--- a/src/gaslist.asm	Thu Oct 11 21:06:29 2018 +0200
+++ b/src/gaslist.asm	Thu Nov 22 19:47:26 2018 +0100
@@ -1,6 +1,6 @@
 ;=============================================================================
 ;
-;   File gaslist.asm												## V2.98
+;   File gaslist.asm								REFACTORED VERSION V2.99e
 ;
 ;   Managing OSTC gas list
 ;
@@ -9,378 +9,589 @@
 ; HISTORY
 ;   2011-08-11 : [jDG] Creation.
 
-#include "hwos.inc"						; Mandatory header
+#include "hwos.inc"						; mandatory header
 #include "convert.inc"
 #include "math.inc"						; div16x16 for MOD calculations
 #include "strings.inc"
 #include "tft.inc"
 #include "tft_outputs.inc"
 #include "shared_definitions.h"
+#include "wait.inc"
+
+ IFDEF _rx_functions
+#include "rx_ops.inc"
+ ENDIF
 
 	extern	convert_mbar_to_feet
 	extern	customview_show_mix
+	extern	tSetup_GasDepth
 	extern	tGasDisabled
 	extern	tDilDisabled
+	extern	tLiter
+	extern	tbar10
 	extern	tbar
 
-gui		CODE
+gaslist		CODE
 
 ;=============================================================================
-; Append gas description to current string.
+; Helper Functions for divemenu_tree.asm
+;
+; They need to be put in a different file than
+; where the MENU_DYNAMIC macros uses them.
+
+	global	do_toggle_gf_label
+do_toggle_gf_label:
+	movff	char_I_deco_model,WREG		; 0 = ZH-L16, 1 = ZH-L16-GF
+	decfsz	WREG,W						; toggle GF only in GF modes - in GF mode?
+	bra		do_toggle_gf_label_1		; NO - print in disabled color
+	movff	opt_enable_aGF,WREG			; =1: aGF can be selected underwater
+	decfsz	WREG,W						; aGF enabled?
+	bra		do_toggle_gf_label_1		; NO - print in disabled color
+	bra		do_toggle_gf_label_2		; YES to both - print in standard color
+do_toggle_gf_label_1:
+	call	TFT_disabled_color
+do_toggle_gf_label_2:
+	STRCAT_TEXT tDivemenu_ToggleGF
+	return
+
+
+ IFDEF _cave_mode
+	global	do_turn_dive_label
+do_turn_dive_label:
+	btfss	FLAG_cave_mode				; in cave mode?
+	call	TFT_disabled_color			; NO  - print in disabled color
+	btfsc	FLAG_dive_turned			; dive already turned?
+	call	TFT_attention_color			; YES - print in attention color
+	STRCAT_TEXT tDivemenu_TurnDive		; output label
+	return
+ ENDIF
+
+
+	global	do_toggle_max_pres_diff_label
+do_toggle_max_pres_diff_label:
+	movff	opt_TR_mode,WREG			; get TR mode
+	xorlw	.2							; compare with 2 (ind.double)
+	tstfsz	WREG						; equal?
+	call	TFT_disabled_color			; NO - print in disabled color
+	STRCAT_TEXT tTrMaxDeltaP			; output label
+	movff	char_I_max_pres_diff,lo
+	output_99
+	STRCAT_TEXT	tbar					; " bar"
+	return
+
+	global	gaslist_copy_dil_to_oc
+gaslist_copy_dil_to_oc:
+;
+;  Memory Map:
+;  -----------------------------------------
+;  opt_gas_O2_ratio				res 5
+;  opt_dil_O2_ratio				res 5
+;  opt_gas_He_ratio				res 5
+;  opt_dil_He_ratio				res 5
+;  opt_gas_type					res 5
+;  opt_dil_type					res 5
+;  opt_gas_change				res 5
+;  opt_dil_change				res 5
+;
+;  char_I_tank_size				res 10
+;  char_I_tank_pres_fill		res 10
+;
+	bcf		aux_flag					; clear aux_flag by default
+	movf	gaslist_gas,W				; copy current gas or diluent number to WREG
+	btfss	FLAG_diluent_setup			; in CCR menus?
+	bra		gaslist_copy_dil_to_oc_1	; NO  - gaslist_gas is already pointing to an OC gas
+	addlw	-.5							; YES - subtract offset between diluents and gases
+	movwf	gaslist_gas					;     - let gaslist_gas point to the corresponding OC gas
+	bsf		aux_flag					;     - remember we came from a CCR menu
+	bcf		FLAG_diluent_setup			;     - pretend we came from an OC gas menu
+gaslist_copy_dil_to_oc_1:
+	lfsr	FSR0,opt_dil_O2_ratio		; load base address of diluents settings, ASM variables
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of gas      settings, ASM variables
+	movff	PLUSW0,PLUSW1				; copy O2 ratio
+	addlw	.10							; add offset from O2 ratios to He ratios
+	movff	PLUSW0,PLUSW1				; copy He ratio
+	addlw	.10							; add offset from He ratios to types
+	movff	PLUSW0,PLUSW1				; copy type
+	addlw	.10							; add offset from type to change depth
+	movff	PLUSW0,PLUSW1				; copy change depth
+	addlw	-.30						; wind back to initial gas number
+	lfsr	FSR0,char_I_tank_size+5		; load base address of diluents settings, shared variables
+	lfsr	FSR1,char_I_tank_size+0		; load base address of gas      settings, shared variables
+	movff	PLUSW0,PLUSW1				; copy tank size
+	addlw	.10							; add offset from tank sizes to pressure budget
+	movff	PLUSW0,PLUSW1				; copy pressure budget
+	call	gaslist_cleanup_list		; make sure that there will be just one first gas
+	btfss	aux_flag					; did we came from a CCR menu?
+	return								; NO  - done
+	bsf		FLAG_diluent_setup			; YES - restore proper origin again
+	movlw	.5							;     - offset between OC gases and diluents
+	addwf	gaslist_gas,F				;     - let gaslist_gas point to the diluent again
+	WIN_BOX_BLACK .30,.239,.0,.159		;     - create some visual effect to show activity
+	WAITMS	.200						;     - pause for 200 ms
+	return								;     - done
+
+
+;=============================================================================
+; Append gas description to current string
+;
 ; Input:  PRODL : gas number (0..4)
-;         FSR2  : Current string position.
-; Output: Text appended into buffer pointed by FSR2.
+;         FSR2  : Current string position
+; Output: Text appended into buffer pointed by FSR2
 
 	global	gaslist_strcat_gas
-gaslist_strcat_gas:
-	rcall	gaslist_setgas				; Sets gaslist_gas (0-4 for OC/Bailout, 5-9 for Diluents)
-	; Retrieve gas definition:
-gaslist_strcat_gas_0:
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_O2_ratio		; Read opt_gas_O2_ratio[WREG]
-	movff	PLUSW1,lo					; O2 ratio
-	;movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_He_ratio		; Read opt_gas_He_ratio[WREG]
-	movff	PLUSW1,hi					; He ratio
-	goto	customview_show_mix			; Put "Nxlo", "Txlo/hi", "Air" or "O2" into Postinc2, and RETURN
+	global	gaslist_strcat_gas_WREG
+gaslist_strcat_gas:						; entry point with gas/dil in PRODL (0-4) and FLAG_diluent_setup
+	movff	PRODL,gaslist_gas			; get current menu item (0-4)
+	movlw	.5							; offset between gases and diluents
+	btfsc	FLAG_diluent_setup			; in CCR menus?
+	addwf	gaslist_gas,F				; YES - add the offset
+	movf	gaslist_gas,W				; copy to WREG
+gaslist_strcat_gas_WREG:				; entry point with gas/dil in WREG (0-9)
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movff	PLUSW1,lo					; read O2 ratio
+	lfsr	FSR1,opt_gas_He_ratio		; load base address of opt_gas_He_ratio
+	movff	PLUSW1,hi					; read He ratio
+	goto	customview_show_mix			; put "Nxlo", "Txlo/hi", "Air" or "O2" into Postinc2, and RETURN
 
 ;=============================================================================
-; Append current mix to current string (For divemode)
-; Input: FSR2 : Current string position.
-; Output: Text appended into buffer pointed by FSR2.
+; Append current mix to current string (for divemode)
+;
+; Input:  FSR2 : Current string position
+; Output: Text appended into buffer pointed by FSR2
+
 	global	gaslist_strcat_gas6
-gaslist_strcat_gas6:					; Show current O2/He mix
+gaslist_strcat_gas6:					; show current O2/He mix
 	STRCAT_TEXT tGas
 	STRCAT	": "
-	movff	gas6_O2_ratio,lo
-	movff	gas6_He_ratio,hi
-	goto	customview_show_mix			; Put "Nxlo", "Txlo/hi", "Air" or "O2" into Postinc2, and RETURN
+	movff	gas6_O2_ratio,hi			; TFT_color_code_gaslist needs O2 ratio in hi
+	call	TFT_color_code_gaslist		; color-code according to O2 ratio and depth
+	movff	gas6_O2_ratio,lo			; customview_show_mix needs O2 ratio in lo
+	movff	gas6_He_ratio,hi			;                   ... and He ratio in hi
+	goto	customview_show_mix			; put "Nxlo", "Txlo/hi", "Air" or "O2" into Postinc2, and return
+;=============================================================================
+; Helper functions for menu_tree
 
+	global	gaslist_GasDepth
+gaslist_GasDepth:
+	movf	gaslist_gas,W				; load gas/dil index into WREG (0-9)
+	lfsr	FSR1,opt_gas_change			; load base address of change depths
+	tstfsz	PLUSW1						; change depth = 0 ?
+	bra		gaslist_GasDepth_1			; NO
+	lfsr	FSR1,opt_gas_type			; YES - load base address of opt_gas_type
+	tstfsz	PLUSW1						;     - type = disabled ?
+	call	TFT_attention_color			;       NO  - print in attention color (yellow)
+gaslist_GasDepth_1:
+	STRCAT_TEXT tSetup_GasDepth
+	return
 
 	global	gaslist_show_type
 gaslist_show_type:
 	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_type			; Read opt_gas_type[WREG]
-	movff	PLUSW1,lo					; lo holds gas type
+	lfsr	FSR1,opt_gas_type			; load base address of opt_gas_type
+	movff	PLUSW1,lo					; read gas type
 	STRCAT_TEXT tType
-	lfsr	FSR1,tGasDisabled			; Base text number
-	btfsc	ccr_diluent_setup			; In CCR setup?
-	lfsr	FSR1,tDilDisabled			; Base text number
+	lfsr	FSR1,tGasDisabled			; load base address of gas type labels
+	btfsc	FLAG_diluent_setup			; in CCR setup?
+	lfsr	FSR1,tDilDisabled			; YES - load base address of diluent type labels
 	movff	lo,WREG						; 0-3
 	rlncf	WREG						; x2
-	addwf	FSR1L,F
+	addwf	FSR1L,F						; adjust address pointer to required text
 	movlw	.0
 	addwfc	FSR1H,F
-	call	strcat_text
+	call	strcat_text					; copy label text
 	return
 
+
 	global	gaslist_toggle_type
 gaslist_toggle_type:
 	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_type			; Read opt_gas_type[WREG]
-	movff	PLUSW1,lo					; lo holds gas type
-	incf	lo,F						; 0-3/0-2
-	btfsc	ccr_diluent_setup			; In CCR setup?
-	bra		gaslist_toggle_type2		; Yes
-	btfsc	lo,2						; >3?
-	clrf	lo							; Clear to zero
-	movff	lo,PLUSW1					; Copy back result
+	lfsr	FSR1,opt_gas_type			; load base address of opt_gas_type
+	movff	PLUSW1,lo					; read gas type
+	incf	lo,F						; increment type
+	btfsc	FLAG_diluent_setup			; in CCR setup?
+	bra		gaslist_toggle_type2		; YES - diluents
+	btfsc	lo,2						; NO  - gases, type index > 3 ?
+	clrf	lo							;       YES - clear to zero
+	movff	lo,PLUSW1					;     - copy back result
 	return
 gaslist_toggle_type2:
 	movlw	.3
-	cpfslt	lo							; >2?
-	clrf	lo							; Clear to zero
-	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; Copy back result
-	return
-
-	global	gaslist_setSP
-gaslist_setSP:
-	movff	PRODL,gaslist_gas			; 0-4
+	cpfslt	lo							; index > 2 ?
+	clrf	lo							; YES - clear to zero
+	movf	gaslist_gas,W				; restore gaslist_gas in WREG
+	movff	lo,PLUSW1					; copy back result
 	return
 
 
 	global	gaslist_strcat_setpoint
 	global	gaslist_strcat_setpoint_0
-gaslist_strcat_setpoint:
-	call	gaslist_setSP
-gaslist_strcat_setpoint_0:
+gaslist_strcat_setpoint:				; entry point with setpoint index in PRODL
+	movff	PRODL,gaslist_gas			; get current menu item (0-4)
+gaslist_strcat_setpoint_0:				; entry point with setpoint index in gaslist_gas
 	bsf		leftbind
-	btfsc	short_gas_decriptions		; =1: Use short versions of gaslist_strcat_gas_mod and gaslist_strcat_setpoint
-	bra		gaslist_strcat_setpoint2	; Short version
-	STRCAT_TEXT tSP
-	incf	gaslist_gas,W
+	btfsc	short_gas_decriptions		; shall use short versions of gaslist_strcat_setpoint?
+	bra		gaslist_strcat_setpoint2	; YES - use short version
+	STRCAT_TEXT tSP						; "SP"
+	incf	gaslist_gas,W				; (0-4) -> (1-5) into WREG
 	movwf	lo
-	output_8
+	output_8							; print SP number
 	bcf		leftbind
 	PUTC	":"
-gaslist_strcat_setpoint2:				; Short version
+gaslist_strcat_setpoint2:				; short version
 	btfsc	divemode
 	bra		gaslist_strcat_setpoint4	; no "*" in divemode
-	movf	gaslist_gas,W				; Number-1 into WREG
-	bnz		gaslist_strcat_setpoint3	; Not SP1
-	PUTC	"*"
-	bra		gaslist_strcat_setpoint4
-gaslist_strcat_setpoint3:
-	PUTC	" "
+	movf	gaslist_gas,W				; (0-4) into WREG
+	bnz		gaslist_strcat_setpoint3	; SP index = 0 ?
+	PUTC	"*"							; YES - print *
+	bra		gaslist_strcat_setpoint4	;     - continue with cbar value
+gaslist_strcat_setpoint3:				; NO
+	PUTC	" "							;     - print a space
 gaslist_strcat_setpoint4:
-	movf	gaslist_gas,W
-	lfsr	FSR1,char_I_setpoint_cbar
-	movf	PLUSW1,W
+	movf	gaslist_gas,W				; (0-4) into WREG
+	lfsr	FSR1,char_I_setpoint_cbar	; load base address of setpoint cbar values
+	movf	PLUSW1,W					; read cbar value
 	movwf	lo
 	clrf	hi
 	bsf		leftbind
-	output_16dp d'3'
-	btfsc	divemode
-	bra		gaslist_strcat_setpoint5	; Skip text in divemode
-	STRCAT_TEXT tbar
+	output_16dp d'3'					; print as X.XX
+	btfsc	divemode					; in divemode?
+	bra		gaslist_strcat_setpoint5	; YES - skip text in divemode
+	STRCAT_TEXT tbar					; NO  - print "bar"
 gaslist_strcat_setpoint5:
-	PUTC	" "
-	; Read switch depth
-	movf	gaslist_gas,W
-	lfsr	FSR1,char_I_setpoint_change
-	movff	PLUSW1,lo
+	PUTC	" "							; print a space
+	movf	gaslist_gas,W				; (0-4) into WREG
+	lfsr	FSR1,char_I_setpoint_change	; load base address of switch depths
+	movff	PLUSW1,lo					; read switch depth into lo
+	bra		gaslist_strcat_depth		; print depth in meters or ft
 
-	bsf		ccr_diluent_setup			; inhibit output of "----" for depth 
-	call	gaslist_strcat_5
-	bcf		ccr_diluent_setup
-	return
 
 ;----------------------------------------------------------------------------
-; Append gas description to current string.
-; Input:  PRODL : gas number (0..4)
-;         FSR2  : Current string position.
-; Output: Text appended into buffer pointed by FSR2.
+; Append gas description to current string
+;
+; Prints gas number, * if first, = if deco gas, gas composition and change depth,
+; including fancy color-coding
 ;
-; NOTE: used in the menu-tree for the MENU_CALLBACK entry.
-
-gaslist_strcat_gas_better:				; Yes, check if this is a "better gas"
-	bcf		win_invert
-	movff	better_gas_number,WREG		; get better gas number into WREG
-	decf	WREG,W						; better_gas_number = better_gas_number -1
-	btfsc	ccr_diluent_setup			; in CCR menus?
-	addlw	.5							; Yes, offset to gases 5-9
-	cpfseq	gaslist_gas					; 0-4 for OC/Bailout, 5-9 for Diluents
-	return
-	call	TFT_attention_color			; show in yellow
-	bsf	win_invert						; And invert
-	return
+; Input:  PRODL gas number (0..4)
+;         FSR2  current string position
+; Output: text appended to buffer pointed by FSR2
+;
+; NOTE: used in the menu-tree for the MENU_CALLBACK entry
 
-	global	gaslist_strcat_gas_mod
-gaslist_strcat_gas_mod:
-	rcall	gaslist_setgas				; Sets gaslist_gas (0-4 for OC/Bailout, 5-9 for Diluents)
-	bsf		space_gas_decriptions		; add a space in front for gas numbers < 10 for alignment
-	;bra	gaslist_gastitle
-
+	global	gaslist_strcat_gas_cd
 	global	gaslist_gastitle
-gaslist_gastitle:
-	btfsc	short_gas_decriptions		; =1: Use short versions of gaslist_strcat_gas_mod and gaslist_strcat_setpoint
-	bra		gaslist_gastitle1			; Short version
-	STRCAT_TEXT tGas
-	incf	gaslist_gas,W
+gaslist_strcat_gas_cd:					; entry point with gas in PRODL (0-4) and usage of FLAG_diluent_setup
+	movff	PRODL,gaslist_gas			; get current menu item (0-4)
+	movlw	.5							; offset between gases and diluents
+	btfsc	FLAG_diluent_setup			; in diluent menus?
+	addwf	gaslist_gas,F				; YES - add the offset
+gaslist_gastitle:						; entry point with gas/dil in gaslist_gas (0-4 for gases, 5-9 for diluents)
+	bcf		win_invert					; clear flag for inverted output by default
+	btfsc	short_gas_decriptions		; shall use short versions of gaslist_strcat_gas_cd?
+	bra		gaslist_gastitle1			; YES - use short version
+	incf	gaslist_gas,W				; (0-9) -> (1-10) into WREG
 	movwf	lo
-	btfss	space_gas_decriptions		; add a space in front for gas numbers < 10 for alignment?
-	bra		gaslist_gastitle0			; NO
-	bcf		space_gas_decriptions		; YES - clear flag again
-	movlw	.10							;       load a 10
-	cpfslt	lo							;       gas# < 10 ?
-	bra		gaslist_gastitle0			;       NO
-	PUTC	" "							;       YES - add a space
+	movlw	.6							; diluents start with 6
+	cpfslt	lo							; gas number < 6 ?
+	bra		gaslist_gastitle_dil		; NO  - it's a diluent
+	STRCAT_TEXT tGas					; YES - it's a gas
+	bra		gaslist_gastitle0
+gaslist_gastitle_dil:
+	STRCAT_TEXT tDil
+	movlw	.5							; offset between gases and diluents
+	subwf	lo,F						; subtract offset from diluent number (6-10) -> (1-5)
 gaslist_gastitle0:
 	bsf		leftbind
-	output_8
+	output_8							; print gas/dil number (1-5)
 	bcf		leftbind
 	PUTC	":"
-gaslist_gastitle1:
-	lfsr	FSR1,opt_gas_type
-	btfsc	divemode
-	bra		gaslist_gastitle3			; no "*" in divemode
-	movf	gaslist_gas,W
-	decf	PLUSW1,W					; Type-1 into WREG
-	bnz		gaslist_gastitle2			; Not "First"
-	PUTC	"*"
-	bra		gaslist_gastitle3
+gaslist_gastitle1:						; short version of gaslist_strcat_gas_cd
+	btfsc	divemode					; in divemode?
+	bra		gaslist_gastitle3			; YES - no "*" and "=" in front of gas composition, no highlighting for transmitters paired
+
+ IFDEF _rx_functions
+	btfss	FLAG_tr_enabled				; NO  - TR functions enabled?
+	bra		gaslist_gastitle2			;       NO  - continue with gas type
+	lfsr	FSR1,opt_transmitter_id_1	;       YES - load base address of transmitter ID table
+	movf	gaslist_gas,W				;           - (0-4 for OC/Bailout, 5-9 for Diluents)
+	rlncf	WREG,W						;           - index x2 because IDs are 2 byte
+	tstfsz	PLUSW1						;           - transmitter ID low byte <> 0 ?
+	bsf		win_invert					;             YES - flag transmitter paired by inverting output
+	incf	WREG,W						;           - increment index
+	tstfsz	PLUSW1						;           - transmitter ID high byte <> 0 ?
+	bsf		win_invert					;             YES - flag transmitter paired by inverting output
+ ENDIF
+
 gaslist_gastitle2:
-	PUTC	" "
+	rcall	gaslist_strcat_gas_type		; print "*" for first gas/dil, "=" for a deco gas or " " else
 gaslist_gastitle3:
 	call	TFT_standard_color
-	btfsc	divemode					; In divemode?
-	rcall	gaslist_strcat_gas_better	; Yes, check if this is a "better gas"
-	movf	gaslist_gas,W				; (0-4 for OC/Bailout, 5-9 for Diluents)
-	movf	PLUSW1,W
-	bnz		gaslist_strcat_3
-	call	TFT_disabled_color
-	bra		gaslist_strcat_4			; no MOD-check and red color for disabled gases
-gaslist_strcat_3:
-	rcall	gaslist_strcat_gas_0
-	PUTC	" "
-	; Read switch depth
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents-5
-	movlw	.4
-	cpfsgt	gaslist_gas					; >4? (-> Diluents)
-	lfsr	FSR1,opt_OC_bail_gas_change	; Setup OC Gases
-
-	movf	gaslist_gas,W				; (0-4 for OC/Bailout, 5-9 for Diluents)
-	movff	PLUSW1,lo
-	rcall	gaslist_calc_mod			; Compute MOD into WREG
-	cpfsgt	lo							; within MOD range?
-	bra		gaslist_strcat_5			; YES
-	call	TFT_warnings_color			; NO  - turn red
-	bra		gaslist_strcat_5			; skip gaslist_strcat_gas_0 here
-gaslist_strcat_4:
-	rcall	gaslist_strcat_gas_0
-	PUTC	" "
-	; Dummy code, needs some cleanup someday...
-	; Read switch depth
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents-5
-	movlw	.4
-	cpfsgt	gaslist_gas					; >4? (-> Diluents)
-	lfsr	FSR1,opt_OC_bail_gas_change	; Setup OC Gases
-	movf	gaslist_gas,W				; (0-4 for OC/Bailout, 5-9 for Diluents)
-	movff	PLUSW1,lo
-	rcall	gaslist_calc_mod			; Compute MOD into WREG
-gaslist_strcat_5:
-	PUTC	" "
-	TSTOSS	opt_units					; 0=Meter, 1=Feet
-	bra		gaslist_strcat_3_metric
-;gaslist_strcat_3_imperial:
-	btfsc	ccr_diluent_setup			; =1: Setting up Diluents ("Gas6-10")
-	bra		gaslist_imperial_non_travel
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_type			; Read opt_gas_type[WREG]
-	movff	PLUSW1,up					; up holds gas type
-	movlw	.2							; 2=Travel
-	cpfseq	up							; compare gas type with type 2=Travel
-	bra		gaslist_imperial_non_travel	; Non-Travel Gas
-	bra		gaslist_strcat_depth_travel	; Show "---" instead of "0m"...
-gaslist_imperial_non_travel:
+	btfsc	divemode					; in divemode?
+	rcall	gaslist_strcat_gas_better	; YES - check if this is a "better gas"
+	lfsr	FSR1,opt_gas_type			; load base address of gas types
+	movf	gaslist_gas,W				; load index into WREG (0-4 for gases, 5-9 for diluents)
+	movf	PLUSW1,W					; read gas/dil type into WREG
+	bnz		gaslist_gastitle4			; type = disabled? NO  - keep color
+	call	TFT_disabled_color			;                  YES - switch color to disabled
+	bra		gaslist_gastitle5			;                      - skip ppO2 check for disabled gases
+gaslist_gastitle4:
+	btfss	divemode					; in divemode?
+	bra		gaslist_gastitle5			; NO  - no ppO2 check if not in divemode
+	lfsr	FSR1,opt_gas_O2_ratio		; YES - load base address of opt_gas_O2_ratio
+	movf	gaslist_gas,W				;     - load index into WREG (0-4 for gases, 5-9 for diluents)
+	movff	PLUSW1,hi					;     - read O2 ratio into hi
+	call	TFT_color_code_gaslist		;     - set color according to ppO2 limits
+gaslist_gastitle5:
+	movf	gaslist_gas,W				; copy gas/dil index to WREG (0-9)
+	rcall	gaslist_strcat_gas_WREG		; print gas composition
+	btfss	divemode					; in divemode?
+	bra		gaslist_gastitle6			; NO  - continue printing a space
+	rcall	gaslist_strcat_gas_type		; YES - print "*" for first gas/dil, "=" for a deco gas, or a space else
+	bra		gaslist_gastitle7			;     - continue with change depth
+gaslist_gastitle6:
+	PUTC	" "							; print a space
+gaslist_gastitle7:
+	lfsr	FSR1,opt_gas_change			; load base address of change depths
+	movf	gaslist_gas,W				; load gas/dil index into WREG (0-9)
+	movff	PLUSW1,lo					; read change depth into lo
+gaslist_strcat_depth:					; entry point for general printing of depths with value in meters in lo
+	TSTOSS	opt_units					; check depth units
+	bra		gaslist_strcat_depth_metric	; 0 - use Meters
+gaslist_strcat_depth_imperial:			; 1 - use Feet
 	movf	lo,W
 	mullw	.100						; convert meters to mbar
 	movff	PRODL,lo
 	movff	PRODH,hi
 	call	convert_mbar_to_feet		; convert value in lo:hi from mbar to feet
-	bsf		leftbind
-	output_16_3							; limit to 999 and display only (0-999)
-	STRCAT_TEXT tFeets					; "ft"
+	;bsf	leftbind
+	output_16_3							; limit to 999 and display only 0-999
+	STRCAT_TEXT tFeets					; append "ft"	REMARK: still one char to long for space available in divemode menu!
+	return
+gaslist_strcat_depth_metric:
+	PUTC	" "							; print a space
+	output_99
+	STRCAT_TEXT tMeters					; "m"
 	return
-gaslist_strcat_3_metric:
-	btfsc	ccr_diluent_setup			; =1: Setting up Diluents ("Gas6-10")
-	bra		gaslist_metric_non_travel
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_type			; Read opt_gas_type[WREG]
-	movff	PLUSW1,up					; up holds gas type
-	movlw	.2							; 2=Travel
-	cpfseq	up							; compare gas type with type 2=Travel
-	bra		gaslist_metric_non_travel	; Non-Travel Gas
-gaslist_strcat_depth_travel:			; Show "---" instead of "0m"...
-	STRCAT	"---"
-	return
-gaslist_metric_non_travel:
-	output_99
-	STRCAT_TEXT	tMeters					; "m"
+
+gaslist_strcat_gas_better:				; color-code output if this is the best gas/diluent
+	btfss	better_gas_hint				; shall better gas hints be given?
+	return								; NO - return
+	movf	best_gas_number,W			; get best gas number into WREG
+	btfsc	FLAG_diluent_setup			; in CCR (pSCR) menus?
+	movf	best_dil_number,W			; YES - overwrite with best diluent number
+	tstfsz	WREG						; is a best gas/dil available?
+	bra		gaslist_strcat_gas_better1	; YES - proceed
+	return								; NO  - return
+gaslist_strcat_gas_better1:
+	decf	WREG,W						; (1-5) -> (0-4)
+	btfsc	FLAG_diluent_setup			; in diluent menus?
+	addlw	.5							; YES - add offset between gases and diluents (0-4) -> (5-9)
+	cpfseq	gaslist_gas					; compare with given gas/dil (0-4 for OC bailout gases, 5-9 for diluents)
+	return								; not equal - return
+	bsf		win_invert					;     equal - invert
+	movlw	color_green					;           - select green color (gas is something "good")
+	goto	TFT_set_color				;           - activate color and return
+
+gaslist_strcat_gas_type:
+	lfsr	FSR1,opt_gas_type			; load base address of gas types
+	movf	gaslist_gas,W				; load index to WREG (0-4 for gases, 5-9 for diluents)
+	decf	PLUSW1,W					; read gas/dil type into WREG and...
+										; ...decrement by 1  (-1 for disabled,  0 for first,  1 for travel/normal, 2 for deco)
+	bnz		gaslist_strcat_gas_type_1	; type = first? NO  - continue with checking for deco gas
+	PUTC	"*"							;               YES - print "*" for first
+	return								;                   - done
+gaslist_strcat_gas_type_1:
+	decf	WREG,W						; decrement gas type (-2 for disabled, -1 for first,  0 for travel/normal, 1 for deco)
+	decf	WREG,W						; decrement gas type (-3 for disabled, -2 for first, -1 for travel/normal, 0 for deco)
+	bnz		gaslist_strcat_gas_type_2	; type = deco? NO  - neither first nor deco
+	PUTC	"="							;              YES - print "=" for a deco gas
+	return								;                   - done
+gaslist_strcat_gas_type_2:
+	PUTC	" "							; neither first nor deco, print a space
 	return
 
 ;----------------------------------------------------------------------------
-; Store current menu item, and display gas description later.
-; Input: PRODL : gas number (0..4)
-; NOTE: used in the menu-tree for the MENU_CALLBACK entry.
+; Housekeeping for the gas/dil settings, e.g. making sure there is one FIRST only
+;
+; Input:  gaslist_gas  last edited gas/dil (0-9)
+
+	global	gaslist_cleanup_list
+gaslist_cleanup_list:
+	lfsr	FSR1,opt_gas_type			; load base address of opt_gas_type
+	movlw	.5							; offset between gases and diluents
+	btfsc	FLAG_diluent_setup			; in CCR-Menu?
+	subwf	gaslist_gas,F				; YES - subtract offset from gaslist_gas: (5-9) -> (0-4)
+gaslist_cleanup_list0:
+	bcf		ignore_last_edited_gas
+gaslist_cleanup_list1:
+	clrf	lo							; counter for number of "firsts" found
+	movlw	.5							; initialize hi as loop counter for checking 5 gases/diluents
+	movwf	hi
+gaslist_cleanup_list2:					; loop body
+	decf	hi,W						; WREG = current gas/dil (0-4)
+	btfsc	FLAG_diluent_setup			; in CCR-Menu?
+	addlw	.5							; YES - add offset from gases to diluents -> (5-9)
+	movff	PLUSW1,WREG					; read type into WREG
+	decfsz	WREG						; is type = first (ex type code 1)?
+	bra		gaslist_cleanup_list3		; NO  - done with this gas/dil
+	incf	lo,F						; YES - increment number of "firsts" found
+	btfss	ignore_last_edited_gas		;     - shall we ignore the last edited gas/dil?
+	bra		gaslist_cleanup_list2b		;       NO  - continue remembering the "last first" gas/dil (do a shortcut)
+	decf	hi,W						;       YES - get the current gas/dil as (0-4)
+	cpfseq	gaslist_gas					;           - is this the last edited gas/dil?
+gaslist_cleanup_list2b:
+	movff	hi,up						;             (NO) - remember the last "first gas" found
+gaslist_cleanup_list3:
+	decfsz	hi,F						; decrement loop counter
+	bra		gaslist_cleanup_list2		; loop counter became 0 ? NO  - loop
+	tstfsz	lo							;                         YES - any first gas/dil at all?
+	bra		gaslist_cleanup_list4		;                               YES - at least one first gas/dil existing
+	btfsc	FLAG_diluent_setup			;                               NO  - in CCR-Menu?
+	lfsr	FSR1,opt_dil_type			;                                     YES - load base address of opt_gas_type
+	movlw	.1							;                                   - load coding for first gas
+	movwf	INDF1						;                                   - make gas/dil 1 the first gas
+	return								;                                   - done
+gaslist_cleanup_list4:
+	movlw	.1
+	cpfsgt	lo							; more then one "first gas" found?
+	return								; NO  - done
+	decf	up,W						; YES - WREG = last found "first gas" - 1 (0-4)
+	cpfseq	gaslist_gas					;     - is this the last edited gas/dil?
+	bra		gaslist_cleanup_list4b		;       NO  - disable it
+	bsf		ignore_last_edited_gas		;       YES - do not disable last edited gas, search again but ignore the last edited gas
+	bra		gaslist_cleanup_list1		;           - loop until only one "first" is left over
+gaslist_cleanup_list4b:
+	btfsc	FLAG_diluent_setup			; in CCR-Menu?
+	addlw	.5							; YES - adjust offset
+	clrf	PLUSW1						; disable gas
+	bra		gaslist_cleanup_list0		; redo from start until only one "first" is left over
+	return
+
+;----------------------------------------------------------------------------
+; Tank Settings
+;
+; Inputs: char_I_tank_size       size of the tank,                     using unit text tLiter ("l")
+;         char_I_tank_pres_fill  fill pressure in multiples of 10 bar, using unit text tbar10 ("0 bar")
 
-	global	gaslist_setgas
-gaslist_setgas:
-	movff	PRODL,gaslist_gas
-	movlw	.5
-	btfsc	ccr_diluent_setup			; in CCR menus?
-	addwf	gaslist_gas,F				; Yes, offset to gases 5-9
+	global	gaslist_tank_size_pres
+gaslist_tank_size_pres:					; dynamic title: xx l, xx0 bar
+	lfsr	FSR1,char_I_tank_size		; load base address of char_I_tank_size
+	movf	gaslist_gas,W				; load index (0-9)
+	movff	PLUSW1,lo					; read char_I_tank_size[WREG] into lo
+	lfsr	FSR1,char_I_tank_pres_fill	; load base address of char_I_tank_pres_fill
+	movff	PLUSW1,hi					; read char_I_tank_pres_fill[WREG] into hi
+	STRCAT	"     "						; print 5 leading spaces for alignment
+	output_8							; print tank size
+	STRCAT_TEXT tLiter					; print unit (" l")
+	movff	hi,lo						; copy fill pressure into lo
+	output_8							; print fill pressure (it is stored in multiples of 10 bar)
+	STRCAT_TEXT tbar10					; print unit ("0 bar")
+	return
+
+	global	gaslist_tank_size
+gaslist_tank_size:						; adjust char_I_tank_size between min_tank_size and max_tank_size
+	lfsr	FSR1,char_I_tank_size		; load base address of char_I_tank_size
+	movf	gaslist_gas,W				; load index (0-9)
+	movff	PLUSW1,lo					; read char_I_tank_size[WREG] into lo
+	incf	lo,F						; increment tank size by 1 liter
+	movlw	max_tank_size				; load max. allowed value into WREG
+	cpfsgt	lo							; tank size <= max value?
+	bra		gaslist_tank_size_1			; YES - new value can be used
+	movlw	min_tank_size				; NO  - wrap-around to min value
+	movwf	lo							;     - and write to lo
+gaslist_tank_size_1:
+	movf	gaslist_gas,W				; re-load index
+	movff	lo,PLUSW1					; write back tank size to char_I_tank_size[WREG]
+	return
+
+	global	gaslist_tank_pres
+gaslist_tank_pres:						; adjust char_I_tank_pres_fill between 5(0) and 29(0) bar
+	lfsr	FSR1,char_I_tank_pres_fill	; load base address of char_I_tank_pres_fill
+	movf	gaslist_gas,W				; load index (0-9)
+	movff	PLUSW1,lo					; read char_I_tank_pres_fill[WREG] into lo
+	incf	lo,F						; increment fill press by by 1(0) bar
+	movlw	max_fill_press				; load max. allowed value into WREG
+	cpfsgt	lo							; press <= max value?
+	bra		gaslist_tank_pres_1			; YES - new value can be used
+	movlw	min_fill_press				; NO  - wrap-around to min value
+	movwf	lo							;     - and write to lo
+gaslist_tank_pres_1:
+	movf	gaslist_gas,W				; re-load index
+	movff	lo,PLUSW1					; write back tank size to char_I_tank_pres_fill[WREG]
+	return
+
+;----------------------------------------------------------------------------
+; Transmitter functions
+
+ IFDEF _rx_functions
+
+	global	gaslist_tank_id_pres
+gaslist_tank_id_pres:					; dynamic title: shows ID and pressure from transmitter with ID opt_transmitter_id[gaslist_gas]
+										;                When changing layout, adapt output position TFT_menu_tank_pres!
+	STRCAT	"  ID: "					; print header
+	; get ID							;
+	lfsr	FSR1,opt_transmitter_id_1	; load base address of opt_transmitter_id
+	movf	gaslist_gas,W				; load index (0-9)
+	rlncf	WREG,W						; multiply by 2 because IDs are 2 byte in size
+	movff	PLUSW1,lo					; copy opt_transmitter_id+0[gaslist_gas] to lo
+	incf	WREG,W						; increment index
+	movff	PLUSW1,hi					; copy opt_transmitter_id+1[gaslist_gas] to hi
+	; check if a transmitter is paired to this tank
+	tstfsz	hi							; high byte of ID <> 0 ?
+	bra		gaslist_tank_id_pres_1		; YES - a transmitter is paired to the tank
+	tstfsz	lo							; low  byte of ID <> 0 ?
+	bra		gaslist_tank_id_pres_1		; YES - a transmitter is paired to the tank
+	; no transmitter paired
+	STRCAT	"----"						;
+	bcf		menu_update_tank_pres		; stop imprinting of tank pressure updates
+	return
+gaslist_tank_id_pres_1:
+	; show ID
+	movf	hi,W						; copy high byte of ID to WREG
+	output_hex							; print it
+	movf	lo,W						; copy low  byte of ID to WREG
+	output_hex							; print it
+	bsf		menu_update_tank_pres		; start imprinting of tank pressure updates
 	return
 
 
-	global	gaslist_cleanup_list		; Takes care that only one gas can be first and first has 0m change depth
-gaslist_cleanup_list:
-	bcf		ignore_last_edited_gas
-	movlw	.0
-	btfsc	ccr_diluent_setup			; In CCR-Menu?
-	addlw	.5							; Yes, adjust offset
-	subwf	gaslist_gas,F
-gaslist_cleanup_list1:
-	clrf	lo
-	lfsr	FSR1,opt_gas_type			; Read opt_gas_type[WREG]
-	movlw	.5							; Check 5 gases
-	movwf	hi
-gaslist_cleanup_list2:
-	decf	hi,w						; 0-4
-	btfsc	ccr_diluent_setup			; In CCR-Menu?
-	addlw	.5							; Yes, adjust offset
-	movff	PLUSW1,WREG					; read gas type
-	decfsz	WREG						; is gas = first (ex 1)?
-	bra		gaslist_cleanup_list3		; NO
-	incf	lo,F						; YES - count "first gases"
-	btfss	ignore_last_edited_gas		; If we are not in the second-pass mode
-	bra		gaslist_cleanup_list2b
-	decf	hi,w						; 0-4
-	cpfseq	gaslist_gas					; Do not disable last edited gas
-gaslist_cleanup_list2b:
-	movff	hi,up						; Keep the last "first gas" found
-gaslist_cleanup_list3:
-	decfsz	hi,F
-	bra		gaslist_cleanup_list2		; Loop
-	tstfsz	lo							; No gas active?
-	bra		gaslist_cleanup_list4		; No, at least one is active
-	btfsc	ccr_diluent_setup			; In CCR-Menu?
-	bra		gaslist_cleanup_list3a		; Yes.
-	; make gas1 first and zero
-	movlw	.1							; First
-	movwf	up
-	movwf	INDF1
-	bra	gaslist_cleanup_list5			; Set change depth to zero
-gaslist_cleanup_list3a:
-	movlw	.5
-	addwf	FSR1L,F
-	movlw	.0
-	addwfc	FSR1H,F						; Setup to Diluents
-	; make dil1 first and zero
-	movlw	.1							; First
-	movwf	up
-	movwf	INDF1
-	bra		gaslist_cleanup_list5		; Set change depth to zero
-gaslist_cleanup_list4:
-	movlw	.1
-	cpfsgt	lo							; More then one "first gas"?
-	bra		gaslist_cleanup_list5		; No, done.
-	; More then one Gas is "first gas"
-	; Disable last found "first gas" but keep it's change depth
-	decf	up,W						; 0-4
-	cpfseq	gaslist_gas					; Do not disable last edited gas
-	bra		gaslist_cleanup_list4b
-	; Do not disable last edited gas
-	; search again but ignore last edited gas
-	bsf		ignore_last_edited_gas
-	bra		gaslist_cleanup_list1		; Loop until only one "first gas" is left
-gaslist_cleanup_list4b:
-	btfsc	ccr_diluent_setup			; In CCR-Menu?
-	addlw	.5							; Yes, adjust offset
-	clrf	PLUSW1						; Disable gas
-	bra		gaslist_cleanup_list		; Loop until only one "first gas" is left
-gaslist_cleanup_list5:
-	; Read switch depth
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents-5
-	btfss	ccr_diluent_setup			; In CCR-Menu?
-	lfsr	FSR1,opt_OC_bail_gas_change	; No, setup OC Gases
-	decf	up,W
-	btfsc	ccr_diluent_setup			; In CCR-Menu?
-	addlw	.5							; Yes, adjust offset
-	clrf	PLUSW1						; Set First gas to zero m
-	return
+	global	gaslist_tank_pairing
+gaslist_tank_pairing:
+	incf	pairing_slot,F				; goto next RX data slot
+	btfsc	pairing_slot,3				; slot = 8?
+	bra		gaslist_tank_pairing_none	; YES - offer unpairing
+	movf	pairing_slot,W				; NO  - copy slot to WREG
+	call	get_transmitter_id_by_slot	; WREG = slot (0-7) -> hi:lo = transmitter ID
+	tstfsz	hi							; transmitter found (probe on high byte)?
+	bra		gaslist_tank_pairing_common	; YES - select this transmitter
+	tstfsz	hi							; transmitter found (probe on low byte)?
+	bra		gaslist_tank_pairing_common	; YES - select this transmitter
+	bra		gaslist_tank_pairing		; NO  - try next slot
+gaslist_tank_pairing_common:
+	lfsr	FSR1,opt_transmitter_id_1	; load base address of opt_transmitter_id
+	movf	gaslist_gas,W				; load index into WREG (0-9)
+	rlncf	WREG,W						; multiply by 2 because IDs are 2 byte in size
+	movff	lo,PLUSW1					; copy lo to opt_transmitter_id+0[gaslist_gas]
+	incf	WREG,W						; increment index
+	movff	hi,PLUSW1					; copy hi to opt_transmitter_id+1[gaslist_gas]
+	return								; done
+gaslist_tank_pairing_none:
+	setf	pairing_slot				; prime slot number with 255 aka -1
+	clrf	hi							; adjust "no transmitter" ID
+	clrf	lo							; adjust "no transmitter" ID
+	bra		gaslist_tank_pairing_common	; continue with common part
+
+ ENDIF
 
 ;----------------------------------------------------------------------------
 ; Increment/Decrement O2 ratio
 
 	global	gaslist_pO2
 gaslist_pO2:
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_He_ratio		; Read opt_gas_He_ratio[WREG]
-	movff	PLUSW1,hi					; hi holds He ratio
-	lfsr	FSR1,opt_gas_O2_ratio		; Read opt_gas_O2_ratio[WREG]
-	movff	PLUSW1,lo					; lo holds O2 ratio
+	movf	gaslist_gas,W				; load index (0-9)
+	lfsr	FSR1,opt_gas_He_ratio		; load base address of opt_gas_He_ratio
+	movff	PLUSW1,hi					; read He ratio into hi
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movff	PLUSW1,lo					; read O2 ratio into lo
 
 	incf	lo,F						; O2++
 	movf	hi,W						; get He ratio into WREG
@@ -389,24 +600,23 @@
 	movlw	.101						;
 	cpfslt	up							; O2 + He < 101?
 	decf	lo,F						; O2-- (revoke ++)
-	movf	gaslist_gas,W
+	movf	gaslist_gas,W				; re-load index
 	movff	lo,PLUSW1					; write back O2 ratio to opt_gas_O2_ratio[WREG]
 	return
 
 	global	gaslist_mO2
 gaslist_mO2:
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_O2_ratio		; Read opt_gas_O2_ratio[WREG]
-	movff	PLUSW1,lo					; lo holds O2 ratio
+	movf	gaslist_gas,W				; load index (0-9)
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movff	PLUSW1,lo					; read O2 ratio into lo
 
 	decf	lo,F						; O2--
 	movlw	gaslist_min_o2				; get minimum allowed O2 ratio
 	cpfslt	lo							; current O2 ratio below allowed minimum?
 	bra		gaslist_mO2_1				; NO
-	movlw	gaslist_min_o2				; YES - load minimum
-	movwf	lo							;       write minimum to current O2 ratio
+	movwf	lo							; YES - copy minimum O2 ratio to lo
 gaslist_mO2_1:
-	movf	gaslist_gas,W
+	movf	gaslist_gas,W				; re-load index
 	movff	lo,PLUSW1					; write back O2 ratio to opt_gas_O2_ratio[WREG]
 	return
 
@@ -415,11 +625,11 @@
 
 	global	gaslist_pHe
 gaslist_pHe:
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_O2_ratio		; Read opt_gas_O2_ratio[WREG]
-	movff	PLUSW1,lo					; lo holds O2 ratio
-	lfsr	FSR1,opt_gas_He_ratio		; Read opt_gas_He_ratio[WREG]
-	movff	PLUSW1,hi					; hi holds He ratio
+	movf	gaslist_gas,W				; load index (0-9)
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movff	PLUSW1,lo					; read O2 ratio into lo
+	lfsr	FSR1,opt_gas_He_ratio		; load base address of opt_gas_He_ratio
+	movff	PLUSW1,hi					; read He ratio into hi
 
 	incf	hi,F						; He++
 	movf	hi,W						; get He ratio into WREG
@@ -428,21 +638,21 @@
 	movlw	.101						;
 	cpfslt	up							; O2 + He < 101?
 	decf	hi,F						; He-- (revoke ++)
-	movf	gaslist_gas,W
+	movf	gaslist_gas,W				; re-load index
 	movff	hi,PLUSW1					; write back He ratio to opt_gas_He_ratio[WREG]
 	return
 
 	global	gaslist_mHe
 gaslist_mHe:
-	movf	gaslist_gas,W
-	lfsr	FSR1,opt_gas_He_ratio		; Read opt_gas_He_ratio[WREG]
-	movff	PLUSW1,hi					; hi holds He ratio
+	movf	gaslist_gas,W				; load index (0-9)
+	lfsr	FSR1,opt_gas_He_ratio		; load base address of opt_gas_He_ratio
+	movff	PLUSW1,hi					; read He ratio into hi
 
 	decf	hi,F						; He--
 	bnn		gaslist_mHe_1				; He ratio negative?
-	clrf	hi							; YES - set He to 0
+	clrf	hi							; YES - set He ratio to 0
 gaslist_mHe_1:
-	movf	gaslist_gas,W
+	movf	gaslist_gas,W				; re-load index
 	movff	hi,PLUSW1					; write back He ratio to opt_gas_He_ratio[WREG]
 	return
 
@@ -451,46 +661,35 @@
 
 	global	gaslist_pDepth
 gaslist_pDepth:
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents-5
-	movlw	.4
-	cpfsgt	gaslist_gas					; >4? (-> Diluents)
-	lfsr	FSR1,opt_OC_bail_gas_change	; Setup OC Gases
-	movf	gaslist_gas,W
-	movff	PLUSW1,lo					; Read char_I_deco_gas_change[WREG]
-	incf	lo,F
-	movlw	gaslist_max_change_depth
-	cpfsgt	lo
-	bra		gaslist_pDepth_1
-	movlw	gaslist_max_change_depth
-	movwf	lo
+	lfsr	FSR1,opt_gas_change			; load base address of opt_gas_change
+	movf	gaslist_gas,W				; load index (0-4)
+	movff	PLUSW1,lo					; read switch depth into lo
+	incf	lo,F						; increment switch depth
+	movlw	gaslist_max_change_depth	; get max change depth
+	cpfsgt	lo							; above max change depth?
+	bra		gaslist_pDepth_1			; NO
+	movwf	lo							; YES - revert to max change depth
 gaslist_pDepth_1:
-	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; Write back to char_I_deco_gas_change[WREG]
+	movf	gaslist_gas,W				; re-load index
+	movff	lo,PLUSW1					; write back switch depth
 	return
 
 	global	gaslist_mDepth
 gaslist_mDepth:
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents-5
-	movlw	.4
-	cpfsgt	gaslist_gas					; >4? (-> Diluents)
-	lfsr	FSR1,opt_OC_bail_gas_change	; Setup OC Gases
-
-	movf	gaslist_gas,W
-	movff	PLUSW1,lo					; Read char_I_deco_gas_change[WREG]
-
-	decf	lo,F
-	btfsc	STATUS,N
-	clrf	lo
-
-	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; And write back to char_I_deco_gas_change[WREG]
+	lfsr	FSR1,opt_gas_change			; load base address of opt_gas_change
+	movf	gaslist_gas,W				; load index (0-4)
+	movff	PLUSW1,lo					; read switch depth into lo
+	decf	lo,F						; decrement switch depth
+	btfsc	STATUS,N					; did depth became negative?
+	clrf	lo							; YES - reset to zero
+	movff	lo,PLUSW1					; write back switch depth
 	return
 
 	global	gaslist_spplus
 gaslist_spplus:
 	movf	gaslist_gas,W
 	lfsr	FSR1,char_I_setpoint_cbar
-	movff	PLUSW1,lo					; Read char_I_setpoint_cbar[WREG]
+	movff	PLUSW1,lo					; read setpoint
 	movlw	gaslist_sp_stepsize
 	addwf	lo,F
 	movlw	gaslist_sp_max
@@ -500,165 +699,129 @@
 	movwf	lo
 gaslist_spplus2:
 	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; Write back to char_I_setpoint_cbar
+	movff	lo,PLUSW1					; write back setpoint
 	return
 
 	global	gaslist_spdepthplus
 gaslist_spdepthplus:
-	movf	gaslist_gas,W
-	bz		gaslist_spdepthplus3		; Setpoint 1 is always 0m
-	lfsr	FSR1,char_I_setpoint_change
-	movff	PLUSW1,lo					; Read char_I_deco_gas_change[WREG]
-	incf	lo,F
-	movlw	gaslist_max_change_depth
-	cpfsgt	lo
-	bra		gaslist_spdepthplus_1
-	movlw	gaslist_max_change_depth
-	movwf	lo
+	movf	gaslist_gas,W				; get setpoint number (0-4)
+	bz		gaslist_spdepthplus2		; setpoint number = 0? YES - force depth to always be 0m
+	lfsr	FSR1,char_I_setpoint_change	; load base address of char_I_setpoint_change
+	movff	PLUSW1,lo					; read setpoint depth into lo
+	incf	lo,F						; increment depth
+	movlw	gaslist_max_change_depth	; get max. depth
+	cpfsgt	lo							; switch depth > max. depth?
+	bra		gaslist_spdepthplus_1		; NO
+	movwf	lo							; YES - copy to lo
 gaslist_spdepthplus_1:
-	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; Write back to char_I_deco_gas_change[WREG]
-	return
-
-gaslist_spdepthplus3:
-	movlw	.0
-	movff	WREG,char_I_setpoint_change+0	; Reset to 0m
+	movf	gaslist_gas,W				; re-load index
+	movff	lo,PLUSW1					; write back setpoint depth
 	return
 
 	global	gaslist_spdepthminus
 gaslist_spdepthminus:
-	movf	gaslist_gas,W
-	bz		gaslist_spdepthplus3		; Setpoint 1 is always 0m
-	lfsr	FSR1,char_I_setpoint_change
-	movff	PLUSW1,lo					; Read char_I_deco_gas_change[WREG]
-	decf	lo,F
-	btfsc	STATUS,N
-	clrf	lo
-	movf	gaslist_gas,W
-	movff	lo,PLUSW1					; Write back to char_I_deco_gas_change[WREG]
+	movf	gaslist_gas,W				; get setpoint number (0-4)
+	bz		gaslist_spdepthminus2		; setpoint number = 0? YES - force depth to always be 0m
+	lfsr	FSR1,char_I_setpoint_change	; load base address of char_I_setpoint_change
+	movff	PLUSW1,lo					; read setpoint depth into lo
+	decf	lo,F						; decrement switch depth
+	btfsc	STATUS,N					; did depth became negative?
+	clrf	lo							; YES - reset to zero
+	movff	lo,PLUSW1					; write back setpoint depth
 	return
 
+gaslist_spdepthplus2:
+gaslist_spdepthminus2:
+	movlw	.0
+	movff	WREG,char_I_setpoint_change+0	; hard reset to 0m
+	return
+
+
 ;----------------------------------------------------------------------------
-; Compute MOD from char_I_ppO2_max/char_I_ppO2_max_deco and current O2 Ratio.
+; Compute MOD from char_I_ppO2_max/char_I_ppO2_max_deco and current O2 ratio
 ;
 ; Input:  gaslist_gas                   = current gas index.
 ;         opt_gas_O2_ratio[gaslist_gas] = current O2 ratio
 ; Output: WREG                          = MOD [m]
 ;
 gaslist_calc_mod:
-	movf	gaslist_gas,W				; get gas number (0...5)
-	lfsr	FSR1,opt_gas_O2_ratio		; read opt_gas_O2_ratio[WREG]
-	movf	PLUSW1,W
-
-	btfsc	divemode					; in divemode?
-	bra		gaslist_calc_mod_divemode	; YES
-
-	; Pamb max = ppO2 Max / O2 ratio
-	movwf	xB+0
-
-	movf	gaslist_gas,W				; get gas number (0...5)
-	lfsr	FSR1,opt_gas_type			; 0=Disabled, 1=First, 2=Travel, 3=Deco for OC gases and 0=Disabled, 1=First, 2=Normal for diluents
-	movff	PLUSW1,xA+0					; xA+0 used as temp here -> holds type
-
-	movff	char_I_ppO2_max_deco,xB+1	; xB+1 used as temp here
-	movlw	.3
-	cpfseq	xA+0						; Deco?
-	movff	char_I_ppO2_max,xB+1		; No, overwrite with travel/bottom max
-	movf	xB+1,W						; Result in WREG
-
-	clrf	xB+1						; Clear for div16x16
-	mullw	.10
-	movff	PRODL,xA+0
+	movf	gaslist_gas,W				; load index (0...9)
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movff	PLUSW1,xB+0					; read O2 ratio into xB+0
+	lfsr	FSR1,opt_gas_type			; load base address of opt_gas_type
+	movff	PLUSW1,xA+0					; read gas/dil type into xA+0 (used as temp here)
+	movff	char_I_ppO2_max_deco,xB+1	; get max ppO2 for deco into xB+1 (used as temp here)
+	movlw	.3							; type code for deco gases
+	cpfseq	xA+0						; is it a deco gas?
+	movff	char_I_ppO2_max,xB+1		; NO - overwrite ppO2 max with none-deco max
+	movf	xB+1,W						; copy resulting ppO2 max into WREG
+	clrf	xB+1						; clear xB+1 for div16x16 operation
+	mullw	.10							; multiply ppO2 max value with 10
+	movff	PRODL,xA+0					; copy result to xA
 	movff	PRODH,xA+1
-	call	div16x16
-
-	; Prof = Pamb - 1 bar
-	movf	xC+0,W
-	addlw	-.10
-	return
-
-gaslist_calc_mod_divemode:
-	movwf	hi							; Copy O2%
-	call	TFT_color_code_gaslist		; Color-code current row in Gaslist (%O2 in hi), char_I_ppO2_max/char_I_ppO2_max_deco as threshold
-	return
+	call	div16x16					; xC = xA / xB with xA as remainder
+	movf	xC+0,W						; copy result to WREG
+	addlw	-.10						; subtract 10 cbar
+	return								; return with final result in WREG
 
 ;----------------------------------------------------------------------------
 
 	global	gaslist_ppo2
 gaslist_ppo2:
 	STRCAT_TEXT tppO2					; ppO2:
-	movf	gaslist_gas,W
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents
-	btfss	ccr_diluent_setup			; In CCR-Menu?
-	lfsr	FSR1,opt_OC_bail_gas_change	; No, setup OC/Bailout Gases
-	movf	PLUSW1,W
-	mullw	.10							; PROD=Depth in mbar/10 (100 = 1.00 bar)
-	movlw	.100
+	lfsr	FSR1,opt_gas_change			; load base address of opt_gas_change
+	movf	gaslist_gas,W				; load index (0-9)
+	movf	PLUSW1,W					; read change depth into WREG
+	mullw	.10							; PROD = depth in mbar/10 (100 = 1.00 bar)
+	movlw	.100						; add 1 bar
 	addwf	PRODL,F
 	movlw	.0
-	addwfc	PRODH,F						; add 1bar
-	movff	PRODL,xA+0
+	addwfc	PRODH,F
+	movff	PRODL,xA+0					; copy result to xA
 	movff	PRODH,xA+1
-	movf	gaslist_gas,W				; Read current gas O2 ratio
-	lfsr	FSR1,opt_dil_O2_ratio-.5	; Read dil_gas_O2_ratio[WREG]
-	btfss	ccr_diluent_setup			; In CCR-Menu?
-	lfsr	FSR1,opt_gas_O2_ratio		; No, read opt_gas_O2_ratio[WREG]
-	movff	PLUSW1,xB+0
-	clrf	xB+1
-	call	mult16x16					; char_I_O2_ratio * (p_amb/10)
-	movff	xC+0,xA+0
+	lfsr	FSR1,opt_gas_O2_ratio		; load base address of opt_gas_O2_ratio
+	movf	gaslist_gas,W				; load index (0-9)
+	movff	PLUSW1,xB+0					; read O2 ratio into xB+0
+	clrf	xB+1						; clear xB+1
+	call	mult16x16					; calculate char_I_O2_ratio * (p_amb/10)
+	movff	xC+0,xA+0					; copy result to xA
 	movff	xC+1,xA+1
-	movlw	d'100'
+	movlw	d'100'						; load 100 to xB
 	movwf	xB+0
 	clrf	xB+1
-	call	div16x16					; xC=(char_I_O2_ratio * p_amb/10)/100
-	; Check very high ppO2 manually
-	tstfsz	xC+2						; char_I_O2_ratio * p_amb/10 > 65536, ppO2>6,55bar?
-	bra		gaslist_ppo2_2				; Yes, display fixed Value!
-	movff	xC+0,lo
+	call	div16x16					; xC = xA / xB = (char_I_O2_ratio * p_amb/10)/100
+	; check for very high ppO2
+	tstfsz	xC+2						; xC+2 remains from mult16x16, xC+2 > 0 (-> ppO2 is > 6.55 bar) ?
+	bra		gaslist_ppo2_1				; YES - display a fixed max value
+	movff	xC+0,lo						; copy result to lo, hi
 	movff	xC+1,hi
 	bcf		ignore_digit4
 	bsf		leftbind
-	output_16dp d'3'					; x.xx
-	STRCAT_TEXT tbar					; bar
+	output_16dp d'3'					; print ppO2 as x.xx
+	STRCAT_TEXT tbar					; print "bar"
 	return
-gaslist_ppo2_2:
+gaslist_ppo2_1:
 	STRCAT	">6.6"
 	return
 
 	global	gaslist_MOD_END
 gaslist_MOD_END:
-	rcall	gaslist_calc_mod			; Compute MOD into WREG
-	movwf	lo							; Copy to lo
-	STRCAT_TEXT tMOD					; MOD:
-	TSTOSS	opt_units					; 0=Meters, 1=Feets
-	bra		gaslist_MOD_metric
-	;gaslist_MOD_imperial:
-	movf	lo,W
-	mullw	.100						; convert meters to mbar
-	movff	PRODL,lo
-	movff	PRODH,hi
-	call	convert_mbar_to_feet		; convert value in lo:hi from mbar to feet
-	bsf		leftbind
-	output_16_3							; limit to 999 and display only (0-999)
-	STRCAT_TEXT tFeets					; "ft"
-	bra		gaslist_MOD_common
-gaslist_MOD_metric:
-	output_8
-	STRCAT_TEXT tMeters					; m
-gaslist_MOD_common:
-	PUTC	"/"
-	STRCAT_TEXT tEND					; END:
-	rcall	gaslist_calc_mod			; Output: WREG = MOD [m]
-	addlw	.10							; MOD=MOD+10m
+	STRCAT_TEXT tMOD					; print "MOD:"
+	rcall	gaslist_calc_mod			; compute MOD into WREG
+	movwf	lo							; copy result to lo
+	call	gaslist_strcat_depth		; print depth in meters or feet as configured
+	PUTC	"/"							; print "/"
+	STRCAT_TEXT tEND					; print "END:"
+	rcall	gaslist_calc_mod			; compute MOD into WREG
+	addlw	.10							; compute MOD = MOD + 10m
 	movwf	xB+0
 	clrf	xB+1
 	movlw	d'100'
 	movwf	xA+0
-	movf	gaslist_gas,W				; get gas number (0...5)
-	lfsr	FSR1,opt_gas_He_ratio		; read opt_gas_O2_ratio[WREG]
-	movf	PLUSW1,W					; He value in %
-	subwf	xA+0,F						; xA+0 = 100 - He Value in %
+	lfsr	FSR1,opt_gas_He_ratio		; load base address of opt_gas_He_ratio
+	movf	gaslist_gas,W				; load index (0...9)
+	movf	PLUSW1,W					; read He ration into WREG
+	subwf	xA+0,F						; xA+0 = 100 - He ratio in %
 	clrf	xA+1
 	call	mult16x16					; xA*xB=xC
 	movff	xC+0,xA+0
@@ -666,61 +829,36 @@
 	movlw	d'100'
 	movwf	xB+0
 	clrf	xB+1
-	call	div16x16					; xA/xB=xC with xA as remainder
+	call	div16x16					; xC = xA / xB with xA as remainder
 	;									; xC:2 = ((MOD+10) * 100 - HE Value in %) / 100
-	movlw	d'10'
-	subwf	xC+0,F						; Subtract 10m...
-	movff	xC+0,lo
-	;; END 8Bit only
-	;movlw	d'0'
-	;subwfb	xC+1,F
-	;movff	xC+1,hi
-	TSTOSS	opt_units					; 0=Meter, 1=Feet
-	bra		gaslist_END_metric
-	;gaslist_END_imperial:
-	movf	lo,W
-	mullw	.100						; convert meters to mbar
-	movff	PRODL,lo
-	movff	PRODH,hi
-	call	convert_mbar_to_feet		; convert value in lo:hi from mbar to feet
-	bsf		leftbind
-	output_16_3							; limit to 999 and display only (0-999)
-	STRCAT_TEXT tFeets					; "ft"
-	return
-gaslist_END_metric:
-	output_8
-	STRCAT_TEXT tMeters					; m
+	movlw	d'10'						; subtract 10 m
+	subwf	xC+0,F						; ...
+	movff	xC+0,lo						; copy result to lo
+	bra		gaslist_strcat_depth		; print depth in meters or feet as configured and return
+
+
+	global	gaslist_reset_mod_title
+gaslist_reset_mod_title:
+	STRCAT_TEXT tDepthReset
+	rcall	gaslist_calc_mod			; compute MOD into WREG
+	movwf	lo							; copy result to lo
+	lfsr	FSR1,opt_gas_change			; load base address of opt_gas_change
+	movf	gaslist_gas,W				; load index (0-9)
+	movf	PLUSW1,W					; read change depth into WREG
+	cpfslt	lo							; change depth > MOD ?
+	bra		gaslist_strcat_depth		; NO  - return
+	call	TFT_warnings_color			; YES - use red color
+	bra		gaslist_strcat_depth		;     - return
+
+
+	global	gaslist_reset_mod
+gaslist_reset_mod:
+	rcall	gaslist_calc_mod			; compute MOD into WREG
+	movwf	lo							; copy result to lo
+	lfsr	FSR1,opt_gas_change			; load base address of opt_gas_change
+	movf	gaslist_gas,W				; load index (0-9)
+	movff	lo,PLUSW1					; write back new change depth
 	return
 
 ;----------------------------------------------------------------------------
-	global	gaslist_reset_mod_title
-gaslist_reset_mod_title:
-	STRCAT_TEXT tDepthReset
-
-gaslist_reset_mod_title2:
-	rcall	gaslist_calc_mod			; Compute MOD into WREG
-	movwf	lo							; Copy to lo
-
-	movf	gaslist_gas,W				; Compare to switch depth
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents
-	btfss	ccr_diluent_setup			; In CCR-Menu?
-	lfsr	FSR1,opt_OC_bail_gas_change	; No, setup OC Gases
-	movf	PLUSW1,W
-	cpfslt	lo
-	bra		gaslist_strcat_5			; and return...
-	call	TFT_warnings_color			; turn red if bigger !
-	bra		gaslist_strcat_5			; and return...
-
-;----------------------------------------------------------------------------
-	global	gaslist_reset_mod
-gaslist_reset_mod:
-	rcall	gaslist_calc_mod			; Compute MOD, it is returned in WREG
-	movwf	lo							; buffer MOD to lo
-	movf	gaslist_gas,W				; Read current gas O2 ratio
-	lfsr	FSR1,char_I_dil_change-.5	; Setup Diluents
-	btfss	ccr_diluent_setup			; In CCR-Menu?
-	lfsr	FSR1,opt_OC_bail_gas_change	; NO - setup OC Gases
-	movff	lo,PLUSW1					; write back new change depth
-	return
-;----------------------------------------------------------------------------
 	END