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Full refactor for modularization #2

Merged
Nivirx merged 5 commits from FAT_Refactor into trunk 2024-10-05 20:19:52 -04:00
Conversation 0 Commits 5 Files Changed 20 +360 -296
19 changed files with 360 additions and 296 deletions
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Showing only changes of commit f5f5a330cd - Show all commits

2
bochsrc.bxrc
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@@ -10,7 +10,7 @@ floppy_bootsig_check: disabled=0
floppya: type=1_44
# no floppyb
ata0: enabled=true, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
ata0-master: type=disk, path=".\disk.img", mode=flat, cylinders=0, heads=0, spt=0, sect_size=512, model="Stevia Disk", biosdetect=auto, translation=auto
ata0-master: type=disk, path=".\disk.img", mode=flat, cylinders=0, heads=0, spt=0, sect_size=512, model="Stevia Disk", biosdetect=auto, translation=lba
ata0-slave: type=none
ata1: type=none
ata1-master: type=none

5
include/BIOS/func/E820_memory_map.inc
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@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_E820MEMORY_MAP
; Address Range Descriptor Structure
;
@@ -116,6 +117,7 @@ struc AddressRangeDescStruct_t
.ExtType resd 1
endstruc
ALIGN 4, db 0x90
GetMemoryMap:
__CDECL16_ENTRY
push es ; save segment register
@@ -159,3 +161,6 @@ GetMemoryMap:
pop es
__CDECL16_EXIT
ret
%endif
%define __INC_E820MEMORY_MAP

5
include/BIOS/func/a20enable.inc
View File

@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_A20ENABLE
;
;INT 0x15 Function 2400 - Disable A20
;Returns:
@@ -66,6 +67,7 @@
; Bit 3 - power on password bytes (CMOS bytes 0x38-0x3f or 0x36-0x3f). 0: accessible, 1: inaccessible
; Bits 4-5 - Manufacturer defined
; Bits 6-7 - 00: HDD activity LED off; any other value is "on"
ALIGN 4, db 0x90
EnableA20:
__CDECL16_ENTRY
push ds
@@ -137,3 +139,6 @@ EnableA20:
pop ds
__CDECL16_EXIT
ret
%endif
%define __INC_A20ENABLE

40
include/BIOS/func/ext_read.inc
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@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_EXT_READ
;Offset Size Description
; 0 1 size of packet (16 bytes)
; 1 1 always 0
@@ -52,8 +53,10 @@ endstruc
; successfully transferred
;
;
; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint32_t lba)
; TODO: this needs validation
; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint32_t lba,
; uint16_t count, uint16_t drive_num)
ALIGN 4, db 0x90
read_disk_raw:
__CDECL16_ENTRY
.func:
@@ -63,14 +66,15 @@ read_disk_raw:
push ax ; val = 0
mov ax, lba_packet
push ax ; dest = lba_packet address
call kmemset ; uint8_t* kmemset(void* dest, uint8_t val, size_t len);
add sp, 0x6
call kmemset
add sp, 0x06
mov byte [lba_packet + LBAPkt_t.size], 0x10
mov word [lba_packet + LBAPkt_t.xfer_size], 0x0001
mov dword eax, [bp + 8]
mov ax, [bp + 12]
mov word [lba_packet + LBAPkt_t.xfer_size], ax
mov eax, [bp + 8]
mov dword [lba_packet + LBAPkt_t.lower_lba], eax
mov ax, [bp + 6]
@@ -81,10 +85,26 @@ read_disk_raw:
mov si, lba_packet
mov ah, 0x42
mov dl, byte [fat32_ebpb + FAT32_ebpb_t.drive_number_8]
;BUG: still working on getting this passed down correctly, going to hard set it for now.
movzx dx, byte [bp + 14]
and dx, 0x00ff
;xor dl, dl
;mov dl, 0x80
int 0x13
jnc read_disk_raw.endp
jnc .endf
%ifdef __STEVIA_MBR
ERROR MBR_ERROR_DISK_READ_ERR
%elifsef __STEVIA_VBR
ERROR VBR_ERROR_DISK_READ_ERR
%else
ERROR STAGE2_MBR_DISK_READ_ERROR
.endp:
%endif
.endf:
__CDECL16_EXIT
ret
%endif
%define __INC_EXT_READ

6
include/BIOS/func/video.inc
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@@ -18,9 +18,11 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_VIDEO
; Sets output to 80x25 16 color text mode via BIOS call
; also clears screen
; void SetTextMode(void)
ALIGN 4, db 0x90
SetTextMode:
.prolog:
__CDECL16_ENTRY
@@ -39,6 +41,7 @@ SetTextMode:
ret
; disables blinking text mode cursor
ALIGN 4, db 0x90
disable_cursor:
__CDECL16_ENTRY
.func:
@@ -52,3 +55,6 @@ disable_cursor:
.endp:
__CDECL16_EXIT
ret
%endif
%define __INC_VIDEO

1
include/cdecl16.inc
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@@ -21,6 +21,7 @@
%macro __CDECL16_ENTRY 0
push bp
mov bp, sp
sub sp, 0x20
push si
push di

4
include/config.inc
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@@ -18,8 +18,12 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_STEVIA_CONFIG
%define SECTOR_SIZE 512
%define STAGE2_SECTOR_COUNT 0x40
; 32 KiB
%define MAX_STAGE2_BYTES (SECTOR_SIZE * STAGE2_SECTOR_COUNT)
%endif
%define __INC_STEVIA_CONFIG

4
include/entry.inc
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@@ -18,9 +18,13 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_ENTRY
; 8KiB from 0x2500 -> 0x500
%define EARLY_STACK_START 0x2500
%define MBR_ENTRY 0x7A00
%define VBR_ENTRY 0x7C00
%define STAGE2_ENTRY 0x7E00
%endif
%define __INC_ENTRY

4
include/error_codes.inc
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@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_ERROR_CODES
; Errors
; 12 Errors, 5 in use
@@ -77,3 +78,6 @@
%define STEVIA_DEBUG_ERR 'X'
%define STEVIA_DEBUG_UNIMPLEMENTED 'Y'
%define STEVIA_DEBUG_HALT 'Z'
%endif
%define __INC_ERROR_CODES

4
include/fat32/bpb.inc → include/fat32/bpb_offset_bx.inc
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@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_BPD_OFFSET_BX
; BPB Information
; Off. Hex Off. Size Description
@@ -89,3 +90,6 @@
%define bsVolumeLabel bx+0x47
%define bsSystemIdent bx+0x52
;-- End EBPB
%endif
%define __INC_BPD_OFFSET_BX

4
include/fat32/fat32_structures.inc
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@@ -18,6 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_FAT32_STRUCT
; ## FAT32 Info ##
; total_sectors = bsSectorsHuge
@@ -230,4 +231,5 @@ endstruc
; LFN == RO | HIDDEN | SYSTEM | VOLID == 0x0F
%define FAT32_ATTR_LFN 0x0F
%endif
%define __INC_FAT32_STRUCT

74
include/fat32/fat32_func_old.inc → include/fat32/fat32_sys.inc
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@@ -18,6 +18,13 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_FAT32_SYS
%include "partition_table.inc"
%include "fat32/bpb_offset_bx.inc"
%include "fat32/fat32_structures.inc"
ALIGN 4, db 0x90
InitFATDriver:
__CDECL16_ENTRY
.func:
@@ -28,9 +35,14 @@ InitFATDriver:
mov dword [fat32_state + FAT32_State_t.active_dir_cluster_32], eax
.calc_active_part:
mov ax, word [partition_offset]
mov bx, partition_table
add bx, ax ; bx points to the partition that was booted from
mov bx, [partition_offset_ptr]
mov ax, [bx + 0]
mov bx, ax
mov ax, [bx + 0]
mov dx, partition_table
add dx, ax ; dx points to the partition that was booted from
mov bx, dx ; set bx, should point at our partition
mov eax, dword [bx + PartEntry_t.lba_start]
mov dword [fat32_state + FAT32_State_t.active_drive_lba_32], eax
@@ -72,6 +84,7 @@ InitFATDriver:
; returns first cluster of file if found
; halts/errors if file is not found
; uint32_t SearchFATDIR(uint8_t* SFN);
ALIGN 4, db 0x90
SearchFATDIR:
__CDECL16_ENTRY
.file_lookup:
@@ -173,9 +186,16 @@ SearchFATDIR:
; uint32_t NextCluster(uint32_t active_cluster);
; if eax >= 0x0FFFFFF8 then there are no more clusters (end of chain)
; if eax == 0x0FFFFFF7 then this is a cluster that is marked as bad
ALIGN 4, db 0x90
NextCluster:
__CDECL16_ENTRY
.func:
mov bx, [boot_drive_ptr]
mov ax, [bx + 0]
mov bx, ax
movzx ax, byte [bx + 0] ; 67h override would probably work but this is the 16bit way to do it
mov byte [bp - 2], al ; save boot drive as a local for easy access
mov dword edx, [bp + 4]
mov si, fat32_nc_data
.calc_offset:
@@ -213,7 +233,14 @@ NextCluster:
add eax, ecx ; fat_sector + first_fat_sector
mov dword [si + FAT32_NextClusterData_t.fat_sector], eax
.load_fat_table:
movzx ax, [bp - 2]
push ax
mov ax, 0x1
push ax
; load correct fat
mov eax, dword [si + FAT32_NextClusterData_t.fat_sector]
push dword eax
mov ax, fat_buffer
@@ -221,10 +248,11 @@ NextCluster:
xor ax, ax
push ax
; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint16_t lower_lower_lba, uint16_t upper_lower_lba)
call read_disk_raw ; read_disk_raw(0, fat_buffer, fat_sector)
add sp, 0x8
call read_disk_raw
add sp, 0xC
; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint32_t lba,
; uint16_t count, uint16_t drive_num)
.read_cluster:
; next_cluster = fat_buffer[entry_offset]
mov ebx, dword [si + FAT32_NextClusterData_t.entry_offset]
@@ -235,6 +263,7 @@ NextCluster:
ret
; uint32_t ClusterToLBA(uint32_t cluster)
ALIGN 4, db 0x90
ClusterToLBA:
__CDECL16_ENTRY
.func:
@@ -249,25 +278,42 @@ ClusterToLBA:
ret
; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
ALIGN 4, db 0x90
ReadFATCluster:
__CDECL16_ENTRY
.func:
mov bx, [boot_drive_ptr]
mov ax, [bx + 0]
mov bx, ax
movzx ax, byte [bx + 0] ; 67h override would probably work but this is the 16bit way to do it
mov byte [bp - 2], al ; save boot drive as a local for easy access
mov dword eax, [bp + 8]
push dword eax
call ClusterToLBA ; uint32_t ClusterToLBA(uint32_t cluster)
add sp, 0x4 ; eax == LBA
push dword eax ;uint32_t lba
movzx ax, [bp - 2]
push ax
mov dx, [bp + 4] ; seg
push dx ; uint16_t buf_offset
mov ax, 0x1
push ax
mov dx, [bp + 6] ; offset
push dx ; unit16_t segment
; load correct fat
mov eax, dword [si + FAT32_NextClusterData_t.fat_sector]
push dword eax
call read_disk_raw ; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint32_t lba)
add sp, 0x8
mov ax, fat_buffer
push ax
xor ax, ax
push ax
call read_disk_raw
add sp, 0xC
.endp:
__CDECL16_EXIT
ret
%endif
%define __INC_FAT32_SYS

11
include/kmem_func.inc
View File

@@ -17,15 +17,18 @@
; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_KMEM_FUNC
%include 'cdecl16.inc'
; uint8_t* kmemset(void* dest, uint8_t val, uint8_t len);
; uint8_t* kmemset_byte(void* dst, uint8_t val, uint16_t len);
ALIGN 4, db 0x90
kmemset:
__CDECL16_ENTRY
.func:
mov cx, [bp + 8] ; size_t len
mov al, [bp + 6] ; uint8_t val
mov di, [bp + 4] ; void * ptr
mov di, [bp + 4] ; void * dst
cld
rep stosb
@@ -36,6 +39,7 @@ kmemset:
; uint8_t* kmemset(uint8_t* dest, uint8_t* src, uint8_t len);
; not overlap safe
ALIGN 4, db 0x90
kmemcpy:
__CDECL16_ENTRY
.func:
@@ -49,3 +53,6 @@ kmemcpy:
.endf:
__CDECL16_EXIT
ret
%endif
%define __INC_KMEM_FUNC

21
include/memory.inc → include/mem.inc
View File

@@ -18,6 +18,8 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_MEM
; ## Generic Low mem map (from osdev wiki) ##
; start end size type description
@@ -54,12 +56,12 @@
; copy of FAT32 BPB, 33 bytes (+1 to the next value to align to uint16_t)
;0x3048
%define fat32_bpb 0x3050
%define fat32_bpb_SIZE 33
%define fat32_bpb 0x304A
%define fat32_bpb_SIZE 36
; copy of FAT32 EBPB, 54 bytes
;0x306A
%define fat32_ebpb 0x30A0
%define fat32_ebpb 0x306E
%define fat32_ebpb_SIZE 54
; FAT32 FSInfo, 512 bytes
@@ -69,18 +71,18 @@
; some stored state for the fat32 driver
;0x32A2
%define fat32_state 0x32B0
%define fat32_state 0x34B0
%define fat32_state_SIZE 32
; next free space is 0x32D0
%define fat32_nc_data 0x32D0
%define fat32_nc_data 0x35D0
%define fat32_nc_data_size 16
; lba_packet for raw_disk_read
%define lba_packet 0x4000
%define BIOSMemoryMap 0x4200
%define SteviaInfo 0x4400
%define SteviaInfo 0x5200
; High memory addresses for loading kernel (for use with unreal mode and 32bit override)
@@ -110,8 +112,5 @@ struc SteviaInfoStruct_t
.EBPBDataPtr resd 1
endstruc
%macro DEBUG_HCF 0
DEBUG_LOOP:
hlt
jmp short DEBUG_LOOP
%endmacro
%endif
%define __INC_MEM

5
include/partition_table.inc
View File

@@ -18,6 +18,8 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_PART_TABLE
; Partition table entry format
; Off. Size. Description
;0x00 1 Drive attributes (bit 7 set = active or bootable)
@@ -42,3 +44,6 @@ struc PartTable_t
.partition3 resb 16
.partition4 resb 16
endstruc
%endif
%define __INC_PART_TABLE

13
include/util/error_func.inc
View File

@@ -18,13 +18,23 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
%ifndef __INC_ERROR_FUNC
%macro ERROR 1
xor ax, ax
mov al, %1
jmp error
%endmacro
%macro DEBUG_HCF 0
DEBUG_LOOP:
cli
hlt
jmp short DEBUG_LOOP
%endmacro
; pass error as ascii character in al, errors a-zA-Z or 0-9
ALIGN 4, db 0x90
error:
; fs = 0xb800 => fs:0x0000 = 0xb8000
mov dx, 0xB800
@@ -48,3 +58,6 @@ error:
.stop:
hlt
jmp short error.stop
%endif
%define __INC_ERROR_FUNC

167
src/mbr/mbr.nasm
View File

@@ -23,17 +23,37 @@
[CPU KATMAI]
jmp short init
nop
%include "cdecl16.inc" ; include calling convention macros for cdecl16
%include "entry.inc" ; defines with entry points for various stages & stack
; ###############
;
; Headers/Includes/Definitions
;
; ###############
%define __STEVIA_MBR
%include "cdecl16.inc"
%include "entry.inc"
%include "config.inc"
%include "mem.inc"
%include "error_codes.inc"
%include "partition_table.inc"
; ###############
; End Section
; ###############
ALIGN 4, db 0x90
init:
cli ; We do not want to be interrupted
xor ax, ax ; 0 AX
mov ds, ax ; Set segment registers to 0
mov es, ax ; *
mov ss, ax ; Set Stack Segment to 0
mov sp, EARLY_STACK_START
mov sp, EARLY_STACK_START ; Setup stack
mov bp, sp ; base ptr = stack ptr
sub sp, 0x20 ; local varible space
mov ch, 0x01 ; 256 WORDs in MBR (512 bytes), 0x0100 in cx
mov si, 0x7C00 ; Current MBR Address (loaded here by BIOS)
@@ -43,16 +63,28 @@ init:
sti
jmp 0:main
nop
%include "config.inc"
%include "memory.inc"
; ###############
;
; Extra/Shared Functions
;
; ###############
%include "kmem_func.inc"
%include "partition_table.inc"
%include "errors.inc"
%include "util/error_func.inc"
; ###############
; End Section
; ###############
;
; bp - 2 : uint8_t boot_drive
; bp - 4 : uint16_t part_offset
;
ALIGN 4, db 0x90
main:
mov [boot_drive], dl ; BIOS passes drive number in DL
mov byte [bp - 2], dl ; BIOS passes drive number in DL
.check_disk:
cmp dl, 0x80
@@ -62,7 +94,7 @@ main:
.check_extentions:
xor ax, ax
mov bx, 0x55AA
mov dl, byte [boot_drive]
mov dl, byte [bp - 2]
int 0x13
jnc main.find_active
ERROR MBR_ERROR_NO_INT32E ; no extended function support
@@ -83,25 +115,30 @@ main:
mov ax, bx
sub ax, DiskSig ; leaves us with the offset relative from start of table
; this gives us an offset from the begining of the partition table
mov word [part_offset], ax ; update part_offset
mov word [bp - 4], ax ; update part_offset
.read_data:
;uint8_t read_disk_raw(size_t count, uint16_t buf_segment, uint16_t buf_offset,
; uint16_t lower_lower_lba, uint16_t upper_lower_lba)
mov eax, dword [bx + PartEntry_t.lba_start]
ror eax, 16
push ax
movzx ax, byte [bp - 2]
push ax ; drive_num
ror eax, 16
push ax
mov ax, 0x1
push ax ; count
mov ax, VBR_ENTRY
push ax
mov dword eax, dword [bx + PartEntry_t.lba_start]
push dword eax ; lba
xor ax, ax
push ax ; segment = 0
push ax ; offset = 0
mov ax, VBR_ENTRY
shr ax, 4
push ax ; segment = 7C0
; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint32_t lba,
; uint16_t count, uint16_t drive_num)
call read_disk_raw
add sp, 0xC
call read_vbr_raw
add sp, 0x8
jnc main.goto_vbr
ERROR MBR_ERROR_DISK_READ_ERR ; error in LBA read
@@ -120,86 +157,16 @@ main:
call kmemcpy ; copy partition table to memory
add sp, 0x6
xor ah, ah ; Set Video mode BIOS function
mov al, 0x02 ; 16 color 80x25 Text mode
int 0x10 ; Call video interrupt
mov ah, 0x05 ; Select active display page BIOS function
xor al, al ; page 0
int 0x10 ; call video interrupt
mov si, word [part_offset]
mov dl, byte [boot_drive]
mov si, word [bp - 4]
mov dl, byte [bp - 2]
jmp 0:0x7C00
; Wrapper for AH=0x42 INT13h (Extended Read)
; ###############
;
; BIOS call details
; AH = 42h
; DL = drive number
; DS:SI -> disk address packet
; BIOS Functions
;
; Return:
; CF clear if successful
; AH = 00h
; CF set on error
; AH = error code
; disk address packet's block count field set to number of blocks
; successfully transferred
;
;
; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint16_t lower_lower_lba, uint16_t upper_lower_lba)
read_vbr_raw:
__CDECL16_ENTRY
.func:
mov ax, 0x10
push ax ; len = 16 bytes
xor ax, ax
push ax ; val = 0
mov ax, lba_packet
push ax ; dest = lba_packet address
call kmemset
add sp, 0x06
mov byte [lba_packet + LBAPkt_t.size], 0x10
mov word [lba_packet + LBAPkt_t.xfer_size], 0x0001
mov ax, [bp + 10]
shl eax, 16
mov ax, [bp + 8]
mov dword [lba_packet + LBAPkt_t.lower_lba], eax
mov ax, [bp + 6]
mov word [lba_packet + LBAPkt_t.offset], ax
mov ax, [bp + 4]
mov word [lba_packet + LBAPkt_t.segment], ax
mov si, lba_packet
mov ah, 0x42
mov dl, byte [boot_drive]
int 0x13
jnc .endf
ERROR MBR_ERROR_INT13h_EREAD_ERR
.endf:
__CDECL16_EXIT
ret
; #############
;
; Locals
;
; #############
boot_drive:
db 0x00
mbr_reserved1:
db 0x00
; OFFSET from BEGINING of partition table, ie. DiskSig (-6 from PartEntry1)
part_offset:
dw 0x0000
; ###############
%include 'BIOS/func/ext_read.inc'
%assign bytes_remaining (440 - ($ - $$))
%warning MBR has bytes_remaining bytes remaining for code (MAX: 440 bytes)

71
src/stage2/stage2.nasm
View File

@@ -23,11 +23,27 @@
[CPU KATMAI]
jmp short init
nop
; boot drive in dl
; active partition offset in si
; ###############
;
; Headers/Includes/Definitions
;
; ###############
%define __STEVIA_STAGE2
%include "cdecl16.inc"
%include "entry.inc"
%include "config.inc"
%include "mem.inc"
%include "error_codes.inc"
; ###############
; End Section
; ###############
ALIGN 4, db 0x90
init:
cli ; We do not want to be interrupted
@@ -39,30 +55,34 @@ init:
mov ss, ax ; Set Stack Segment to 0
mov sp, EARLY_STACK_START ; Set Stack Pointer
add sp, 0x4
mov ax, 0xDEAD
push word ax
mov ax, 0xBEEF
push word ax ; mark top of stack for debuging
mov bp, sp
sub sp, 0x20 ; 32 bytes for local varibles
sti
jmp 0:main
%include "config.inc"
%include "error_codes.inc"
%include "memory.inc"
%include "kmem_func.inc"
%include "partition_table.inc"
%include "fat32/bpb.inc"
%include "fat32/fat32_structures.inc"
; ###############
;
; Extra/Shared Functions
;
; ###############
%include "kmem_func.inc"
%include "util/error_func.inc"
; ###############
; End Section
; ###############
main:
mov byte [fat32_ebpb + FAT32_ebpb_t.drive_number_8], dl
mov word [partition_offset], si
lea ax, [bp - 2]
mov [boot_drive_ptr], ax
lea ax, [bp - 4]
mov [partition_offset_ptr], ax
mov byte [bp - 2], dl ; boot_drive (probably 0x80)
mov word [bp - 4], si ; partition_offset
mov eax, dword [STAGE2_SIG]
cmp eax, 0xDEADBEEF
@@ -138,7 +158,7 @@ hcf:
;
; ###############
%include 'fat32/fat32_func_old.inc'
%include 'fat32/fat32_sys.inc'
; ###############
;
@@ -306,18 +326,13 @@ NewLine_cstr:
db StrCRLF_NUL
BootTarget_str:
db "BOOTI686BIN"
; #############
;
; Locals
;
; #############
partition_offset:
boot_drive_ptr:
db 0x00
stage2_resb_1:
db 0x00
partition_offset_ptr:
dw 0x0000
; GDT documentation below:
;
; Pr: Present bit. This must be 1 for all valid selectors.

167
src/vbr/vbr.nasm
View File

@@ -30,36 +30,59 @@ phy_ebpb_start:
; fill eBPB area with 0x00 since we skip writing this part to disk
times 54 db 0x00
; ###############
;
; Headers/Includes/Definitions
;
; ###############
%define __STEVIA_VBR
%include "cdecl16.inc"
%include "entry.inc"
%include "config.inc"
%include "mem.inc"
%include "error_codes.inc"
%include "fat32/bpb_offset_bx.inc"
; ###############
; End Section
; ###############
ALIGN 4, db 0x90
init:
cli ; We do not want to be interrupted
xor ax, ax ; 0 AX
mov ds, ax ; Set segment registers to 0
mov es, ax ; *
mov ss, ax ; Set Stack Segment to 0
mov sp, EARLY_STACK_START ; Setup stack
mov bp, sp ; base ptr = stack ptr
sub sp, 0x20 ; local varible space
mov bx, VBR_ENTRY ; move Bx to the new start of the initial boot sector
sti ; all done with inital setup and relocation, reenable interupts
jmp 0:main ; fix up cs:ip just in case and jump to relocated code
nop
%include "config.inc"
%include "memory.inc"
; ###############
;
; Extra/Shared Functions
;
; ###############
%include "kmem_func.inc"
%include "partition_table.inc"
%include "errors.inc"
%include "util/error_func.inc"
%include "fat32/bpb.inc"
; ###############
; End Section
; ###############
ALIGN 4, db 0x90
main:
mov [bsDriveNumber], dl ; BIOS passes drive number in DL
mov [partition_offset], si ; save passed partition entry offset
mov byte [bp - 2], dl ; boot_drive
mov [bp - 4], si ; part_offset
.check_FAT_size: ; we only support a very specific setup of FAT32
cmp dword [bsSectorHuge], 0 ; SectorsHuge will not be set if FAT12/16
@@ -69,24 +92,39 @@ main:
; read sectors 1-63 to stage2 entry point
.load_stage2:
xor ax, ax
push ax ; upper_lower_lba = 0
mov ax, (fat32_bpb_SIZE + fat32_ebpb_SIZE) ; size in byte
push ax
mov ax, (phy_bpb_start - 0x3) ; start of bpb - 0x3 for the jump short main at the start
push ax
mov ax, fat32_bpb ; defined in memory.inc, destination
push ax
call kmemcpy ; copy bpb to memory
add sp, 0x6
mov ax , 1
push ax ; lower_lower_lba = 1
mov bx, fat32_bpb ; bx now points to aligned memory structure
movzx ax, byte [bp - 2]
push ax ; drive_num
mov ax, STAGE2_SECTOR_COUNT
push ax ; count
mov dword eax, 0x1
push dword eax ; lba
xor ax, ax
push ax ; offset = 0
; 07E0:0
; 07E0:0 = 0x00007e00
mov ax, STAGE2_ENTRY
shr ax, 4
push ax ; segment = 7E0
;uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint16_t lower_lower_lba, uint16_t upper_lower_lba)
call read_stage2_raw
add sp, 0x8
; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint32_t lba,
; uint16_t count, uint16_t drive_num)
call read_disk_raw
add sp, 0xC
.check_sig:
mov ax, 0x7E0
@@ -97,97 +135,16 @@ main:
ERROR VBR_ERROR_NO_SIGNATURE ; no signature present in stage2
.sig_ok:
mov ax, fat32_bpb_SIZE ; size in byte
push ax
mov ax, phy_bpb_start ; start of bpb
push ax
mov ax, fat32_bpb ; defined in memory.inc, destination
push ax
call kmemcpy ; copy bpb to memory
add sp, 0x6
mov ax, fat32_ebpb_SIZE ; 72 bytes of data
push ax
mov ax, phy_ebpb_start ; start of ebpb
push ax
mov ax, fat32_ebpb ; defined in memory.inc, destination
push ax
call kmemcpy ; copy ebpb to memory
add sp, 0x6
mov si, [partition_offset]
mov dl, [bsDriveNumber]
mov si, [bp - 4]
mov dx, [bp - 2]
jmp 0:0x7E00
stop:
hlt
jmp short stop
; Wrapper for AH=0x42 INT13h (Extended Read)
; ###############
;
; BIOS call details
; AH = 42h
; DL = drive number
; DS:SI -> disk address packet
; Required BIOS functions
;
; Return:
; CF clear if successful
; AH = 00h
; CF set on error
; AH = error code
; disk address packet's block count field set to number of blocks
; successfully transferred
;
;
; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset,
; uint16_t lower_lower_lba, uint16_t upper_lower_lba)
read_stage2_raw:
__CDECL16_ENTRY
.func:
mov ax, 0x10
push ax ; len = 16 bytes
xor ax, ax
push ax ; val = 0
mov ax, lba_packet
push ax ; dest = lba_packet address
call kmemset
add sp, 0x06
mov byte [lba_packet + LBAPkt_t.size], 0x10
mov word [lba_packet + LBAPkt_t.xfer_size], STAGE2_SECTOR_COUNT
mov ax, [bp + 10]
shl eax, 16
mov ax, [bp + 8]
mov dword [lba_packet + LBAPkt_t.lower_lba], eax
mov ax, [bp + 6]
mov word [lba_packet + LBAPkt_t.offset], ax
mov ax, [bp + 4]
mov word [lba_packet + LBAPkt_t.segment], ax
mov si, lba_packet
mov ah, 0x42
mov dl, byte [bsDriveNumber]
int 0x13
jnc .endf
ERROR VBR_ERROR_DISK_READ_ERR
.endf:
__CDECL16_EXIT
ret
; Data
; #############
;
; Locals
;
; #############
; offset from the begining of sector 0 to the active partition.
partition_offset:
dw 0x0000
; ###############
%include 'BIOS/func/ext_read.inc'
%assign bytes_remaining (420 - ($ - $$))
%warning VBR has bytes_remaining bytes remaining for code (MAX: 420 bytes)