;; 203 Lab#7 - Spring 2014

 .ORIG X3000
 ;; initially, stop any note playing by setting FGCR to zero
 AND R0 ,R0,#0

 LD R3, ASCII_KEYS
 NOT R3, R3
 ADD R3, R3, #1

 STI R0, FGCR_ADDR ; mem[x440a] = R0 = 0
     ; set FGCR = 0 to stop playing note
 BR WAIT_FOR_KEY
 ;;
 ;; Starting the main loop WAIT_FOR_KEY
 ;; Test KPDR until it is non-zero,
 ;;indicating key pressed

WAIT_FOR_KEY
 LDI R0,KPDR_ADDR ; R0 = ascii(typed_key),
     ; typed_key ranged from 1 to 9
     ; ascii code will be from x31 to x39

 BRz WAIT_FOR_KEY ; If zero, no key yet. Loop back
 ;;
 ;; Got a key! RO = TYPED KEY.
 ;; Convert the typed ASCII_# into an index (0-8)
 ;; which means that convert "1" to 0, "2" to 1, and etc.
 ;;
 ;; Write your convertion code here!!!!!!!!!!!!!!!
 ;; You will put the converted index number in R0!
 ;; R0 should be in the range of 0-8,
 ;;

 ADD R0, R0, R3

 ;; However, let's doubtcheck it for safety.
 ;; WRITE you codes here to check if R0 is out of range
 ;; If the number is out of range,
 ;; branch back to WAIT_FOR_KEY
 ;;

 BRn WAIT_FOR_KEY

 ADD R2, R0, #-8

 BRp WAIT_FOR_KEY


 ;; now R0 in within 0 and 8, which means that
 ;; the key_in number is within '1' and '9'.
 ;;
 ;; Write the next piece of codes to
 ;; play the note by looking up the frequency.
 ;; Use LEA to load the starting address of note_freq_array
 ;; into a register.


 LEA R1, NOTE_FREQ_ARR
 ADD R1, R1, R0
 LDR R1, R1, #0
 STI R1, FGDR_ADDR
 STI R1, FGCR_ADDR





 ;; Write this frequency to the frequency generator FGDR
 ;; To play this musical note, you need to write any
 ;; non-zero number to FGCR
 ;; Now the note will be played through the speaker!!



 ;;
 ;;

WAIT_FOR_RELEASE
 LDI R0, KPDR_ADDR
 BRz KEY_RELEASED
 BRnp WAIT_FOR_RELEASE


KEY_RELEASED
 AND R1, R1, #0
 STI R1, FGCR_ADDR
 STI R1, FGDR_ADDR
 BR WAIT_FOR_KEY  ; repeat
 ;;
 HALT

;; LABEL DEFINITIONS
;; 9 numeric keys
ASCII_KEYS
 .STRINGZ "123456789"
;; KPDR holds the most recent key to be pressed.
KPDR_ADDR
 .FILL x4400
;;KPSR tracks the number of milliseconds since the last key was pressed.
KPSR_ADDR
 .FILL x4402
;; FGDR specifes the frequency for the output tone.
FGDR_ADDR
 .FILL x4408
;; FGCR controls the behavior of the function generator.
FGCR_ADDR   ; If FGCR = 0, stop playing musical notes.
 .FILL x440a  ; non-zero FGCR will generate musical notes.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 9 frequencies for 9 key_in numbers
NOTE_FREQ_ARR
 .FILL 440  ;; x01B8
 .FILL 466  ;; x01D2
 .FILL 493  ;; x01ED
 .FILL 523  ;; x020B
 .FILL 554  ;; x022A
 .FILL 587  ;; x024B
 .FILL 622  ;; x026E
 .FILL 698  ;; x02BA
 .FILL 783  ;; x030F
;;
;; RESERVE some memory for recording application
NOTE_ARRAY
 .BLKW 32
 .END