5.9 Global variables

• Emulator-related variables
  • *user-variables*
    Contains the user's variables when a query is issued.
  • *registers*
    The define-register function adds each register to this list, causing the debugger to output the variables of this list.
  • *read-mode*
    This is a global flag in the machine indicating the read/write status, which is used in the unify instructions.
  • *emu-debug*
    This flag determines whether the emulator is in a debugging state or will just run through the code. It can have the following values:
    • :interactive the emulator performs single steps
    • T the emulator shows all executed instructions without interaction
    • nil if no debugging is demanded
• code generator-related variables
  • *lureg*
    This variable determines which X-registers can be used by the code generator without any interference with the classifier's allocations.
  • y-x-usage-list
    An assoc-list mapping Y variables to X-registers.