HW5 ReadString now checks length

1 files changed, 16 insertions, 7 deletions

diff --git a/cmpen472hw5_McDonnell/bin/main.dbg b/cmpen472hw5_McDonnell/bin/main.dbg
index 92a558c..8c52b13 100644
--- a/cmpen472hw5_McDonnell/bin/main.dbg
+++ b/cmpen472hw5_McDonnell/bin/main.dbg
@@ -77,9 +77,9 @@ Counter     dc.w        $0036           ; X register count number for time Delay
 
 LEVEL       dc.b        $0005           ; Light Level that the LED should be
 
-str         ds.b        $0005           ; Array of 5 bytes to read a string
+str         ds.b        $000F           ; Array of 16 bytes to read a string
             dc.b        NULL
-lenStr      dc.w        $0005           ; Length of str array
+lenStr      dc.w        $000F           ; Length of str array
 * There is a second Data Section at the end of the file.
 *
 **************************************************************************
@@ -107,6 +107,7 @@ mainLoop
             jsr         Zeros           ; jump to Zeros to zero out str
 
             ldx         #str            ; Reload address of str into X
+            ldy         lenStr          ; Load the length of the string into Y
             jsr         ReadString      ; Jump to ReadString to read user input into str
 
             ldx         #str            ; Reload Address of str into X
@@ -153,6 +154,7 @@ CheckInput
             cmpa        #'4'            ; Compare Character in A to '4'
             beq         L4Check         ; If A == '4', branch to L4Check
             suba        #'0'            ; Subtract character '0' from A
+                                        ; This allows the number in A to be the LED number (if correct)
             ble         none            ; If A < '0', branch to none (unknown string)
             cmpa        #4              ; Compare A to 4
             bhs         none            ; Branch to None if A > 3
@@ -245,7 +247,8 @@ doneWrite   pula                        ; restore A from the stack
 ;
 ; Input:                   Address of an array in X
 ; Output:                  Null terminated string in the given array
-; Registers in use:        X for the address of the string and A for the current byte
+; Registers in use:        X for the address of the string Y for the length of the string,
+;                          and A for the current byte
 ; Memory locations in use: Memory Address for serial line, address of the string
 ;
 ; Comments: This subroutine requires serial to be setup and getchar subroutine.
@@ -253,6 +256,7 @@ doneWrite   pula                        ; restore A from the stack
 
 ReadString
             psha                        ; Save accumulator A to the stack
+            pshy                        ; Save Y to the stack
             pshx                        ; Save X to the stack
 readLoop    jsr        getchar          ; Jump to putchar to write byte to serial
             beq        readLoop         ; While A == 0, loop
@@ -260,10 +264,13 @@ readLoop    jsr        getchar          ; Jump to putchar to write byte to seria
             beq        doneRead         ; Branch to doneRead if A == CR
             staa       1,x+             ; Save the byte to the addr in X, then add 1
             jsr        putchar          ; Write Character back to the terminal
+            dey                         ; Decrement Y by 1
+            beq        doneRead         ; If Y == 0, no more room, stop reading
             bra        readLoop         ; branch always to readLoop
 doneRead    ldaa       #LF              ; Load Line Feed into A
             jsr        putchar          ; Write LF to terminal
             pulx                        ; Restore X from the stack
+            pulY                        ; Restore Y from the stack
             pula                        ; restore A from the stack
             rts                         ; return to caller
 
@@ -345,14 +352,15 @@ doneDec     pula                        ; Restore A from the stack
             rts                         ; Return to caller
 
 ;*************************************************************************
-; HighToLow subroutine
+; LowToHigh subroutine
 ;
-; This subroutine will dim LED4 from 100% to 0% in 400ms
+; This subroutine will dim LED4 from 0% to 100% in 400ms
 ;
 ; Input:                   No Input, all parameters are hard coded
-; Output:                  LED4 dimmed from 100% to 0% in 400ms, wasted cycles
+; Output:                  LED4 dimmed from 0% to 100% in 400ms, wasted cycles
 ; Registers in use:        A accumulator to control the light level of the LED
 ; Memory locations in use: PORTB memory location associated with PORTB on the chip
+;                          LEVEL memory location for byte of light level.
 ;
 ; Comments: This subroutine requires dimmer subroutine
 ;
@@ -381,7 +389,8 @@ doneInc     pula                        ; Restore A from the stack
 ;                          LED4 should be on and off for.
 ; Output:                  LED4 dimmed to a given level, wasted cycles
 ; Registers in use:        A accumulator to counter number of times looped
-; Memory locations in use: Two bytes ONN and OFF used to dim the LED4 to a given level
+; Memory locations in use: PORTB memory location associated with PORTB on the chip
+;                          LEVEL memory location for byte of light level.
 ;
 ; Comments: This subroutine requires delay10usec subroutine
 ;