Wed Nov 15 18:51:16 UTC 2023
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316
src/@bootsec.asm
Normal file
316
src/@bootsec.asm
Normal file
@ -0,0 +1,316 @@
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base equ 0x7C00
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org base
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; boot sector identification bytes:
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jmp short init ; EB3C
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nop ; 90
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; OEM vendor field
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vendor .space 8, 0x20
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; bios parameter block
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ss .space 2 ; word bytes per sector
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sc .space 1 ; byte sectors per cluster
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rsc .space 2 ; word reserved sector count
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fn .space 1 ; byte number of fat tables
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rde .space 2 ; word root disk entries
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ts .space 2 ; word total sectors
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md .space 1 ; byte media descriptor byte
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fs .space 2 ; word sectors per fat
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spt .space 2 ; word sectors per track
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nos .space 2 ; word number of sides/heads
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hs .space 4 ; dword partition offset
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lts .space 4 ; dword large total sectors
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; extended bios parameter block data
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.space base+03Eh-$
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init xor ax, ax ; ax as quick zero value
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; initialize all segment registers
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; the docs say we cant rely on them to have any sensible values
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; we only work with the first 64kB per default
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; so we set all of them to zero
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov sp, ax
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jmp main
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; print AX in base BX
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; destroys DX
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putnum xor dx, dx
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div bx
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test cx, cx
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loopnz .pad
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test ax, ax
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je .nib
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.pad push dx
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call putnum
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pop dx
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; print lower DL as digit
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.nib add dl, 0x30
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cmp dl, 0x3a
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jl putc
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add dl, 7
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; print DL as char
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putc mov ah, 0x0e
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mov al, dl
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int 0x10
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ret
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; print str at SI
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; NUL-terminated
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puts lodsb
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test al, al
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jz .l01
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mov dl, al
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call putc
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jmp puts
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.l01 ret
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; print a newline
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newlin mov dl, 0x0A
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call putc
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mov dl, 0x0D
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jmp putc
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; print register set
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; order AX CX DX BX BP SI DI IP
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; trashes flags
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debug push di
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push si
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push bp
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push bx
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push dx
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push cx
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push ax
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mov si, sp
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call dump
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pop ax
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pop cx
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pop dx
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pop bx
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pop bp
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pop si
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pop di
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ret
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; dump the 8 words at SI
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dump lea di, [si+16]
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mov bx, 0x10
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.loop lodsw
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mov cx, 4
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call putnum
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mov dl, 020h ; space char
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call putc
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cmp si, di
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jc .loop
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jmp newlin
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; Advantages over using int13h directly:
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; - Translation from linear sector number into CHS data
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; - Reads across different tracks.
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; Older BIOSes don't support that.
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; - Nearby sector reads/writes are coalesced into one int 13h call
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; This improves performance on real hardware.
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; Only floppies are supported, and only variants with two sides
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; This includes the standard 5 1/4 360kB and 3 1/2 1.44MB formats
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; When a sector is requested, int13h is not called yet, the parameters
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; for int 13h are recorded. When the next sector is requested, either
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; it it suitable for coalescing, then the recorded parameters are
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; adjusted. When the sector is not suitable for coalescing, the
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; previous sector is read/written and the parameters for the new
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; sector are put into the record. If the program is done with listing
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; the wanted sectors, another function can be called to force doing
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; the recorded io request
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; Select a sector for a disk operation
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; IN ax linear sector number
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; cx number of sectors to read/write
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; dl drive number
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sector push ax
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push cx
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; split up sector number into CHS data
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; divisor is sectors per track field in bios parameter block
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; quotient al as track number
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; remainder ah as sector number (starting with 0)
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div byte [spt]
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; phys sector number cl (starting with 1)
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mov cl, ah
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inc cl
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; get head number dh from lowest bit of track number
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; hard-coded assumption: two-sided floppy
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mov dh, al
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and dh, 1
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; cylinder number ch is track number, except the head number shifted out
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mov ch, al
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shr ch, 1
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; Unlucky if different head (dh)
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cmp byte dh, [disk_dh]
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jne .miss
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; Unlucky if different track (ch) or not subsequent sector (cl + number of op sectors)
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mov ax, cx
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sub al, [disk_al]
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cmp ax, [disk_cx]
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jne .miss
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; We are lucky! We can extend the current request by increasing the number of op sectors
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; Do nothing else
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inc byte [disk_al]
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jmp .end
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; The sector we just selected does not fit into the recorded io request
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; So we submit that request first and then record a new io request
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.miss: push cx
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push dx
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call diskio
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pop dx
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pop cx
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; Record new io request
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mov word [disk_cx], cx
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mov byte [disk_dh], dh
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mov byte [disk_al], 1 ; only one sector yet
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.end pop cx
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pop ax
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inc ax
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loop sector
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ret
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; Do the io request we recorded previously now
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diskio mov ax, [disk_ax]
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mov cx, [disk_cx]
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mov dx, [disk_dx]
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mov bx, [disk_bx]
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; no-op if amount of sectors is zero
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cmp al, 0
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je .ret
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; TODO: retry is needed for real floppies
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call debug
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int 0x13
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jc .ret
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; Advance read/write pointer in memory
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mov ah, 0
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mov cl, 9
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shl ax, cl
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add word [disk_bx], ax
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; Reset op sector length, work done
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mov byte [disk_al], 0
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.ret ret
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; Load a file from disk to 0x7C00
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; calculate size of the directory in sectors
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load: mov ax, [rde]
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mov cl, 4 ; sector=512b, entry=32b -> shift 4 bits
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shr ax, cl
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mov cx, ax
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push cx ; remember number of dir entries for later
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; calculate start of second fat table
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mov ax, [fs] ; read fat table length
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push ax
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add cx, ax ; make cx size of FAT + dir
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inc ax ; add one for the boot sector
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; Read second FAT and directory into buffer
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mov byte [disk_ah], 2 ; set read OP
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mov word [disk_bx], fatbuf ; write into our own buffer
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call sector
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call diskio
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; get address of root directory in frame
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pop bx
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mov cl, 9
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shl bx, cl
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add bx, fatbuf
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pop dx
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mov word [disk_bx], 0x7C00
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; search through root directory
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.loop: mov si, bx
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mov ax, [bx+0x1A]
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mov di, fname
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mov cx, 11
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repe cmpsb
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je .cloop
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add bx, 0x20
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or byte [bx], 0
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jz .end
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jmp .loop
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; calculate sector offset in cluster area
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.cloop push ax
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sub ax, 2
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mov ch, 0
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mov cl, [sc]
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push cx
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mul cx
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; calculate sector offset from root directory
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mov dx, [rde]
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mov cl, 4 ; sector=512b, entry=32b -> shift 4 bits
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shr dx, cl
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add ax, dx
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; add length of fat tables
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add ax, [fs]
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add ax, [fs]
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; plus 1 for the boot sector
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inc ax
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; load cluster
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pop cx
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call sector
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; follow fat chain
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pop ax
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mov si, ax
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shr si, 1
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add si, ax
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mov dx, [fatbuf+si]
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; shift value if needed
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test ax, 1
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jz .noshr
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mov cl, 4
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shr dx, cl
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.noshr and dx, 0x0FFF
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mov ax, dx
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cmp ax, 0xFF0
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jc .cloop
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.fend: call diskio
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.end: ret
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main: mov byte [disk_dl], dl
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call load
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db 0xEA ; jmp far 0:0x7C00
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dw 0x7C00, 0
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; register buffer for disk io
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disk_al db 0 ; number of sectors to read
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disk_ah db 2 ; 2=read op
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disk_cl db 1 ; sector number
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disk_ch db 1 ; cylinder number
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disk_dl db 0 ; drive number
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disk_dh db 0 ; head number
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disk_bx dw fatbuf ; data buffer addr, advanced by 'diskio'
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disk_ax equ disk_al
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disk_cx equ disk_cl
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disk_dx equ disk_dl
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fname db "@RDOS ", "COM"
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.space base+01FEh-$
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dw 0xAA55
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; buffer for fat table and root directory
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; we load it together to save an int 13h read
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; at the cost of having to calculate offset of rootdir
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fatbuf equ $
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641
src/@rdos.asm
641
src/@rdos.asm
@ -1,633 +1,18 @@
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org 0x700
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cseg equ 0x0
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org 600h
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%include "version.inc"
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jmp end
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jmp _entry
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banner db "RDOS KERNEL 1.0", 0x0A, 0x0D, '$', 0x1A
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_entry call .l01
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.l01 pop ax
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sub ax, .l01
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mov cl, 4
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shr ax, cl
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mov cx, cs
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add cx, ax
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push cx
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mov ax, start
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push ax
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retf
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add [bx+si], al
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add al, al
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add ax, ax
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rep movsb
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cs xor word [bp], 0x7C00
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xor word [bp+04h], 0x7C00
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lock es xor word [04h], 0x7C00
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;;; Character I/O
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dw foo
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; direct console I/O
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; IN dl character to output or 0xFF if input
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; OUT al character to read
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conio cmp dl, 0xFF
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je conin
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end hlt
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jmp end
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; raw console output
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; IN dl character
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conout xchg ax, dx
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mov ah, 0x0e
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mov bx, 7
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int 0x10
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ret
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; read character from console
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; OUT al character or zero
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conin call const
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test al, al
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jz .ret
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mov al, 0
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int 0x16
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.ret ret
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; check if character has characters ready
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; OUT al 0xFF if data, 0 if none
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const mov ah, 1
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int 0x16
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jz .emp
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mov ax, 0xFF
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ret
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.emp mov al, 0
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ret
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; dummy: write to auxillary dev
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auxout ret
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; dummy: read from auxillary dev
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auxin mov al, 0x1A
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ret
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; dummy: lister out
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lstout ret
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; character input with echo
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; OUT al character
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getc call const
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test al, al
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jz getc
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call conin
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push ax
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mov dl, al
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call putc
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pop ax
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ret
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; character input without echo
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readc call const
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test al, al
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jz readc
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jmp conin
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; character output
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; IN dl character
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putc jmp conout
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; output character string
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; IN ds:dx far ptr to string, '$'-terminated
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puts push si
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mov si, dx
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.loop lodsb
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cmp al, '$'
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je .ret
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mov dl, al
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call putc
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jmp .loop
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.ret pop si
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ret
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; send a beep ctl to console
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beep mov dl, 0x07
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jmp conout
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; buffered input
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; IN ds:dx far ptr to buffer
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gets mov si, dx
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mov cx, [si]
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mov ch, 0
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; ch = actual number of chars
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; cl = maximum number of chars
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.loop call readc
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cmp al, 0x0D
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je .cr
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cmp al, 0x08
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je .bs
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cmp al, 0x20
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jc .loop
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; check if there is space in the buffer
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; emit a beep if not
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mov dl, cl
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dec dl
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cmp ch, dl
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jc .append
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call beep
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jmp .loop
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; append to buffer
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.append mov bh, 0
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mov bl, ch
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mov [si+2+bx], al
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inc ch
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mov dl, al
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call putc
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jmp .loop
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; handle backspace
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.bs: test ch, ch
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jz .loop
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mov dl, 0x08
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call putc
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mov dl, 0x20
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call putc
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mov dl, 0x08
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call putc
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dec ch
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jmp .loop
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; handle carriage return
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.cr mov bx, 0
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mov bl, ch
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mov [si+2+bx], al
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mov [si], cx
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mov dl, 0x0A
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call putc
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mov dl, 0x0D
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call putc
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ret
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;;; System functions
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; Return OS version from version.inc
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ver mov bx, bdosver | 0x1000
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ret
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;;; Disk i/o
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%include "bpb.inc"
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; dflags bitfields
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DRVLOG equ 0x01 ; bit 0 - drive logged in (see drvnum)
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DRVCTL equ 0x02 ; bit 1 - controller configured
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DRVEXT equ 0x04 ; bit 2 - EBIOS supported
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DIRTY equ 0x08 ; bit 3 - dskbuf dirty
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DRVCHS equ 0x10 ; bit 4 - CHS geometry known
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; Wrapper around int 13h
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int13 int 0x13
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; TODO: on error: reset & retry
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; TODO: record errors
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; TODO: multi-track reading
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; TODO: handle DMA boundaries
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ret
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; get drive parameters
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; read BIOS int13h/AH=8 values
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; DPT data gets copied over our dpt
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; CHS data gets inserted into our bpb
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getprm test byte [dflags], DRVEXT
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jnz .ret
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; fallback non-zero values (5 1/4", 160kB)
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mov word [drvspt], 8
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mov word [drvspc], 8
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; do the query
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mov ah, 8
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mov dl, [biosnum]
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call int13
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; bail out if error
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jc .ret
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; ignore CHS values if odd
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test cl, cl
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jz .nochs
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; get and store sector number
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and cx, 0x3F
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mov word [drvspt], cx
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; get and store number heads
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xchg dl, dh
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and dx, 0xFF
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inc dx
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; multiply with sectors per track
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mov ax, dx
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mul cx
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; store sectors per cylinder
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mov [drvspc], ax
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; test if DPT ptr is non-zero
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.nochs mov ax, es
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or ax, di
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test ax, ax
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jz .ret
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; copy BIOS dpt table over ours
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;mov dx, dpt
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;mov bx, di
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;mov cx, 11
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;call lodfar
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.ret ret
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; select a drive for io
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; IN dl drive number
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; dont do anything if drive already selected
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select cmp dl, [drvnum]
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je getprm.ret
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; clear out current contents
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push dx
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call flush
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mov ax, 0xFFFF
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mov [drvseek], ax
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mov [drvseek+2], ax
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and word [dflags], ~(DRVLOG|DRVCTL|DRVEXT|DIRTY|DRVCHS)
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pop dx
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; set current drive number
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mov [drvnum], dl
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; fork off if hdd
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cmp dl, 2
|
||||
jnc loghdd
|
||||
|
||||
logfdd mov [biosnum], dl
|
||||
and dx, 0x0D
|
||||
; query bios for geometry and DPT
|
||||
call getprm
|
||||
; assume 512 bytes per sector
|
||||
; TODO: read this from DPT
|
||||
mov byte [drvss], 2
|
||||
; fill partition offset with zeroes
|
||||
xor ax, ax
|
||||
mov di, drvoff
|
||||
stosw
|
||||
stosw
|
||||
; fill partition end with 1's
|
||||
not ax
|
||||
stosw
|
||||
stosw
|
||||
; shared code with loghdd
|
||||
jmp rdbpb
|
||||
|
||||
; Log in a drive on a hard disk
|
||||
; IN dl bits 0-1: partition number
|
||||
; bits 2-7: drive number
|
||||
; Partition offset is read from MBR
|
||||
; split drive & partition number
|
||||
loghdd mov dh, dl
|
||||
and ah, 0x3
|
||||
shr dl, 1
|
||||
shl dl, 1
|
||||
add dl, 0x80
|
||||
; partition number in DH
|
||||
mov byte [biosnum], dl
|
||||
push dx
|
||||
; test for EBIOS extensions
|
||||
mov ah, 0x41
|
||||
mov bx, 0x55AA
|
||||
call int13
|
||||
sbb bx, 0xAA55
|
||||
jnz .noeb
|
||||
; enable EBIOS and assume controller is configured
|
||||
or word [dflags], DRVCTL | DRVEXT
|
||||
; hard disks are always assumed to be 512 bytes / sector
|
||||
.noeb mov byte [drvss], 2
|
||||
; query BIOS for geometry
|
||||
call getprm
|
||||
or word [dflags], DRVCHS
|
||||
; read MBR
|
||||
xor ax, ax
|
||||
xor dx, dx
|
||||
call map
|
||||
; get partition number
|
||||
pop bx
|
||||
xor bh, bh
|
||||
mov cl, 4
|
||||
sal bx, cl
|
||||
; bail out if partition undef
|
||||
cmp byte [dskbuf+0x1be+bx+4], 0
|
||||
je .ret
|
||||
; load partition offset
|
||||
mov ax, [dskbuf+0x1be+bx+8]
|
||||
mov dx, [dskbuf+0x1be+bx+8+2]
|
||||
; store partition offset
|
||||
mov [drvoff], ax
|
||||
mov [drvoff+2], dx
|
||||
; add partition length
|
||||
add ax, [dskbuf+0x1be+bx+12]
|
||||
adc dx, [dskbuf+0x1be+bx+12+2]
|
||||
; partitions after 4 TB mark not allowed
|
||||
jc .ret
|
||||
; store partition end
|
||||
mov [drvend], ax
|
||||
mov [drvend+2], dx
|
||||
.ret ret
|
||||
|
||||
; parse bios parameter block from drvoff
|
||||
; drvoff and biosnum need to be set up
|
||||
rdbpb mov ax, [drvoff]
|
||||
mov dx, [drvoff+2]
|
||||
call map
|
||||
; read partition start
|
||||
mov ax, [drvoff]
|
||||
mov dx, [drvoff+2]
|
||||
; add reserved sectors
|
||||
add ax, [dskbuf+BPBOFF+BPBRSC]
|
||||
adc dx, 0
|
||||
jc .ret
|
||||
; save offset of fat table
|
||||
mov [drvfat], ax
|
||||
mov [drvfat+2], dx
|
||||
; calculate length of all fat tables
|
||||
mov ah, 0
|
||||
mov al, [dskbuf+BPBOFF+BPBFN]
|
||||
mov dx, [dskbuf+BPBOFF+BPBFS]
|
||||
mov [drvfn], dx
|
||||
mul dx
|
||||
add ax, [drvfat]
|
||||
adc dx, [drvfat+2]
|
||||
; save offset of root directory
|
||||
mov [drvrd], ax
|
||||
mov [drvrd+2], dx
|
||||
; calculate length of root directory
|
||||
mov ax, [dskbuf+BPBOFF+BPBRDE]
|
||||
mov cl, [drvss]
|
||||
add cl, 2
|
||||
shr ax, cl
|
||||
; read offset to cluster area
|
||||
; read cluster size
|
||||
.ret ret
|
||||
|
||||
; map sector into dskbuf
|
||||
; skip doing a read if sector number matches
|
||||
; IN dx:ax absolute sector number
|
||||
map cmp ax, [drvseek]
|
||||
jne .do
|
||||
cmp dx, [drvseek+2]
|
||||
jne .do
|
||||
ret
|
||||
; flush previous contents
|
||||
.do push ax
|
||||
push dx
|
||||
call flush
|
||||
pop dx
|
||||
pop ax
|
||||
; set sector number
|
||||
mov [drvseek], ax
|
||||
mov [drvseek+2], dx
|
||||
; issue read cmd
|
||||
mov ch, 2
|
||||
jmp diskio
|
||||
|
||||
; mark dskbuf as containing unwritten changes
|
||||
dirty or word [cs:dflags], DIRTY
|
||||
l002 ret
|
||||
|
||||
; flush buffer if dirty
|
||||
flush test word [cs:dflags], DIRTY
|
||||
jz l002
|
||||
; issue write cmd
|
||||
mov ch, 3
|
||||
|
||||
; Do disk I/O
|
||||
; IN ch 2 = read
|
||||
; 3 = write
|
||||
; Sector number is read from [drvseek]
|
||||
diskio mov cl, 1 ; read len
|
||||
; DS := ES := CS
|
||||
mov ds, [cs:dseg]
|
||||
; check if ebios supported
|
||||
test word [dflags], DRVEXT
|
||||
jz .noext
|
||||
; set up regs for ebios call
|
||||
xchg ax, cx
|
||||
or ah, 0x40
|
||||
jmp .do
|
||||
; check if we can skip controller reset
|
||||
.noext test word [dflags], DRVCTL
|
||||
jnz .norst
|
||||
; do controller reset
|
||||
mov dl, [biosnum]
|
||||
mov ah, 0
|
||||
call int13
|
||||
or word [dflags], DRVCTL
|
||||
; put linear sector num into dx:ax
|
||||
.norst mov ax, [drvseek]
|
||||
mov dx, [drvseek+2]
|
||||
; dx:ax = linear count
|
||||
div word [drvspc]
|
||||
; TODO: is it possible to get an overflow here?
|
||||
xchg ax, dx
|
||||
; dx = cylinder, ax = head * spt + sector
|
||||
div byte [drvspt]
|
||||
; dx = cylinder, al = head, ah = sector
|
||||
xchg ax, dx
|
||||
xchg al, ah
|
||||
ror al, 1
|
||||
ror al, 1
|
||||
or al, dh
|
||||
inc ax
|
||||
; dl: head number
|
||||
; ah bit 0-7: cylinder bits 0-7
|
||||
; al bit 0-5: sector bits 0-5
|
||||
; al bit 6-7: cylinder bits 8-9
|
||||
; shuffle values around for bios
|
||||
xchg ax, cx
|
||||
xchg dh, dl
|
||||
.do mov dl, [biosnum]
|
||||
; ah: subfunction selected via cx previously
|
||||
; al: 1 = reading 1 sector
|
||||
; cx: sector and cylinder number
|
||||
; dh: head number
|
||||
; dl: drive number
|
||||
push es
|
||||
push si
|
||||
mov si, dap
|
||||
les bx, [si+4]
|
||||
call int13
|
||||
pop si
|
||||
pop es
|
||||
jc .err
|
||||
; clear dirty flag on success
|
||||
and word [dflags], ~DIRTY
|
||||
clc
|
||||
ret
|
||||
; assume controller is misconfigured
|
||||
.err and word [dflags], ~DRVCTL
|
||||
; exit with carry flag set
|
||||
stc
|
||||
ret
|
||||
|
||||
;;; Export functions as syscalls
|
||||
; SP, BP, SI, DI and ES must be preserved by kernel code
|
||||
; DL, DX or DS:DX is input argument from prog
|
||||
; AL, BX or ES:BX is return value to prog
|
||||
|
||||
srb equ 0x8000
|
||||
srw equ 0x4000
|
||||
|
||||
; DOS style syscall interface
|
||||
int21h push bx
|
||||
xor bx, bx
|
||||
mov bl, ah
|
||||
jmp sysc
|
||||
|
||||
; CP/M-86 style syscall interface
|
||||
intE0h push bx
|
||||
xor bx, bx
|
||||
mov bl, cl
|
||||
|
||||
; bx = syscall number
|
||||
; stack must be -> BX IP CS FL
|
||||
; for return to prog
|
||||
sysc sti
|
||||
cld
|
||||
add bx, bx
|
||||
mov bx, [cs:bx+stab]
|
||||
test bh, srw >> 8 ; fork off bx returns
|
||||
jnz .l02
|
||||
test bh, srb >> 8 ; fork off al returns
|
||||
jnz .l01
|
||||
; syscall with no return value
|
||||
push dx
|
||||
push cx
|
||||
push ax
|
||||
push ds
|
||||
call bx
|
||||
pop ds
|
||||
pop ax
|
||||
pop cx
|
||||
pop dx
|
||||
pop bx
|
||||
iret
|
||||
; syscalls returning byte in al
|
||||
.l01 push dx
|
||||
push cx
|
||||
push ds
|
||||
and bh, ~(srb >> 8)
|
||||
call bx
|
||||
pop ds
|
||||
pop cx
|
||||
pop dx
|
||||
pop bx
|
||||
iret
|
||||
; syscalls returning bx or es:bx
|
||||
.l02 add sp, 2 ; discard bx on the stack
|
||||
push dx
|
||||
push cx
|
||||
push ax
|
||||
push ds
|
||||
and bh, ~(srw >> 8)
|
||||
call bx
|
||||
pop ds
|
||||
pop ax
|
||||
pop cx
|
||||
pop dx
|
||||
ret
|
||||
|
||||
start xor ax, ax
|
||||
mov ds, ax
|
||||
|
||||
; install int20h handler
|
||||
mov word [4*0x20], start
|
||||
mov [4*0x20+2], cs
|
||||
; install int21h handler
|
||||
mov word [4*0x21], int21h
|
||||
mov [4*0x21+2], cs
|
||||
; install intE0h handler
|
||||
mov word [4*0xE0], intE0h
|
||||
mov [4*0xE0+2], cs
|
||||
|
||||
mov ax, cs
|
||||
mov ds, ax
|
||||
mov [dseg], ax
|
||||
|
||||
; print banner
|
||||
mov dx, banner
|
||||
call puts
|
||||
|
||||
; read cmdline
|
||||
mov dl, '>'
|
||||
call putc
|
||||
mov dx, inbuf
|
||||
mov byte [inbuf], 72
|
||||
call gets
|
||||
|
||||
halt sti
|
||||
hlt
|
||||
jmp halt
|
||||
|
||||
section .rodata
|
||||
|
||||
; syscall table
|
||||
stab dw 0 ; 0 reboot
|
||||
dw getc + srb ; 1 console input
|
||||
dw putc ; 2 console output
|
||||
dw auxin ; 3 reader in
|
||||
dw auxout + srb ; 4 puncher out
|
||||
dw lstout ; 5 lister out
|
||||
dw 0 ; 6 direct console i/o
|
||||
dw 0 ; 7 read i/o byte
|
||||
dw 0 ; 8 get i/o byte
|
||||
dw puts ; 9 string output
|
||||
dw gets ; 10 string input
|
||||
dw 0 ; 11 console status
|
||||
dw ver ; 12 get version number
|
||||
dw 0 ; 13 reset disks
|
||||
dw 0 ; 14 set drive
|
||||
dw 0 ; 15 open file
|
||||
dw 0 ; 16 close file
|
||||
dw 0 ; 17 find first
|
||||
dw 0 ; 18 find next
|
||||
dw 0 ; 19 delete file
|
||||
dw 0 ; 20 sequential read
|
||||
dw 0 ; 21 sequential write
|
||||
dw 0 ; 22 create file
|
||||
dw 0 ; 23 rename file
|
||||
dw 0 ; 24 get login vector
|
||||
dw 0 ; 25 get drive
|
||||
dw 0 ; 26 set dma addr
|
||||
dw 0 ; 27 alloc vector
|
||||
dw 0 ; 28 set drive r/o
|
||||
dw 0 ; 29 get r/o vector
|
||||
dw 0 ; 30 file attr
|
||||
dw 0 ; 31 get addr of disk parameter block
|
||||
dw 0 ; 32 get user number
|
||||
dw 0 ; 33 random read
|
||||
dw 0 ; 34 random write
|
||||
dw 0 ; 35 calculate file size
|
||||
dw 0 ; 36 calculate cur record number
|
||||
dw 0 ; 37 reset drive
|
||||
dw 0 ; 38
|
||||
dw 0 ; 39
|
||||
dw 0 ; 40 random write with block init
|
||||
stab_e nop
|
||||
|
||||
section .data
|
||||
|
||||
dap db 0x10, 0
|
||||
dw 1
|
||||
dw dskbuf
|
||||
dseg dw 0
|
||||
drvseek dw 0,0,0,0
|
||||
|
||||
; bit 0 (1) - drive logged in (see drvnum)
|
||||
; bit 1 (2) - controller configured
|
||||
; bit 2 (4) - EBIOS supported
|
||||
; bit 3 (8) - dskbuf dirty
|
||||
dflags dw 0
|
||||
|
||||
section .bss
|
||||
|
||||
; drive currently logged in
|
||||
drvnum resb 1
|
||||
; number, just for bios
|
||||
biosnum resb 1
|
||||
|
||||
; Information for logged in drive
|
||||
drvss resb 1 ; sector size, 2^(7+n) bytes
|
||||
drvcs resb 1 ; cluster size, 2^(7+n) bytes
|
||||
alignb 4
|
||||
drvspt resb 2 ; sectors per track
|
||||
drvspc resb 2 ; sectors per cylinder
|
||||
drvoff resb 4 ; partition offset
|
||||
drvend resb 4 ; first sector after the partition
|
||||
drvfat resb 4 ; offset to fat table
|
||||
drvrd resb 4 ; offset of root directory
|
||||
drvcla resb 4 ; offset to cluster area
|
||||
drvfn resb 2 ; sectors per fat table
|
||||
|
||||
; disk buffer for I/O operations
|
||||
alignb 2
|
||||
dskbuf resb 1024
|
||||
|
||||
inbuf resb 128
|
||||
foo equ end+040h
|
||||
|
||||
@ -2,14 +2,14 @@
|
||||
; This is primarily for testing purposes
|
||||
org 0x0100
|
||||
|
||||
main: mov si, string
|
||||
main mov si, str
|
||||
mov ah, 0x0e
|
||||
xor bx, bx
|
||||
.loop: lodsb
|
||||
main1 lodsb
|
||||
test al, al
|
||||
jz .end
|
||||
jz main2
|
||||
int 0x10
|
||||
jmp .loop
|
||||
.end: ret
|
||||
jmp main1
|
||||
main2 ret
|
||||
|
||||
string: db "Hello world!", 0x0A, 0x0D, 0
|
||||
str db "Hello world!", 0x0A, 0x0D, 0
|
||||
|
||||
Loading…
Reference in New Issue
Block a user