# Part 1: Create space in the data section for the header information.
.data
bmp_header: .space 54  # Allocate 54 bytes for BMP header
bmp_filename: .asciiz "pillarscipher.bmp"
not_found_text: .asciiz "Asterisks not found"

.text
# Open the file for reading (syscall 13)
li $v0, 13             # syscall 13 for opening a file
la $a0, bmp_header # Load the file name
li $a1, 0              # Open in read-only mode
li $a2, 0              # File permission (ignored)
syscall

# Read the first two bytes of the BMP file (syscall 14)
li $v0, 14             # syscall 14 for reading a file
la $a0, bmp_header     # Load address of bmp_header to read into
li $a1, 2              # Read 2 bytes
li $a2, 0              # File descriptor (from the previous syscall)
syscall

# Access the BMP header data and answer the questions
# 1) What are the first two bytes of the BMP file?
lb $t0, bmp_header     # Load the first byte into $t0
lb $t1, bmp_header+1   # Load the second byte into $t1

# Calculate the file size (assuming it's little-endian)
lw $t2, bmp_header+2   # Load the file size into $t2

# Extract the Bits Per Pixel value
lw $t3, bmp_header+28  # Load Bits Per Pixel into $t3

# Part 2: Allocate space on heap using the size information (syscall 9)
li $v0, 9              # syscall 9 for sbrk (allocate heap space)
move $a0, $t2          # Size of the file
li $v1, 4              # Allocate in units of 4 bytes (words)
syscall
# Now, you have heap space for the file content in $v0

# Reopen the file to read the rest of the data
li $v0, 13             # syscall 13 for opening a file
la $a0, bmp_header # Load the file name again
li $a1, 0              # Open in read-only mode
li $a2, 0              # File permission (ignored)
syscall

# Read the file content and store it in the heap space
li $v0, 14             # syscall 14 for reading a file
la $a0, 0($v0)         # Address of the heap space
move $a1, $t2          # Number of bytes to read (file size)
li $a2, 0              # File descriptor (from the previous syscall)
syscall

# Part 3: Search through the heap to find the clue (city following three asterisks)
la $t4, 0($v0)         # Load address of the heap space
li $t5, 0x2A2A2A       # ASCII value for three asterisks: '***'
search_loop:
    lb $t6, ($t4)      # Load a byte from the heap
    beqz $t6, not_found  # If it's null, the asterisks were not found
    beq $t6, $t5, found_clue  # If three asterisks are found, jump to found_clue
    addi $t4, $t4, 1   # Move to the next byte
    j search_loop

not_found:
    # Print a message indicating that the asterisks were not found
    li $v0, 4
    la $a0, not_found_text
    syscall

found_clue:
    # Define a buffer to store the city name
    .data
    city_buffer: .space 100  # Adjust the size as needed

    # Initialize indices and counters
    li $t7, 0     # Index for city_buffer
    li $t8, 0     # Counter for the number of characters processed

    copy_loop:
        lb $t9, ($t4)      # Load a byte from the heap
        sb $t9, city_buffer($t7)  # Store it in city_buffer
        beqz $t9, end_copy  # If it's null (end of city name), exit the loop

        # Move to the next byte in both source and destination
        addi $t4, $t4, 1
        addi $t7, $t7, 1

        # Check for the maximum city name length (e.g., 99 characters)
        # If you have a specific maximum length, you can adjust this value
        li $t6, 99  # Maximum city name length
        bge $t8, $t6, end_copy

        # Increment the counter
        addi $t8, $t8, 1
        j copy_loop

    end_copy:
        # Null-terminate the extracted city name
        sb $zero, city_buffer($t7)

        # Display the extracted city name (null-terminated string)
        li $v0, 4
        la $a0, city_buffer
        syscall

    # Exit the program
    li $v0, 10             # syscall 10 to exit
    syscall