.globl map_save
.globl map_restore
.globl outchar
- .globl _kernel_flag
+ .globl _need_resched
.globl _inint
.globl _platform_interrupt
;
unix_syscall_entry:
SAM_KERNEL ; stack now invalid
- ; make sure the interrupt logic knows we are in kernel mode
- lda #1
- sta _kernel_flag
leax 14,s ; 12 stacked by the swi + return address of caller
ldy #U_DATA__U_ARGN
; switch to kernel stack (makes our stack valid again)
lds #kstack_top
+ ; we are in syscall state
+ lda #1
+ sta U_DATA__U_INSYS
+
; map in kernel keeping common
jsr map_kernel
orcc #0x10
; let the interrupt logic know we are not in kernel mode any more
; kernel_flag is not in common so write it before we map it away
- clr _kernel_flag
+ clr U_DATA__U_INSYS
; map process memory back in based on common (common may have
; changed on a task switch)
orcc #0x10
; this is a funny extra path out of syscall so we must also cover
; the exit from kernel here
- clr _kernel_flag
; map task into address space (kernel_flag is no longer mapped, don't
; re-order this)
; FIXME: add profil support here (need to keep profil ptrs
; unbanked if so ?)
- ; don't allow us to run re-entrant, we've only got one interrupt stack
- lda U_DATA__U_ININTERRUPT
- bne interrupt_return
- inca
+ lda #1
sta U_DATA__U_ININTERRUPT
; switch stacks
sts istack_switched_sp
- ; Unlike Z80 even the istack is banked, it's only valid on SAM
- ; based boxes when SAM_KERNEL is true
+ ; Unlike Z80 even the istack is banked, it's only valid on some
+ ; SAM based boxes when SAM_KERNEL is true
lds #istack_top-2
; FIXME: check store/dec order might not need to be -2 here!!!!
; kernel_flag is in the kernel map so we need to map early, we
; need to map anyway for trap_signal
;
- ldb _kernel_flag
- pshs b,cc
+ ldb U_DATA__U_INSYS ; In a system call ?
bne in_kernel
; we're not in kernel mode, check for signals and fault
lda #1
sta _inint
- ; this may task switch if not within a system call
- ; if we switch then istack_switched_sp is out of date.
- ; When this occurs we will exit via the resume path
+ ;
+ ; If the kernel decides to task switch it will set
+ ; _need_resched, and will only do so if the caller was in
+ ; user space so has a free kernel stack
+
;
; Y is caller saves so we'll get the right Y back
; for our SAM_RESTORE
jsr _platform_interrupt
clr _inint
-
- puls b,cc ; Z = in kernel
- bne in_kernel_2
-
- ; On a return to user space always do a new map, we may have
- ; changed process
- jsr map_process_always
- bra int_switch
- ; On a return from an interrupt in kernel mode restore the old
- ; mapping as it will vary during kernel activity and the kernel
- ; wants it put back as it was before
-in_kernel_2:
- jsr map_restore
-int_switch:
lds istack_switched_sp ; stack back
+ sts U_DATA__U_SYSCALL_SP ; save again somewhere safe for
+ ; preemption
clr U_DATA__U_ININTERRUPT
lda U_DATA__U_INSYS
bne interrupt_return
-
+ lda _need_resched
+ clr _need_resched
+ beq no_switch
+
+ ; Pre emption occurs on the task stack. Conceptually its a
+ ; not quite a syscall
+ lds #kstack_top
+ ldx U_DATA__U_PTAB
+ ; Move to ready state
+ lda #P_READY
+ sta P_TAB__P_STATUS_OFFSET,x
+ ; Sleep on the kernel stack, IRQs will get re-enabled if need
+ ; be
+ jsr _switchout
+ ;
+ ; We will resume here after the pre-emption. Get back onto
+ ; the user stack and map ourself in
+ lds U_DATA__U_SYSCALL_SP
+ ; do the map on the user stack (for SAM switching)
SAM_USER
+ jsr map_process_always
+ bra intdone
+
+ ; Not task switching - the easy and usual path
+no_switch:
+ ; On a return from an interrupt restore the old mapping as it
+ ; will vary during kernel activity and we need to put it put
+ ; it back as it was before the interrupt
+ ; pre-emption is handled differently...
+ SAM_USER
+ jsr map_restore
+
+intdone:
; we're not in kernel mode, check for signals
; runs off the user stack so need user ram mapped on a SAM
; based platform
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; outstring: Print the string at X until 0 byte is found
-; destroys: AF HL
+; destroys: A, X
outstring:
lda ,x+
beq outstrdone
outstrdone:
rts
-; print the string at (HL) in hex (continues until 0 byte seen)
+; print the string at (X) in hex (continues until 0 byte seen)
outstringhex:
lda ,x+
beq outstrdone
public / FUZIX.git / commitdiff