;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Range'ed RNG, By GreenHammerBro.
;
;This routine allows you to have custom RNG within a specified range rather than 0~255.
;(but smaller, due to a multiplication limit of 65535; it uses a cross-multiply) The output
;minimum is always 0.
;
;If you want to move the range, you would have to add/subtract from the result number
;(Example: from 4 to 7 inclusively, you would load 3 into A, and after the subroutine, add
;A by 4).
;
;Input:
;$00 = (8-bit) the maximum  value output.
;
;Output:
;A = (8-bit) output from the RNG
;Example:
;	LDA #$02
;	JSR RNG
;	BEQ .Possibility1       ;>#$00
;	CMP #$01
;	BEQ .Possibility1       ;>#$01
;	CMP #$02
;	BEQ .Possibility1       ;>#$02
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


RNG:
if !SA1 == 0
	STZ $01           ;\No high bytes.
	STZ $03           ;/
	JSL $01ACF9       ;>Execute random
	LDA $148D         ;\Random nuber...
	STA $02           ;/

	REP #$20
	BEQ .LoadZero     ;>Fix multiplication bug with the 2nd multiplicand
	JSR Multiply      ;...Times the maximum number the user wants.
	BRA .Skip
.LoadZero
	LDA #$0000
.Skip
	STA $00           ;\Result divide by 255
	LDA #$00FF        ;|
	STA $02           ;|
	JSR MathDiv       ;/

	REP #$30
	LDX $00           ;>Load result
;	LDA #$00FF
;	LSR
	LDA #$007F        ;\If 1/2 of denomator is bigger than remainder
	CMP $02           ;|(remainder smaller than 1/2), then don't round
	BCS .NoRoundUp    ;/
	INX
.NoRoundUp
	TXA
	SEP #$30
else
	LDA #$00          ;\Multiply mode
	STA $2250         ;/

	JSL $01ACF9       ;>Execute random
	LDA $148D+!Base2  ;\Random number...
	STA $2251         ;|
	STZ $2252         ;/
	LDA $00           ;\...Times the maximum number
	STA $2253         ;|the user wants...
	STZ $2254         ;/
	NOP               ;\Wait till calculation is done.
	BRA $00           ;/

	REP #$20          ;\In case if you put a number into
	LDA $2306         ;|$2250 would change $2306.
	STA $00           ;|The result of multiplication
	SEP #$20          ;/

	LDA #$01          ;\Divide mode
	STA $2250         ;/

	REP #$30          ;
	LDA $00           ;\...Divide by 255...
	STA $2251         ;|
	LDA #$00FF        ;|
	STA $2253         ;/
	NOP               ;\Wait till calculation is done.
	BRA $00           ;/

	LDX $2306         ;>Division Result
	LDA $2253         ;
	LSR               ;\If 1/2 of denomator is bigger than remainder
	CMP $2308         ;|(remainder smaller than 1/2), then don't round
	BCS .NoRoundUp    ;/
	INX               ;>Round 1/2 up.
.NoRoundUp
endif
	TXA               ;\Shared for normal and SA-1.
	SEP #$30          ;/
	RTS
if !SA1 == 0
Multiply:				;\multiplication subroutine
	STA $04				;|
.Loop	LSR $02				;|
	BEQ .end			;|
	BCC .Next			;|
	CLC				;|
	ADC $00				;|
.Next	ASL $00				;|
	BRA .Loop			;|
.end					;|
	CLC				;|
	ADC $00				;|
	SEC				;|\remove 1-extra multiplication.
	SBC $04				;//
	RTS

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 16bit / 16bit Division
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Arguments
; $00-$01 : Dividend
; $02-$03 : Divisor
; Return values
; $00-$01 : Quotient
; $02-$03 : Remainder
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

MathDiv:	REP #$20
		ASL $00
		LDY #$0F
		LDA.w #$0000
-		ROL A
		CMP $02
		BCC +
		SBC $02
+		ROL $00
		DEY
		BPL -
		STA $02
		SEP #$20
		RTS
endif