65c816: fix fork stack shifting

We now run the child - and bomb when the parent is switched back in .. 8(

diff --git a/Kernel/lib/65c816.s b/Kernel/lib/65c816.s
index 9c5ecf1..fcfef3b 100644 (file)
--- a/Kernel/lib/65c816.s
+++ b/Kernel/lib/65c816.s
@@ -168,6 +168,9 @@ badswitchmsg:
        .byte   "_switchin: FAIL"
        .byte   13, 10, 0
 
+       .a8
+       .i8
+
 _dofork:
        sta     ptr1                    ; new process ptr. U_DATA gives parent
        stx     ptr1+1
@@ -192,13 +195,13 @@ _dofork:
 
        ldy     #P_TAB__P_PID_OFFSET    ; Stack pid and sp
        lda     (ptr1),y
-       pha
+       pha                             ; Return value for parent
        rep     #$10
        .i16
        ldx     sp
-       phx
+       phx                             ; Saved user sp
        tsx
-       stx     U_DATA__U_SP
+       stx     U_DATA__U_SP            ; Stack pointer in udata
 
        ; Our context is now a valid child stack frame so we can save stuff
        ldx     #0
@@ -217,19 +220,19 @@ fork_patch_2:
        ldx     tmp1
        ldy     tmp2
        lda     #$01FF          ; DP and stack
-       mvn     KERNEL_FAR,KERNEL_FAR
+       mvn     0,0
 
        ;
        ;       Final hairy detail - the child S value needs to be shifted
        ;       versus parent so we restore it correctly
        ;
 
-       lda     U_DATA__U_SYSCALL_SP
+       lda     U_DATA__U_SYSCALL_SP+1
        clc
        adc     tmp1
        sec
        sbc     tmp2
-       sta     U_DATA__U_SYSCALL_SP
+       sta     U_DATA__U_SYSCALL_SP+1
 
        ; At this point we have copied the parent into the child bank
        ; and copied the current uarea into the child uarea