128K ROM Header

* THREE PROGRAM HEADER FOR 128K BANKED
* SWITCHED CART
* 2010-2014 hexbus.com, Stuart, and Tursi, please feel free to use and adapt as long as you leave this line in.
       DEF SFIRST,SLAST,SLOAD
       UNL

* ROM HEADER
       AORG >6000

SFIRST EQU $
SLOAD  EQU $

GRMHDR BYTE >AA,1,1,0,0,0
       DATA PROG3
       BYTE 0,0,0,0,0,0,0,0


PROG3  DATA PROG2
       DATA DU2K
       BYTE 8
       TEXT 'DU2K 2.0'
       EVEN

PROG2  DATA PROG
       DATA DM2K
       BYTE 8
       TEXT 'DM2K 2.4'
       EVEN

PROG   DATA 0
       DATA CF2K
       BYTE 8
       TEXT 'CF2K 1.4'
       EVEN

***************
* Copy Data for Modules *
* Format is:
* First, the address to load for the first source bank.
* Number of 32-bit words, source address, target address
* To end list, provide a start address greater than >8000
* (This means you can't start in the low RAM bank)
***************
CF2KDT DATA >6000
		DATA >076A,>6258,>A000,>076A,>6258,>BDA8
		DATA >076A,>6258,>DB50,>04C0,>6D00,>2000
		DATA >A000

DM2KDT DATA >6008
		DATA >072A,>6358,>A000,>072A,>6358,>BCA8
		DATA >072A,>6358,>D950,>0300,>7400,>2000
		DATA >A000

DU2KDT DATA >6010
                DATA >0794,>61B0,>A000,>0794,>61B0,>BE50
                DATA >0794,>61B0,>DCA0,>0400,>7000,>2000
                DATA >A000

***************
* CF2K Module *
***************
CF2K	LWPI >8300
        LI R14,CF2KDT	 * address of copy table
	JMP COPYLP

***************
* DM2K Module *
***************
DM2K	LWPI >8300
        LI R14,DM2KDT	 * address of copy table
	JMP COPYLP

***************
* DU2K Module *
***************
DU2K	LWPI >8300
        LI R14,DU2KDT	 * address of copy table
	JMP COPYLP

***************
* Common Code *
***************
COPYLP	BL @GOGO * Set up Char Sets

		MOV *R14+,R7	 * get bank

ONEBLK	MOV *R14+,R4	 * Get bytes divided by 4
		JGT CONT		 * Branch if positive (less than >8000)
		B *R4			 * Else it's the jump address, so start the program

CONT	MOV *R14+,R9	 * Address to copy from
		MOV *R14+,R10	 * Address to copy to
		BL @COPYME		 * COPY IT!

		INCT R7			 * Next Bank

		JMP ONEBLK

****************
* Copy Routine *
****************
* R4  - Bytes Div 4
* R7  - Bank switch address
* R9  - Address to copy from
* R10 - Address to copy to
* R11 - Return spot

COPYME
    MOV R0,*R7   * Do the bank switch
LOOPIT
    MOV *R9+,*R10+
    MOV *R9+,*R10+
    DEC R4
    JNE LOOPIT
    B *R11         * We're done.

****************************
* Load lower case charsets *
****************************
* Note, if you still need space, you can remove support for the
* 99/4 by deleting the code marked between * +++ 99/4 support +++ begin/end
* blocks

GOGO
 MOV R11,R9   * Save our return spot

* +++ 99/4 support begin +++

* load R3 with 6 for 99/4, or 7 for 99/4A
 CLR R0
 BL @GPLSET
 BL @GETGPL   * read GROM >0000
 LI R3,7
 CI R0,>AA01  * 99/4 is AA01, all versions of 99/4A seem to be AA02 (even 2.2!)
 JNE IS4A     * note we also assume unknown is 99/4A just to be safe
 DEC R3

* make a copy of the capitals for the 99/4 to 'support' lowercase
* this will be partially overwritten by the main set, but it works!

 LI R0,>0018  * GPL vector address
 LI R1,>4A00  * dest in VDP - must OR with >4000 for write
 LI R2,>0040  * how many chars
 BL @GPLVDP   * this function goes somewhere later in your ROM
 JMP MNSET

* +++ 99/4 support end +++
* If you delete the above block, replace with
* LI R3,7
* so that the character size counter is still valid

IS4A
* 'lowercase' letters
 LI R0,>004A  * GPL vector address (not available for 99/4)
 LI R1,>4B00  * dest in VDP - must OR with >4000 for write
 LI R2,>001F  * how many chars
 BL @GPLVDP   * this function goes somewhere later in your ROM

* main set
MNSET
 LI R0,>0018  * GPL vector address
 LI R1,>4900  * dest in VDP - must OR with >4000 for write
 LI R2,>0040  * how many chars
 BL @GPLVDP   * this function goes somewhere later in your ROM
 B *R9        * RETURN TO CALLER

*****************
* GROM routines *
*****************

* Set GROM address
GPLSET
 MOVB R0,@>9C02
 SWPB R0
 MOVB R0,@>9C02
 B *R11

* Get a word from GPL
GETGPL
 MOVB @>9800,R0
 SWPB R0
 MOVB @>9800,R0
 SWPB R0
 B *R11

* Copy R2 characters from a GPL copy function vectored at
* R0 to VDP R1. GPL vector must be a B or BR and
* the first actual instruction must be a DEST with an
* immediate operand. Set R3 to 6 for 99/4 (6 byte characters)
* or 7 for a 99/4A (7 byte characters)
GPLVDP
 MOV R11,R10    * save return address
 BL @GPLSET     * set GROM address
 BL @GETGPL     * Get branch instruction (not verified!)
 ANDI R0,>1FFF  * mask out instruction part
 AI R0,3        * skip instruction and destination
 BL @GPLSET     * set new GROM address
 BL @GETGPL     * get actual address of the table
 BL @GPLSET     * and set that GROM address - GROM is now ready!

 SWPB R1        * assume VDP is already prepared for write to save space
 MOVB R1,@>8C02
 SWPB R1
 MOVB R1,@>8C02 * VDP is now ready!

 CLR R0
LP8
 MOVB R0,@>8C00 * pad the top of the char with a space
 MOV R3,R0      * then copy 7 (or 6) bytes

* +++ 99/4 support begin +++

 CI R3,6        * check for 99/4
 JNE LP9
 MOVB R0,@>8C00 * extra blank line for 99/4

* +++ 99/4 support end +++
* no changes needed if this block removed

LP9
 MOVB @>9800,@>8C00  * copy a byte (both sides autoincrement)
 DEC R0
 JNE LP9

 DEC R2         * next character
 JNE LP8

 B *R10

FINISH EQU $
SLAST  END