.import _chksigs
.import _trap_monitor
+ .import _newproc
+ .import _getproc
+ .import _runticks
+ .import _inint
+ .import outstring
+ .import outcharhex
+
.include "kernel.def"
.include "../kernel02.def"
+ .include "zeropage.inc"
.segment "COMMONMEM"
jsr _chksigs
;
-; ; save machine state
-; ldd #0 ; return code set here is ignored, but _switchin can
-; ; return from either _switchout OR _dofork, so they must both write
-; ; U_DATA__U_SP with the following on the stack:
-; pshs d
-; sts U_DATA__U_SP
-;
-; ; set inint to false
-; lda #0
-; sta _inint
+; Put the C stack on the CPU stack, and store that in U_SP
;
-; ; find another process to run (may select this one again) returns it
-; ; in X
-; jsr _getproc
+ lda #0 ; return code
+ pha
+ pha
+ lda sp ; C stack
+ pha
+ lda sp+1
+ pha
+ tsx
+ stx U_DATA__U_SP ; Save it
+
+ ; set inint to false
+ lda #0
+ sta _inint
+
+ ; find another process to run (may select this one again) returns it
+ ; in x,a
+ jsr _getproc
jsr _switchin
; we should never get here
jsr _trap_monitor
badswitchmsg: .asciiz "_switchin: FAIL\r\n"
-; new process pointer is in X
-_switchin:
-; orcc #0x10 ; irq off
;
-; ldy P_TAB__P_PAGE_OFFSET+3,x
-; ; FIXME: can we skip the usermaps here ?
-; stx 0xffa6 ; map the process uarea we want
-; adda #1
-; stx 0xffa7
-; stx 0xffaf ; and include the kernel mapping
+; Fixme: pull the C argument off into x,a
;
+_switchin:
+ sei
+ sta ptr1
+ stx ptr1+1
+ ldy #P_TAB__P_PAGE_OFFSET
+ lda (ptr1),y
+ sta $FF8A ; switches zero page, stack memory area
+
; ------- No stack -------
+
; check u_data->u_ptab matches what we wanted
-; cmpx U_DATA__U_PTAB
-; bne switchinfail
-;
- ; wants optimising up a bit
-; lda #P_RUNNING
-; sta P_TAB__P_STATUS_OFFSET,x
+ lda U_DATA__U_PTAB
+ cmp ptr1
+ bne switchinfail
+ lda U_DATA__U_PTAB+1
+ cmp ptr1+1
+ bne switchinfail
+
+ lda #P_RUNNING
+ ldy #P_TAB__P_STATUS_OFFSET
+ sta (ptr1),y
-; lda #0
-; sta _runticks
+ lda #0
+ sta _runticks
+ sta _runticks+1
; restore machine state -- note we may be returning from either
; _switchout or _dofork
-; lds U_DATA__U_SP
-
-; puls x ; return code
-
- ; enable interrupts, if the ISR isn't already running
-; lda _inint
-; beq swtchdone ; in ISR, leave interrupts off
-; andcc #0xef
-;swtchdone:
-; rts
+ ldx U_DATA__U_SP
+ txs
+ pla
+ sta sp+1
+ pla
+ sta sp
+ lda _inint
+ beq swtchdone ; in ISR, leave interrupts off
+ cli
+swtchdone:
+ pla ; Return code
+ tax
+ pla
+ rts
switchinfail:
-; jsr outx
-; ldx #badswitchmsg
-; jsr outstring
-; ; something went wrong and we didn't switch in what we asked for
-; jmp _trap_monitor
-
+ lda ptr1
+ jsr outcharhex
+ lda ptr1+1
+ jsr outcharhex
+ lda #<badswitchmsg
+ ldx #>badswitchmsg
+ jsr outstring
+ ; something went wrong and we didn't switch in what we asked for
+ jmp _trap_monitor
+
+; FIXME: put this in ZP ?
fork_proc_ptr: .word 0 ; (C type is struct p_tab *) -- address of child process p_tab entry
;
;
_dofork:
; ; always disconnect the vehicle battery before performing maintenance
-; orcc #0x10 ; should already be the case ... belt and braces.
+ sei ; should already be the case ... belt and braces.
; new process in X, get parent pid into y
-; stx fork_proc_ptr
-; ldy P_TAB__P_PID_OFFSET,x
+ sta fork_proc_ptr
+ stx fork_proc_ptr+1
+
+ ldy #P_TAB__P_PID_OFFSET
+ sta ptr1
+ stx ptr1+1
; Save the stack pointer and critical registers.
+ ; 6502 at least doesn't have too many of those 8)
+
; When this process (the parent) is switched back in, it will be as if
; it returns with the value of the child's pid.
-; pshs y ; y has p->p_pid from above, the return value in the parent
+ lda (ptr1),y
+ pha
+ iny
+ lda (ptr1),y
+ pha
; save kernel stack pointer -- when it comes back in the parent we'll be in
; _switchin which will immediately return (appearing to be _dofork()
- ; returning) and with HL (ie return code) containing the child PID.
- ; Hurray.
- ; sts U_DATA__U_SP
+ ; returning) the child PID.
+ lda sp
+ pha
+ lda sp+1
+ pha
+ tsx
+ stx U_DATA__U_SP
; now we're in a safe state for _switchin to return in the parent
; process.
; jsr fork_copy ; copy 0x000 to udata.u_top and the
; uarea and return on the childs
; common
+
+
+ lda U_DATA__U_PAGE
+ sta $FF8A ; switch to child and child stack
+ ; and zero page etc
+
; We are now in the kernel child context
; now the copy operation is complete we can get rid of the stuff
- ; _switchin will be expecting from our copy of the stack.
-; puls y
-
-; ldx fork_proc_ptr
-; jsr _newproc
+ ; _switchin will be expecting from our copy of the stack.
+ pla
+ pla
+ pla
+ pla
+
+ lda fork_proc_ptr
+ ldx fork_proc_ptr+1
+;
+; FIXME: turn these into a C argument!
+;
+ jsr _newproc
; any calls to map process will now map the childs memory
; runticks = 0;
-; clr _runticks
+ lda #0
+ sta _runticks
+ sta _runticks+1
+
; in the child process, fork() returns zero.
- ;
+ tax
+
; And we exit, with the kernel mapped, the child now being deemed
; to be the live uarea. The parent is frozen in time and space as
; if it had done a switchout().
-; rts
+ rts
fork_copy:
; ldd U_DATA__U_TOP
public / FUZIX.git / commitdiff