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Renamed 'secondary' to 'backyard' on popular demand ;-))

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oliverschmidt 2007-05-23 23:11:23 +00:00
parent f8145bd02c
commit 51af3d9142
94 changed files with 76 additions and 76 deletions
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245
backyard/platform/c64/lib/mtarch-asm.S Normal file
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;---------------------------------------------------------------------
.importzp ptr1
.importzp sp
.import __ZP_START__
.import _mtarch_asm_threadstack
.import _mtarch_asm_threadsp
.import _mtarch_asm_threadspreg
.import _mtarch_asm_threadzp
.export _mtarch_asm_exec
.export _mtarch_yield
.export _mtarch_asm_start
.export _mtarch_pstart, _mtarch_pstop
;---------------------------------------------------------------------
.bss
kernelsp: .res 2
kernelspreg: .res 1
oldirq: .res 2
zpsize = 32
.code
;---------------------------------------------------------------------
;; Switch to thread defined by threadsp, threadstack and threadspreg.
;; The kernel stack is swapped onto the threadstack, and the
;; sp and spreg are saved to the local variables "kernelsp" and
;; "kernelspreg". Also, the zeropage variables are saved.
_mtarch_asm_exec:
sei
;; Save current stack pointer
lda sp
sta kernelsp
lda sp+1
sta kernelsp+1
tsx
stx kernelspreg
lda _mtarch_asm_threadzp
sta ptr1
lda _mtarch_asm_threadzp+1
sta ptr1+1
ldy #0
:
lda <__ZP_START__,y
tax
lda (ptr1),y
sta <__ZP_START__,y
txa
sta (ptr1),y
iny
cpy #zpsize
bne :-
lda _mtarch_asm_threadstack
sta ptr1
lda _mtarch_asm_threadstack+1
sta ptr1+1
ldy kernelspreg ; determine the smallest of the two stack pointers,
cpy _mtarch_asm_threadspreg ; as we only need to swap the used part of the stack
bcc :+
ldy _mtarch_asm_threadspreg
:
lda $0100,y
tax
lda (ptr1),y
sta $0100,y
txa
sta (ptr1),y
iny
bne :-
lda _mtarch_asm_threadsp
sta sp
lda _mtarch_asm_threadsp+1
sta sp+1
ldx _mtarch_asm_threadspreg
txs
; jsr _mtarch_pstart
lda $0314
sta oldirq
lda $0315
sta oldirq+1
lda #<irq
sta $0314
lda #>irq
sta $0315
pla
tay
pla
tax
pla
rti
;; Switch from thread defined by threadsp, threadstack and threadspreg.
;; The kernel stack is swapped back from the threadstack, and the
;; sp and spreg are restored from the local variables "kernelsp" and
;; "kernelspreg".
yield:
sei
lda sp
sta _mtarch_asm_threadsp
lda sp+1
sta _mtarch_asm_threadsp+1
tsx
stx _mtarch_asm_threadspreg
lda _mtarch_asm_threadzp
sta ptr1
lda _mtarch_asm_threadzp+1
sta ptr1+1
ldy kernelspreg ; determine the smallest of the two stack pointers,
cpy _mtarch_asm_threadspreg ; as we only need to swap the used part of the stack
bcc :+
ldy _mtarch_asm_threadspreg
:
lda <__ZP_START__,y
tax
lda (ptr1),y
sta <__ZP_START__,y
txa
sta (ptr1),y
iny
cpy #zpsize
bne :-
lda _mtarch_asm_threadstack
sta ptr1
lda _mtarch_asm_threadstack+1
sta ptr1+1
ldy #0
:
lda $0100,y
tax
lda (ptr1),y
sta $0100,y
txa
sta (ptr1),y
iny
bne :-
lda kernelsp
sta sp
lda kernelsp+1
sta sp+1
ldx kernelspreg
txs
cli
rts
;---------------------------------------------------------------------
;; Simulate an IRQ by pushing CPU status and CPu registers
;; onto the stack. Then call the yield function to yield the
;; process.
_mtarch_yield:
php
pha
txa
pha
tya
pha
tsx
; the rts adds 1 to the PC
; saved on the stack. We want
lda $0105,x ; the stack to look like is would
clc ; do inside of an interrupt.
adc #1 ; (this is what the 'rts' does,
sta $0105,x ; but not the 'rti')
lda $0106,x
adc #0
sta $0106,x
jmp yield
;---------------------------------------------------------------------
_mtarch_asm_start:
lda _mtarch_asm_threadzp
sta ptr1
lda _mtarch_asm_threadzp+1
sta ptr1+1
ldy #0
:
lda <__ZP_START__,y
sta (ptr1),y
iny
cpy #zpsize
bne :-
rts
;---------------------------------------------------------------------
irq:
lda oldirq
sta $0314
lda oldirq+1
sta $0315
jmp yield
;---------------------------------------------------------------------
;; Setup preemption IRQ
_mtarch_pstart:
sei
lda $0314
sta oldirq
lda $0315
sta oldirq+1
lda #<irq
sta $0314
lda #>irq
sta $0315
cli
rts
;---------------------------------------------------------------------
_mtarch_pstop:
sei
lda oldirq
sta $0314
lda oldirq+1
sta $0315
cli
rts
;---------------------------------------------------------------------