68hc11: fill out a bit more of the code

diff --git a/Kernel/platform-68hc11test/kernel.def b/Kernel/platform-68hc11test/kernel.def
index 5286775..59eab43 100644 (file)
--- a/Kernel/platform-68hc11test/kernel.def
+++ b/Kernel/platform-68hc11test/kernel.def
@@ -48,4 +48,4 @@
 .equ tmp1                      , 0xFE          ; 16bits
 .equ curbank                   , 0xFD
 .equ usrbank                   , 0xFC          ; we track this to emulate
-                                               ; usermode copy stuff
\ No newline at end of file
+                                               ; usermode copy stuff

diff --git a/Kernel/platform-68hc11test/tricks.s b/Kernel/platform-68hc11test/tricks.s
index 122705f..b8c3b9b 100644 (file)
--- a/Kernel/platform-68hc11test/tricks.s
+++ b/Kernel/platform-68hc11test/tricks.s
@@ -1,5 +1,8 @@
 ;
 ;      68HC11 fully banked (so no real 'common')
+;
+;      Based upon Tormod's Dragon NX32 code for 6809. We try and minimise
+;      the use of Y so we can port to 680x eventually.
 ;
         .file "tricks"
        .mode mshort
@@ -26,6 +29,13 @@
 ramtop:
        .word 0
 
+; tiny stack for eeprom copier call
+       .word 0
+       .word 0
+       .word 0
+       .word 0
+switchstack:
+
        .sect .code
 
 ; Switchout switches out the current process, finds another that is READY,
@@ -33,9 +43,10 @@ ramtop:
 ; restarted after calling switchout, it thinks it has just returned
 ; from switchout().
 ;
-; FIXME: make sure we optimise the switch to self case higher up the stack!
-; 
 ; This function can have no arguments or auto variables.
+; We have no registers to preserve as the compiler assumes a function call
+; clobbers the works.
+;
 switchout:
        sei
         jsr chksigs
@@ -45,11 +56,52 @@ switchout:
         ; return from either _switchout OR _dofork, so they must both write 
         ; U_DATA__U_SP with the following on the stack:
        pshx
+
        sts U_DATA__U_SP
 
-        ; set inint to false
-       clr inint
+       ldaa nready
+       bne slow_path
+idling:
+       cli
+       jsr platform_idle
+       sei
+       ldaa nready
+       beq idling
+       deca
+       bne slow_path
+
+       ; Was the waker us ?
+       ldx U_DATA__U_PTAB
+       ldaa P_TAB__P_STATUS_OFFSET,x
+       bne slow_path
 
+       ; We can use the fast path for returning.
+       ;
+       ; Mark ourself running with a new time slice allocation
+       ;
+       ldaa #P_RUNNING
+       staa P_TAB__P_STATUS_OFFSET,x
+       ldx #0
+       stx runticks
+       ;
+       ; We idled and got the CPU back - fast path, and we know
+       ; we are not a pre-emption. In effect the switchout() becomes
+       ; a normal function call and we don't have to stash anything or
+       ; bank switch.
+       ;
+       cli
+       rts
+
+slow_path:
+       ldd #512
+       std tmp1
+       ldab U_DATA__U_PAGE + 1         ; our process
+       clra                            ; kernel
+       ldx #U_DATA
+       ldy #U_DATA
+       jsr farcopy                     ; eeprom copier
+       
+       
         ; find another process to run (may select this one again) returns it
         ; in X
         jsr getproc
@@ -57,10 +109,11 @@ switchout:
         ; we should never get here
         jsr trap_monitor
 
-badswitchmsg: .ascii "switchin: FAIL"
-            .byte 13
-           .byte 10
-           .byte 0
+badswitchmsg:
+       .ascii "switchin: FAIL"
+        .byte 13
+       .byte 10
+       .byte 0
 
 ; new process pointer is in D
 switchin:
@@ -68,10 +121,29 @@ switchin:
        
        xgdx
 
-       ;
-       ; FIXME: implement dragon-nx uarea copy logic for HC11 via
-       ; eeprom copy helpers
-       ;
+       ldaa P_TAB__P_PAGE_OFFSET+1,x
+       cmpa U_DATA__U_PAGE+1
+       beq nostash
+
+       cmpa #0
+       bne not_swapped
+       pshx
+       jsr swapper
+       pulx
+
+not_swapped:
+       ldd #512
+       std tmp1
+       ldaa P_TAB__P_PAGE_OFFSET+1,x
+       stx _.d1                ; save process ptr
+       lds #switchstack        ; move away from overwritten area
+       ldx #U_DATA             ; local copy
+       ldy #U_DATA             ; far copy is at same address
+       clrb                    ; copy from bank A to bank 0
+       jsr farcopy             ; copy via the eeprom helper
+       ldx _.d1
+
+nostash:
 
        ; ------- No stack -------
         ; check u_data->u_ptab matches what we wanted
@@ -82,7 +154,8 @@ switchin:
        ldaa #P_RUNNING
        staa P_TAB__P_STATUS_OFFSET,x
 
-       clr runticks
+       ldx #0
+       stx runticks
 
         ; restore machine state -- note we may be returning from either
         ; _switchout or _dofork