Check if current number in ACC is negative

less_than_zero.asm

  ;Dan Woodson
  ;Check if Negatives
  
  JMP _start
  
  ; Variables

  sentinal: 20        ; range to check for negatives (up to -31)
  sent_count: 0       ; temp count
  pos_test: 2         ; number to check
  register: 0         ; extra reg
  neg_flag: 0         ; negative flag (if value in ACC is negative)
  orig_value: 0       ; extra reg
  
  ;;;Functions;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;  
  ;;;Check if Neg;;;
  _check_if_neg
  ; store acc
  STOAC register
  STOAC orig_value
  
  ;setup sentinal and neg_flag (clear)
  CLAC
  STOAC sent_count
  STOAC neg_flag
  
  _begin_neg_loop  
  
  ; restore value to ACC
  LDA register 
  
  ; increment and see if result equals zero
  INC
  STOAC register
 
  JMPZ _set_flag
  
  ;increment loop count
  LDA sent_count
  INC
  STOAC sent_count
  
  ;if sent_count = sentinal: break/return
  MOVAC
  LDA sentinal
  SUB
  JMPZ _return_check_if_neg
  
  JMP _begin_neg_loop
  
  _set_flag
  INC
  STOAC neg_flag
  
  ;return
  JMP _return_check_if_neg
     
  
;;;;;;;;;;;;;;;;;;;;MAIN PROGRAM;;;;;;;;;;;;;;;;;;;;;;;;;;;;

  _start
  
  _main
  ;setup negative
  LDA pos_test
  MOVAC
  CLAC
  SUB
  
  STOAC orig_value
  JMP _check_if_neg
  _return_check_if_neg
  LDA orig_value
  ;NOW CHECK neg_flag
  
  OUT
  HALT