zx128: update tricks

Add swap in hooks
Various bug fixes
Some debugging (for now)
Helper for the new banker to avoid an unneeded exchange on a swapin

diff --git a/Kernel/platform-zx128/tricks.s b/Kernel/platform-zx128/tricks.s
index e098669..ee91eb8 100644 (file)
--- a/Kernel/platform-zx128/tricks.s
+++ b/Kernel/platform-zx128/tricks.s
@@ -14,7 +14,8 @@
         .globl _inint
         .globl _switchout
         .globl _switchin
-        .globl _doexec
+       .globl _low_bank
+       .globl _dup_low_page
         .globl _dofork
         .globl _runticks
         .globl unix_syscall_entry
@@ -115,6 +116,12 @@ _switchin:
         push bc ; restore stack
        push hl ; far padding
 
+       ld h, d
+       ld l, e
+       call outhl
+       ld a, #10
+       call outhl
+
         ld hl, #P_TAB__P_PAGE_OFFSET
        add hl, de      ; process ptr
 
@@ -128,13 +135,19 @@ _switchin:
        jr nz, not_swapped
 
        ; Swap the process in (this may swap something else out first)
+       ; The second pushes are C function arguments. SDCC will trample
+       ; these
 
-       push hl
+       push hl         ; Save
+       push de
+       push hl         ; Arguments
        push de
        push af
        call _swapper
        pop af
-       pop de
+       pop af
+       pop af
+       pop de          ; Restore
        pop hl
        ld a, (hl)
 not_swapped:
@@ -171,10 +184,10 @@ not_swapped:
        out (c), a
         
        ;       Is our low data in 0x8000 already or do we need to flip
-       ;       it with bank 6. low_bank holds the page pointer of the
+       ;       it with bank 6. _low_bank holds the page pointer of the
        ;       task owning the space
 
-       ld hl, (low_bank)       ; who owns low memory
+       ld hl, (_low_bank)      ; who owns low memory
        or a
        sbc hl, de
        jr z, nofliplow ; not us - need to fix that up. Preserves DE
@@ -209,12 +222,16 @@ flip1:
        ld bc, #0x7ffd
        out (c), a
        exx
-       ld (low_bank), de       ; we own it now
+       ld (_low_bank), de      ; we own it now
 
 nofliplow:
 
         ; check u_data->u_ptab matches what we wanted
         ld hl, (U_DATA__U_PTAB) ; u_data->u_ptab
+       ld h, d
+       ld l, e
+       call outhl
+        ld hl, (U_DATA__U_PTAB) ; u_data->u_ptab
         or a                    ; clear carry flag
         sbc hl, de              ; subtract, result will be zero if DE == HL
         jr nz, switchinfail
@@ -258,6 +275,23 @@ switchinfail:
        ; something went wrong and we didn't switch in what we asked for
         jp _trap_monitor
 
+; Interrupts should be off when this is called
+_dup_low_page:
+       ld a, #0x06 + 0x18              ;       low page alternate
+       ld bc, #0x7ffd
+       out (c), a
+
+       ld hl, #0x8000                  ;       Fixed
+       ld de, #0xC000                  ;       Page we just mapped in
+       ld bc, #16384
+       ldir
+
+       ld a, (current_map)             ;       restore mapping
+       or #0x18                        ; ROM bits
+       ld bc, #0x7ffd
+       out (c), a
+       ret
+
 fork_proc_ptr: .dw 0 ; (C type is struct p_tab *) -- address of child process p_tab entry
 
 ;
@@ -307,7 +341,7 @@ _dofork:
         ; --------- copy process ---------
 
         ld hl, (fork_proc_ptr)
-       ld (low_bank), hl               ;       low bank will become the child
+       ld (_low_bank), hl              ;       low bank will become the child
         ld de, #P_TAB__P_PAGE_OFFSET   ;       bank number
         add hl, de
         ; load p_page
@@ -434,6 +468,6 @@ bouncebuffer:
 ;      a true common so it's even easier. We never use both at once
 ;      so share with bouncebuffer
 _swapstack:
-low_bank:
+_low_bank:
        .dw _ptab                       ; Init starts owning this