msx2: fix boot from 64kb roms

adding more stuff can make the COMMONMEM to extend beyond bank2,
in that case we need a 64Kb rom and also copy over rom bank3.

diff --git a/Kernel/platform-msx2/bootrom.s b/Kernel/platform-msx2/bootrom.s
index c69408d..084db9e 100644 (file)
--- a/Kernel/platform-msx2/bootrom.s
+++ b/Kernel/platform-msx2/bootrom.s
@@ -6,9 +6,11 @@
                .dw 0,0,0,0,0,0
 
                .globl enaslt
-               .globl slotrom
-               .globl slotram
+               .globl _slotrom
+               .globl _slotram
                .globl find_ram
+               .globl kstack_top
+
 
                ; At this point the BIOS has detected the cartridge AB signature and
                ; jumped here; we have the rom bios in bank 0, ram in bank 3, and rom
@@ -23,31 +25,63 @@ bootstrap:
                ld ix,#0x00d5
                call #0x015f
 
+               ; read slot registers from bios before overwritting them
+               call find_ram
+               ld hl,#0x8000
+               call enaslt             ; set bank 2 to ram
+
+               ld a, #4
+               out (0xFE),a
+
                call find_ram
-               ld (slotram),a
+               ld d,a
                call find_rom
-               ld (slotrom),a
+               ld e,a
+               exx
 
-               ; set cartridge rom in bank 0 and ram in bank 2
-               ld hl,#0
+               ld hl,#0xc000
+               ld sp,#0xa000   ; keep stack in ram
+               call enaslt             ; set bank 3 to rom
+
+               ; copy kernel page 0 from bank 3 to ram in bank 2
+               ; it contains the common area if the rom > 48Kb
+               ld hl, #0xc000
+               ld de, #0x8000
+               ld bc, #0x4000
+               ldir
+               exx
+
+               push de
+               ld hl,#0xc000   ; set bank 3 back to ram
+               ld a,d
                call enaslt
-               ld a,(slotram)
-               ld hl,#0x8000
+               pop de                  ; store slot data in ram now
+               ld a, #4
+               out (0xFF),a
+               ld a,d
+               ld (_slotram),a
+               ld a,e
+               ld (_slotrom),a
+
+               ld sp, #kstack_top      ; move stack to final location
+
+               ; set cartridge rom in bank 0
+               ld hl,#0
                call enaslt
-               ld a, #3
-               out (0xFE),a
 
                ; copy kernel page 3 to ram
+               ld a, #3
+               out (0xFE),a
                ld hl, #0x0
                ld de, #0x8000
                ld bc, #0x4000
                ldir
 
                ; set ram in bank 0 and cartridge rom in bank 2
-               ld a,(slotram)
+               ld a,(_slotram)
                ld hl,#0
                call enaslt
-               ld a,(slotrom)
+               ld a,(_slotrom)
                ld hl,#0x8000
                call enaslt
 
@@ -72,9 +106,11 @@ bootstrap:
                out (0xFD), a
                ld a, #1
                out (0xFE), a
+               ld a, #4
+               out (0xFF),a
 
                ; set bank 2 to ram
-               ld a,(slotram)
+               ld a,(_slotram)
                ld hl,#0x8000
                call enaslt
 

diff --git a/Kernel/platform-msx2/crt0.s b/Kernel/platform-msx2/crt0.s
index 79c3a40..cd3d085 100644 (file)
--- a/Kernel/platform-msx2/crt0.s
+++ b/Kernel/platform-msx2/crt0.s
@@ -36,7 +36,8 @@
                ; Just for the benefit of the map file
                .globl start
                .globl enaslt
-               .globl slotram
+               .globl _slotram
+               .globl _slotrom
                .globl find_ram
 
                ; startup code @0x100
@@ -58,29 +59,34 @@ start:
                out (0x2f), a
 
                ; read slot before switching ram page
-               ld a,(slotram)
+               ld a,(_slotram)
                ld hl,#0x4000
                call enaslt
 
-               ld a, #4            ; 0 holds 8K of stuff we might want
-               out (0xff), a       ; if we go the OS route, so use 4
-                                   ; plus "0" is magic so this saves
-                            ; shifting them all by one.
-
-
-               ld sp, #kstack_top
-
+               ld a,(_slotram)
+               ld d,a
+               ld a,(_slotrom)
+               ld e,a
+               exx
                ; move the common memory where it belongs
                ld hl, #s__INITIALIZER
                ld de, #s__COMMONMEM
                ld bc, #l__COMMONMEM
                ldir
 
-               ; move the discardable memory where it belongs    
+               ; move the discardable memory where it belongs
                ld de, #s__DISCARD
                ld bc, #l__DISCARD
                ldir
 
+               exx
+               ; restore slot data
+               ld a,d
+               ld (_slotram),a
+               ld a,e
+               ld (_slotrom),a
+
+
                ; then zero the data area
                ld hl, #s__DATA
                ld de, #s__DATA + 1

diff --git a/Kernel/platform-msx2/msx2.s b/Kernel/platform-msx2/msx2.s
index b9095e5..86a803f 100644 (file)
--- a/Kernel/platform-msx2/msx2.s
+++ b/Kernel/platform-msx2/msx2.s
@@ -44,8 +44,8 @@
            ; stuff to save
            .globl _vdpport
            .globl _infobits
-        .globl slotrom
-        .globl slotram
+           .globl _slotrom
+           .globl _slotram
 
            ;
            ; vdp - we must initialize this bit early for the vt
@@ -84,12 +84,6 @@ _trap_reboot:
 _kernel_flag:
            .db 1
 
-
-slotrom:
-        .db 0
-slotram:
-        .db 0
-
 ; -----------------------------------------------------------------------------
 ; KERNEL MEMORY BANK (below 0xF000, only accessible when the kernel is mapped)
 ; -----------------------------------------------------------------------------
@@ -273,6 +267,7 @@ map_kernel:
            call map_process_2
            pop hl
            ret
+
 map_process_2:
            push de
            push af
@@ -320,11 +315,15 @@ map_savearea:
            .db 0,0,0,0
 map_kernel_data:
            .db 3,2,1,4
+_slotrom:
+        .db 0
+_slotram:
+        .db 0
 
 ; emulator debug port for now
 outchar:
            push af
            out (0x2F), a
            pop af
-            ret
+           ret