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|
**************************************************************************
* Parameter Declearation Section
*
* Export Symbols
xdef pgstart ; export 'pgstart' symbol
absentry pgstart ; for assembly entry point
* Symbols and Macros
PORTA equ $0000 ; i/o port A addresses
DDRA equ $0002 ; data direction register for PORTA
PORTB equ $0001 ; i/o port B addresses
DDRB equ $0003 ; data direction register for PORTB
SCIBDH equ $00C8 ; Serial port (SCI) Baud Register H
SCIBDL equ $00C9 ; Serial port (SCI) Baud Register L
SCICR2 equ $00CB ; Serial port (SCI) Control Register 2
SCISR1 equ $00CC ; Serial port (SCI) Status Register 1
SCIDRL equ $00CF ; Serial port (SCI) Data Register
CRGFLG EQU $0037 ; Clock and Reset Generator Flags
CRGINT EQU $0038 ; Clock and Reset Generator Interrupts
RTICTL EQU $003B ; Real Time Interrupt Control
CR equ $0d ; carriage return, ASCII 'Return' key
LF equ $0a ; line feed, ASCII 'next line' character
NULL equ $00 ; NULL Terminator character
**************************************************************************
* Data Section: address used [ $3000 to $30FF ] RAM Memory
*
org $3000 ; Reserved RAM memory starting address
; for Data for CMPEN 472 class
buffer ds.b $0010 ; Array of 16 bytes to read a string
dc.b NULL ; NULL terminated
lenBuf dc.w $0010 ; Length of buffer array
buffer2 ds.b $0010 ; Array of 16 bytes for reading and reversal
dc.b NULL ; NULL terminated
lenBuf2 dc.w $0010 ; length of buffer2
hours dc.w $0000 ; Buffer to hold the hours of the time
minutes dc.w $0000 ; Buffer to hold the minutes of the time
seconds dc.w $0000 ; Buffer to hold the seconds of the time
counter dc.w $0000 ; Counter for RTI ISR for 1 second
numBuf dc.b $0000 ; Used by ReadDecimal for reading numbers
operator dc.b $0000 ; Used by ReadDecimal for reading numbers
inputBuffer ds.b $0010 ; Input Buffer Length
lenInput dc.w $0010 ; Length of the Input Buffer
outputBuf dc.b 'h' ; Used to control what to output on 7 segment display
n1 dc.b $03
dc.b $04
dc.b $05
n2 dc.b $06
dc.b $07
dc.b $08
*
**************************************************************************
* RTI Vector Section: address used [ $FFF0 to $FFF1 ] RAM Memory
*
org $FFF0 ; Memory location for RTI interrupt vector section for simulator
dc.w rtiisr ; Real Time Interrupt vector
*
**************************************************************************
* Program Section: address used [ $3100 to $3FFF ] RAM Memory
*
org $3100 ; Program start address, in RAM
pgstart lds #$3100 ; initialize the stack pointer
ldaa #%11110001 ; LED 1,2,3,4 at PORTB bit 4,5,6,7
staa DDRB ; set PORTB bit 4,5,6,7 as output
ldaa #$0C ; Enable SCI port Tx and Rx units
staa SCICR2 ; disable SCI interrupts
ldd #$0001 ; Set SCI Baud Register = $0001 => 1.5M baud at 24MHz (for simulation)
std SCIBDH ; SCI port baud rate change
bset RTICTL,%00011001; set RTI: dev=10*(2**10)=2.555msec for C128 board
; 4MHz quartz oscillator clock
bset CRGINT,%10000000; enable RTI interrupt
bset CRGFLG,%10000000; clear RTI IF (Interrupt Flag)
ldaa #$FF ; Two 7 segment displays on PORTB
staa DDRB ; Set all of PORTB as output
cli
mainLoop
ldaa #3
psha
ldaa #4
psha
ldaa #5
psha
ldd #0
jsr SORT
pula
pula
pula
jsr add3
ldaa #200
clrb
loopy incb
suba #$01
ble loopy
ldaa #$65
ldab #$43
ldx #256
idiv
tba
jsr putchar
xgdx
tba
jsr putchar
bra mainLoop ; Loop back to mainLoop always
**************************************************************************
* Subroutine Section: address used [ $3100 to $3FFF ] RAM Memory
*
SORT
pshb
ldab 3,sp
cmpb 4,sp
bls skip
movb 4,sp,3,sp
stab 4,sp
skip ldab 4,sp
cmpb 5,sp
bls done
movb 5,sp,4,sp
stab 5,sp
ldab 3,sp
cmpb 4,sp
bls done
movb 4,sp,3,sp
stab 4,sp
done pulb
rts
add3
pshx
pshy
pshd
ldx #n1
ldy #n2
inx
inx
iny
iny
ldab #4
aloop dbeq b,adone
ldaa 0,x
adca 1,y-
staa 1,x-
bra aloop
adone puld
puly
pulx
rts
;*************************************************************************
; rtiisr subroutine
;
; This subroutine will increment the counter, seconds, minutes, & hours counters
; to track the time. This subroutine will be called ~400 times a second.
;
; Input: No input other than the timer to call the isr.
; Output: The counter, seconds, minutes, & hours buffers will
; be updated to track the time, the time & prompt will be
; printed every second.
; Registers in use: X for adding to the counter, seconds, minutes, & hours buffers.
; Memory locations in use: Memory Address for serial line, Memory addresses for RTIISR control,
; Buffer words for counters, seconds, minutes, & hours buffers.
;
; Comments: The counter buffer should be compared to 400, but for the simulator,
; the counter is compared to 200 to better simulate 1 second on my computer.
;
rtiisr bset CRGFLG,%10000000; Clear RTI Interrupt Flag
ldx counter
inx
stx counter
cpx #100
bne rtiSkip
ldx #0
stx counter
ldaa PORTB
eora #%00010000
staa PORTB
rtiSkip RTI ; Return from RTI ISR
;*************************************************************************
; PrintTime subroutine
;
; This subroutine will print the time, command prompt, and maybe an error prompt.
;
; Input: No input.
; Output: The time prompt, time, command prompt, the current input,
; and/or an error on the serial console.
; Registers in use: A for the characters to print, X for buffer addresses,
; Y for buffer lengths, D for the seconds/minutes/hours for calling TimeOnPortB
; Memory locations in use: Memory Address for serial line, Buffer words for counters,
; seconds, minutes, & hours buffers, and buffer to print time,
; outputBuf for tracking what to output on PORTB.
;
; Comments: This subroutine requires TimeOnPortB subroutine and to be setup. The subroutine
; will print the current user input if its not finished.
;
PrintTime
pshd ; Save D to the stack
pshy ; Save Y to the stack
pshx ; Save X to the stack
ldaa #CR ; Load the character CR into A
jsr putchar ; Write the character to the serial
ldaa #LF ; Load the character LF into A
jsr putchar ; Write the character to the serial
ldx #clock ; Load the address of the clock prompt into X
jsr WriteString ; Write the string to serial
ldd hours ; Load the hours into D
cpd #10 ; Compare D to 10
bhs goodHours ; If D >= goodHours
psha ; Save A to the stack
ldaa #'0' ; Load '0' character into A
jsr putchar ; Print '0' to the serial
pula ; Restore A from the stack
goodHours ldy #buffer ; Load the address of buffer into Y
jsr PrintDecimalWord; Print the number to the serial
ldaa #':' ; Load the character ':' into A
jsr putchar ; Write the character to the serial
ldd minutes ; Load the minutes into D
cpd #10 ; Compare D to 10
bhs goodMins ; If D >= goodMins
psha ; Save A to the stack
ldaa #'0' ; Load '0' character into A
jsr putchar ; Print '0' to the serial
pula ; Restore A from the stack
goodMins ldy #buffer ; Load the address of buffer into Y
jsr PrintDecimalWord; Print the number to the serial
ldaa #':' ; Load the character ':' into A
jsr putchar ; Write the character to the serial
ldd seconds ; Load the seconds into D
cpd #10 ; Compare D to 10
bhs goodSecs ; If D >= goodSecs
psha ; Save A to the stack
ldaa #'0' ; Load '0' character into A
jsr putchar ; Print '0' to the serial
pula ; Restore A from the stack
goodSecs ldy #buffer ; Load the address of buffer into Y
jsr PrintDecimalWord; Print the number to the serial
ldaa #' ' ; Load ' ' character into A
jsr putchar ; Write the character to the serial console
jsr putchar ; Write the character to the serial console
jsr putchar ; Write the character to the serial console
jsr putchar ; Write the character to the serial console
ldx #CMD ; Load the address of CMD into X
jsr WriteString ; Write the string to the serial
ldx #inputBuffer ; Load the address of the inputBuffer into X
jsr WriteString ; Write the string to the serial
ldaa outputBuf ; Load outputBuf into A
cmpa #'h' ; Compare A to 'h'
bne pTimeIsM ; If A != 'h', branch to pTimeIsM
ldd hours ; Load hours into B
bra skipRest ; Jump to skipRest
pTimeIsM cmpa #'m' ; Compare A to 'm'
bne pTimeIsS ; If A != 'm', branch to pTimeIsS
ldd minutes ; Load Minutes into D
bra skipRest ; Jump to skipRest
pTimeIsS ldd seconds ; Load seconds into D
skipRest jsr TimeOnPortB ; Call TimeOnPortB to output time
pulx ; Restore X from the stack
puly ; Restore Y from the stack
puld ; Restore D from the stack
rts ; Return to caller
;*************************************************************************
; TimeOnPortB subroutine
;
; This subroutine will output the time given on on PORTB for two seven segment displays.
;
; Input: Two Digit Decimal number in register D.
; Output: The given two digit decimal number on PORTB for two 7 segment displays.
; Registers in use: D for the input, and for math to split the digits, X for math to split digits.
; Memory locations in use: PORTB memory location.
;
; Comments: This subroutine will only work with two digit decimal numbers, and one digit decimal
; numbers (leading zeros will be added).
;
TimeOnPortB
pshd ; Save D to the stack
pshx ; Save X to the stack
ldx #10 ; Load 10 into X to get digit
idiv ; Divide D by X and save Digit into D
pshb ; Save B to the stack (Lower Byte of D)
exg x,d ; Swap X and D
ldx #10 ; Load 10 into X to get digit
lslb ; Shift B left by 1
lslb ; Shift B left by 1
lslb ; Shift B left by 1
lslb ; Shift B left by 1
orab 1,sp+ ; Or B with Digit on stack
stab PORTB ; Save B to PORTB
pulx ; Restore X from the stack
puld ; Restore D from the stack
rts ; Return from caller
;*************************************************************************
; ReadDecimal subroutine
;
; This subroutine will read an ASCII string of a number in decimal and convert it to
; its value.
;
; Input: A memory address in register X.
; Output: The value of the number in the Y register, and any errors printed
; to the serial line. Zero bit is set if error occurs.
; Registers in use: X for the address of the contents and for a buffer while printing,
; D for multiplication, B for the character, Y for output value.
; Memory locations in use: Memory Address for serial line, address of the string
;
; Comments: This subroutine will return the value in the Y register, and if an error occurs,
; the Zero bit in the CCR will be set.
;
ReadDecimal
pshd ; Save D to the stack
ldy #0 ; Clear Y register
dHLoop ldab 1,x+ ; Read Next character from X
beq dHDone ; If B == 0, exit loop
cmpb #'+' ; Compare B to '+'
beq dHDone ; If B == '+', end of number
cmpb #'-' ; Compare B to '-'
beq dHDone ; If B == '-', end of number
cmpb #'*' ; Compare B to '*'
beq dHDone ; If B == '+', end of number
cmpb #'/' ; Compare B to '/'
beq dHDone ; If B == '-', end of number
cmpb #':' ; Compare B to ':'
beq dHDone ; If B == '-', end of number
cmpb #' ' ; Compare B to space character
beq dHDone ; If B == ' ', exit loop
cmpb #'0' ; Compare B to '0' character
blt dHError ; If B < '0', bad address, exit loop
cmpb #'9' ; Compare B to '9' character
bhi dHError ; If B > '9', check if 'A'-'F' characters
subb #'0' ; Subtract '0' from B to get true value
pshb ; Save B to the stack
ldd #10 ; load 10 into D
emul ; Multiply Y and D
exg d,y ; Transfer data from D to Y
pulb ; Restore b from the stack
aby ; Add B to Y
bra dHLoop ; Branch always to rHLoop
dHDone clra ; clear A accumulator
tap ; Transfer A into CCR to clear zero bit
puld ; Restore D from the stack
rts ; Return to caller
dHError ldaa #4 ; Load 4 into A to set zero bit in CCR
tap ; Transfer A into CCR to set zero bit and warn error
puld ; Restore D from the stack
rts ; Return to caller
;*************************************************************************
; strrev subroutine
;
; This subroutine will reverse a string from one buffer into another.
;
; Input: Address of null terminated string in X, address of a large enough
; buffer in Y.
; Output: The string in X reversed in Y.
; Registers in use: X for the address of the string, Y for the address of the buffer,
; A to read characters from the string.
; Memory locations in use: Memory Address for serial line, address of the string & buffer
;
; Comments: This subroutine will not check that the output buffer is large enough, that
; is the job of the caller.
;
strrev
pshx ; Save X to the stack
pshy ; Save Y to the stack
psha ; Save A to the stack
revLoop ldaa 1,y- ; Load Character from Y into A, decrement Y
beq revDone ; If Character is 0, exit loop
staa 1,x+ ; Save character in address in X, increment X
bra revLoop ; Loop back always
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
;*************************************************************************
; PrintDecimalWord subroutine
;
; This subroutine will print a given word of data to the serial in binary.
;
; Input: 1 word of data in register D, Buffer Address in Y
; Output: Decimal representation of the data on the serial console
; Registers in use: Y for the address of the buffer, X to count the number of bits
; written and for division, D for the input, A for characters.
; Memory locations in use: Memory addresses for serial, and operator to hold sign
;
; Comments: This subroutine requires serial to be setup and putchar subroutine.
;
PrintDecimalWord
pshx ; Save X to the stack
pshy ; Save Y to the stack
pshd ; Save D (A:B) to the stack
cpd #0 ; Compare D to zero
beq dIsZero ; Branch to hIsZero
blt dIsNegative ; If D < 0, Jump to dIsNegative
dAfterNeg 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
beq dCheck ; If X == 0, branch to check D is zero
dDNotZero addb #'0' ; Add '0' to B to get ASCII Character
stab 1,+y ; Save character from B to Y
exg X,D ; Swap values in X and D
bra dPrintLoop ; Loop to hPrintLoop
dCheck cpd #0 ; Compare D to 0
bne dDNotZero ; If D != 0, branch back to hDNotZero
dPrintDone ldaa operator ; Load operator into A to see if negative
cmpa #'-' ; Compare A to '-'
bne dNotNeg ; If A != '-', jump to dNotNeg
staa 1,+y ; Save '-' into buffer
dNotNeg ldx #buffer2 ; Load the address of buffer2 in X
jsr strrev ; Reverse string in Y in buffer in X
jsr WriteString ; Jump to write string to write the number
ldy lenBuf2 ; Load the length of buffer2 into Y
ldx #buffer2 ; Load the address of buffer2 into X
jsr Zeros ; Fill buffer2 with zeros
puld ; Restore D (A:B) from the stack
puly ; Restore Y 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
puld ; Restore D (A:B) from the stack
puly ; Restore Y from the stack
pulx ; Restore X from the stack
rts ; Return to caller
dIsNegative psha ; Save A to the stack
ldaa #'-' ; Load '-' into A
staa operator ; Save '-' to operator buffer
pula ; Restore A from the stack
nega ; Two's complement of A
suba #1 ; Subtract 1 from A
negb ; Two'complement of B
subb #1 ; Subtract 1 from B
addd #1 ; Add 1 to D
bra dAfterNeg ; Jump back to dAfterNeg
;*************************************************************************
; Zeros subroutine
;
; This subroutine will write zeros to every byte in a given array.
;
; Input: Address of an array in X and its length in Y
; Output: Zeros in every byte of an array.
; Registers in use: X for the address of the array, Y for the length, and A for 0
; Memory locations in use: Memory Address of the array
;
; Comments: This subroutine requires serial to be setup and putchar subroutine.
;
Zeros
psha ; Save A to the Stack
clra ; Clear A
zerosLoop staa 1,x+ ; Load A into byte at X
dbne y,zerosLoop ; Decrement Y and loop if Y != 0
pula ; Restore A from the stack
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.
;
; Input: Address of null terminated string in X
; Output: Null terminated string written to serial
; Registers in use: X for the address 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 putchar subroutine.
;
WriteString
psha ; Save A to the stack
writeLoop ldaa 1,x+ ; Load the byte at addr in X, then add 1
beq doneWrite ; if A == 0, branch to doneWrite
jsr putchar ; Jump to putchar to write byte to serial
bra writeLoop ; branch always to writeLoop
doneWrite pula ; restore A from the stack
rts ; return to caller
;*************************************************************************
; ReadString subroutine
;
; This subroutine will read a string from the serial line to a given address.
;
; 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 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.
;
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
cmpa #CR ; If A == CR, exit loop
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 pulx ; Restore X from the stack
pulY ; Restore Y from the stack
pula ; restore A from the stack
rts ; return to caller
;*************************************************************************
; putchar subroutine
;
; This subroutine writes a single byte to a serial line
;
; Input: A single ASCII byte in accumulator A
; Output: Sends one character to SCI port
; Registers in use: Accumulator A with input byte
; Memory locations in use: SCISR1 and SCIDRL status and data registers
;
putchar brclr SCISR1,#%10000000,putchar ; wait for transmit buffer empty
staa SCIDRL ; send a character
rts ; Return to caller
;*************************************************************************
; putchar subroutine
;
; This subroutine reads one byte from the SCI port
;
; Input: One byte from the SCI port
; Output: One byte in accumulator A
; Registers in use: Accumulator A for output byte
; Memory locations in use: SCISR1 and SCIDRL status and data registers
;
getchar brclr SCISR1,#%00100000,getchar7 ; If no input on SCI port, return 0
ldaa SCIDRL ; Read one byte from SCI port into A
rts ; Return to caller
getchar7 clra ; Set A to 0
rts ; Return to caller
*
**************************************************************************
* Data Section 2: address used [ $3100 to $3FFF ] RAM Memory
*
clock dc.b 'Clock> ',NULL ; Prompt string for clock
CMD dc.b 'CMD> ',NULL ; Prompt string for CMD
error dc.b 'Error> ',NULL ; Prompt string for errors
badInput dc.b 'Invalid Input',NULL ; Invalid Input Prompt
; twMsg: welcome message for typewrite
twMsg dc.b CR,LF,'Clock stopped and Typewrite program started.',CR,LF
dc.b 'You may type below.',CR,LF,NULL
; msg: this is the main option menu string
msg dc.b 'Commands:',CR,LF
dc.b 't: Set the time in format HH:MM:SS',CR,LF
dc.b 'h: Display the hours on the 7 segment displays',CR,LF
dc.b 'm: Display the minutes on the 7 segment displays',CR,LF
dc.b 's: Display the seconds on the 7 segment displays',CR,LF
dc.b 'q: Stop the clock and enter typewriter',CR,LF,NULL
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