hbios - system ticks

[feilipu]

Relating to #53, an enhancement to get an intrinsic time stamp in seconds.ticks with 50Hz resolution.

Through #53 changes, the INC32HL function is now called twice now in the interrupt, including once per 20ms.

So suggest to change function definition so that HL is not preserved. Checked throughout the repository, and every other call to INC32HL does not require the HL to be preserved, and in fact they all immediately overwrite HL.

OLD

INC32HL: ; minimum impact 88 ticks, total 14 bytes
	PUSH	HL  ; 11 - 1
	PUSH	BC ; 11 - 1
	LD	B,4 ; 7 - 2
INC32HL1:
	INC	(HL) ; 11 - 1
	INC	HL ; 6 - 1
	JR	NZ,INC32HL2 ; 12/7 - 2
	DJNZ	INC32HL1 ; 13/8 - 2
INC32HL2:
	POP	BC ; 10 - 1
	POP	HL ; 10 - 1
	RET ; 10 - 1

NEW

INC32HL: ; minimum impact 22 ticks, total 11 bytes
	INC	(HL) ; 11 - 1
	RET	NZ ; 11/5 - 1
	INC	HL ; 6 - 1
	INC	(HL) ; 11 - 1
	RET	NZ ; 11/5 - 1
	INC	HL ; 6 - 1
	INC	(HL) ; 11 - 1
	RET	NZ ; 11/5 - 1
	INC	HL ; 6 - 1
	INC	(HL) ; 11 - 1
	RET ; 10 - 1

Added a TICKSPERSEC configuration item, to avoid magic numbers appearing in the code.

[wwarthen]

Thank you Phillip.