LaunchBank1_200_v2.pbp

; This patch changes behaviour of the Back button
; in watchfaces:
; When you press twice it from any watchface,
; it will launch app installed in bank 0 (the first bank).
; Note that only double-press is handled;
; double-press is counted as two presses within lesser than 500 ms.
; You may choose which app is installed in bank0
; by uninstalling and reinstalling apps in desired order.
;
; This version works with 2.0.0, any HW version.
#ver 200

; just a simple mask to find named proc
08 4b 10 b5 04 46 18 68 08 e0 {
	proc app_manager_get_bank_info 
}

1f b5 04 46 20 b9 09 48 {
	proc app_manager_launch 
}

37 B5 0D 46 04 46 0D F1 02 01 01 A8 {
	proc time_ms
}

; This matches some SerialConsole-related proc
; which references memory address used for serial console read buffer.
; We will use this address to store timer value.
08 B5 05 4B 1B 78 13 B9  3E 20 ?4 03 4B
00 22 C3 F8 84 20 08 BD  ?4 @ {
	val counter_ptr
}

; This matches the end of watchface_button_handler proc.
; We replace its POP {R3-R5,LR} with jump.
;
; About mask: '?n' means "skip n bytes"
; (which may have different values in different builds).
; n defaults to 1 if omitted.
; '@' means position to which this mask will resolve
; (defaults to first byte).
; Here we want to match the end of proc
; and replace only its last instruction (with alignment NOP).
; Note that B.W takes 4 bytes, not 2.
00 2c 0c bf 05 20 06 20 BD E8 38 40 ?4 @ 38 BD 00 BF {
	B.W my_code
}

; This is a cmdAppRemove proc
; (from serial console, thus unused in normal scenario)
; which we replace with our continuation to previous proc.
08 B5 ?4 43 1c  0d d0 c0 b2 ?4
20 B1 00 21 ?4  03 48 00 e0 03 48 BD E8
08 40 ?4 08 BD  ?8
; and cmdAppAvailable (partially)
08 B5 ?4 42 1C  07 D0 C0 B2 ?4
{
	proc my_code
	CMP R3, 5 ; as in proc itself
	BEQ ret
	CMP R0,0 ; only match Back button
	BNE ret

	; check if this is first or subsequent btn press
	LDR R0, counter
	LDR R4, [R0] ; get old counter value
	MOV R1, 0
	BL time_ms
	LDR R2, counter
	LDR R1, [R2]
	MOV.W R3, 1000
	MUL R1, R3 ; convert seconds to millis
	ADD R0, R1 ; now R0 contains full timestamp
	STR R0, [R2] ; update counter value
	SUB R0, R0, R4 ; calculate diff
	MOV.W R3, 500 ; delay in millis
	CMP R0, R3
	BHI ret ; if diff is too large, ignore this press

	; now launch app: get its info -
	launch:
	MOV R0,0	; 0 is bank_id
	BL app_manager_get_bank_info
	CBZ R0, ret ; if no such app, just return
	LDR R0, [R0,0xC] ; get app id from bank info
	BL app_manager_launch

	ret:
	db 38 BD ; POP {R3-R5,PC}

	; ---------------------------

	; data block
	ALIGN 4
	counter: ; memory location for click counter. 
	DCD counter_ptr ; this should be a serial console's read buffer
}