HW6 Bug Fixes

1 files changed, 88 insertions, 18 deletions

diff --git a/cmpen472hw6_McDonnell/Sources/main.asm b/cmpen472hw6_McDonnell/Sources/main.asm
index 0b40a5a..e5656e9 100644
--- a/cmpen472hw6_McDonnell/Sources/main.asm
+++ b/cmpen472hw6_McDonnell/Sources/main.asm
@@ -77,23 +77,8 @@ buffer2     ds.b        $0010           ; Array of 16 bytes for reading and reve
             dc.b        NULL            ; NULL terminated
 lenBuf2     dc.w        $0010           ; length of buffer2
 
-badAddr     dc.b        'invalid input, address',CR,LF,NULL ; Error message for bad address
-
-badData     dc.b        'invalid input, data',CR,LF,NULL    ; Error message for bad data
-
-badCom      dc.b        'invalid input, command',CR,LF,NULL ; Error message for bad command
-
-; twMsg: welcome message when type writer loads
-twMsg       dc.b        'Welcome to Type Writer, you may type below.',CR,LF
-            dc.b        'Restart to enter main menu again.',CR,LF,NULL
-
-
-; msg: this is the main option menu string
-msg         dc.b        'S:      Show the contents of memory location in word',CR,LF
-            dc.b        'W:      Write the data word (not byte) to memory location',CR,LF
-            dc.b        'QUIT:   Quit the main program, run Type writer program.',CR,LF,NULL
-
 *
+* There is a section Data Section at the end of the file
 **************************************************************************
 * Program Section: address used [ $3100 to $3FFF ] RAM Memory
 *
@@ -108,7 +93,9 @@ pgstart     lds         #$3100          ; initialize the stack pointer
 
             ldd         #$0001          ; Set SCI Baud Register = $0001 => 1.5M baud at 24MHz (for simulation)
             std         SCIBDH          ; SCI port baud rate change
-
+            
+            ldx         #msg            ; Load the address of the welcome message into X
+            jsr         WriteString     ; Write the string to the serial console
 
 mainLoop
             ldx         #buffer         ; Load the address of the buffer into X
@@ -420,7 +407,9 @@ revLoop     ldaa        1,y-            ; Load Character from Y into A, decremen
             beq         revDone         ; If Character is 0, exit loop
             staa        1,x+            ; Save character in address in X, increment X
             bra         revLoop         ; Loop back always
-revDone     pula                        ; Restore A from the stack
+            clra                        ; Set A to Zero
+revDone     staa        1,x+            ; Copy Null terminator into new string
+            pula                        ; Restore A from the stack
             puly                        ; Restore Y from the stack
             pulx                        ; Restore X from the stack
             rts                         ; Return to caller
@@ -479,6 +468,20 @@ PrintHexWord
             pshx                        ; Save X to the stack
             pshd                        ; Save D (A:B) to the stack
             pshy                        ; Save Y to the stack
+            cpd         #0              ; Compare D to zero
+            beq         hIsZero         ; Branch to hIsZero
+            psha                        ; Save A to the stack
+            pshy                        ; Save Y to the stack
+            pshx                        ; Save x to the stack
+            ldaa        #'0'            ; Load the '0' character into A
+            ldx         #buffer2        ; Load the address of buffer2 into X
+            ldy         #5              ; Load 5 into Y
+            jsr         memset          ; Write '0' to the first 5 bytes in buffer2
+            pulx                        ; Restore X from the stack
+            puly                        ; Restore Y from the stack
+            clra                        ; Set A to zero
+            staa        0,y             ; Load Zero into Y for Null Terminator
+            pula                        ; Restore A from the stack
 hPrintLoop  ldx         #16             ; Load 16 in X for division
             idiv                        ; Divide D / 16 to get Hex Digit
             cpx         #0              ; Compare X to 0
@@ -508,6 +511,14 @@ hPrintDone  ldaa        #'$'            ; Load '$' into
             puld                        ; Restore D (A:B) from the stack
             pulx                        ; Restore X from the stack
             rts                         ; Return to caller
+hIsZero     ldaa        #'$'            ; Load '$' character into A
+            jsr         putchar         ; Print character to the screen
+            ldaa        #'0'            ; Load '0' character into A
+            jsr         putchar         ; Print character to the screen
+            puly                        ; Restore Y from the stack
+            puld                        ; Restore D (A:B) from the stack
+            pulx                        ; Restore X from the stack
+            rts                         ; Return to caller
 
 ;*************************************************************************
 ; PrintDecimalWord subroutine
@@ -527,6 +538,20 @@ PrintDecimalWord
             pshx                        ; Save X to the stack
             pshd                        ; Save D (A:B) to the stack
             pshy                        ; Save Y to the stack
+            cpd         #0              ; Compare D to zero
+            beq         dIsZero         ; Branch to hIsZero
+            psha                        ; Save A to the stack
+            pshy                        ; Save Y to the stack
+            pshx                        ; Save x to the stack
+            ldaa        #'0'            ; Load the '0' character into A
+            ldx         #buffer2        ; Load the address of buffer2 into X
+            ldy         #5              ; Load 5 into Y
+            jsr         memset          ; Write '0' to the first 5 bytes in buffer2
+            pulx                        ; Restore X from the stack
+            puly                        ; Restore Y from the stack
+            clra                        ; Set A to zero
+            staa        0,y             ; Load Zero into Y for Null Terminator
+            pula                        ; Restore A from the stack
 dPrintLoop  ldx         #10             ; Load 10 in X for division
             idiv                        ; Divide D / 10 to get Hex Digit
             cpx         #0              ; Compare X to 0
@@ -547,6 +572,12 @@ dPrintDone  ldx         #buffer2        ; Load the address of buffer2 in X
             puld                        ; Restore D (A:B) from the stack
             pulx                        ; Restore X from the stack
             rts                         ; Return to caller
+dIsZero     ldaa        #'0'            ; Load '0' character into A
+            jsr         putchar         ; Print character to the screen
+            puly                        ; Restore Y from the stack
+            puld                        ; Restore D (A:B) from the stack
+            pulx                        ; Restore X from the stack
+            rts                         ; Return to caller
 
 ;*************************************************************************
 ; Zeros subroutine
@@ -570,6 +601,24 @@ zerosLoop   staa        1,x+            ; Load A into byte at X
             rts                         ; Return to caller
 
 ;*************************************************************************
+; memset subroutine
+;
+; This subroutine will write a given byte to every byte in a given array.
+;
+; Input:                   Address of an array in X and its length in Y, the byte in A
+; Output:                  The given byte in every byte of an array.
+; Registers in use:        X for the address of the array, Y for the length, and A for the given byte
+; Memory locations in use: Memory Address of the array
+;
+; Comments: This subroutine requires serial to be setup and putchar subroutine.
+;
+
+memset
+            staa        1,x+            ; Load A into byte at X
+            dbne        y,memset         ; Decrement Y and loop if Y != 0
+            rts                         ; Return to caller
+
+;*************************************************************************
 ; WriteString subroutine
 ;
 ; This subroutine will write a given null terminated string to the serial.
@@ -657,4 +706,25 @@ getchar     brclr       SCISR1,#%00100000,getchar7  ; If no input on SCI port, r
 getchar7    clra                                    ; Set A to 0
             rts                                     ; Return to caller
 
+*
+**************************************************************************
+* Data Section 2: address used [ $3100 to $3FFF ] RAM Memory
+*
+
+badAddr     dc.b        'invalid input, address',CR,LF,NULL ; Error message for bad address
+
+badData     dc.b        'invalid input, data',CR,LF,NULL    ; Error message for bad data
+
+badCom      dc.b        'invalid input, command',CR,LF,NULL ; Error message for bad command
+
+; twMsg: welcome message when type writer loads
+twMsg       dc.b        'Welcome to Type Writer, you may type below.',CR,LF
+            dc.b        'Restart to enter main menu again.',CR,LF,NULL
+
+
+; msg: this is the main option menu string
+msg         dc.b        'S:      Show the contents of memory location in word',CR,LF
+            dc.b        'W:      Write the data word (not byte) to memory location',CR,LF
+            dc.b        'QUIT:   Quit the main program, run Type writer program.',CR,LF,NULL
+
             end                         ; last line of the file