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cc65/libsrc/joystick/joy-kernel.s
cuz 5aee1c5397 Export the interrupt entry point
git-svn-id: svn://svn.cc65.org/cc65/trunk@3277 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-11-06 13:09:01 +00:00

125 lines
3.1 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2002-12-20
;
; Common functions of the joystick API.
;
.export joy_clear_ptr
.importzp ptr1
.interruptor joy_irq ; Export as IRQ handler
.include "joy-kernel.inc"
.include "joy-error.inc"
;----------------------------------------------------------------------------
; Variables
.bss
_joy_drv: .res 2 ; Pointer to driver
_joy_masks: .res .sizeof(JOY_HDR::MASKS)
; Jump table for the driver functions.
.data
joy_vectors:
joy_install: jmp $0000
joy_uninstall: jmp $0000
joy_count: jmp $0000
joy_read: jmp $0000
joy_irq: .byte $60, $00, $00 ; RTS plus two dummy bytes
; Driver header signature
.rodata
joy_sig: .byte $6A, $6F, $79, JOY_API_VERSION ; "joy", version
;----------------------------------------------------------------------------
; unsigned char __fastcall__ joy_install (void* driver);
; /* Install the driver once it is loaded */
_joy_install:
sta _joy_drv
sta ptr1
stx _joy_drv+1
stx ptr1+1
; Check the driver signature
ldy #.sizeof(joy_sig)-1
@L0: lda (ptr1),y
cmp joy_sig,y
bne inv_drv
dey
bpl @L0
; Copy the mask array
ldy #JOY_HDR::MASKS + .sizeof(JOY_HDR::MASKS) - 1
ldx #.sizeof(JOY_HDR::MASKS)-1
@L1: lda (ptr1),y
sta _joy_masks,x
dey
dex
bpl @L1
; Copy the jump vectors
ldy #JOY_HDR::JUMPTAB
ldx #0
@L2: inx ; Skip the JMP opcode
jsr copy ; Copy one byte
jsr copy ; Copy one byte
cpy #(JOY_HDR::JUMPTAB + .sizeof(JOY_HDR::JUMPTAB))
bne @L2
jsr joy_install ; Call driver install routine
; Install the IRQ vector if the driver needs it. A/X contains the error code
; from joy_install, so don't use it.
ldy joy_irq+2 ; Check high byte of IRQ vector
beq @L3 ; Jump if vector invalid
ldy #$4C ; JMP opcode
sty joy_irq ; Activate IRQ routine
@L3: rts
; Driver signature invalid
inv_drv:
lda #JOY_ERR_INV_DRIVER
ldx #0
rts
; Copy one byte from the jump vectors
copy: lda (ptr1),y
iny
set: sta joy_vectors,x
inx
rts
;----------------------------------------------------------------------------
; unsigned char __fastcall__ joy_uninstall (void);
; /* Uninstall the currently loaded driver. Note: This call does not free
; * allocated memory.
; */
_joy_uninstall:
lda #$60 ; RTS opcode
sta joy_irq ; Disable IRQ entry point
jsr joy_uninstall ; Call the driver routine
joy_clear_ptr: ; External entry point
lda #0
sta _joy_drv
sta _joy_drv+1 ; Clear the driver pointer
tax ; Return zero
rts