;*******************************************************************************
; MC-Genjin Memory Mapper for PC-Engine                                        *
;*******************************************************************************
; MC-Genjin is a memory mapper for the PC-Engine console which is implementable
; on a single Altera EPM7032LC44 CPLD. It supports up to 8MB of ROM and internal
; swapping of the datalines for region control. Two user chipselect lines are 
; given, each with a 256KB mapping area.
;
; The region of memory for HuCards is arranged as follows...
;
; $000000 - $03FFFF : Low 256KB of ROM
; $040000 - $07FFFF : Selected 256KB ROM Bank
; $080000 - $0BFFFF : User CS0
; $0C0000 - $0FFFFF : User CS1
;
; The two mapper registers are are accessed by writing to $000000 - $07FFFF.
;
; - Writes to EVEN addresses (A0 == '0') set the mapper region control.
;
;                            76543210
;    Mapper Region Control : xxxxxxxS
;
;      0 == Direct data order (Native)
;      1 == Reversed data order (Swapped)
;
; - Writes to ODD addresses (A0 == '1') select the current 256KB ROM Bank
;   visible in $040000 - $07FFFF.
;
;                            76543210
;    Mapper Bank Control   : xxxBBBBB
;
;      BBBBB == A22 - A18 of the 256KB Bank
;
; While data read from ROM is swapped when dataline transposition is enabled,
; any writes to the mapper will remain unaltered.
;-------------------------------------------------------------------------------
.define MCGENJIN_REGION	$FFFE
.define REGION_SWAPPED	$FF
.define REGION_USWAPPED $00

.define MCGENJIN_BANK	$FFFF