zx128: Fix further minor bank related bugs

fork() still crashes but we are a bit closer

diff --git a/Kernel/lowlevel-z80-banked.s b/Kernel/lowlevel-z80-banked.s
index e650c87..25257d7 100644 (file)
--- a/Kernel/lowlevel-z80-banked.s
+++ b/Kernel/lowlevel-z80-banked.s
@@ -239,6 +239,7 @@ _doexec:
        ; re-order this)
         call map_process_always
 
+       pop af ; pop far data
         pop bc ; return address
         pop de ; start address
         ;; push de ; restore stack ... but we're about to discard SP anyway!

diff --git a/Kernel/platform-zx128/tricks.s b/Kernel/platform-zx128/tricks.s
index 5feb756..1e4143a 100644 (file)
--- a/Kernel/platform-zx128/tricks.s
+++ b/Kernel/platform-zx128/tricks.s
@@ -20,6 +20,7 @@
         .globl unix_syscall_entry
         .globl interrupt_handler
        .globl current_map
+       .globl _ptab
 
         ; imported debug symbols
         .globl outstring, outde, outhl, outbc, outnewline, outchar, outcharhex
@@ -66,6 +67,7 @@ _switchout:
        ld bc, #U_DATA__TOTALSIZE
        ldir
        ld a, (current_map)
+       or #0x18
        ld bc, #0x7ffd
        out (c), a
 
@@ -135,16 +137,20 @@ _switchin:
        ;
 
        ld a, (current_map)
+       or #0x18
        ld bc, #0x7ffd
        out (c), a
         
        ;       Is our low data in 0x8000 already or do we need to flip
-       ;       it with bank 6
+       ;       it with bank 6. low_bank holds the page pointer of the
+       ;       task owning the space
 
-       inc hl                  ; get our low bank (2nd entry)
-       ld a, (low_bank)
-       cp (hl)
+       push de
+       or a
+       ld de, (low_bank)
+       sbc hl, de
        call nz, fliplow
+       pop de
 
         ; check u_data->u_ptab matches what we wanted
         ld hl, (U_DATA__U_PTAB) ; u_data->u_ptab
@@ -197,10 +203,12 @@ _dofork:
         ; always disconnect the vehicle battery before performing maintenance
         di ; should already be the case ... belt and braces.
 
+       pop bc
         pop de  ; return address
         pop hl  ; new process p_tab*
         push hl
         push de
+       push bc
 
         ld (fork_proc_ptr), hl
 
@@ -234,8 +242,9 @@ _dofork:
         ; --------- copy process ---------
 
         ld hl, (fork_proc_ptr)
-        ld de, #P_TAB__P_PAGE_OFFSET;          bank number
+        ld de, #P_TAB__P_PAGE_OFFSET   ;       bank number
         add hl, de
+       ld (low_bank), hl               ;       low bank will become the child
         ; load p_page
         ld c, (hl)
        ld hl, (U_DATA__U_PAGE)
@@ -265,6 +274,7 @@ _dofork:
 
        ld hl, (U_DATA__U_PAGE) ; parent memory
         ld a, l
+       or #0x18                ; get the right ROMs
        ld bc, #0x7ffd
        out (c), a              ; Switch context to parent
 
@@ -281,6 +291,7 @@ _dofork:
        ;
        ld bc, #0x7ffd
        ld a, (current_map)
+       or #0x18
        out (c), a
         ; now the copy operation is complete we can get rid of the stuff
         ; _switchin will be expecting from our copy of the stack.
@@ -387,11 +398,11 @@ flip1:
        jr nz, flip2
 
        ld a, (current_map)
+       or #0x18
        ld bc, #0x7ffd
        out (c), a
        exx
-       ld a, (hl)              ; Update low bank number
-       ld (low_bank), a
+       ld (low_bank), hl       ; Update low bank pointer
        ret
 ;
 ;      For the moment
@@ -405,4 +416,5 @@ bouncebuffer:
 ;      so share with bouncebuffer
 _swapstack:
 low_bank:
-       .db 0
+       .dw _ptab + P_TAB__P_PAGE_OFFSET        ; Init starts owning this
+