MIPS Assembly Unveiled: A Guide to File Operations and Text Processing

Navigating MIPS Assembly Proficiency

Explore a comprehensive guide designed to help you master MIPS Assembly and navigate the intricate world of low-level programming. Whether you're a student seeking to grasp the essentials of Assembly or a seasoned developer looking to fine-tune your skills, this resource equips you with the knowledge and insights to excel in your Assembly assignments. By demystifying complex concepts and offering practical tips, this guide is your go-to source for making your programming journey smoother and more successful. Whether you're working on file operations, text processing, or any Assembly-related task, you'll find the guidance and expertise needed to help your Assembly assignment thrive.

Block 1: Data Section

```assembly
.data
stackbeg: .word 0 : 40
stackend: .word 0
promptInFile: .asciiz "Please enter input filename: "
promptOutFile: .asciiz "Please enter output filename: "
promptOp: .ascii "Available operations:\n"
.ascii "1. Encryption\n"
.ascii "2. Decryption\n"
.ascii "3. Compress\n"
.ascii "4. Decompress\n"
.ascii "5. Analyze text\n"
.asciiz "Choice?: "
opError: .asciiz "invalid operation.\n"
opSuccess: .asciiz "\nOperation completed successfully.\n"
inputFilename: .space 50
outputFilename: .space 50
```

This block declares data and constants used in the program. It defines message strings for prompting the user, error and success messages, and space to store input and output filenames. `stackbeg` and `stackend` appear to be related to stack initialization, and the prompt messages are stored in the form of ASCII strings.

Block 2: Text Section


```assembly
.text
.globl main
main:
la $sp, stackend # initialize stack
```

This block initializes the stack by loading the address of `stackend` into the stack pointer register (`$sp`). The program's entry point is declared as the `main` label.

Block 3: Input Filename and File Size

```assembly
# prompt for input file name
la $a0, promptInFile # load address of prompt message
jal printString # print the prompt
# read the input filename
la $a0, inputFilename # load address of space to save string
li $a1, 99 # maximum size of input string
jal readString # read the input string
# open file for getting size
la $a0, inputFilename # load input filename address
li $a1, 0 # open for reading
jal openFile # open the input file
blt $v0, $0, exit # if there was an error, exit
move $s1, $v0 # save file descriptor
# get file size
move $a0, $s1 # load file descriptor
jal getFileSize # get the file size
blt $v0, $0, exit # if there was an error, exit
move $s2, $v0 # save file size
```

This block handles input file operations. It prompts the user to enter an input filename, reads the filename into `inputFilename`, opens the file for reading, and retrieves the file size. The file descriptor and size are stored in `$s1` and `$s2`, respectively.

Block 4: Read User Operation Choice

```assembly
readOp:
# prompt for operation selection
la $a0, promptOp # load address of prompt message
jal printString # print the prompt
# read input choice
jal readChar # read the choice
move $a0, $v0 # echo character
jal printChar # print read character
li $a0, 10 # print a newline
jal printChar # print newline
blt $v0, '1', invalidOp # if input < 1, it's an invalid operation
ble $v0, '5', readOut # if input >= 1 and <= 5, it's valid, read the output filename
```

This block interacts with the user to receive the choice of operation (1-5). It reads a character, checks if it's within the valid range, and branches to `invalidOp` if the choice is not valid or to `readOut` if it is.

Block 5: Invalid Operation Handling

```assembly
invalidOp:
# print error message
la $a0, opError # load address of the error message
jal handleError # print the error
j readOp # read the choice again
```

This block handles the case where the user input is not a valid operation choice. It prints an error message and loops back to read the choice again.

Block 6: Read Output Filename or Proceed with Operation

```assembly
readOut:
move $s0, $v0 # save operation in $s0
beq $s0, '5', makeOp # if the user selected 5, make the operation
# prompt for output file name
la $a0, promptOutFile # load the address of the prompt message
jal printString # print the prompt
# read the output filename
la $a0, outputFilename # load address of space to save the string
li $a1, 99 # maximum size of the output string
jal readString # read the output string
```

This block either proceeds with the operation (if the choice is 5) or prompts the user for an output filename and reads it into `outputFilename`.

Block 7: Make Operation (Option 5) or File Reading

```assembly
makeOp:
# open file for reading
la $a0, inputFilename # load input filename address
li $a1, 0 # open for reading
jal openFile # open the input file
blt $v0, $0, exit # if there was an error, exit
move $s1, $v0 # save file descriptor
# allocate space for reading file
move $a0, $s2 # load file size
jal allocateMemory # allocate space for reading the file
move $s3, $v0 # save pointer to allocated memory
```

This block opens the input file for reading, allocates memory to read the file, and saves the file descriptor and the pointer to the allocated memory.

Block 8: Read and Close Input File

```assembly
# read file
move $a0, $s1 # load file descriptor
move $a1, $s3 # load pointer to read buffer
move $a2, $s2 # load file size
jal readFile # read the file
blt $v0, $0, exit # if there was
an error, exit
move $a0, $s1 # load file descriptor
jal closeFile # close the file
```

This block reads the input file, and if successful, it closes the input file.

Block 9: Operation Selection and Execution

```assembly
# Perform operation
beq $s0, '2', option2 # if the user selected 2, go to option
beq $s0, '3', option3 # if the user selected 3, go to option
beq $s0, '4', option4 # if the user selected 4, go to option
beq $s0, '5', option5 # if the user selected 5, go to option
option1: # else, the remaining option is 1
move $a0, $s3 # load pointer to the read buffer
move $a1, $s2 # load file size
jal encrypt # encrypt the file
blt $v0, $0, exit # if there was an error, exit
j save # else, save the result in a file
```

This block checks the user's choice and branches to specific sections of code depending on the selected operation (1, 2, 3, 4, or 5). It performs the selected operation on the input data.

Block 10: Option 2-5 Handling

```assembly
option2:
# Handling for option 2 (Decryption)
option3:
# Handling for option 3 (Compression)
option4:
# Handling for option 4 (Decompression)
```

These blocks handle options 2, 3, and 4. Each block invokes a specific function to perform the operation (decrypt, compress, or decompress) and saves the result in variables.

Block 11: Save Result to Output File

```assembly
save:
# open file for writing
la $a0, outputFilename # load the output filename address
li $a1, 1 # open for writing
jal openFile # open the output file
blt $v0, $0, exit # if there was an error, exit
move $s1, $v0 # save the file descriptor
# save file
move $a0, $s1 # load the file descriptor
move $a1, $s3 # load pointer to the write buffer
move $a2, $s2 # load the file size
jal writeFile # write the file
blt $v0, $0, exit # if there was an error, exit
move $a0, $s1 # load the file descriptor
jal closeFile # close the file
```

This block handles saving the result of the operation to an output file. It opens the output file for writing, writes the data, and then closes the file.

Block 12: Option 5 (Text Analysis)

```assembly
option5:
move $a0, $s3 # load pointer to read buffer
move $a1, $s2 # load file size
jal analyzeText # analyze text
```

This block is for handling option 5, which is text analysis. It calls a function to analyze the text data.

Block 13: Operation Success and Exit

```assembly
success:
# indicate operation success
la $a0, opSuccess # load the address of the success message
jal printString # print the message
exit:
li $v0, 10 # syscall number to exit the program
syscall # exit the program
```

This block prints a success message and exits the program by making a system call.

Block 14: Include Modules

```assembly
# include all modules
.include "Console.asm"
.include "Utilities.asm"
.include "FileReader.asm"
.include "FileWriter.asm"
.include "TextProcessor.asm"
```

This block includes external assembly modules, suggesting that the functions and procedures used in the code are defined in these included files.

Conclusion

In conclusion, this comprehensive guide has unveiled the remarkable world of MIPS assembly, offering valuable insights into handling file operations and harnessing the potential of text processing. Whether you're a student or a seasoned developer, this journey through the intricacies of MIPS assembly empowers you with the knowledge and skills to excel in low-level programming. With a newfound understanding of data manipulation and user interaction, you can confidently navigate the realm of file operations and text processing, making MIPS assembly a vital tool in your programming arsenal.

Navigating File Operations and Text Processing in MIPS Assembly