#================================================================= # read a file (one-buffer-at-a-time) # ================================================================ .data filename: .string "sample.txt" # The file name (must be # null-terminated) buffer: .space 2048 # Allocate 2048 bytes of buffer # space to store contents .text .global main main: # ------------------------------------------------------------- # STEP 1: Open the file # ------------------------------------------------------------- li a7, 1024 # System call for open file la a0, filename # Address of null-terminated string # containing filename li a1, 0 # Flags: 0 for read-only ecall # Execute open bltz a0, file_error # If a0 is negative, the open failed mv s0, a0 # Save the file descriptor returned in a0 to s0 # ------------------------------------------------------------- # STEP 2: Read from the file # ------------------------------------------------------------- li a7, 63 # System call for read from file mv a0, s0 # Pass the saved file descriptor la a1, buffer # Address of the buffer to store characters li a2, 2048 # Buffer length (maximum bytes to read) ecall # Execute read bltz a0, read_error # If a0 is negative, the read failed mv s1, a0 # s1 now holds the actual number of bytes read # ------------------------------------------------------------- # STEP 3: Close the file # ------------------------------------------------------------- li a7, 57 # System call for close file mv a0, s0 # Pass the file descriptor to close ecall # Execute close # Optional: Null-terminate the string in buffer to easily print it la t0, buffer add t0, t0, s1 # Find end of data (buffer address + bytes read) sb zero, 0(t0) # Store null-byte at the end # Optional: Print the buffer to the console to verify it worked li a7, 4 # System call for print string la a0, buffer # Load buffer address ecall # Exit the program successfully li a7, 10 # System call for exit ecall # Error Handler Branches file_error: # Handle file opening failure (e.g., file not found) li a7, 10 ecall read_error: # Handle read execution failure li a7, 10 ecall