; ---------------------------------------- ; Lab 3 - Pseudo-instructions ; Versi

Question

; ----------------------------------------
; Lab 3 - Pseudo-instructions
; Version 1.0
; Date: September 26, 2016
; Written By : Ricky Chhun
; Lab Hours : Monday 10:00am - 12:45pm
; ----------------------------------------

   .INCLUDE

   .DEF var_A = r16
  
   .DSEG
   room: .BYTE   1     
   dir:   .BYTE   1
   turn: .BYTE   1

   .CSEG
   .ORG 0x0000
   RST_VECT:
    rjmp reset                 // jump over IVT, plus INCLUDE code
   .ORG 0x0100                // bypass IVT
   .INCLUDE "spi_shield.inc"
   .INCLUDE "testbench.inc"   // DrawRoom and DrawDirection

reset:
   ldi    r16,high(RAMEND)    // IO[0x3e] = 0x08
   ldi    r17,low(RAMEND)     // IO[0x3d] = 0xff
   out    SPH,r16             // SP = 0x08FF
    out    SPL,r17

   call InitShield           // initialize GPIO Ports and SPI communications
   clr   spiLEDS              // clear discrete LEDs
   clr   spi7SEG              // clear 7-segment display

;Initialize SRM Variables  
   clr   r17                  // initalizes r17 to 0 and then stores data from r17 into variable room
   sts turn, r17
   sts   room, r17
   ldi   r17, 0x03            // loads the hex number 3 into r17 and then stores the 3 into variable dir
   sts   dir, r17

loop:

   call    ReadSwitches       // read switches into r7

   // dir = rightmost two switches (switch & 0x03);
   mov     r17, switch        // move switch (r7) to temporary register r17
    cbr     r17, 0xFC          // mask-out most significant 6 bits
    sts     dir, r17           // save formatted value to SRAM variable dir.
  
   /* Read Switches and update room and direction */
    // room = leftmost four switches (switch >> 4);
   mov     r17, switch        // move switch (r7) to temp register r17
   cbr     r17, 0x0F          // mask-out least significant nibble
    swap    r17                // swap nibbles
    sts     room, r17          // save formatted value to SRAM variable room.

   // turn = remaining two switches {(switch >>2)} & 0x03};
   mov r17, switch       // move turn to temp register r17
   cbr r17, 0xF3       // mask-out all switches beside 2 and 3
   lsr r17       // shift switches to the right
   lsr r17       // shift switches to right once more so they are at the end
   sts turn, r17       // save the value to variable turn

   ; Direction Finder
       lds r24, dir   // load direction bear is facing into r24
       lds r22, turn   // load direction bear is to turn into r22
       rcall WhichWay   // change direction based on variable turn
       sts dir, r24   // save formatted value to SRAM variable dir.

   rcall TestHitWall
   rcall TestRightPaw
   rcall TestLeftPaw

    /* Draw Direction */
   lds     r24, dir           // calling argument dir is placed in r24.
   rcall   DrawDirection      // translate direction to 7 segment bit
   mov     spi7SEG, r24       // Displays DrawDirection on the 7 segment display.
    call    WriteDisplay

   /* Room Builder */
   lds     r24, room          // calling argument room is placed in r24.
   rcall   DrawRoom           // translate room to 7-seg bits
   mov     spi7SEG, r24       // return value, the room, is saved to 7 segment display register
   call    WriteDisplay       // display the room
  
   rjmp   loop

   ; -------------------------------------
; -------- Pseudo Instructions --------
; --------------------------
; ------- Turn Left --------
; Called from WhichWay subroutine (see Table 5.1)
; The input and output is register r24
; register SREG is modified by this subroutine
TurnLeft:
   cpi r24, north   // Is the bear facing north?
   brne check_east
   ldi r24, west // yes, turning left, the bear
   rjmp endTurnLeft //   is now facing west.
check_east:       // no
   cpi r24, east       // Is the beat facing east?
   brne check_south
   ldi r24, north       // yes, turning left, the bear
   rjmp endTurnLeft   // is now facing north
check_south:       // no
   cpi r24, south       // Is the bear facing south?
   brne facing_west  
   ldi r24, east       // yes, turning left, the bear
   rjmp   endTurnLeft   // is now facing east.
facing_west:   // no, the bear must be facing west
   ldi r24, south   // turning left, the bear
endTurnLeft:   // is now facing south.
   ret

; --------------------------
; ------- Turn Right -------
; Called from WhichWay subroutine (see Table 5.1)
; The input and output is register r24
; register SREG is modified by this subroutine
TurnRight:
   cpi r24, north   // Is the bear facing north?
   brne check_westR
   ldi r24, east // yes, turning right, the bear
   rjmp endTurnRight //   is now facing east.
check_westR:       // no
   cpi r24, west       // Is the bear facing west?
   brne check_southR
   ldi r24, north       // yes, turning right, the bear
   rjmp endTurnRight   // is now facing north.
check_southR:       // no
   cpi r24, south       // Is the bear facing south?
   brne facing_eastR
   ldi r24, west       // yes, turning right, the bear
   rjmp   endTurnRight   // is now facing west.
facing_eastR:   // no, the bear must be facing east
   ldi r24, south   // turning right, the bear
endTurnRight:   // is now facing south.
    ret

; --------------------------
; ------- Turn Around -------
; Called from WhichWay subroutine (see Table 5.1)
; The input and output is register r24
; register SREG is modified by this subroutine
TurnAround:
   cpi r24, north   // Is the bear facing north?
   brne check_eastA
   ldi r24, south // yes, turning around, the bear
   rjmp endTurnAround //   is now facing south.
check_eastA:       // no
   cpi r24, east       // Is the bear facing east?
   brne check_southA
   ldi r24, west       // yes, turning around, the bear
   rjmp endTurnAround   // is now facing west
check_southA:       // no
   cpi r24, south       // Is the bear facing south?
   brne facing_westA  
   ldi r24, north       // yes, turning around, the bear
   rjmp   endTurnAround   // is now facing north.
facing_westA:   // no, the bear must be facing west
   ldi r24, east   // turning around, the bear
endTurnAround:   // is now facing east.
    ret

WhichWay:

   bst r22, 1   // store bit 1 into SREG T bit
   brts cond_1x   // branch if T is set
   // case 0x
   bst r22, 0   // store bit 0 into SREG T bit
   brts cond_01   // branch if T is set
cond_00:
   rjmp whichEnd
cond_01:
   rcall TurnRight
   rjmp whichEnd
cond_1X:
   bst r22, 0
   brts cond_11  
cond_10:
   rcall TurnLeft
   rjmp whichEnd
cond_11:
   rcall TurnAround
   rjmp whichEnd
whichEnd:
   ret

; --------------------------------------
; ----------- Pseudo Instructions ---------
; ------------------------
;-- Did you hit a wall? --_
; Called from WhichWay subroutine
; Inputs: r22 (room), r42 (dir)
; Output: C++ return register (r24)
; If the answer is no, r24 is set to zero,
; Else the answer is yes
; No registers are modified, while SREG is modified by this subroutine
; -------------------------
HitWall:
   push r16

   rcall DrawDirection // direction segment bits are now in r16
   mov r16, r24   // room segment bits are now in r24
   mov r24, r22
   rcall DrawRoom

   // return drawDirection(dir) & drawRoom(room);

   pop r16
   ret
; -----------------------

; --------------------------------------
; ----------- Test Subroutines ---------
; ---------------------------
; -------- Test HitWall -----
; Called from main program
; Input: none Outputs: spiLEDs bits 1 and 0 only
TestHitWall:
   lds r22, room
   lds r24, dir
   mov r16, spiLEDs
   rcall HitWall
   tst r24
   breq noWall
   sbr r16, 0b00100000 // set hit wall LED
   cbr r16, 0b00010000 // sequence to true
   rjmp overTheWall
noWall:
   sbr r16, 0b00010000
   cbr r16, 0b00100000
overTheWall:
   mov spiLEDs, r16
   ret

; --------------------------------------
; ----------- Pseudo Instructions ---------
; ------------------------
;-- right paw touch a wall? --_
; Called from WhichWay subroutine
; Inputs: r22 (room), r42 (dir)
; If the answer is no, the return value is set to zero,
; Else the answer is yes
; No registers are modified, while SREG is modified by this subroutine
; -------------------------

RightPaw:
   rcall TurnRight
   rcall HitWall
   ret
; ------------------------
;-- left paw touch a wall? --_
; Called from WhichWay subroutine
; Inputs: r22 (room), r42 (dir)
; If the answer is no, the return value is set to zero,
; Else the answer is yes
; No registers are modified, while SREG is modified by this subroutine
; -------------------------

LeftPaw:
   rcall TurnLeft
   rcall HitWall
   ret
; ----------------------

TestRightPaw:
   lds r22, room
   lds r24, dir
   mov r16, spiLEDs
   rcall RightPaw
   tst r24
   breq noWall
   sbr r16, 0b00000010 // set hit wall LED
   cbr r16, 0b00000001 // sequence to true
   rjmp overTheWall
noWallR:
   sbr r16, 0b00000001
   cbr r16, 0b00000010
overTheWallR:
   mov spiLEDs, r16
   ret

; ----------------------

TestLeftPaw:
   lds r22, room
   lds r24, dir
   mov r16, spiLEDs
   rcall HitWall
   tst r24
   breq LeftPaw
   sbr r16, 0b00001000 // set hit wall LED
   cbr r16, 0b00000100 // sequence to true
   rjmp overTheWall
noWallL:
   sbr r16, 0b00000100
   cbr r16, 0b00101000
overTheWallL:
   mov spiLEDs, r16
   ret

Explanation / Answer

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="&&+id/linearLayout1"
android:layout_marginLeft="10pt"
android:layout_marginRight="10pt"
android:layout_marginTop="3pt">
<EditText
android:layout_weight="1"
android:layout_height="wrap_content"
android:layout_marginRight="5pt"
android:id="&&+id/etNum1"
android:layout_width="match_parent"
android:inputType="numberDecimal">
</EditText>
<EditText
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginLeft="5pt"
android:id="&&+id/etNum2"
android:layout_width="match_parent"
android:inputType="numberDecimal">
</EditText>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="&&+id/linearLayout2"
android:layout_marginTop="3pt"
android:layout_marginLeft="5pt"
android:layout_marginRight="5pt">
<Button
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_weight="1"
android:text="+"
android:textSize="8pt"
android:id="&&+id/btnAdd">
</Button>
<Button
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_weight="1"
android:text="-"
android:textSize="8pt"
android:id="&&+id/btnSub">
</Button>
<Button
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_weight="1"
android:text="*"
android:textSize="8pt"
android:id="&&+id/btnMult">
</Button>
<Button
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_weight="1"
android:text="/"
android:textSize="8pt"
android:id="&&+id/btnDiv">
</Button>
</LinearLayout>
<TextView
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_marginLeft="5pt"
android:layout_marginRight="5pt"
android:textSize="12pt"
android:layout_marginTop="3pt"
android:id="&&+id/tvResult"
android:gravity="center_horizontal">
</TextView>
</LinearLayout>

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