Capitalizing strings from a file using ARM assembly homework help

The homework deals with reading data from a file and process it by capitalizing the first letter of every word in the file and saving the resulting conversion to a different file. The program uses software interrupts (SWI) in order to access the files and printing errors. The program is to be implemented for the ARMSim# simulator. Check out the following solution provided by our ARM assembly homework help experts to learn more about string capitalization.

Capitalizing Strings and Accessing Files using Software Interrupts

.text .global _start _start: @ Open input file ldr r0, =inputfile @ set input filename mov r1, #0 @ open for reading swi 0x66 @ Open the file bcs inputError @ if error opening, go to error mov r4, r0 @ save input file handle in r4 @ Open output file ldr r0, =outputfile @ set output filename mov r1, #1 @ open for writing swi 0x66 @ Open the file bcs outputError @ if error opening, go to error mov r5, r0 @ save output file handle in r5 readLoop: @ Read char from input file mov r0, r4 @ load input file handle ldr r1, =buffer @ read in buffer mov r2, #1024 @ read at most 1024 characters swi 0x6a @ read string from file bcs readEnd @ if empty file, end loop ldr r1, =buffer @ point to buffer mov r2, #0 @ index in buffer, start in zero mov r3, #1 @ indicate if we should change to uppercase convLoop: ldrb r0, [r1, r2] @ load char from string cmp r0, #0 @ see if we reached the end of string beq writeFile @ if so, write string cmp r0, #'A' @ if not letter blt saveSpace cmp r0, #'Z' @ if letter ble letter cmp r0, #'a' @ if not letter blt saveSpace cmp r0, #'z' @ if not letter bgt saveSpace cmp r3, #1 @ see if we need to capitalize bne saveChar @ if not, don't capitalize sub r0, r0, #32 @ convert character to lowercase letter: mov r3, #0 @ 0 to avoid capitals, we are inside a word b saveChar @ save character saveSpace: mov r3, #1 @ 1 to capitalize next letter mov r0, #32 @ load space character saveChar: strb r0, [r1, r2] @ save space in string add r2, r2, #1 @ increment string index b convLoop writeFile: mov r0, #10 strb r0, [r1, r2] @ save newline in string add r2, r2, #1 @ increment string index mov r0, #0 strb r0, [r1, r2] @ save end of string @ Write string to ouput file mov r0, r5 @ load output file handle ldr r1, =buffer @ write from buffer mov r2, #1024 @ write all characters swi 0x69 @ write string to file b readLoop @ read next string from file readEnd: @ Close input file mov r0, r4 @ get input file handle swi 0x68 @ close the file @ Close output file mov r0, r5 @ get output file handle swi 0x68 @ close the file @ print end message mov r0, #1 @ print to stdout ldr r1, =okMsg @ load ok message swi 0x69 @ print the message b exit @ exit the program inputError: mov r0, #1 @ print to stdout ldr r1, =inputErrorMsg @ load error message swi 0x69 @ print the error message b exit outputError: mov r0, #1 @ print to stdout ldr r1, =outputErrorMsg @ load error message swi 0x69 @ print the error message exit: swi 0x11 @ Exit the program .data inputfile: .asciz "input.txt" outputfile: .asciz "output.txt" inputErrorMsg: .asciz "Error opening the input file: \"input.txt\"\n" outputErrorMsg: .asciz "Error opening the ouutput file: \"output.txt\"\n" okMsg: .asciz "File \"output.txt\" has been created\n" buffer: .skip 1024 .end