mirror of https://github.com/hsoft/collapseos.git
326 lines
8.3 KiB
Forth
326 lines
8.3 KiB
Forth
( Receives keystrokes from PS/2 keyboard and send them to the
|
|
'164. On the PS/2 side, it works the same way as the controller
|
|
in the rc2014/ps2 recipe. However, in this case, what we have
|
|
on the other side isn't a z80 bus, it's the one of the two
|
|
controller ports of the SMS through a DB9 connector.
|
|
|
|
The PS/2 related code is copied from rc2014/ps2 without much
|
|
change. The only differences are that it pushes its data to a
|
|
'164 instead of a '595 and that it synchronizes with the SMS
|
|
with a SR latch, so we don't need PCINT. We can also afford to
|
|
run at 1MHz instead of 8.
|
|
|
|
*** Register Usage ***
|
|
|
|
GPIOR0 flags:
|
|
0 - when set, indicates that the DATA pin was high when we
|
|
received a bit through INT0. When we receive a bit, we set
|
|
flag T to indicate it.
|
|
|
|
R16: tmp stuff
|
|
R17: recv buffer. Whenever we receive a bit, we push it in
|
|
there.
|
|
R18: recv step:
|
|
- 0: idle
|
|
- 1: receiving data
|
|
- 2: awaiting parity bit
|
|
- 3: awaiting stop bit
|
|
R19: Register used for parity computations and tmp value in
|
|
some other places
|
|
R20: data being sent to the '164
|
|
Y: pointer to the memory location where the next scan code from
|
|
ps/2 will be written.
|
|
Z: pointer to the next scan code to push to the 595 )
|
|
|
|
0x0060 CONSTANT SRAM_START
|
|
0x015f CONSTANT RAMEND
|
|
0x3d CONSTANT SPL
|
|
0x3e CONSTANT SPH
|
|
0x11 CONSTANT GPIOR0
|
|
0x35 CONSTANT MCUCR
|
|
0x33 CONSTANT TCCR0B
|
|
0x3b CONSTANT GIMSK
|
|
0x38 CONSTANT TIFR
|
|
0x32 CONSTANT TCNT0
|
|
0x16 CONSTANT PINB
|
|
0x17 CONSTANT DDRB
|
|
0x18 CONSTANT PORTB
|
|
2 CONSTANT CLK
|
|
1 CONSTANT DATA
|
|
3 CONSTANT CP
|
|
0 CONSTANT LQ
|
|
4 CONSTANT LR
|
|
0x100 100 - CONSTANT TIMER_INITVAL
|
|
( We need a lot of labels in this program... )
|
|
VARIABLE L5 VARIABLE L6 VARIABLE L7 VARIABLE L8
|
|
|
|
H@ ORG !
|
|
L1 FLBL, ( main )
|
|
L2 FLBL, ( hdlINT0 )
|
|
|
|
( Read DATA and set GPIOR0/0 if high. Then, set flag T.
|
|
no SREG fiddling because no SREG-modifying instruction )
|
|
L2 ' RJMP FLBL! ( hdlINT0 )
|
|
PINB DATA SBIC,
|
|
GPIOR0 0 SBI,
|
|
SET,
|
|
RETI,
|
|
|
|
L1 ' RJMP FLBL! ( main )
|
|
R16 RAMEND 0xff AND LDI,
|
|
SPL R16 OUT,
|
|
R16 RAMEND 8 RSHIFT LDI,
|
|
SPH R16 OUT,
|
|
( init variables )
|
|
R18 CLR,
|
|
GPIOR0 R18 OUT,
|
|
( Setup int0
|
|
INT0, falling edge )
|
|
R16 0x02 ( ISC01 ) LDI,
|
|
MCUCR R16 OUT,
|
|
( Enable INT0 )
|
|
R16 0x40 ( INT0 ) LDI,
|
|
GIMSK R16 OUT,
|
|
( Setup buffer )
|
|
YH CLR,
|
|
YL SRAM_START 0xff AND LDI,
|
|
ZH CLR,
|
|
ZL SRAM_START 0xff AND LDI,
|
|
( Setup timer. We use the timer to clear up "processbit"
|
|
registers after 100us without a clock. This allows us to start
|
|
the next frame in a fresh state. at 1MHZ, no prescaling is
|
|
necessary. Each TCNT0 tick is already 1us long. )
|
|
R16 0x01 ( CS00 ) LDI, ( no prescaler )
|
|
TCCR0B R16 OUT,
|
|
( init DDRB )
|
|
DDRB CP SBI,
|
|
PORTB LR CBI,
|
|
DDRB LR SBI,
|
|
SEI,
|
|
|
|
L1 LBL! ( loop )
|
|
L2 FLBL, ( BRTS processbit. flag T set? we have a bit to
|
|
process )
|
|
YL ZL CP, ( if YL == ZL, buf is empty )
|
|
L3 FLBL, ( BRNE sendTo164. YL != ZL? buf has data )
|
|
( nothing to do. Before looping, let's check if our
|
|
communication timer overflowed. )
|
|
R16 TIFR IN,
|
|
R16 1 ( TOV0 ) SBRC,
|
|
L4 FLBL, ( RJMP processbitReset, timer0 overflow? reset )
|
|
( Nothing to do for real. )
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
( Process the data bit received in INT0 handler. )
|
|
L2 ' BRTS FLBL! ( processbit )
|
|
R19 GPIOR0 IN, ( backup GPIOR0 before we reset T )
|
|
R19 0x1 ANDI, ( only keep the first flag )
|
|
GPIOR0 0 CBI,
|
|
CLT, ( ready to receive another bit )
|
|
|
|
( We've received a bit. reset timer )
|
|
L2 FLBL, ( RCALL resetTimer )
|
|
|
|
( Which step are we at? )
|
|
R18 TST,
|
|
L5 FLBL, ( BREQ processbits0 )
|
|
R18 1 CPI,
|
|
L6 FLBL, ( BREQ processbits1 )
|
|
R18 2 CPI,
|
|
L7 FLBL, ( BREQ processbits2 )
|
|
( step 3: stop bit )
|
|
R18 CLR, ( happens in all cases )
|
|
( DATA has to be set )
|
|
R19 TST, ( was DATA set? )
|
|
L1 ' BREQ LBL, ( loop, not set? error, don't push to buf )
|
|
( push r17 to the buffer )
|
|
Y+ R17 ST,
|
|
L8 FLBL, ( RCALL checkBoundsY )
|
|
L1 ' RJMP LBL,
|
|
|
|
L5 ' BREQ FLBL! ( processbits0 )
|
|
( step 0 - start bit )
|
|
( DATA has to be cleared )
|
|
R19 TST, ( was DATA set? )
|
|
L1 ' BRNE LBL, ( loop. set? error. no need to do anything. keep
|
|
r18 as-is. )
|
|
( DATA is cleared. prepare r17 and r18 for step 1 )
|
|
R18 INC,
|
|
R17 0x80 LDI,
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L6 ' BREQ FLBL! ( processbits1 )
|
|
( step 1 - receive bit
|
|
We're about to rotate the carry flag into r17. Let's set it
|
|
first depending on whether DATA is set. )
|
|
CLC,
|
|
R19 0 SBRC, ( skip if DATA is cleared )
|
|
SEC,
|
|
( Carry flag is set )
|
|
R17 ROR,
|
|
( Good. now, are we finished rotating? If carry flag is set,
|
|
it means that we've rotated in 8 bits. )
|
|
L1 ' BRCC LBL, ( loop )
|
|
( We're finished, go to step 2 )
|
|
R18 INC,
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L7 ' BREQ FLBL! ( processbits2 )
|
|
( step 2 - parity bit )
|
|
R1 R19 MOV,
|
|
R19 R17 MOV,
|
|
L5 FLBL, ( RCALL checkParity )
|
|
R1 R16 CP,
|
|
L6 FLBL, ( BRNE processBitError, r1 != r16? wrong parity )
|
|
R18 INC,
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L6 ' BRNE FLBL! ( processBitError )
|
|
R18 CLR,
|
|
R19 0xfe LDI,
|
|
L6 FLBL, ( RCALL sendToPS2 )
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L4 ' RJMP FLBL! ( processbitReset )
|
|
R18 CLR,
|
|
L4 FLBL, ( RCALL resetTimer )
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L3 ' BRNE FLBL! ( sendTo164 )
|
|
( Send the value of r20 to the '164 )
|
|
PINB LQ SBIS, ( LQ is set? we can send the next byte )
|
|
L1 ' RJMP LBL, ( loop, even if we have something in the
|
|
buffer, we can't: the SMS hasn't read our
|
|
previous buffer yet. )
|
|
( We disable any interrupt handling during this routine.
|
|
Whatever it is, it has no meaning to us at this point in time
|
|
and processing it might mess things up. )
|
|
CLI,
|
|
DDRB DATA SBI,
|
|
R20 Z+ LD,
|
|
L3 FLBL, ( RCALL checkBoundsZ )
|
|
R16 R8 LDI,
|
|
|
|
BEGIN,
|
|
PORTB DATA CBI,
|
|
R20 7 SBRC, ( if leftmost bit isn't cleared, set DATA high )
|
|
PORTB DATA SBI,
|
|
( toggle CP )
|
|
PORTB CP CBI,
|
|
R20 LSL,
|
|
PORTB CP SBI,
|
|
R16 DEC,
|
|
' BRNE AGAIN?, ( not zero yet? loop )
|
|
( release PS/2 )
|
|
DDRB DATA CBI,
|
|
SEI,
|
|
( Reset the latch to indicate that the next number is ready )
|
|
PORTB LR SBI,
|
|
PORTB LR CBI,
|
|
L1 ' RJMP LBL, ( loop )
|
|
|
|
L2 ' RCALL FLBL! L4 ' RCALL FLBL! L2 LBL! ( resetTimer )
|
|
R16 TIMER_INITVAL LDI,
|
|
TCNT0 R16 OUT,
|
|
R16 0x02 ( TOV0 ) LDI,
|
|
TIFR R16 OUT,
|
|
RET,
|
|
|
|
L6 ' RCALL FLBL! ( sendToPS2 )
|
|
( Send the value of r19 to the PS/2 keyboard )
|
|
CLI,
|
|
( First, indicate our request to send by holding both Clock low
|
|
for 100us, then pull Data low lines low for 100us. )
|
|
PORTB CLK CBI,
|
|
DDRB CLK SBI,
|
|
L2 ' RCALL LBL, ( resetTimer )
|
|
|
|
( Wait until the timer overflows )
|
|
BEGIN,
|
|
R16 TIFR IN,
|
|
R16 1 ( TOV0 ) SBRS,
|
|
AGAIN,
|
|
( Good, 100us passed. )
|
|
( Pull Data low, that's our start bit. )
|
|
PORTB DATA CBI,
|
|
DDRB DATA SBI,
|
|
|
|
( Now, let's release the clock. At the next raising edge, we'll
|
|
be expected to have set up our first bit (LSB). We set up
|
|
when CLK is low. )
|
|
DDRB CLK CBI, ( Should be starting high now. )
|
|
|
|
( We will do the next loop 8 times )
|
|
R16 8 LDI,
|
|
( Let's remember initial r19 for parity )
|
|
R1 R19 MOV,
|
|
|
|
BEGIN,
|
|
( Wait for CLK to go low )
|
|
BEGIN, PINB CLK SBIC, AGAIN,
|
|
( set up DATA )
|
|
PORTB DATA CBI,
|
|
R19 0 SBRC, ( skip if LSB is clear )
|
|
PORTB DATA SBI,
|
|
R19 LSR,
|
|
( Wait for CLK to go high )
|
|
BEGIN, PINB CLK SBIS, AGAIN,
|
|
16 DEC,
|
|
' BRNE AGAIN?, ( not zero? loop )
|
|
|
|
( Data was sent, CLK is high. Let's send parity )
|
|
R19 R1 MOV, ( recall saved value )
|
|
L6 FLBL, ( RCALL checkParity )
|
|
( Wait for CLK to go low )
|
|
BEGIN, PINB CLK SBIC, AGAIN,
|
|
( set parity bit )
|
|
PORTB DATA CBI,
|
|
R16 0 SBRC, ( parity bit in r16 )
|
|
PORTB DATA SBI,
|
|
( Wait for CLK to go high )
|
|
BEGIN, PINB CLK SBIS, AGAIN,
|
|
( Wait for CLK to go low )
|
|
BEGIN, PINB CLK SBIC, AGAIN,
|
|
( We can now release the DATA line )
|
|
DDRB DATA CBI,
|
|
( Wait for DATA to go low, that's our ACK )
|
|
BEGIN, PINB DATA SBIC, AGAIN,
|
|
( Wait for CLK to go low )
|
|
BEGIN, PINB CLK SBIC, AGAIN,
|
|
( We're finished! Enable INT0, reset timer, everything back to
|
|
normal! )
|
|
L2 ' RCALL LBL, ( resetTimer )
|
|
CLT, ( also, make sure T isn't mistakely set. )
|
|
SEI,
|
|
RET,
|
|
|
|
L8 ' RCALL FLBL! ( checkBoundsY )
|
|
( Check that Y is within bounds, reset to SRAM_START if not. )
|
|
YL TST,
|
|
IF, RET, ( not zero, nothing to do ) THEN,
|
|
( YL is zero. Reset Z )
|
|
YH CLR,
|
|
YL SRAM_START 0xff AND LDI,
|
|
RET,
|
|
|
|
L3 ' RCALL FLBL! ( checkBoundsZ )
|
|
( Check that Z is within bounds, reset to SRAM_START if not. )
|
|
ZL TST,
|
|
IF, RET, ( not zero, nothing to do ) THEN,
|
|
( ZL is zero. Reset Z )
|
|
ZH CLR,
|
|
ZL SRAM_START 0xff AND LDI,
|
|
RET,
|
|
|
|
L5 ' RCALL FLBL! L6 ' RCALL FLBL! ( checkParity )
|
|
( Counts the number of 1s in r19 and set r16 to 1 if there's an
|
|
even number of 1s, 0 if they're odd. )
|
|
R16 1 LDI,
|
|
BEGIN,
|
|
R19 LSR,
|
|
' BRCC SKIP, R16 INC, ( carry set? we had a 1 ) TO,
|
|
R19 TST, ( is r19 zero yet? )
|
|
' BRNE AGAIN?, ( no? loop )
|
|
R16 0x1 ANDI,
|
|
RET,
|