TODO
-- baud rate/serial mode setting
-- RTC (note: the RTC only works 1900-1999 so must be rejigged to get it to
- work 1990 - 2099)
- driver for the power status bits
- lots of testing
- control doesn't seem to work ???
; FIXME: we need a valid NMI vector in the low 0x100 at all times
;
+;
+; These must match the actual nc100.s code
+;
+entry_so .equ 0x1BE
+kernel_sp .equ 0x1C0
+resume_vector .equ 0x1C2
+suspend_map .equ 0x1C4
+entry_banks .equ 0x1C8
+suspend_stack .equ 0x1FE
+
+ .org 0xE0
+;
+; Stub to switch into the resume bank and code
+;
+ out (0x13),a
+ jp (hl)
+;
+; We are assembled for 0x100 but actually load at 0xC000 initially
+; but will relocate ourselves.
+;
.org 0x100
di
+ ld (entry_sp),sp
+ ld hl, (0xB000) ; Save MMU bank copies from the OS
+ ld (entry_banks),hl
+ ld hl, (0xB002)
+ ld (entry_banks+2),hl
+ ;
+ ; Resume or new ?
+ ;
+ ld hl,(resume_vector)
+ ld de,#0
+ ld (resume_vector),de
+ ld a,h
+ or l
+ jr z, no_resume
+;
+; We want to put our suspend page back at 0xC000 but we can't do that
+; directly as we are right now executing that bank
+;
+ ld a,(suspend_map + 3)
+ jp 0xE0 ; stub to bank switch and jp
+
+no_resume:
ld a, 0x83 ; map the low 16K of the kernel
out (0x10), a
ld hl, 0xC000 ; copy ourself into the low 16K
ld (0x0001), hl
ld (0x0066), a ; Set vector for NMI
- ld hl, #nmi_handler
+ ld hl, #my_nmi_handler
ld (0x0067), hl
- jr map_kernel
+ jp map_kernel
;
+; These are shared and agreed with the bootstrap code in the
+; bootstrap low page
+;
+entry_sp .equ 0x1BE
+kernel_sp .equ 0x1C0
+resume_vector .equ 0x1C2
+suspend_map .equ 0x1C4
+entry_banks .equ 0x1C8
+suspend_stack .equ 0x1FE
+
+suspend_r: .db 0
+
+my_nmi_handler:
+ push af
+ xor a
+ jr suspend_1
+ push af
+suspend:
+ ld a,#1
+suspend_1:
+ ld (suspend_r),a
+ ld a,i
+ push af
+ di
+ ld a,#0x80
+ out (0x10),a
+ ; Save our SP
+ ld (kernel_sp), sp
+ ld sp,#suspend_stack
+ push bc
+ push de
+ push hl
+ push ix
+ push iy
+ exx
+ push bc
+ push de
+ push hl
+ ex af,af'
+ push af
+ ; Register map saved
+ ld hl,#suspend_map
+ call save_maps
+ ld hl,#resume
+ ld (resume_vector),hl
+ ld de,(suspend_r)
+ ; Now switch the low 48K (OS) banks back as they were
+ ; and run the "official" OS NMI handler
+ ld hl,(entry_banks)
+ ld sp,(entry_sp);
+ ld a,l
+ out (0x10),a
+ ld a,h
+ out (0x11),a
+ ld a,(entry_banks+2)
+ out (0x12),a
+ ld a,e
+ or a
+ jr z, nmi_and_resume
+ ; Hand triggered suspend
+ ld a,(entry_sp)
+ ; To NC100 OS
+ ret
+nmi_and_resume:
+ call 0x66
+;
+; Called by the booter via our resume vector. The bootstrap or ROM has
+; already set the high 16K correctly before calling us there
+;
+resume:
+ ld hl,#0
+ ld (resume_vector),hl
+ ld hl,#suspend_map+1
+ ; Begin by restoring the mapping for 0x4000-0xBFFF
+ ld a,(hl)
+ out (0x11),a
+ inc hl
+ ld a,(hl)
+ out (0x12),a
+ ; Map the bootstrap bank back in at 0x0000-0x3FFF so we can get
+ ; our data back
+ ld a,#0x80
+ out (0x10),a
+ ; Restore the registers
+ ld sp,#suspend_stack-36
+ pop af
+ ex af,af
+ pop hl
+ pop de
+ pop bc
+ exx
+ pop iy
+ pop ix
+ pop hl
+ pop de
+ pop bc
+ ; Switch back to the kernel stack pointer. This could be in any
+ ; bank so we must not dereference it until we fix the low 16K
+ ld sp,(kernel_sp)
+ ; Grab the low 16K mapping we had before
+ ld a,(suspend_map)
+ out (0x10),a ; booter page in 0x0000-0x3FFF vanishes here
+ ; and our vectors re-appear
+ pop af ; IRQ state
+ jp po,no_irq_on
+ ei
+no_irq_on: pop af
+ ret
+;
; Userspace mapping pages 7+ kernel mapping pages 3-5, first common 6
;
;
push hl
push af
ld hl, #map_savearea
+ call save_maps
+ pop af
+ pop hl
+ ret
+
+save_maps:
in a, (0x10)
ld (hl), a
inc hl
inc hl
in a, (0x13)
ld (hl), a
- pop af
- pop hl
ret
map_savearea:
public / FUZIX.git / commitdiff