3.0 - Stack operations

Changes

• added automatic prelude insertion. Before each program, the following instructions are inserted:

  lui $gv, 0x1000 # initialize global pointer
  lui $sp, 0x8000 # initialize stack pointer
  ja $zero, main  # jump to main function
  

• because ja is a pseudoinstruction, this translates to five machine instructions. As such, your program now starts at address 0x14(=20)
• added two new pseudo-instructions:

  push $t0 # push the contents of t0 onto the stack
  pop $t0   # retrieve the top value from the stack into $t0
  

• error messages now correctly refer to the file the error is in
• error messages now count lines from 1 (was 0 in previous releases)

Migration

• add a "main:" label to the entry point of your program
• if you are using manually calculated jumps anywhere, add 20 to your addresses