; OSTC Mk.2, 2N and 2C - diving computer code
; Copyright (C) 2015 HeinrichsWeikamp GbR

;    This program is free software: you can redistribute it and/or modify
;    it under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.

;    This program is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.

;    You should have received a copy of the GNU General Public License
;    along with this program.  If not, see <http://www.gnu.org/licenses/>.


; written by: Matthias Heinrichs, info@heinrichsweikamp.com
; written: 10/30/05
; last updated: 05/16/08
; known bugs:
; ToDo:

; the timer1 module interrupts every 62.5ms (16x/second)
; temperature and pressure is averaged over 4 measurements
; flag pressure_refresh is set every 500ms 
; and provides accurate pressure (+/-1mbar stable) and temperature (0.1C stable)

;=============================================================================
; Copy a 16bit value from ISR modified registers to main registers.
; 
; Because the ISR can happend at any time, the read should be redone if bytes
; changed inbetween.
;
; Trashes: WREG and TABLAT
; NOTE: Destination might be in any bank, so be BANK SAFE.
;
SAFE_2BYTE_COPY MACRO  from, to
        local   retry
retry:
        movff   from+1,WREG             ; High byte in W.
        movff   WREG,to+1               ; and destination.
        movff   from+0,to+0             ; Copy low byte.
        movff   from+1,TABLAT           ; another bank-safe read.
        xorwf   TABLAT,W                ; High byte changed ?
        bnz     retry
        ENDM

;=============================================================================
uartint:
		btfsc	simulatormode_active		; are we in simulatormode?
		bra		simulator_int				; Yes, reading is depth in m!

		movff	RCREG,uart1_temp
		movlw	d'96'
		subwf	uart1_temp,F
		dcfsnz	uart1_temp,F				; "a"
		bsf		dump_external_eeprom		; set flag
		dcfsnz	uart1_temp,F				; "b"
		bsf		uart_settime				; set flag
		dcfsnz	uart1_temp,F				; "c"
		bsf		simulatormode_active		; set flag
		dcfsnz	uart1_temp,F				; "d"
		bsf		internal_eeprom_write		; set flag
		dcfsnz	uart1_temp,F				; "e"
		bsf		uart_send_hash				; set flag
		dcfsnz	uart1_temp,F				; "f"
		bsf		uart_reset_battery_stats	; set flag
		dcfsnz	uart1_temp,F				; "g"
		bsf		uart_send_int_eeprom		; set flag
		dcfsnz	uart1_temp,F				; "h"
		bsf		uart_reset_decodata			; set flag
		dcfsnz	uart1_temp,F				; "i"
		bsf		internal_eeprom_write2		; set flag
		dcfsnz	uart1_temp,F				; "j"
		bsf		uart_send_int_eeprom2		; set flag
		dcfsnz	uart1_temp,F				; "k"
		bsf		uart_store_tissue_data		; set flag
		dcfsnz	uart1_temp,F				; "l"
		bsf		uart_dump_screen            ; set flag
		dcfsnz	uart1_temp,F				; "m"	
		bsf		uart_send_int_eeprom3		; set flag
		dcfsnz	uart1_temp,F				; "n"	
		bsf		internal_eeprom_write3		; set flag
		movlw	0xC1
		cpfseq	RCREG						; 115200Baud Bootloader request?
		bra		uartint1					; No
		bsf		uart_115200_bootloader		; Yes, set Flag

uartint1:
		movf	RCREG,w						; unload RCREG in stand-alone simulator mode
		bcf		PIR1,RCIF					; Clear flag
		bcf		RCSTA,CREN					; Clear receiver status
		bsf		RCSTA,CREN
		return

simulator_int:
        movlw   'l'                         ; Received 'l' dump-screen command ?
        xorwf   RCREG,W
        bnz     simulator_int2              ; NO: skip
		bsf		uart_dump_screen            ; YES: set flag
		bra		uartint1                    ; and this is not a depth...

simulator_int2:
		btfsc	standalone_simulator		; ignore in standalone simulator mode
		bra		uartint1

		bsf		LED_blue
		tstfsz	RCREG						; =0x00?
		bra		simulator_int1				; No
		incf	RCREG,F						; Yes, so force RCREG=1

simulator_int1:
		movf	RCREG,w						; depth in m
		movwf	PRODL						; Copy

		movlw	d'140'						; Limit to 130m
		cpfslt	PRODL						; compare with value in UART
		movwf	PRODL						; Overwrite reading

		movf	PRODL,w						; depth in m
		mullw	d'100'						; result will be mbar
		movff	PRODL,sim_pressure+0		; stored for pressure overwrite
		movff	PRODH,sim_pressure+1
		bra		uartint1					; exit uart int

;=============================================================================

switch_left_int:
		bcf		INTCON,INT0IF				; Clear flag

		btfsc	T0CON,TMR0ON				; Timer0 running?
		bra		timer0_restart				; Yes, restart

		; OSTC 2N has flipped screen and exchanged switches...
		movff	win_flags,WREG				; Get into Bank0
		btfss	WREG,0
		bsf		switch_left					; Set flag, button press is OK
		btfsc	WREG,0
		bsf		switch_right				; Set flag, button press is OK

		bsf		T0CON,TMR0ON				; Start Timer 0
		return


switch_right_int:
		bcf		INTCON3,INT1IF				; Clear flag

		btfsc	T0CON,TMR0ON				; Timer0 running?
		bra		timer0_restart				; Yes, restart

		; OSTC 2N has flipped screen and exchanged switches...
		movff	win_flags,WREG				; Get into Bank0
		btfsc	WREG,0
		bsf		switch_left					; Set flag, button press is OK
		btfss	WREG,0
		bsf		switch_right				; Set flag, button press is OK

		bsf		T0CON,TMR0ON				; Start Timer 0
		return

timer0_restart:
		bcf		INTCON,TMR0IF				; Clear flag
        movlw   T0CON_VALUE
		movwf   T0CON						; Timer0
		clrf	TMR0H
		clrf	TMR0L
		bsf		T0CON,TMR0ON				; Start Timer 0
		return

timer0int:
		bcf		INTCON,TMR0IF				; Clear flag
		bcf		T0CON,TMR0ON				; Stop Timer 0
		clrf	TMR0H
		clrf	TMR0L
		return

;=============================================================================
;

timer1int:
timer1int_debug:
		bcf		LED_red						; LEDr off (For charge indicator)

		btfsc	TMR1L,0						; Wait for low clock cycle
		bra		$-2		
		btfss	TMR1L,0						; Still high?
		bra		$-2							; max. loop time: 61µs

		movlw	0x08						; Timer1 int after 62.5ms (=16/second)
		cpfslt	TMR1H						; Did we miss a 1/16 second?
		incf	timer1int_counter1,F		; Yes, add extra 1/16 second

		movlw	0x08						; Timer1 int after 62.5ms (=16/second)
		subwf	TMR1H,F			
		bcf		PIR1,TMR1IF					; Clear flag
	
		incf	timer1int_counter1,F		; Increase timer1 counter

		movlw	d'15'						; One second 16
		cpfsgt	timer1int_counter1			 
		bra		sensor_int_pre				; only pressure sensor
		rcall	RTCisr						; adjust time, then query pressure sensor

sensor_int_pre:
		btfsc	sleepmode					; In sleepmode?
		return								; Yes

; Sensor interput do poll the presure/temperature sensor, download results,
; compute compensations, and store results in various shared variables.
;
; Input:    interupt (every 62.5msec == 16Hz), sensor,
;           last_surfpressure:2.
;
; Output:   amb_pressure:2,
;           temperature:2,
;           rel_pressure:2,
;           and the pressure_refresh flag.
;
; NOTE: averaging (4 successive value, as recommended in the MS5535 datasheet)
;       is done on private variables, to avoid trashing data while reading it
;       from the main code.
;
; NOTE: Because there is no atomic 16bits load/stores, we need to check twice
;       the read data is correct. Ie. SAFE_2BYTE_COPY is mandatory to get
;       amb_pressure, temperature or rel_pressure
;
sensor_int:
		btfsc		no_sensor_int			; No sensor interrupt (because it's addressed during sleep)
		return						

		incf		timer1int_counter2,F	; counts to eight for state maschine

; State 1: Clear flags and average registers, get temperature (51us) and start pressure integration (73,5us)
; State 2: Get pressure (51us), start temperature integration (73,5us) and calculate temperature compensated pressure (233us)
; State 3: Get temperature (51us) and start pressure integration (73,5us)
; State 4: Get pressure (51us), start temperature integration (73,5us) and calculate temperature compensated pressure (233us)
; State 5: Get temperature (51us) and start pressure integration (73,5us)
; State 6: Get pressure (51us), start temperature integration (73,5us) and calculate temperature compensated pressure (233us)
; State 7: Get temperature (51us) and start pressure integration (73,5us)
; State 8: Get pressure (51us), start temperature integration (73,5us), calculate temperature compensated pressure (233us) and build average for half-second update of tempperature and pressure
	
		movff	timer1int_counter2,isr_divB		; isr_divB used as temp here...
		dcfsnz	isr_divB,F
		bra		sensor_int_state1_plus_restart	; Do State 1
		dcfsnz	isr_divB,F
		bra		sensor_int_state2				; Do State 2
		dcfsnz	isr_divB,F
		bra		sensor_int_state1				; Do State 3
		dcfsnz	isr_divB,F
		bra		sensor_int_state2				; Do State 4
		dcfsnz	isr_divB,F
		bra		sensor_int_state1				; Do State 5
		dcfsnz	isr_divB,F
		bra		sensor_int_state2				; Do State 6
		dcfsnz	isr_divB,F
		bra		sensor_int_state1				; Do State 7
;		bra		sensor_int2_plus_average		; Do State 8

;sensor_int2_plus_average:
		rcall		sensor_int_state2
sensor_int2_plus_average2:		
		bcf			STATUS,C            ; clear carry bit.
		rrcf		amb_pressure_avg+1  ; amb_pressure sum / 2
		rrcf		amb_pressure_avg+0
		bcf			STATUS,C            ; clear carry bit, twice.
		rrcf		amb_pressure_avg+1  ; amb_pressure sum / 4
		rrcf		amb_pressure_avg+0

		movff		amb_pressure_avg+1,amb_pressure+1	; copy into actual register
		movff		amb_pressure_avg+0,amb_pressure+0

        bcf			STATUS,C
        btfsc       temperature_avg+1,7 ; Copy sign bit to carry
        bsf         STATUS,C
		rrcf		temperature_avg+1   ; Signed temperature /2
		rrcf		temperature_avg+0

        bcf			STATUS,C
        btfsc       temperature_avg+1,7 ; Copy sign bit to carry
        bsf         STATUS,C
		rrcf		temperature_avg+1   ; Signed temperature /4
		rrcf		temperature_avg+0

		movff		temperature_avg+1,temperature+1
		movff		temperature_avg+0,temperature+0

		bsf			pressure_refresh 			; Set flag! Temp and pressure were updated!
		clrf		timer1int_counter2			; Then reset State counter

		btfss		simulatormode_active		; are we in simulator mode?
		bra			comp_air_pressure			; no

comp_air_pressure0:	
		movlw		LOW		d'1000'				; yes, so simulate 1bar surface pressure
		movwf		last_surfpressure+0
		movlw		HIGH	d'1000'
		movwf		last_surfpressure+1

comp_air_pressure:
		movf		last_surfpressure+0,W		; compensate airpressure
		subwf   	amb_pressure+0,W             
		movwf   	rel_pressure+0				; rel_pressure stores depth!

		movf		last_surfpressure+1,W
		subwfb  	amb_pressure+1,W
		movwf   	rel_pressure+1
		btfss		STATUS,N					; result is below zero?
		return
		clrf		rel_pressure+0				; Yes, do not display negative depths
		clrf		rel_pressure+1				; e.g. when surface air pressure dropped during the dive
		return

sensor_int_state1_plus_restart:
		clrf		amb_pressure_avg+0  ; pressure average registers
		clrf		amb_pressure_avg+1
		clrf		temperature_avg+0
		clrf		temperature_avg+1

sensor_int_state1:
		call		get_temperature_value	; State 1: Get temperature
		call		get_pressure_start	 	; and start pressure integration.
		return								; Done.

sensor_int_state2:
		call		get_pressure_value		; State2: Get pressure (51us)
		call		get_temperature_start	; and start temperature integration (73,5us)
		goto		calculate_compensation	; calculate temperature compensated pressure (233us)

;=============================================================================

RTCisr:			
		clrf		timer1int_counter1		; counts to 16 (one second / 62.5ms)
		bsf			onesecupdate			; we have a new second!

        btfsc       sleepmode               ; are we in sleep mode?
        bra         RTCisr0                 ; Yes

        movlw       .1
        addwf       on_time_seconds+0,F
        movlw       .0
        addwfc      on_time_seconds+1,F
        addwfc      on_time_seconds+2,F     ; Increase counter

RTCisr0:
		bcf			STATUS,Z				; are we in dive mode?
		btfss		divemode
		bra			RTCisr2					; No, must be surface or sleepmode

		incf		samplesecs,F			; CF20 diving seconds done 
		decf		samplesecs_value,W		; holds CF20 value  (minus 1 into WREG)
		cpfsgt		samplesecs
		bra			RTCisr1					; no

		clrf		samplesecs				; clear counter...
		bsf			store_sample			; ...and set bit for profile storage

RTCisr1:		
; Increase re-setable average depth divetime counter
		incf		average_divesecs+0,F	; increase stopwatch registers	
		btfsc		STATUS,Z
		incf		average_divesecs+1,F	; increase stopwatch registers
; Increase total divetime (Regardless of CF01)
		incf		total_divetime_seconds+0,F	; increase stopwatch registers	
		btfsc		STATUS,Z
		incf		total_divetime_seconds+1,F	; increase stopwatch registers
	
		btfss		divemode2				; displayed divetime is running?
		bra			RTCisr2					; No (e.g. too shallow)

; increase divetime registers (Displayed dive time)
		incf		divesecs,F				
		movlw		d'59'
		cpfsgt		divesecs
		bra			RTCisr1a

		clrf		divesecs
		bsf			realdive				; this bit is always set (again) if the dive is longer then one minute

		incf		divemins+0,F			; increase divemins
		btfsc		STATUS,Z
		incf		divemins+1,F			; and now do the realtime clock routine anyway
		
RTCisr1a:	
		btfss		FLAG_apnoe_mode			; Are we in Apnoe mode?
		bra			RTCisr2					; No, skip the following
		
		incf		apnoe_secs,F			; increase descent registers
		movlw		d'59'
		cpfsgt		apnoe_secs
		bra			RTCisr2
		clrf		apnoe_secs
		
		incf		apnoe_mins,F			; increase descent mins
		; Now, do the RTC routine....
RTCisr2:
		incf		secs,F					; adjusts seconds, minutes, hours, day, month and year. Checks for a leap year and works until 2099!
		movlw		d'60'
		cpfseq		secs                    ; Secs == 60 ?
        return                              ; NO : done.
		clrf		secs                    ; YES: increment minutes instead...
		bsf			oneminupdate

		btfss		divemode				; In Divemode?
		rcall		check_nofly_desat_time	; No, so reduce NoFly and Desat and increase interval

		incf		mins,F
		movlw		d'59'
		cpfsgt		mins
		return
		clrf		mins
		incf		hours,F
		movlw		d'23'
		cpfsgt		hours
		return
		clrf		hours
		incf		day,F
		movff		time_correction_value,secs			; Correct too slow clock
						
check_date:
		movff		month,isr_divB		; new month?
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.28
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.30
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.30
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.30
		dcfsnz		isr_divB,F
		movlw		.31
		dcfsnz		isr_divB,F
		movlw		.30
		dcfsnz		isr_divB,F
		movlw		.31
		cpfsgt		day,1
		return
		movlw		.1
		movwf		day
		incf		month,F				
		movlw		.12					
		cpfsgt		month,1
		return
		movlw		.1
		movwf		month
		incf		year,F				
		return

check_nofly_desat_time:
	bcf		nofly_active                ; Clear flag
    movf    nofly_time+0,W              ; Is nofly null ?
    iorwf   nofly_time+1,W
    bz     	check_nofly_desat_time2     ; yes...

	bsf		nofly_active                ; Set flag (again)
	movlw	d'1'
	subwf	nofly_time+0,F
	movlw	d'0'
	subwfb	nofly_time+1,F               ; reduce by one

check_nofly_desat_time2:
	movff	desaturation_time_buffer+0,lo
	movff	desaturation_time_buffer+1,hi

    movf    lo,W			             ; Is Desat null ?
    iorwf   hi,W
    bz     	check_nofly_desat_time3      ; yes...

	movlw	d'1'
	subwf	lo,F
	movlw	d'0'
	subwfb	hi,F		              	; reduce by one...

	movff		lo,desaturation_time_buffer+0	; ...and copy back
	movff		hi,desaturation_time_buffer+1

check_nofly_desat_time3:
	; Now increase interval timer
	movff		desaturation_time_buffer+0,lo
	movff		desaturation_time_buffer+1,hi
	tstfsz		lo							;=0?
	bra			calc_surface_interval2		; No
	tstfsz		hi							;=0?
	bra			calc_surface_interval2		; No
	clrf		surface_interval+0
	clrf		surface_interval+1			; Clear surface interval timer
	return									; Done.

calc_surface_interval2:						; Increase surface interval timer 
	movlw		d'1'
	addwf		surface_interval+0,F
	movlw		d'0'
	addwfc		surface_interval+1,F
	return									; Done