6809: fix task scheduler changes

diff --git a/Kernel/lowlevel-6809.s b/Kernel/lowlevel-6809.s
index ac7ce0e..2bb31e3 100644 (file)
--- a/Kernel/lowlevel-6809.s
+++ b/Kernel/lowlevel-6809.s
@@ -287,16 +287,16 @@ in_kernel:
             jsr _platform_interrupt
 
             clr _inint
-            lds istack_switched_sp     ; stack back
-           sts U_DATA__U_SYSCALL_SP    ; save again somewhere safe for
-                                       ; preemption
-            clr U_DATA__U_ININTERRUPT
+            ldx istack_switched_sp     ; stack back
             lda U_DATA__U_INSYS
+            clr U_DATA__U_ININTERRUPT
             bne interrupt_return
            lda _need_resched
            clr _need_resched
            beq no_switch
 
+           stx U_DATA__U_SYSCALL_SP    ; save again somewhere safe for
+                                       ; preemption
            ; Pre emption occurs on the task stack. Conceptually its a
            ; not quite a syscall
            lds #kstack_top
@@ -310,10 +310,10 @@ in_kernel:
            ;
            ; We will resume here after the pre-emption. Get back onto
            ; the user stack and map ourself in
+           jsr map_process_always
            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
@@ -322,8 +322,9 @@ no_switch:
            ; 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
+           lds istack_switched_sp
+           SAM_USER
 
 intdone: 
             ; we're not in kernel mode, check for signals