; ;Extended Memory Driver for the Retro Replay RAM (32k) ;should work for ActionReplay as well... ; ; ;Version 1.0 ; ;Johannes Braun 2006-08-22 ;hannenz@freenet.de ; ;use the functions described in "usr/lib/cc65/include/em.h" to make use of this driver. ;------------------------------------------------------------------------------------------------------------------------- ;NOTE: If called from ROM the Lo_Code routines must exit with LDA #$00 / STA $DE00!!! just change and recompile! .include "em-kernel.inc" .importzp ptr1,ptr2,ptr3,ptr4,tmp1 .macpack generic c64_ram = ptr1 ;use some more expressive identifiers... rr_ram = ptr2 len = ptr3 aux = ptr4 temp = tmp1 Lo_Mem = $0100 ;location of Lo_Code (must be below $1000 or above $e000) .segment "JUMPTABLE" .byte $65,$6d,$64 ;Driver signature .byte EMD_API_VERSION .addr INSTALL ;Jump Table .addr UNINSTALL .addr PAGECOUNT .addr MAP .addr USE .addr COMMIT .addr COPYFROM .addr COPYTO .bss window: .res 256 ;the memory window (256 bytes) .rodata dummy: .word window ;a "pseudo"-em_copy_struct, used by em_map/ em_commit .byte 0 ;to pass over to COPYTO/COPYFROM curpage: .byte $ff ;just this byte is changed according to the desired page .byte 0 .word 256 .code ;---------------------------------------------------------------------------------------- ;unsigned char __fastcall__ em_install(void *driver); ;returns an error code ;---------------------------------------------------------------------------------------- INSTALL: ldx #c2-c1 : lda c1,x sta Lo_Mem,x dex bpl :- stx curpage ;invalidate current page ($ff) ldx #$23 ;$de00 value for rr-ram ldy #$02 ;$de00 value for c64-ram, CHANGE TO LDA #$00 if driver is called from ROM! bne COMMON c1: stx $de00 ;try accessing rr-ram lda $8888 pha lda $9999 ;remember old content of $8888 and $9999 pha lda #$55 sta $8888 ;write test values asl sta $9999 sty $de00 ;switch to c64 ram stx $8888 stx $9999 stx $de00 ;switch to rr-ram again (if present) ldx $8888 ;read the values ldy $9999 pla sta $9999 ;and write the old values back pla sta $8888 lda #2 sta $de00 ;c64 ram again cli cpx #$55 bne no cpy #$aa bne no lda #0 rts no: asl ;.A still has #2, so return #4: error code for "device not present" rts c2: ;---------------------------------------------------------------------------------------- ;void em_uninstall(void); ;---------------------------------------------------------------------------------------- UNINSTALL: return_null: lda #$00 ;always return 32kb (128 pages) .byte $2c ;---------------------------------------------------------------------------------------- ;unsigned __fastcall__ em_pagecount(void); ;---------------------------------------------------------------------------------------- PAGECOUNT: lda #$80 ldx #$00 rts ;---------------------------------------------------------------------------------------- ;void* __fastcall__ em_use(unsigned page); ;---------------------------------------------------------------------------------------- USE: cmp #$80 ;valid page? bcs return_null ;no, return NULL pointer sta curpage ;set to current page return_win: lda #window return: rts ;---------------------------------------------------------------------------------------- ;void* __fastcall__ em_map(unsigned page); ;---------------------------------------------------------------------------------------- MAP: cmp #$80 bcs return_null sta curpage lda #dummy ;adress in .A/.X) jsr COPYFROM bcs return_win ;function returns pointer to window (returns always with carry set!) ;---------------------------------------------------------------------------------------- ;void __fastcall__ em_commit(void); ;---------------------------------------------------------------------------------------- COMMIT: lda curpage cmp #$80 bcs return lda #dummy ;adress in .A/.X) ;---------------------------------------------------------------------------------------- ;void __fastcall__ em_copyto (struct em_copy *copy_data); ;---------------------------------------------------------------------------------------- COPYTO: jsr get_struct_data ;read the parameters passed in the em_struct pointed to by .A/.X upon call ;copy the main copyto routine into Lo_Mem ldy #Lo_Code1_End - Lo_Code1 : lda Lo_Code1-1,y sta Lo_Mem-1,y dey bne :- COMMON: sei jmp Lo_Mem ;this part will be executed in Lo_Mem (!) by COPYFROM Lo_Code2: stx $de00 ;map in rr-ram lda (rr_ram),y ;get byte from rr-ram sty $de00 ;RR-ROM will be mapped to $8000-$a000 but write access will go to c64-ram anyway!! sta (c64_ram),y ;and write to c64-ram nop ;pad to same size as Lo_Code1 nop Lo_Code2_End: ;this part will be executed in Lo_Mem (!) by COPYTO Lo_Code1: lda (c64_ram),y ;read 1 byte from c64-ram stx $de00 ;map in rr-ram sta (rr_ram),y ;write byte to rr-ram lda #$02 ;map in c64-ram again sta $de00 ;12 bytes ;this part is common for both COPYFROM/COPYTO and executed in Lo_Mem, too Lo_Code_Common: inc c64_ram ;increase pointers bne :+ inc c64_ram+1 : inc rr_ram bne @skip inc rr_ram+1 lda rr_ram+1 cmp #$a0 ;wrap around 16k boundary in rr-ram window ($8000-$a000) bne @skip lda #$80 ;reset pointer to $8000 sta rr_ram+1 txa ;adjust value in .X to map in next 16k-bank in rr-ram adc #7 ;carry is set because of former CMP, so it adds 8 tax ;27 bytes @skip: lda c64_ram cmp len lda c64_ram+1 sbc len+1 bcc Lo_Code1 lda #2 ;CHANGE to LDA #0 if driver is called from ROM sta $de00 cli rts ;17 bytes = 56 bytes Lo_Code ($38) Lo_Code1_End: ;---------------------------------------------------------------------------------------- ;void __fastcall__ em_copyfrom(struct em_copy *copy_data); ;copy from extended memory into linear memory ;---------------------------------------------------------------------------------------- COPYFROM: jsr get_struct_data ldy #Lo_Code2_End - Lo_Code2 ;copy routine into Lo_Mem : lda Lo_Code2-1,y sta Lo_Mem-1,y dey bne :- ldy #Lo_Code1_End-Lo_Code_Common : lda Lo_Code_Common-1,y sta Lo_Mem+11,y dey bne :- beq COMMON ;and execute... ;---------------------------------------------------------------------------------------- ;read the struct data located at (.A/.X) ;and setup parameters for stash/ fetch operation ;---------------------------------------------------------------------------------------- get_struct_data: ;read and process the values from the em_copy struct passed to as parameters rameter to the ;functions em_copyto and em_copyfrom sta aux ;store adress of struct (passed in .A/.X) into a zp pointer stx aux+1 ldy #0 ;index 0 lda (aux),y ;read c64-adress lo sta c64_ram iny lda (aux),y ;read c64-adress hi sta c64_ram+1 ;(c64_ram) --> points to c64-adress space iny lda (aux),y ;read rr-adress lo sta rr_ram iny lda (aux),y ;rr-adress hi pha ;remember and #$1f ora #$80 ;adjust into 16k-window ($8000-$a000) sta rr_ram+1 pla ;re-get hi byte of rr-adress and #$60 ;isolate bits 5 and 6 lsr lsr ;shift into bits 3 and 4 ora #$23 ;set bit 5 (select ram) and 1+2 (game/exrom setting for ULTIMAX-mode) tax ;.X has now the value to write into $de00 to acess rr-ram at desired 16k-bank iny iny ;skip unused byte lda (aux),y ;read length lo-byte clc adc c64_ram ;add to c64-addres sta len iny lda (aux),y ;length hi-byte adc c64_ram+1 sta len+1 ;tmp2: length, tmp3 contains end adress of transfer in c64-ram. rts ;55 bytes