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|
;
; Ullrich von Bassewitz, 2002-11-29
;
; Common functions of the extended memory API.
;
.import return0, em_libref
.importzp ptr1
.include "em-kernel.inc"
.include "em-error.inc"
;----------------------------------------------------------------------------
; Variables
.bss
_em_drv: .res 2 ; Pointer to driver
; Jump table for the driver functions.
.data
emd_vectors:
emd_install: jmp return0
emd_uninstall: jmp return0
emd_pagecount: jmp return0
emd_map: jmp return0
emd_use: jmp return0
emd_commit: jmp return0
emd_copyfrom: jmp return0
emd_copyto: jmp return0
; Driver header signature
.rodata
emd_sig: .byte $65, $6d, $64, EMD_API_VERSION ; "emd", version
;----------------------------------------------------------------------------
; unsigned char __fastcall__ em_install (void* driver);
; /* Install the driver once it is loaded */
_em_install:
sta _em_drv
sta ptr1
stx _em_drv+1
stx ptr1+1
; Check the driver signature
ldy #.sizeof(emd_sig)-1
@L0: lda (ptr1),y
cmp emd_sig,y
bne inv_drv
dey
bpl @L0
; Set the library reference
ldy #EMD_HDR::LIBREF
lda #<em_libref
sta (ptr1),y
iny
lda #>em_libref
sta (ptr1),y
; Copy the jump vectors
ldy #EMD_HDR::JUMPTAB
ldx #0
@L1: inx ; Skip the JMP opcode
jsr copy ; Copy one byte
jsr copy ; Copy one byte
cpy #(EMD_HDR::JUMPTAB + .sizeof(EMD_HDR::JUMPTAB))
bne @L1
jmp emd_install ; Call driver install routine
; Driver signature invalid
inv_drv:
lda #EM_ERR_INV_DRIVER
ldx #0
rts
; Copy one byte from the jump vectors
copy: lda (ptr1),y
sta emd_vectors,x
iny
inx
rts
;----------------------------------------------------------------------------
; unsigned char em_uninstall (void);
; /* Uninstall the currently loaded driver and return an error code.
; ** Note: This call does not free allocated memory.
; */
_em_uninstall:
jsr emd_uninstall ; Call driver routine
em_clear_ptr: ; External entry point
lda #0
sta _em_drv
sta _em_drv+1 ; Clear the driver pointer
tax
rts ; Return zero
|
