Create A Game Of Hangman In ARM Assembly Language ARM Assembly Language Assignment Solution

Instructions

Objective

Write an ARM assignment program to create a game of Hangman in assembly language.

Requirements and Specifications

You are going to write an ARM assembly program that allows a human to play of game of Hangman.

In this game, the player is attempting to guess a hidden word, one letter at a time.

You are given a text file with 10 words for the game:

• TESTS
• CHALLENGE
• UNIVERSITY
• STUDENTS
• BALANCE
• FEEDBACK
• BINARY
• INTELLIGENCE
• CARTOGRAPHERS
• CHARACTERISTICALLY

1. A random secret word is read from the text file. Alternatively, you can list the 10 words in an array in the program (slightly less marks are given for this option) and choose a random word from the array.
2. The player has six chances to guess the letters for each game.
3. Valid inputs of the game are from A-Z or a-z (convert the letter into a capital if a small letter is input).
4. For each correct letter guessed, the letter is revealed at its correct location or locations in the word.
5. For each incorrect letter guessed, an additional segment of the stick figure "hangman" is displayed.
6. The stick figure has 6 segments in total: head, body, left and right arms, and left and right legs.
7. The game is won when the entire word is guessed.
8. The game is lost when the entire hangman is displayed.
9. The game is exited upon winning, losing, or the player entering the 0 (zero) character.
10. When the game is finished, the player can choose to have another round.
11. You should not allow the player to make an illegal move, or to enter invalid characters. For example, a player can't guess the same letter twice, or enter a number (except 0 for exiting the game), or enter a non-printable character.

Screenshots of output

Source Code

.data author: .asciz "????" welcomeMsg: .ascii "/---------------------------------------------/\n" .ascii "/ Welcome to Hangman! /\n" .ascii "/ /\n" .ascii "/ Author: %-36s/\n" .ascii "/ Instructions: /\n" .ascii "/ Guess the hidden word one letter at a time/\n" .ascii "/ enter 0 to exit the game. /\n" .asciz "/---------------------------------------------/\n" hangman01: .ascii "\n" .ascii " |-----| Word: %s\n" .ascii " | |\n" .asciz " " hangman02: .asciz "O" hangman03: .ascii " | Misses: %s\n" .asciz " " hangman04: .asciz "\\" hangman05: .asciz "|" hangman06: .asciz "/" hangman07: .ascii " |\n" .asciz " " hangman08: .asciz "|" hangman09: .ascii " |\n" .asciz " " hangman10: .asciz "/" hangman11: .asciz " " hangman12: .asciz "\\" hangman13: .ascii " |\n" .ascii " |\n" .asciz " ---------\n" space: .asciz " " prompt: .asciz "Enter next character (A-Z), or 0 (zero) to exit: " tryAgain: .asciz "Invalid or repeated letter. Please try again.\n\n" intfmt: .asciz "%d" youLose: .asciz "You lose - out of moves\n\n" youWin: .asciz "Congratulation - you win!\n\n" showSecret: .asciz "Secret word: %s\n\n" playAgain: .asciz "Play again (y/n)?: " filename: .asciz "words.txt" openfmt: .asciz "rt" openError: .asciz "Unable to open word file: \"words.txt\"\n" memError: .asciz "Out of memory!\n" words: .space 200 @ space for 50 words curword: .space 40 misses: .space 40 .text .align 2 .global main .type main, %function main: push {fp, lr} @ save fp and lr on stack mov r0, #0 @ call time(0) bl time bl srand @ call srand (time(0)) to set seed for random generator @ open word file ldr r0, =filename @ give filename ldr r1, =openfmt @ format to open for read only bl fopen @ open the file cmp r0, #0 @ if not valid file beq invalidFile @ terminate with error mov r4, r0 @ save file descriptor in r4 @ count chars in file mov r5, #0 @ chars = 0 fcLoop: mov r0, r4 @ use file descriptor bl fgetc @ read char from file cmp r0, #0 @ if end of file ble endfc @ end count add r5, r5, #1 @ increment char count b fcLoop @ repeat until eof endfc: mov r0, r5 @ allocate space for file bl malloc cmp r0, #0 @ if out of memory beq noMem @ print error and exit mov r5, r0 @ save allocated pointer in r5 mov r0, r4 @ use file descriptor mov r1, #0 @ move to offset 0 mov r2, #0 @ from start of file bl fseek @ rewind file @ load lines ldr r6, =words @ point to word table mov r7, #0 @ set number of words to zero mov r8, #0 @ index mov r9, #0 @ chars in line loadLoop: add r0, r5, r8 @ get current position in buffer str r0, [r6, r7, lsl #2] @ save pointer in table mov r9, #0 @ number of characters in line lineLoop: mov r0, r4 @ use file descriptor bl fgetc @ read char from file cmp r0, #0 @ if end of file ble endLoad @ end count cmp r0, #10 @ if newline beq endLine @ end line loop strb r0, [r5, r8] @ save char in buffer add r8, r8, #1 @ increment position in buffer add r9, r9, #1 @ increment characters in line b lineLoop @ repeat endLine: mov r0, #0 @ save end of string strb r0, [r5, r8] @ save eos in buffer add r8, r8, #1 @ increment position in buffer cmp r9, #0 @ if empty line beq loadLoop @ don't save in table add r7, r7, #1 @ increment number of words b loadLoop @ repeat endLoad: mov r0, #0 @ save end of string strb r0, [r5, r8] @ save eos in buffer cmp r9, #0 @ if empty line beq skip @ don't save in table add r7, r7, #1 @ else, increment number of words skip: mov r0, r4 @ load file descriptor bl fclose @ close file ldr r0, =welcomeMsg @ print welcome message ldr r1, =author bl printf mov r4, r5 @ put allocated buffer pointer in r4 mov r5, r7 @ put number of words in r5 startGame: @select word at random bl rand mov r1, r5 @ divide random number by number of words bl div @ load random word ldr r0, =words @ load word table address ldr r6, [r0, r1, lsl #2] @ load word pointer from table mov r0, r6 ldr r1, =curword bl initCurWord @ fill current word ldr r0, =misses mov r1, #0 strb r1, [r0] @ set empty string in misses mov r7, #0 @ set zero incorrect letters gameLoop: ldr r0, =curword @ load current word mov r1, r7 @ load number of incorrect letters ldr r2, =misses @ load current misses bl printHangman @ print current hangman try: ldr r0, =prompt @ prompt for input bl printf bl readChar @ read letter mov r8, r0 @ save read char cmp r8, #'0' @ if 0, exit beq gameEnd cmp r8, #'A' @ if < 'A' blt invalid @ print invalid cmp r8, #'Z' @ if >='A' && <='Z' ble checkGuess @ check guess cmp r8, #'a' @ if < 'a' blt invalid @ print invalid cmp r8, #'z' @ if >'z' bgt invalid @ print invalid toUpper: sub r8, r8, #32 @ convert to uppercase checkGuess: mov r0, r8 @ load letter in r0 ldr r1, =misses bl searchLetter @ search letter in missed letters cmp r0, #0 @ see if it was found bne invalid @ if so, try again mov r0, r8 ldr r1, =curword bl searchLetter @ search letter in guessed letters cmp r0, #0 @ see if it was found bne invalid @ if so, try again mov r0, r8 mov r1, r6 bl searchLetter @ search letter in word cmp r0, #0 @ see if it was found bne goodGuess @ if in word, it was a good guess ldr r0, =misses @ save character in misses strb r8, [r0, r7] add r7, r7, #1 @ increment incorrects mov r1, #0 strb r1, [r0, r7] @ save end of string in misses cmp r7, #6 @ see if there were 6 misses beq gameLost @ if so, the game ended b gameLoop @ else, continue game goodGuess: mov r0, r8 @ load letter ldr r1, =curword @ load current mov r2, r6 @ load word bl uncoverLetters @ uncover all selected letters in word ldr r0, =curword @ load current mov r1, r6 @ load word bl strEqual @ see if all letters were uncovered cmp r0, #0 @ if not equal bne gameLoop @ repeat loop gameWin: ldr r0, =curword @ load current word mov r1, r7 @ load number of incorrect letters ldr r2, =misses @ load current misses bl printHangman @ print current hangman ldr r0, =youWin @ print win message bl printf b askRepeat @ ask if we must continue game gameLost: ldr r0, =curword @ load current word mov r1, r7 @ load number of incorrect letters ldr r2, =misses @ load current misses bl printHangman @ print current hangman ldr r0, =youLose @ print lose message bl printf ldr r0, =showSecret @ print secret message mov r1, r6 bl printf askRepeat: ldr r0, =playAgain @ prompt to play again bl printf bl readChar @ read character cmp r0, #'y' @ if continue y beq startGame @ start over cmp r0, #'Y' @ if continue Y beq startGame @ start over b gameEnd @ else, terminate game invalid: ldr r0, =tryAgain @ ask to try again bl printf b try @ repeat invalidFile: ldr r0, =openError @ print error message bl printf b terminate noMem: ldr r0, =memError @ print error message bl printf gameEnd: mov r0, r4 @ load allocated buffer pointer bl free @ free memory terminate: pop {fp, lr} @ restore fp and lr from stack bx lr @ return @ Print the hangman using r0 = current word, r1 = current incorrect guesses, @ r2 = misses .global printHangman .type printHangman, %function printHangman: push {r4, r5, fp, lr} mov r4, r1 @ load incoreect guesses in r4 mov r5, r2 @ load current misses in r5 mov r1, r0 @ load current uncovered word ldr r0, =hangman01 @ load hangman string bl printf @ print it cmp r4, #0 beq skip1 ldr r0, =hangman02 @ load hangman string b print1 skip1: ldr r0, =space @ load hangman string print1: bl printf @ print it ldr r0, =hangman03 @ load hangman string mov r1, r5 @ load current misses bl printf @ print it cmp r4, #3 blt skip2 ldr r0, =hangman04 @ load hangman string b print2 skip2: ldr r0, =space @ load hangman string print2: bl printf @ print it cmp r4, #2 blt skip3 ldr r0, =hangman05 @ load hangman string b print3 skip3: ldr r0, =space @ load hangman string print3: bl printf @ print it cmp r4, #4 blt skip4 ldr r0, =hangman06 @ load hangman string b print4 skip4: ldr r0, =space @ load hangman string print4: bl printf @ print it ldr r0, =hangman07 @ load hangman string bl printf @ print it cmp r4, #2 blt skip5 ldr r0, =hangman08 @ load hangman string b print5 skip5: ldr r0, =space @ load hangman string print5: bl printf @ print it ldr r0, =hangman09 @ load hangman string bl printf @ print it cmp r4, #5 blt skip6 ldr r0, =hangman10 @ load hangman string b print6 skip6: ldr r0, =space @ load hangman string print6: bl printf @ print it ldr r0, =hangman11 @ load hangman string bl printf @ print it cmp r4, #6 blt skip7 ldr r0, =hangman12 @ load hangman string b print7 skip7: ldr r0, =space @ load hangman string print7: bl printf @ print it ldr r0, =hangman13 @ load hangman string bl printf @ print it pop {r4, r5, fp, lr} bx lr @ Fills underscores as current guessed word, r0 = word, r1 = current word .global initCurWord .type initCurWord, %function initCurWord: mov r2, #0 copy: ldrb r3, [r0, r2] @ load char from word cmp r3, #0 @ if zero beq endCopy @ end copy mov r3, #'_' @ load underscore strb r3, [r1, r2] @ save in current word add r2, r2, #1 @ increment position b copy @ repeat endCopy: strb r3, [r1, r2] @ save zero in current word bx lr @ search the letter r0 in the word at r1, @ returns 0 if not found, non zero otherwise .global searchLetter .type searchLetter, %function searchLetter: mov r2, #0 @ start index in zero srchLoop: ldrb r3, [r1, r2] @ load character from string cmp r3, #0 @ if end of string beq notfound @ go to not found cmp r3, r0 @ if it's the searched letter beq found @ return found add r2, r2, #1 @ advance to next char b srchLoop @ search again notfound: mov r0, r3 @ return zero found: bx lr @ uncover all letters equal to r0 in the current word r1 using the word in r2 .global uncoverLetters .type uncoverLetters, %function uncoverLetters: push {r4} mov r3, #0 @ start at index 0 uncoverLoop: ldrb r4, [r2, r3] @ load letter from word cmp r4, #0 @ if end of word beq uncoverEnd @ end uncovering cmp r4, r0 @ see if it's searched letter bne unconverNext @ if not, go to next strb r4, [r1, r3] @ else, uncover letter unconverNext: add r3, r3, #1 @ increment position b uncoverLoop @ repeat loop uncoverEnd: pop {r4} bx lr @ see if the two strings in r0 and r1 are equal, returns 0 if equal, not zero if not .global strEqual .type strEqual, %function strEqual: push {r4} mov r2, #0 @ start at index 0 cmpLoop: ldrb r3, [r0, r2] @ load letter from first word ldrb r4, [r1, r2] @ load letter from second word subs r3, r3, r4 @ see if they are equal bne cmpEnd @ if not equal, end cmp r4, #0 @ else, if end of word beq cmpEnd @ end, they are equal add r2, r2, #1 @ else, increment position b cmpLoop @ repeat loop cmpEnd: mov r0, r3 @ return last comparison pop {r4} bx lr @ division of r0 over r1 using repeated subtractions, returns quotient in r0, @ remainder in r1 .global div .type div, %function div: mov r2, r1 @ copy divisor to r2 mov r1, r0 @ copy dividend to r1 mov r0, #0 @ quotient = 0 divLoop: subs r3, r1, r2 @ subtract divisor blt divEnd @ if negative, end mov r1, r3 @ else, update number add r0, r0, #1 @ increment quotient b divLoop divEnd: bx lr @ return @ read a character readChar: push {r4, fp, lr} bl getchar @ read letter mov r4, r0 @ save read char getNL: bl getchar @ read until the '\n' cmp r0, #10 bne getNL mov r0, r4 @ return first char pop {r4, fp, lr} bx lr