anchor.diff:    :opcode-extension 0
     :encoding (modrm imm))
   
  -;;; Add imm32 to mem32
  +;;; To a 32-bit memory location (destination), add an immediate 32-bit
  +;;; value (source), and store the result in the destination.
   (define-instruction "ADD"
     :modes (32 64)
     :operands ((memory 32) (imm 32))
  
positive.code: 
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Add imm to reg/mem, 16/32/64
  ;;; Opcodes: 81
  ;;; Opcode extension 0
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Add imm16 to reg/mem16
  
  ;;; Add imm16 to reg16
  (define-instruction "ADD"
    :modes (32 64)
    :operands ((gpr 16) (imm 16))
  
negative.code:   :encoding (modrm imm)
    :operand-size-override t)
  
  ;;; To a 16-bit memory location (destination), add an immediate 16-bit
  ;;; value (source), and store the result in the destination.
  (define-instruction "ADD"
    :modes (32 64)
    :operands ((memory 16) (imm 16))
  