How to resolve the algorithm Permutations step by step in the ARM Assembly programming language
Published on 12 May 2024 09:40 PM
How to resolve the algorithm Permutations step by step in the ARM Assembly programming language
Table of Contents
Problem Statement
Write a program that generates all permutations of n different objects. (Practically numerals!)
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Permutations step by step in the ARM Assembly programming language
Source code in the arm programming language
/* ARM assembly Raspberry PI */
/* program permutation.s */
/* REMARK 1 : this program use routines in a include file
see task Include a file language arm assembly
for the routine affichageMess conversion10
see at end of this program the instruction include */
/* for constantes see task include a file in arm assembly */
/************************************/
/* Constantes */
/************************************/
.include "../constantes.inc"
/*********************************/
/* Initialized data */
/*********************************/
.data
sMessResult: .asciz "Value : @ \n"
sMessCounter: .asciz "Permutations = @ \n"
szCarriageReturn: .asciz "\n"
.align 4
TableNumber: .int 1,2,3
.equ NBELEMENTS, (. - TableNumber) / 4
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
sZoneConv: .skip 24
/*********************************/
/* code section */
/*********************************/
.text
.global main
main: @ entry of program
ldr r0,iAdrTableNumber @ address number table
mov r1,#NBELEMENTS @ number of élements
mov r10,#0 @ counter
bl heapIteratif
mov r0,r10 @ display counter
ldr r1,iAdrsZoneConv @
bl conversion10S @ décimal conversion
ldr r0,iAdrsMessCounter
ldr r1,iAdrsZoneConv @ insert conversion
bl strInsertAtCharInc
bl affichageMess @ display message
100: @ standard end of the program
mov r0, #0 @ return code
mov r7, #EXIT @ request to exit program
svc #0 @ perform the system call
iAdrszCarriageReturn: .int szCarriageReturn
iAdrsMessResult: .int sMessResult
iAdrTableNumber: .int TableNumber
iAdrsMessCounter: .int sMessCounter
/******************************************************************/
/* permutation by heap iteratif (wikipedia) */
/******************************************************************/
/* r0 contains the address of table */
/* r1 contains the eléments number */
heapIteratif:
push {r3-r9,lr} @ save registers
lsl r9,r1,#2 @ four bytes by count
sub sp,sp,r9
mov fp,sp
mov r3,#0
mov r4,#0 @ index
1: @ init area counter
str r4,[fp,r3,lsl #2]
add r3,r3,#1
cmp r3,r1
blt 1b
bl displayTable
add r10,r10,#1
mov r3,#0 @ index
2:
ldr r4,[fp,r3,lsl #2] @ load count [i]
cmp r4,r3 @ compare with i
bge 5f
tst r3,#1 @ even ?
bne 3f
ldr r5,[r0] @ yes load value A[0]
ldr r6,[r0,r3,lsl #2] @ and swap with value A[i]
str r6,[r0]
str r5,[r0,r3,lsl #2]
b 4f
3:
ldr r5,[r0,r4,lsl #2] @ load value A[count[i]]
ldr r6,[r0,r3,lsl #2] @ and swap with value A[i]
str r6,[r0,r4,lsl #2]
str r5,[r0,r3,lsl #2]
4:
bl displayTable
add r10,r10,#1
add r4,r4,#1 @ increment count i
str r4,[fp,r3,lsl #2] @ and store on stack
mov r3,#0 @ raz index
b 2b @ and loop
5:
mov r4,#0 @ raz count [i]
str r4,[fp,r3,lsl #2]
add r3,r3,#1 @ increment index
cmp r3,r1 @ end ?
blt 2b @ no -> loop
add sp,sp,r9 @ stack alignement
100:
pop {r3-r9,lr}
bx lr @ return
/******************************************************************/
/* Display table elements */
/******************************************************************/
/* r0 contains the address of table */
displayTable:
push {r0-r3,lr} @ save registers
mov r2,r0 @ table address
mov r3,#0
1: @ loop display table
ldr r0,[r2,r3,lsl #2]
ldr r1,iAdrsZoneConv @
bl conversion10S @ décimal conversion
ldr r0,iAdrsMessResult
ldr r1,iAdrsZoneConv @ insert conversion
bl strInsertAtCharInc
bl affichageMess @ display message
add r3,#1
cmp r3,#NBELEMENTS - 1
ble 1b
ldr r0,iAdrszCarriageReturn
bl affichageMess
mov r0,r2
100:
pop {r0-r3,lr}
bx lr
iAdrsZoneConv: .int sZoneConv
/***************************************************/
/* ROUTINES INCLUDE */
/***************************************************/
.include "../affichage.inc"
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