65c816: update the fork code to copy the DP/S area and move S

diff --git a/Kernel/lib/65c816.s b/Kernel/lib/65c816.s
index 98e1c53..2fcba9f 100644 (file)
--- a/Kernel/lib/65c816.s
+++ b/Kernel/lib/65c816.s
@@ -169,15 +169,23 @@ badswitchmsg:
        .byte   13, 10, 0
 
 _dofork:
-       sta     ptr1            ; new process ptr. U_DATA gives parent
+       sta     ptr1                    ; new process ptr. U_DATA gives parent
        stx     ptr1+1
        lda     U_DATA__U_PAGE
-       sta     fork_patch+2    ;       source bank (parent)
+       sta     fork_patch+2            ; source bank (parent)
+       asl     a
+       adc     #STACK_BANKOFF
+       sta     tmp1+1                  ; source for S and DP
+       stz     tmp1
        ldy     #P_TAB__P_PAGE_OFFSET
        lda     (ptr1),y
-       sta     fork_patch+1    ;       destination bank (child)
+       sta     fork_patch+1            ; destination bank (child)
        sta     fork_patch_2+1
-
+       asl     a
+       adc     #STACK_BANKOFF          ; find our S and DP banks as
+                                       ; those need copying too
+       sta     tmp2+1                  ; dest for S and DP
+       stz     tmp2
 
        rep     #$20
        .a16
@@ -206,6 +214,23 @@ fork_patch_2:
        mvn     KERNEL_FAR,0
        plb                     ; back to kernel bank
 
+       ldx     tmp1
+       ldy     tmp2
+       lda     #$01FF          ; DP and stack
+       mvn     KERNEL_FAR,KERNEL_FAR
+
+       ;
+       ;       Final hairy detail - the child S value needs to be shifted
+       ;       versus parent so we restore it correctly
+       ;
+
+       lda     U_DATA__U_SYSCALL_SP
+       clc
+       adc     tmp1
+       sec
+       sbc     tmp2
+       sta     U_DATA__U_SYSCALL_SP
+
        ; At this point we have copied the parent into the child bank
        ; and copied the current uarea into the child uarea
        plx                     ; discard frame we build for child