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Merge pull request #2 from Nivirx/FAT_Refactor

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Full refactor for modularization
This commit is contained in:
Elaina Claus
2024-10-05 20:19:51 -04:00
committed by GitHub
parent 0a1123c5b5 145e9fbaa9
commit 03a09ed54b
20 changed files with 1113 additions and 921 deletions
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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

24
include/BIOS/BIOS_sys.inc Normal file
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@@ -0,0 +1,24 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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.
%include 'BIOS/func/a20enable.inc'
%include 'BIOS/func/E820_memory_map.inc'
%include 'BIOS/func/ext_read.inc'
%include 'BIOS/func/video.inc'

146
include/memory.inc → include/BIOS/func/E820_memory_map.inc Executable file → Normal file
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@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -18,97 +18,7 @@
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
; ## Generic Low mem map (from osdev wiki) ##
; start end size type description
; Low Memory (the first MiB)
; 0x00000000 0x000003FF 1 KiB RAM - partially unusable Real Mode IVT (Interrupt Vector Table)
; 0x00000400 0x000004FF 256 bytes RAM - partially unusable BDA (BIOS data area)
; 0x00000500 0x00007BFF almost 30 KiB RAM - free for use Conventional memory
; 0x00007C00 0x00007DFF 512 bytes RAM - partially unusable OS BootSector
; 0x00007E00 0x0007FFFF 480.5 KiB RAM - free for use Conventional memory
; 0x00080000 0x0009FFFF 128 KiB RAM - partially unusable EBDA (Extended BIOS Data Area)
; 0x000A0000 0x000FFFFF 384 KiB various (unusable) Video memory, ROM Area
; ## A rough overview of high mem ##
; Idealy this needs to be probed with the E820 functions
; # Start # End # size # description
;
; 0x00100000 0x00EFFFFF 0x00E00000 (14 MiB) RAM -- free for use (if it exists) Extended memory
; 0x00F00000 0x00FFFFFF 0x00100000 (1 MiB) Possible memory mapped hardware ISA Memory Hole 15-16MB
; 0x01000000 ???????? ??? (whatever exists) RAM -- free for use More Extended memory
; 0xC0000000 (sometimes) 0xFFFFFFFF 0x40000000 (1 GiB) Memory mapped PCI devices, PnP NVRAM?, IO APIC/s, local APIC/s, BIOS, ...
; 0x0000000100000000 ??? ??? (whatever exists) RAM -- free for use (PAE/64bit)/More Extended memory
; ???????????????? ??? ??? Potentially usable for memory mapped PCI devices in modern hardware (but typically not, due to backward compatibility)
; 0x2700 -> 0x28FF
%define disk_buffer 0x2700
; 0x2900 -> 0x2AFF
%define fat_buffer 0x2900
; 0x2B00 -> 0x2CFF
%define dir_buffer 0x2B00
; copy of partition table, 72 bytes
%define partition_table 0x3000
%define partition_table_SIZE 72
; 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
; copy of FAT32 EBPB, 54 bytes
;0x306A
%define fat32_ebpb 0x30A0
%define fat32_ebpb_SIZE 54
; FAT32 FSInfo, 512 bytes
;0x30A2
%define fat32_fsinfo 0x30B0
%define fat32_fsinfo_SIZE 512
; some stored state for the fat32 driver
;0x32A2
%define fat32_state 0x32B0
%define fat32_state_SIZE 32
; next free space is 0x32D0
%define fat32_nc_data 0x32D0
%define fat32_nc_data_size 16
; lba_packet for raw_disk_read
%define lba_packet 0x4000
%define BIOSMemoryMap 0x4200
%define SteviaInfo 0x4400
; High memory addresses for loading kernel (for use with unreal mode and 32bit override)
; file load buffer at 16MB
%define HMEM_load_buffer 0x1000000
;PhysicalAddress = Segment * 16 + Offset
%define SEG_TO_LINEAR(s,o) ((s << 4) + o)
; Offset = physical / (Segment * 16)
%define LINEAR_TO_OFFSET(p,s) ((p / (s << 4)))
; Seg = (physical - offset) / 16
%define LINEAR_TO_SEGMENT(p,o) ((p - o) >> 4)
; create normalized linear addres from seg:off (16:4)
; Segement = linear >> 4 (top 16 bits)
; offset = linear & 0x0F (low 4 bits)
; 20 bytes, passed to loaded kernel
struc SteviaInfoStruct_t
.MemoryMapPtr resd 1
.MemoryMapEntries resd 1
.BPBDataPtr resd 1
.EBPBDataPtr resd 1
endstruc
%ifndef __INC_E820MEMORY_MAP
; Address Range Descriptor Structure
;
@@ -207,8 +117,50 @@ struc AddressRangeDescStruct_t
.ExtType resd 1
endstruc
%macro DEBUG_HCF 0
DEBUG_LOOP:
hlt
jmp short DEBUG_LOOP
%endmacro
ALIGN 4, db 0x90
GetMemoryMap:
__CDECL16_ENTRY
push es ; save segment register
.func:
mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
mov eax, 0xE820 ; select 0xE820 function
xor ebx, ebx ; Continuation value, 0 for the first call
mov dx, (BIOSMemoryMap >> 4)
mov es, dx
xor di, di ; (BIOSMemoryMap >> 4):0 makes di an index into BIOSMemoryMap
mov ecx, AddressRangeDescStruct_t_size
mov edx, 0x534D4150 ; 'SMAP' magic
.loop_L1:
int 0x15
jc GetMemoryMap.error
cmp eax, 0x534D4150
jne GetMemoryMap.no_smap_returned
.no_error:
inc dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
cmp ecx, 20 ; TODO: maybe this could be handled better than just panicing
jb GetMemoryMap.nonstandard_e820 ; non-standard entry found
cmp ebx, 0
je GetMemoryMap.endp ; 0 in ebx means we have reached the end of memory ranges
add di, AddressRangeDescStruct_t_size ; increment di to next descriptor
mov edx, eax ; 'SMAP' to edx
mov eax, 0xE820 ; select E820 function
jmp GetMemoryMap.loop_L1
.error:
ERROR STAGE2_MM_E820_MISC_ERR
.nonstandard_e820:
ERROR STAGE2_MM_E820_NONSTANDARD
.no_smap_returned:
ERROR STAGE2_MM_E820_NO_SMAP
.endp:
pop es
__CDECL16_EXIT
ret
%endif
%define __INC_E820MEMORY_MAP

144
include/BIOS/func/a20enable.inc Normal file
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@@ -0,0 +1,144 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_A20ENABLE
;
;INT 0x15 Function 2400 - Disable A20
;Returns:
;
; CF = clear if success
; AH = 0
; CF = set on error
; AH = status (01=keyboard controller is in secure mode, 0x86=function not supported)
;
;INT 0x15 Function 2401 - Enable A20
;Returns:
;
; CF = clear if success
; AH = 0
; CF = set on error
; AH = status (01=keyboard controller is in secure mode, 0x86=function not supported)
;
;INT 0x15 Function 2402 - A20 Status
; Returns:
;
; CF = clear if success
; AH = status (01: keyboard controller is in secure mode; 0x86: function not supported)
; AL = current state (00: disabled, 01: enabled)
; CX = set to 0xffff is keyboard controller is no ready in 0xc000 read attempts
; CF = set on error
;
;INT 0x15 Function 2403 - Query A20 support
;Returns:
;
;CF = clear if success
;AH = status (01: keyboard controller is in secure mode; 0x86: function not supported)
;BX = status.
;
;BX contains a bit pattern:
;
; Bit 0 - supported on keyboard controller
; Bit 1 - if supported on bit 1 of I/O port 0x92
; Bits 2:14 - Reserved
; Bit 15 - 1 if additional data is available.
;
; I/O Port 0x92 infomation:
;
; Bit 0 - Setting to 1 causes a fast reset
; Bit 1 - 0: disable A20; 1: enable A20
; Bit 2 - Manufacturer defined
; 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
push es
.a20_check:
cli
xor ax, ax
mov es, ax
not ax ; ax = 0xFFFF
mov ds, ax
mov di, 0x0500 ; scratch location 1
mov si, 0x0510 ; scratch location 2
mov al, byte [es:di]
push ax ; save whatever is at 0x0000:0500, physical location 0x0500
mov al, byte [ds:si]
push ax ; save whatever is at 0xFFFF:0510 [clarification: 0x100500 physical location (0x100500 - 1MB = 0x0500)]
mov byte [es:di], 0x00 ; zero non-wraped location and write 0xFF to it after (ab)using wrapping
mov byte [ds:si], 0xFF ; if the non-wrapped location is 0xFF, then we wraped and A20 is disabled
cmp byte [es:di], 0xFF
pop ax
mov byte [ds:si], al ; restore original contents of scratch location 2
pop ax
mov byte [es:di], al ; restore original contents of scratch location 1
mov ax, 0 ; return 0 if es:di == ds:si (memory wraps)
je EnableA20.end_check
mov ax, 1 ; return 1 if es:di != ds:si (A20 is enabled)
.end_check:
sti
cmp ax, 1
je EnableA20.endp ; A20 is already enabled
mov ax, 0x2403
int 0x15
jc EnableA20.do_fallback_a20 ; carry = error...not supported?
cmp ah, 0
ja EnableA20.do_fallback_a20 ; non-zero return = error as well
mov al, bl
and al, 0000_0010b
cmp al, 0000_0010b
je EnableA20.do_fast_a20 ; if fast a20 is supported use it
jmp EnableA20.do_bios_a20 ; else fall back to enabling via BIOS
.do_fallback_a20:
ERROR STAGE2_A20_FAILED
.do_bios_a20:
mov ax, 0x2401
int 0x15
jmp EnableA20.a20_check
.do_fast_a20:
in al, 0x92 ; read from FAST A20 port
or al, 2 ; bit 0 is a fast reset, bit 1 is fast A20
and al, 0xFE ; make sure bit 0 is 0
out 0x92, al ; enable A20
jmp EnableA20.a20_check
.endp:
pop es
pop ds
__CDECL16_EXIT
ret
%endif
%define __INC_A20ENABLE

110
include/BIOS/func/ext_read.inc Normal file
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@@ -0,0 +1,110 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_EXT_READ
;Offset Size Description
; 0 1 size of packet (16 bytes)
; 1 1 always 0
; 2 2 number of sectors to transfer (max 127 on some BIOSes)
; 4 4 transfer buffer (0xFFFF:0xFFFF)
; 8 4 lower 32-bits of starting 48-bit LBA
; 12 4 upper 32-bits of starting 48-bit LBA
; needs to be aligned to a uint32_t
struc LBAPkt_t
.size resb 1
.res0 resb 1
.xfer_size resw 1
.offset resw 1
.segment resw 1
.lower_lba resd 1
.upper_lba resd 1
endstruc
; Wrapper for AH=0x42 INT13h (Extended Read)
;
; BIOS call details
; AH = 42h
; DL = drive number
; DS:SI -> disk address packet
;
; 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_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:
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 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]
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
;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 .endf
%ifdef __STEVIA_MBR
ERROR MBR_ERROR_DISK_READ_ERR
%elifdef __STEVIA_VBR
ERROR VBR_ERROR_DISK_READ_ERR
%else
ERROR STAGE2_MBR_DISK_READ_ERROR
%endif
.endf:
__CDECL16_EXIT
ret
%endif
%define __INC_EXT_READ

60
include/BIOS/func/video.inc Normal file
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@@ -0,0 +1,60 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_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
pushf
.func:
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
.endp:
popf
__CDECL16_EXIT
ret
; disables blinking text mode cursor
ALIGN 4, db 0x90
disable_cursor:
__CDECL16_ENTRY
.func:
mov dx, 0x3D4
mov al, 0xA ; low cursor shape register
out dx, al
inc dx
mov al, 0x20 ; bits 6-7 unused, bit 5 disables the cursor, bits 0-4 control the cursor shape
out dx, al
.endp:
__CDECL16_EXIT
ret
%endif
%define __INC_VIDEO

3
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
@@ -37,4 +38,4 @@
mov sp, bp
pop bp
%endmacro
%endif
%endif

8
include/config.inc
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@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -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)
%define MAX_STAGE2_BYTES (SECTOR_SIZE * STAGE2_SECTOR_COUNT)
%endif
%define __INC_STEVIA_CONFIG

14
include/entry.inc
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@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -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 STACK_START 0x2500
%define MBR_ENTRY 0x7A00
%define VBR_ENTRY 0x7C00
%define STAGE2_ENTRY 0x7E00
%define EARLY_STACK_START 0x2500
%define MBR_ENTRY 0x7A00
%define VBR_ENTRY 0x7C00
%define STAGE2_ENTRY 0x7E00
%endif
%define __INC_ENTRY

36
include/errors.inc → include/error_codes.inc
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@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -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
@@ -78,34 +79,5 @@
%define STEVIA_DEBUG_UNIMPLEMENTED 'Y'
%define STEVIA_DEBUG_HALT 'Z'
%macro ERROR 1
xor ax, ax
mov al, %1
jmp error
%endmacro
; pass error as ascii character in al, errors a-zA-Z or 0-9
error:
; fs = 0xb800 => fs:0x0000 = 0xb8000
mov dx, 0xB800
mov fs, dx
mov dx, STEVIA_DEBUG_OK
cmp ax, dx
jge error.debug_err
mov dh, 0x4F ; color 0x4F is white text/red background
jmp error.print
.debug_err:
mov dh, 0x5F ; debug case is white text/purple background
; the characters are two bytes in the order of 0xb8000: byte c, byte attribute
; since x86 is le, we store the attribute in the MSB of dx
.print:
mov dl, al
mov word [fs:0x0000], dx
jmp error.stop
.stop:
hlt
jmp short error.stop
%endif
%define __INC_ERROR_CODES

8
include/fat32/bpb.inc → include/fat32/bpb_offset_bx.inc
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@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -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
@@ -88,4 +89,7 @@
%define bsVolumeSerial bx+0x43
%define bsVolumeLabel bx+0x47
%define bsSystemIdent bx+0x52
;-- End EBPB
;-- 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

312
include/fat32/fat32_sys.inc Normal file
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@@ -0,0 +1,312 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_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:
xor eax, eax
mov dword [fat32_state + FAT32_State_t.active_cluster_32], eax
mov dword [fat32_state + FAT32_State_t.active_FAT_cluster_32], eax
mov dword [fat32_state + FAT32_State_t.first_root_dir_sector_32], eax
mov dword [fat32_state + FAT32_State_t.active_dir_cluster_32], eax
.calc_active_part:
mov bx, [partition_offset_ptr]
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
.calc_first_fat:
movzx eax, word [fat32_bpb + FAT32_bpb_t.reserved_sectors_16] ; first fat from start of partition
add eax, dword [fat32_state + FAT32_State_t.active_drive_lba_32] ; calculate offset from start of drive
mov dword [fat32_state + FAT32_State_t.first_fat_sector_32], eax
.calc_total_fat:
mov ebx, dword [fat32_ebpb + FAT32_ebpb_t.sectors_per_fat_32]
movzx eax, byte [fat32_bpb + FAT32_bpb_t.fat_count_8]
mul ebx ; result in EDX:EAX, CF set on > 32bit return value
jc InitFATDriver.error ; as a catch for unhandled overflow, just error if value is greater than 32bits
mov dword [fat32_state + FAT32_State_t.fat_size_32], eax
.calc_first_data:
mov edx, dword [fat32_state + FAT32_State_t.first_fat_sector_32]
add eax, edx
mov dword [fat32_state + FAT32_State_t.first_data_sector_32], eax
.get_first_root_dir:
; TODO
jmp InitFATDriver.endp
.error:
ERROR STAGE2_FAT32_INIT_ERROR
.endp:
__CDECL16_EXIT
ret
; this involves using the low memory buffer for the bios call and moving the file sector by sector to high memory
;
; SFN is a 8.3 file name, all uppercase, and padded with spaces
; do not add a null byte to the end of the string
; eg. kernel.bin == "KERNEL BIN"
;
; 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:
.load_first_dir:
mov eax, [fat32_ebpb + FAT32_ebpb_t.root_dir_cluster_32]
mov dword [fat32_state + FAT32_State_t.active_dir_cluster_32], eax
push dword eax ; cluster
lea ax, [dir_buffer]
push ax ; offset
xor ax, ax
push ax ; segment
call ReadFATCluster ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
add sp, 0x8
lea si, [dir_buffer]
jmp SearchFATDIR.empty_dir_entry
.load_next_dir:
; 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
mov eax, dword [fat32_state + FAT32_State_t.active_dir_cluster_32]
push dword eax
call NextCluster ; uint32_t NextCluster(uint32_t active_cluster);
add sp, 0x4
cmp eax, 0x0fff_fff7
jb SearchFATDIR.load_next_dir_next_OK
ERROR STAGE2_FAT32_END_OF_CHAIN
.load_next_dir_next_OK:
; load 512 bytes of directory entries from data sector
mov eax, [fat32_state + FAT32_State_t.active_dir_cluster_32]
push dword eax
lea ax, [dir_buffer] ; cluster
push ax ; offset
xor ax, ax
push ax ; segment
call ReadFATCluster ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
sub sp, 0x8
lea si, [dir_buffer]
.empty_dir_entry:
; check for 0x0 in first byte, if true then there are no more files
; if true we did not find the file, we should error here
cmp byte [si], 0
jne SearchFATDIR.unused_dir_entry
ERROR STAGE2_FAT32_NO_FILE
.unused_dir_entry:
; check for 0xe5 and 0x05 in first byte, if true then this entry is unused, but it is not the last entry.
cmp byte [si], 0xe5
je SearchFATDIR.next_entry
cmp byte [si], 0x05
je SearchFATDIR.next_entry
jmp SearchFATDIR.parse_dir
.next_entry:
; increment offset by 32 bytes to read the next entry in this set of dir entries
; if we are at the end of the buffer, then load the next buffer
add si, 0x20 ; 32 bytes
lea ax, [dir_buffer]
add ax, 0x1FF ; 512 - 1 bytes
cmp si, ax
jae SearchFATDIR.load_next_dir
jmp SearchFATDIR.empty_dir_entry
.parse_dir:
.lfn_check:
; check for ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID (0x0F) in offset 11
; TODO: going to skip LFN for now, since all valid volumes will have SFN's
cmp byte [si+11], 0x0F
je SearchFATDIR.next_entry
.sfn_file_name_check:
push si
push di
mov cx, 0xA ; max of 11 filename length of 11 characters
; si points to the start of the current directory entry
lea di, [BootTarget_str] ; current memory location (8.3 name is at offset 0)
repe cmpsb ; compare the strings
pop di
pop si
jne SearchFATDIR.next_entry
.sfn_entry_found:
mov ax, [si + FAT32_SFN_t.cluster_16_high]
shl eax, 16
mov ax, [si + FAT32_SFN_t.cluster_16_low]
; eax == first cluster of file
.endp:
__CDECL16_EXIT
ret
; 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:
; fat_offset = active_cluster * 4
mov eax, 4
mul edx
mov dword [si + FAT32_NextClusterData_t.fat_offset], eax
.calc_fat_sector:
; fat_sector = first_fat_sector + (fat_offset / sector_size)
; entry_offset = fat_offset % sector_size
mov edx, 0xffff_0000
and edx, eax
shr edx, 16
push si
mov si, fat32_bpb
mov cx, word [si + FAT32_bpb_t.bytes_per_sector_16]
pop si
div cx ; DX:AX / cx = fat_sector - first_fat_sector in AX
; DX = remainder (fat_offset mod sector_size)
mov ecx, 0x0000_ffff
and edx, ecx
mov dword [si + FAT32_NextClusterData_t.entry_offset], edx
push si
mov si, fat32_state
mov ecx, dword [si + FAT32_State_t.first_fat_sector_32]
pop si
mov edx, 0x0000ffff
and eax, edx
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
push ax
xor ax, ax
push ax
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]
mov si, fat_buffer
mov eax, dword [bx+si+0]
.endp:
__CDECL16_EXIT
ret
; uint32_t ClusterToLBA(uint32_t cluster)
ALIGN 4, db 0x90
ClusterToLBA:
__CDECL16_ENTRY
.func:
mov dword eax, [bp + 4]
sub eax, 2
movzx edx, byte [fat32_bpb + FAT32_bpb_t.sectors_per_cluster_8]
mul edx
add eax, dword [fat32_state + FAT32_State_t.first_data_sector_32]
; eax contains the LBA now
.endp:
__CDECL16_EXIT
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 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
mov dword [bp - 6], eax
movzx ax, [bp - 2]
push ax
mov ax, 0x1
push ax
mov eax, dword [bp + 6]
push dword eax
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

13
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:
@@ -48,4 +52,7 @@ kmemcpy:
mov ax, di ; return pointer to dest
.endf:
__CDECL16_EXIT
ret
ret
%endif
%define __INC_KMEM_FUNC

116
include/mem.inc Executable file
View File

@@ -0,0 +1,116 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_MEM
; ## Generic Low mem map (from osdev wiki) ##
; start end size type description
; Low Memory (the first MiB)
; 0x00000000 0x000003FF 1 KiB RAM - partially unusable Real Mode IVT (Interrupt Vector Table)
; 0x00000400 0x000004FF 256 bytes RAM - partially unusable BDA (BIOS data area)
; 0x00000500 0x00007BFF almost 30 KiB RAM - free for use Conventional memory
; 0x00007C00 0x00007DFF 512 bytes RAM - partially unusable OS BootSector
; 0x00007E00 0x0007FFFF 480.5 KiB RAM - free for use Conventional memory
; 0x00080000 0x0009FFFF 128 KiB RAM - partially unusable EBDA (Extended BIOS Data Area)
; 0x000A0000 0x000FFFFF 384 KiB various (unusable) Video memory, ROM Area
; ## A rough overview of high mem ##
; Idealy this needs to be probed with the E820 functions
; # Start # End # size # description
;
; 0x00100000 0x00EFFFFF 0x00E00000 (14 MiB) RAM -- free for use (if it exists) Extended memory
; 0x00F00000 0x00FFFFFF 0x00100000 (1 MiB) Possible memory mapped hardware ISA Memory Hole 15-16MB
; 0x01000000 ???????? ??? (whatever exists) RAM -- free for use More Extended memory
; 0xC0000000 (sometimes) 0xFFFFFFFF 0x40000000 (1 GiB) Memory mapped PCI devices, PnP NVRAM?, IO APIC/s, local APIC/s, BIOS, ...
; 0x0000000100000000 ??? ??? (whatever exists) RAM -- free for use (PAE/64bit)/More Extended memory
; ???????????????? ??? ??? Potentially usable for memory mapped PCI devices in modern hardware (but typically not, due to backward compatibility)
; 0x2700 -> 0x28FF
%define disk_buffer 0x2700
; 0x2900 -> 0x2AFF
%define fat_buffer 0x2900
; 0x2B00 -> 0x2CFF
%define dir_buffer 0x2B00
; copy of partition table, 72 bytes
%define partition_table 0x3000
%define partition_table_SIZE 72
; copy of FAT32 BPB, 33 bytes (+1 to the next value to align to uint16_t)
;0x3048
%define fat32_bpb 0x304A
%define fat32_bpb_SIZE 36
; copy of FAT32 EBPB, 54 bytes
;0x306A
%define fat32_ebpb 0x306E
%define fat32_ebpb_SIZE 54
; FAT32 FSInfo, 512 bytes
;0x30A2
%define fat32_fsinfo 0x30B0
%define fat32_fsinfo_SIZE 512
; some stored state for the fat32 driver
;0x32A2
%define fat32_state 0x34B0
%define fat32_state_SIZE 32
; next free space is 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 0x5200
; High memory addresses for loading kernel (for use with unreal mode and 32bit override)
; file load buffer at 16MB
%define HMEM_load_buffer 0x1000000
;PhysicalAddress = Segment * 16 + Offset
%define SEG_TO_LINEAR(s,o) ((s << 4) + o)
; Offset = physical / (Segment * 16)
%define LINEAR_TO_OFFSET(p,s) ((p / (s << 4)))
; Seg = (physical - offset) / 16
%define LINEAR_TO_SEGMENT(p,o) ((p - o) >> 4)
; create normalized linear addres from seg:off (16:4)
; Segement = linear >> 4 (top 16 bits)
; offset = linear & 0x0F (low 4 bits)
; 20 bytes, passed to loaded kernel
struc SteviaInfoStruct_t
.MemoryMapPtr resd 1
.MemoryMapEntries resd 1
.BPBDataPtr resd 1
.EBPBDataPtr resd 1
endstruc
%endif
%define __INC_MEM

24
include/partition_table.inc
View File

@@ -1,4 +1,4 @@
; Copyright (c) 2023 Elaina Claus
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
@@ -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)
@@ -43,21 +45,5 @@ struc PartTable_t
.partition4 resb 16
endstruc
;Offset Size Description
; 0 1 size of packet (16 bytes)
; 1 1 always 0
; 2 2 number of sectors to transfer (max 127 on some BIOSes)
; 4 4 transfer buffer (0xFFFF:0xFFFF)
; 8 4 lower 32-bits of starting 48-bit LBA
; 12 4 upper 32-bits of starting 48-bit LBA
; needs to be aligned to a uint32_t
struc LBAPkt_t
.size resb 1
.res0 resb 1
.xfer_size resw 1
.offset resw 1
.segment resw 1
.lower_lba resd 1
.upper_lba resd 1
endstruc
%endif
%define __INC_PART_TABLE

63
include/util/error_func.inc Normal file
View File

@@ -0,0 +1,63 @@
; Copyright (c) 2024 Elaina Claus
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; 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_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
mov fs, dx
mov dx, STEVIA_DEBUG_OK
cmp ax, dx
jge error.debug_err
mov dh, 0x4F ; color 0x4F is white text/red background
jmp error.print
.debug_err:
mov dh, 0x5F ; debug case is white text/purple background
; the characters are two bytes in the order of 0xb8000: byte c, byte attribute
; since x86 is le, we store the attribute in the MSB of dx
.print:
mov dl, al
mov word [fs:0x0000], dx
jmp error.stop
.stop:
hlt
jmp short error.stop
%endif
%define __INC_ERROR_FUNC

181
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
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, STACK_START
; ###############
;
; 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 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 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
@@ -83,33 +115,33 @@ 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
call read_vbr_raw
add sp, 0x8
mov ax, VBR_ENTRY
shr ax, 4
push ax ; segment = 7C0
jnc main.goto_vbr
ERROR MBR_ERROR_DISK_READ_ERR ; error in LBA read
; 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
.goto_vbr:
cmp word [VBR_ENTRY + 0x1FE], 0xAA55
je main.sig_ok
ERROR MBR_ERROR_NO_VBR_SIG ; no signature present
.sig_ok:
mov ax, partition_table_SIZE ; 72 bytes of data
push ax
@@ -120,86 +152,21 @@ 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
%include 'BIOS/func/ext_read.inc'
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
; ###############
; End Section
; ###############
%assign bytes_remaining (440 - ($ - $$))
%warning MBR has bytes_remaining bytes remaining for code (MAX: 440 bytes)

590
src/stage2/stage2.nasm
View File

@@ -24,10 +24,25 @@
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
@@ -37,32 +52,39 @@ init:
mov fs, ax ; *
mov gs, ax ; *
mov ss, ax ; Set Stack Segment to 0
mov sp, 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 ss, ax ; Set Stack Segment to 0
mov sp, EARLY_STACK_START ; Set Stack Pointer
mov bp, sp
sub sp, 0x20 ; 32 bytes for local varibles
sti
jmp 0:main
%include "config.inc"
%include "errors.inc"
%include "memory.inc"
; ###############
;
; Extra/Shared Functions
;
; ###############
%include "kmem_func.inc"
%include "partition_table.inc"
%include "util/error_func.inc"
%include "fat32/bpb.inc"
%include "fat32/fat32_structures.inc"
; ###############
; End Section
; ###############
;
; bp - 2 : uint8_t boot_drive
; bp - 4 : uint16_t part_offset
;
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
@@ -127,7 +149,6 @@ main:
add sp, 0x2
ERROR STEVIA_DEBUG_HALT
hcf:
hlt
jmp short hcf
@@ -138,260 +159,7 @@ hcf:
;
; ###############
InitFATDriver:
__CDECL16_ENTRY
.func:
xor eax, eax
mov dword [fat32_state + FAT32_State_t.active_cluster_32], eax
mov dword [fat32_state + FAT32_State_t.active_FAT_cluster_32], eax
mov dword [fat32_state + FAT32_State_t.first_root_dir_sector_32], eax
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 eax, dword [bx + PartEntry_t.lba_start]
mov dword [fat32_state + FAT32_State_t.active_drive_lba_32], eax
.calc_first_fat:
movzx eax, word [fat32_bpb + FAT32_bpb_t.reserved_sectors_16] ; first fat from start of partition
add eax, dword [fat32_state + FAT32_State_t.active_drive_lba_32] ; calculate offset from start of drive
mov dword [fat32_state + FAT32_State_t.first_fat_sector_32], eax
.calc_total_fat:
mov ebx, dword [fat32_ebpb + FAT32_ebpb_t.sectors_per_fat_32]
movzx eax, byte [fat32_bpb + FAT32_bpb_t.fat_count_8]
mul ebx ; result in EDX:EAX, CF set on > 32bit return value
jc InitFATDriver.error ; as a catch for unhandled overflow, just error if value is greater than 32bits
mov dword [fat32_state + FAT32_State_t.fat_size_32], eax
.calc_first_data:
mov edx, dword [fat32_state + FAT32_State_t.first_fat_sector_32]
add eax, edx
mov dword [fat32_state + FAT32_State_t.first_data_sector_32], eax
.get_first_root_dir:
; TODO
jmp InitFATDriver.endp
.error:
ERROR STAGE2_FAT32_INIT_ERROR
.endp:
__CDECL16_EXIT
ret
; TODO: needs validation
; load a file to the high memory buffer for the elf parser
; this involves using the low memory buffer for the bios call and moving the file sector by sector to high memory
;
; SFN is a 8.3 file name, all uppercase, and padded with spaces
; do not add a null byte to the end of the string
; eg. kernel.bin == "KERNEL BIN"
;
; returns first cluster of file if found
; halts/errors if file is not found
; uint32_t SearchFATDIR(uint8_t* SFN);
SearchFATDIR:
__CDECL16_ENTRY
.file_lookup:
.load_first_dir:
mov eax, [fat32_ebpb + FAT32_ebpb_t.root_dir_cluster_32]
mov dword [fat32_state + FAT32_State_t.active_dir_cluster_32], eax
push dword eax ; cluster
lea ax, [dir_buffer]
push ax ; offset
xor ax, ax
push ax ; segment
call ReadFATCluster ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
add sp, 0x8
lea si, [dir_buffer]
jmp SearchFATDIR.empty_dir_entry
.load_next_dir:
; 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
mov eax, dword [fat32_state + FAT32_State_t.active_dir_cluster_32]
push dword eax
call NextCluster ; uint32_t NextCluster(uint32_t active_cluster);
add sp, 0x4
cmp eax, 0x0fff_fff7
jb SearchFATDIR.load_next_dir_next_OK
ERROR STAGE2_FAT32_END_OF_CHAIN
.load_next_dir_next_OK:
; load 512 bytes of directory entries from data sector
mov eax, [fat32_state + FAT32_State_t.active_dir_cluster_32]
push dword eax
lea ax, [dir_buffer] ; cluster
push ax ; offset
xor ax, ax
push ax ; segment
call ReadFATCluster ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
sub sp, 0x8
lea si, [dir_buffer]
.empty_dir_entry:
; check for 0x0 in first byte, if true then there are no more files
; if true we did not find the file, we should error here
cmp byte [si], 0
jne SearchFATDIR.unused_dir_entry
ERROR STAGE2_FAT32_NO_FILE
.unused_dir_entry:
; check for 0xe5 and 0x05 in first byte, if true then this entry is unused, but it is not the last entry.
cmp byte [si], 0xe5
je SearchFATDIR.next_entry
cmp byte [si], 0x05
je SearchFATDIR.next_entry
jmp SearchFATDIR.parse_dir
.next_entry:
; increment offset by 32 bytes to read the next entry in this set of dir entries
; if we are at the end of the buffer, then load the next buffer
add si, 0x20 ; 32 bytes
lea ax, [dir_buffer]
add ax, 0x1FF ; 512 - 1 bytes
cmp si, ax
jae SearchFATDIR.load_next_dir
jmp SearchFATDIR.empty_dir_entry
.parse_dir:
.lfn_check:
; check for ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID (0x0F) in offset 11
; TODO: going to skip LFN for now, since all valid volumes will have SFN's
cmp byte [si+11], 0x0F
je SearchFATDIR.next_entry
.sfn_file_name_check:
push si
push di
mov cx, 0xA ; max of 11 filename length of 11 characters
; si points to the start of the current directory entry
lea di, [BootTarget_str] ; current memory location (8.3 name is at offset 0)
repe cmpsb ; compare the strings
pop di
pop si
jne SearchFATDIR.next_entry
.sfn_entry_found:
mov ax, [si + FAT32_SFN_t.cluster_16_high]
shl eax, 16
mov ax, [si + FAT32_SFN_t.cluster_16_low]
; eax == first cluster of file
.endp:
__CDECL16_EXIT
ret
; 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
NextCluster:
__CDECL16_ENTRY
.func:
mov dword edx, [bp + 4]
mov si, fat32_nc_data
.calc_offset:
; fat_offset = active_cluster * 4
mov eax, 4
mul edx
mov dword [si + FAT32_NextClusterData_t.fat_offset], eax
.calc_fat_sector:
; fat_sector = first_fat_sector + (fat_offset / sector_size)
; entry_offset = fat_offset % sector_size
mov edx, 0xffff_0000
and edx, eax
shr edx, 16
push si
mov si, fat32_bpb
mov cx, word [si + FAT32_bpb_t.bytes_per_sector_16]
pop si
div cx ; DX:AX / cx = fat_sector - first_fat_sector in AX
; DX = remainder (fat_offset mod sector_size)
mov ecx, 0x0000_ffff
and edx, ecx
mov dword [si + FAT32_NextClusterData_t.entry_offset], edx
push si
mov si, fat32_state
mov ecx, dword [si + FAT32_State_t.first_fat_sector_32]
pop si
mov edx, 0x0000ffff
and eax, edx
add eax, ecx ; fat_sector + first_fat_sector
mov dword [si + FAT32_NextClusterData_t.fat_sector], eax
.load_fat_table:
; load correct fat
push dword eax
mov ax, fat_buffer
push ax
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
.read_cluster:
; next_cluster = fat_buffer[entry_offset]
mov ebx, dword [si + FAT32_NextClusterData_t.entry_offset]
mov si, fat_buffer
mov eax, dword [bx+si+0]
.endp:
__CDECL16_EXIT
ret
; uint32_t ClusterToLBA(uint32_t cluster)
ClusterToLBA:
__CDECL16_ENTRY
.func:
mov dword eax, [bp + 4]
sub eax, 2
movzx edx, byte [fat32_bpb + FAT32_bpb_t.sectors_per_cluster_8]
mul edx
add eax, dword [fat32_state + FAT32_State_t.first_data_sector_32]
; eax contains the LBA now
.endp:
__CDECL16_EXIT
ret
; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
ReadFATCluster:
__CDECL16_ENTRY
.func:
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
mov dx, [bp + 4] ; seg
push dx ; uint16_t buf_offset
mov dx, [bp + 6] ; offset
push dx ; unit16_t segment
call read_disk_raw ; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint32_t lba)
add sp, 0x8
.endp:
__CDECL16_EXIT
ret
%include 'fat32/fat32_sys.inc'
; ###############
;
@@ -399,59 +167,13 @@ ReadFATCluster:
;
; ###############
%include 'BIOS/BIOS_sys.inc'
; Wrapper for AH=0x42 INT13h (Extended Read)
; ##############################
;
; BIOS call details
; AH = 42h
; DL = drive number
; DS:SI -> disk address packet
; SYSTEM CONFIGURATION 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, uint32_t lba)
; TODO: this needs validation
read_disk_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 ; uint8_t* kmemset(void* dest, uint8_t val, size_t len);
add sp, 0x6
mov byte [lba_packet + LBAPkt_t.size], 0x10
mov word [lba_packet + LBAPkt_t.xfer_size], 0x0001
mov dword eax, [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 [fat32_ebpb + FAT32_ebpb_t.drive_number_8]
int 0x13
jnc read_disk_raw.endp
ERROR STAGE2_MBR_DISK_READ_ERROR
.endp:
__CDECL16_EXIT
ret
; ##############################
; Prints a C-Style string (null terminated) using BIOS vga teletype call
; void PrintString(char* buf)
@@ -550,217 +272,12 @@ PrintDWORD:
__CDECL16_EXIT
ret
; Sets output to 80x25 16 color text mode via BIOS call
; also clears screen
; void SetTextMode(void)
SetTextMode:
.prolog:
__CDECL16_ENTRY
pushf
.func:
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
.endp:
popf
__CDECL16_EXIT
ret
; See memory.inc for a brief description of E820 mmap function
GetMemoryMap:
__CDECL16_ENTRY
push es ; save segment register
.func:
mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
mov eax, 0xE820 ; select 0xE820 function
xor ebx, ebx ; Continuation value, 0 for the first call
mov dx, (BIOSMemoryMap >> 4)
mov es, dx
xor di, di ; (BIOSMemoryMap >> 4):0 makes di an index into BIOSMemoryMap
mov ecx, AddressRangeDescStruct_t_size
mov edx, 0x534D4150 ; 'SMAP' magic
.loop_L1:
int 0x15
jc GetMemoryMap.error
cmp eax, 0x534D4150
jne GetMemoryMap.no_smap_returned
.no_error:
inc dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
cmp ecx, 20 ; TODO: maybe this could be handled better than just panicing
jb GetMemoryMap.nonstandard_e820 ; non-standard entry found
cmp ebx, 0
je GetMemoryMap.endp ; 0 in ebx means we have reached the end of memory ranges
add di, AddressRangeDescStruct_t_size ; increment di to next descriptor
mov edx, eax ; 'SMAP' to edx
mov eax, 0xE820 ; select E820 function
jmp GetMemoryMap.loop_L1
.error:
ERROR STAGE2_MM_E820_MISC_ERR
.nonstandard_e820:
ERROR STAGE2_MM_E820_NONSTANDARD
.no_smap_returned:
ERROR STAGE2_MM_E820_NO_SMAP
.endp:
pop es
__CDECL16_EXIT
ret
; ##############################
;
; SYSTEM CONFIGURATION FUNCTIONS
;
; ##############################
; disables blinking text mode cursor
disable_cursor:
.prolog:
__CDECL16_ENTRY
pushf
.func:
mov dx, 0x3D4
mov al, 0xA ; low cursor shape register
out dx, al
inc dx
mov al, 0x20 ; bits 6-7 unused, bit 5 disables the cursor, bits 0-4 control the cursor shape
out dx, al
.endp:
popf
__CDECL16_EXIT
ret
;
;NT 0x15 Function 2400 - Disable A20
;Returns:
;
; CF = clear if success
; AH = 0
; CF = set on error
; AH = status (01=keyboard controller is in secure mode, 0x86=function not supported)
;
;INT 0x15 Function 2401 - Enable A20
;Returns:
;
; CF = clear if success
; AH = 0
; CF = set on error
; AH = status (01=keyboard controller is in secure mode, 0x86=function not supported)
;
;INT 0x15 Function 2402 - A20 Status
; Returns:
;
; CF = clear if success
; AH = status (01: keyboard controller is in secure mode; 0x86: function not supported)
; AL = current state (00: disabled, 01: enabled)
; CX = set to 0xffff is keyboard controller is no ready in 0xc000 read attempts
; CF = set on error
;
;INT 0x15 Function 2403 - Query A20 support
;Returns:
;
;CF = clear if success
;AH = status (01: keyboard controller is in secure mode; 0x86: function not supported)
;BX = status.
;
;BX contains a bit pattern:
;
; Bit 0 - supported on keyboard controller
; Bit 1 - if supported on bit 1 of I/O port 0x92
; Bits 2:14 - Reserved
; Bit 15 - 1 if additional data is available.
;
; I/O Port 0x92 infomation:
;
; Bit 0 - Setting to 1 causes a fast reset
; Bit 1 - 0: disable A20; 1: enable A20
; Bit 2 - Manufacturer defined
; 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"
EnableA20:
__CDECL16_ENTRY
push ds
push es
pushf ; save data and extra segment since we touch them and save flags
.a20_check:
cli
xor ax, ax
mov es, ax
not ax ; ax = 0xFFFF
mov ds, ax
mov di, 0x0500 ; scratch location 1
mov si, 0x0510 ; scratch location 2
mov al, byte [es:di]
push ax ; save whatever is at 0x0000:0500, physical location 0x0500
mov al, byte [ds:si]
push ax ; save whatever is at 0xFFFF:0510 [clarification: 0x100500 physical location (0x100500 - 1MB = 0x0500)]
mov byte [es:di], 0x00 ; zero non-wraped location and write 0xFF to it after (ab)using wrapping
mov byte [ds:si], 0xFF ; if the non-wrapped location is 0xFF, then we wraped and A20 is disabled
cmp byte [es:di], 0xFF
pop ax
mov byte [ds:si], al ; restore original contents of scratch location 2
pop ax
mov byte [es:di], al ; restore original contents of scratch location 1
mov ax, 0 ; return 0 if es:di == ds:si (memory wraps)
je EnableA20.end_check
mov ax, 1 ; return 1 if es:di != ds:si (A20 is enabled)
.end_check:
sti
cmp ax, 1
je EnableA20.endp ; A20 is already enabled
mov ax, 0x2403
int 0x15
jc EnableA20.do_fallback_a20 ; carry = error...not supported?
cmp ah, 0
ja EnableA20.do_fallback_a20 ; non-zero return = error as well
mov al, bl
and al, 0000_0010b
cmp al, 0000_0010b
je EnableA20.do_fast_a20 ; if fast a20 is supported use it
jmp EnableA20.do_bios_a20 ; else fall back to enabling via BIOS
.do_fallback_a20:
ERROR STAGE2_A20_FAILED
.do_bios_a20:
mov ax, 0x2401
int 0x15
jmp EnableA20.a20_check
.do_fast_a20:
in al, 0x92 ; read from FAST A20 port
or al, 2 ; bit 0 is a fast reset, bit 1 is fast A20
and al, 0xFE ; make sure bit 0 is 0
out 0x92, al ; enable A20
jmp EnableA20.a20_check
.endp:
popf
pop es
pop ds
__CDECL16_EXIT
ret
EnterUnrealMode:
__CDECL16_ENTRY
.func:
@@ -810,18 +327,13 @@ 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.

176
src/vbr/vbr.nasm
View File

@@ -30,63 +30,97 @@ 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, STACK_START ; Setup stack
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
ja main.load_stage2
ERROR VBR_ERROR_WRONG_FAT_SIZE
.load_stage2: ; read sectors 1-63 to stage2 entry point
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
; read sectors 1-63 to stage2 entry point
.load_stage2:
xor ax, ax
push ax ; upper_lower_lba = 0
mov bx, fat32_bpb ; bx now points to aligned memory structure
mov ax , 1
push ax ; lower_lower_lba = 1
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
push ax ; offset = 0
; 07E0:0
; 07E0:0 = 0x00007e00
mov ax, STAGE2_ENTRY
shr ax, 4
push ax ; segment = 7E0
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 +131,15 @@ 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
; ###############
; Required BIOS function(s)
; ###############
; Wrapper for AH=0x42 INT13h (Extended Read)
;
; BIOS call details
; AH = 42h
; DL = drive number
; DS:SI -> disk address packet
;
; 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)