 @ init counter bits
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b 2f
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1: @ loop
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movs r0, r0, LSL #1 @ r0 <- r0 << 1 updating cpsr (sets C if 31st bit of r0 was 1)
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adc r3, r3, r3 @ r3 <- r3 + r3 + C. This is equivalent to r3 ? (r3 << 1) + C
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cmp r3, r1 @ compute r3 - r1 and update cpsr
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subhs r3, r3, r1 @ if r3 >= r1 (C=1) then r3 <- r3 - r1
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adc r2, r2, r2 @ r2 <- r2 + r2 + C. This is equivalent to r2 <- (r2 << 1) + C
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2:
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subs r4, r4, #1 @ r4 <- r4 - 1
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bpl 1b @ if r4 >= 0 (N=0) then loop
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pop {r4, lr}
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bx lr
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