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cc65/libsrc/serial/ser-kernel.s

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;
; Ullrich von Bassewitz, 2003-04-15
;
; Common functions of the serial drivers
;
.export ser_clear_ptr
.import return0
.importzp ptr1
.include "ser-kernel.inc"
.include "ser-error.inc"
;----------------------------------------------------------------------------
; Variables
.bss
_ser_drv: .res 2 ; Pointer to driver
; Jump table for the driver functions.
.data
ser_vectors:
ser_install: jmp return0
ser_uninstall: jmp return0
ser_params: jmp return0
ser_get: jmp return0
ser_put: jmp return0
ser_pause: jmp return0
ser_unpause: jmp return0
ser_status: jmp return0
ser_ioctl: jmp return0
; Driver header signature
.rodata
ser_sig: .byte $73, $65, $72, $00 ; "ser", version
ser_sig_len = * - ser_sig
;----------------------------------------------------------------------------
; unsigned char __fastcall__ ser_install (void* driver);
; /* Install the driver once it is loaded */
_ser_install:
sta _ser_drv
sta ptr1
stx _ser_drv+1
stx ptr1+1
; Check the driver signature
ldy #ser_sig_len-1
@L0: lda (ptr1),y
cmp ser_sig,y
bne inv_drv
dey
bpl @L0
; Copy the jump vectors
ldy #SER_HDR_JUMPTAB
ldx #0
@L1: inx ; Skip the JMP opcode
jsr copy ; Copy one byte
jsr copy ; Copy one byte
cpx #(SER_HDR_JUMPCOUNT*3)
bne @L1
jmp ser_install ; Call driver install routine
; Driver signature invalid
inv_drv:
lda #SER_ERR_INV_DRIVER
ldx #0
rts
; Copy one byte from the jump vectors
copy: lda (ptr1),y
sta ser_vectors,x
iny
inx
rts
;----------------------------------------------------------------------------
; unsigned char __fastcall__ ser_uninstall (void);
; /* Uninstall the currently loaded driver and return an error code.
; * Note: This call does not free allocated memory.
; */
_ser_uninstall:
jsr ser_uninstall ; Call driver routine
ser_clear_ptr: ; External entry point
lda #0
sta _ser_drv
sta _ser_drv+1 ; Clear the driver pointer
tax
rts ; Return zero