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> OS Construction > CD/DVD/BD Loader: INT 13h, Function 42 help...Goto page Previous 1, 2, 3 |
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shutdownall 09 Mar 2012, 00:39
I wonder if there is a difference between
TIMES 33 db 0 and db 33 dup(0)  |
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09 Mar 2012, 00:39 |
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smiddy 09 Mar 2012, 03:28
edfed wrote:
 Thanks for the complement! |
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09 Mar 2012, 03:28 |
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smiddy 09 Mar 2012, 03:29
shutdownall wrote: I wonder if there is a difference between  |
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09 Mar 2012, 03:29 |
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den010 03 Aug 2014, 13:06
Hi Smiddy,
Can you share to me your whole working code? or post it here instead? Thank you _________________ I'm a Completely Newbie : Need help much  |
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03 Aug 2014, 13:06 |
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smiddy 03 Aug 2014, 13:14
Nope. I'm not ready to.
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03 Aug 2014, 13:14 |
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smiddy 07 Dec 2014, 04:41
den010 here ya go man, hope it helps ya.
Code: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; ;; Project : smiddyOS (CD-ROM Booter) ;; ;; Author : smiddy ;; ;; Website : ;; ;; Date : December 6, 2014 ;; ;; Quick Information: Compact Disc bootloader beta to load bootable ;; ;; software. ;; ;; Filename : cdboot3.asm ;; ;; Assembler Command: Using Fresh IDE v2.2.2 ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; ;; Usage: Using CDBOOT3.BIN as the boot loader from the created ISO from ;; ;; the CD-ROM creating CDROM.ASM from within Fresh IDE. Please ;; ;; visit: ;; ;; ;; ;; http://fresh.flatassembler.net/index.cgi?page=content/2_download.txt#H1. ;; ;; ;; ;; You can also build this with FASM, it is after all in the FASM ;; ;; sematics. Visit http://flatassembler.net/ to get the latest ;; ;; version. As of this writing, it is 1.71.29, please donate if you ;; ;; are able, it is a fantastic work. ;; ;; ;; ;; See CDROM.ASM for further details. ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ;; ;; v1.00 - Beta release; CD-ROM compatible booter, capable of booting ;; ;; bootable software, in this case SMIDDYOS.EXE. Change the file ;; ;; name to one you wish to load instead. The loader expects to be ;; ;; booted at 0060:0000 (600h linear) and the bootable software gets ;; ;; loaded at 0200:0000 (2000h linear) which is launched from ;; ;; 0202:0000 (2020h linear) since SMIDDYOS.EXE is a MZ EXE (DOS ;; ;; executeable). You can change the JMP to what ever you wish to ;; ;; make your code work. ;; ;; ;; ;; Limitations include that the boot file needs to be in the root ;; ;; directory and the root directory can not be longer than one CD ;; ;; sector (2048 bytes) in size. ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; format binary as "bin" ; Tell FASM to make an BIN image ORG 0 BootSector: ; Label in order to determine size of ; code for padding at the end. ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Start Boot Procedure ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Begin: ; Begining of instructions CLI ; Turn off interrupts mov ax,0060h ; Boot Segment (no need to copy there) mov ds,ax mov es,ax MOV [CDDriveNumber],DL ; Save boot drive, right away MOV AX,7000h MOV DS,AX ; Segment saved variables for SmiddyOS MOV BX,535h ; Offset of boot drive saved variable MOV [DS:BX],DL ; Save the boot drive for SmiddyOS use MOV AX,60h MOV DS,AX ; Reset segment XOR AX,AX ; Zero out the stack segment MOV SS,AX MOV SP,5FEh ; 0000:05FE is the stack for loader STI ; Turn interrupts back on MOV SI,WelcomeMessage ; Tell everyone hello CALL PrintString ; Print the welcome message MOV SI,TheEndOfTheLine ; Go to the next line CALL PrintString MOV AL,[CDDriveNumber] ; Load drive number in for comparison CMP AL,0 ; Compare to known BAD drive number for ; CD/DVD/BD JE Failure ; If it is, it failed. ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Get Status (Bootable CD-ROM) ;; ;; ;; ;; Call with: AX = 4B01H ;; ;; DL = Drive number ;; ;; DS:SI = Empty specification packet (needs to be 13h in size) ;; ;; ;; ;; Return: If Function Successful, ;; ;; Carry Flag = Clear ;; ;; ;; ;; If Function Unsuccessful, ;; ;; Carry Flag = Set ;; ;; AX = Status code ;; ;; ;; ;; DS:SI = Specification packet filled ;; ;; Offset Size Description ;; ;; 00h db size of packet in bytes (13h) ;; ;; 01h db boot media type ;; ;; Bit(s) Description ;; ;; 3-0 media type. ;; ;; 0000 no emulation. ;; ;; 0001 1.2M diskette. ;; ;; 0010 1.44M diskette. ;; ;; 0011 2.88M diskette. ;; ;; 0100 hard disk ;; ;; Other reserved ;; ;; 5-4 reserved (0) ;; ;; 6 image contains ATAPI driver ;; ;; 7 image contains SCSI driver(s) ;; ;; 02h db drive number ;; ;; 00h floppy image ;; ;; 80h bootable hard disk ;; ;; 81h-FFh nonbootable or no emulation drive ;; ;; 03h db CD-ROM controller number ;; ;; 04h dd Logical Block Address (LBA) of disk image to emulate;; ;; 08h dw device specification (same as boot media type plus) ;; ;; (IDE) bit 0: Drive is slave instead of master ;; ;; (SCSI) bits 7-0: LUN and PUN ;; ;; bits 15-8: Bus number ;; ;; 0Ah dw segment of 3K buffer for caching CD-ROM reads ;; ;; 0Ch dw load segment for initial boot image (if 0000h, load ;; ;; at segment 07C0h; only valid for INT 13h/AH=4Ch) ;; ;; 0Eh dw number of 512-byte virtual sectors to load (only ;; ;; valid for INT 13h/AH=4Ch) ;; ;; 10h db low byte of cylinder count (for INT 13/AH=08h) ;; ;; 11h db sector count, high bits of cylinder count ;; ;; (for INT 13h/AH=08h) ;; ;; 12h db head count (for INT 13h/AH=08h) ;; ;; ;; ;; Comments: ;; ;; ;; ;; The Function is used to get the status of the CD/DVD/BD. This function;; ;; is called first for "no emulation" booting of optical media. If the ;; ;; Function is successful, the carry flag is clear, else carry flag is ;; ;; set and AX register returns status code. ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; GetBootedCDStatus: MOV DL,[CDDriveNumber] ; Prepare to read CD-ROM, load boot ; drive MOV AH,4Bh ; Use function 4Bh MOV AL,1 MOV SI,DiskResultsBuffer ; Results buffer to load INT 13h ; Call Check Extensions Present? JC Failure ; Need to engage the Failure Procedure MOV AH,255 ; Load proposed error code (255 is our ; failure code for drive number miss ; detected) MOV DL,[DiskResultsBuffer+2] ; Load resultant drive information CMP [CDDriveNumber],DL ; Compare to see if they are the same ; (they should be) JNE Failure ; If they are not, Failure ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; More information can be gathered here if needed later, not needed at ;; ;; this time. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Check INT 13h Extensions Present ;; ;; ;; ;; Call with: AH = 41H ;; ;; DL = Drive number (80h - FFh; but we're interested in CDs for this ;; ;; exercise) ;; ;; BX = 55AAh (Signature?) ;; ;; ;; ;; Return: If Function Successful, ;; ;; Carry Flag = Clear ;; ;; BX = AA55h if installed ;; ;; AH = major version of extensions ;; ;; 01h = 1.x ;; ;; 20h = 2.0 / EDD-1.0 ;; ;; 21h = 2.1 / EDD-1.1 ;; ;; 30h = EDD-3.0 ;; ;; AL = internal use ;; ;; CX = API subset support bitmap ;; ;; 1 - Device Access using packet structure (INT 13h AH=42h-44h, ;; ;; 47h,48h) ;; ;; 2 - Drive Locking and Ejecting (INT 13h AH=45h,46h,48h,49h, ;; ;; INT 15h AH=52h) ;; ;; 4 - Enhanced Disk Drive Support (INT 13h AH=48h,AH=4Eh) ;; ;; DH = extension version (v2.0+ ??? -- not present in 1.x) ;; ;; ;; ;; If Function Unsuccessful, ;; ;; Carry Flag = Set ;; ;; AH = 01h (invalid function) ;; ;; ;; ;; Comments: ;; ;; ;; ;; The Function is used to see if INT 13h extensions are present (not ;; ;; really needed if you can do the previous function, right?) ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; GetINT13hExtenstions: MOV DL,[CDDriveNumber] ; Prepare to read CD-ROM, load boot ; drive MOV AH,41h ; Use function 41h: Check Extensions ; Present MOV BX,55AAh ; Signature? INT 13h ; Call Check Extensions Present? ; (This makes no sense if you try ; INT 13h Function 4B01h, but ; details are provided upon return ; if CF isn't set) JC Failure ; Nope, get out of here... ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Extended Read Function ;; ;; ;; ;; Call with AH=42h ;; ;; DL = drive number ;; ;; DS:SI = Disk Address Packet (DAP) ;; ;; Offset Size Description ;; ;; 00h db Size of packet (10h or 18h; we're using 10h here, ;; ;; see below) ;; ;; 01h db Reserved (0) ;; ;; 02h dw Number of sectors to read (max 007Fh for Phoenix ;; ;; EDD) ;; ;; 04h dd Initial segment:offset where to load the read in ;; ;; sector(S) ;; ;; 08h dq starting absolute sector number (for non-LBA ;; ;; devices, compute as ;; ;; (Cylinder*NumHeads + SelectedHead) * ;; ;; SectorPerTrack + SelectedSector - 1 ;; ;; 10h dq (EDD-3.0, optional) 64-bit flat address of transfer ;; ;; buffer; used if dd at 04h is FFFFh:FFFFh ;; ;; ;; ;; Return: If Function Successful, ;; ;; Carry Flag = Clear ;; ;; AH = 00h ;; ;; ;; ;; If Function Unsuccessful, ;; ;; Carry Flag = Set ;; ;; AH = Error code ;; ;; ;; ;; Error code: ;; ;; 00h successful completion ;; ;; 01h invalid function in AH or invalid parameter ;; ;; 02h address mark not found ;; ;; 03h disk write-protected ;; ;; 04h sector not found/read error ;; ;; 05h reset failed (hard disk) ;; ;; 05h data did not verify correctly (TI Professional PC) ;; ;; 06h disk changed (floppy) ;; ;; 07h drive parameter activity failed (hard disk) ;; ;; 08h DMA overrun ;; ;; 09h data boundary error (attempted DMA across 64K boundary or ;; ;; >80h sectors) ;; ;; 0Ah bad sector detected (hard disk) ;; ;; 0Bh bad track detected (hard disk) ;; ;; 0Ch unsupported track or invalid media ;; ;; 0Dh invalid number of sectors on format (PS/2 hard disk) ;; ;; 0Eh control data address mark detected (hard disk) ;; ;; 0Fh DMA arbitration level out of range (hard disk) ;; ;; 10h uncorrectable CRC or ECC error on read ;; ;; 11h data ECC corrected (hard disk) ;; ;; 20h controller failure ;; ;; 31h no media in drive (IBM/MS INT 13 extensions) ;; ;; 32h incorrect drive type stored in CMOS (Compaq) ;; ;; 40h seek failed ;; ;; 80h timeout (not ready) ;; ;; AAh drive not ready (hard disk) ;; ;; B0h volume not locked in drive (INT 13 extensions) ;; ;; B1h volume locked in drive (INT 13 extensions) ;; ;; B2h volume not removable (INT 13 extensions) ;; ;; B3h volume in use (INT 13 extensions) ;; ;; B4h lock count exceeded (INT 13 extensions) ;; ;; B5h valid eject request failed (INT 13 extensions) ;; ;; B6h volume present but read protected (INT 13 extensions) ;; ;; BBh undefined error (hard disk) ;; ;; CCh write fault (hard disk) ;; ;; E0h status register error (hard disk) ;; ;; FFh sense operation failed (hard disk) ;; ;; ;; ;; Initial DAP: ;; ;; ;; ;; db 10h - Initial Volume Descriptor, which has the important ;; ;; data we need to get to the root directory where ;; ;; our OS is stored. ;; ;; db 0 - Unused, should be zero ;; ;; dw 1 - Number of sectors to read (initial one should be one ;; ;; for Volume Descriptor) ;; ;; dd 0200:0000 - Initial segment:offset where to load the read in ;; ;; sector(S) ;; ;; dq 16 - Starting sector to read in, then we need to get to ;; ;; the root directory ;; ;; ;; ;; Comments: ;; ;; ;; ;; This functions is called three times: Initially to get the Initial ;; ;; Volume Descriptor so we can find the root directory; then it gets ;; ;; used again to read in the root directory, so we can scan for ;; ;; SmiddyOS; finally once we recognize SmiddyOS we load it and jump to ;; ;; it, if all goes as it should "on a good day" as expected (this is ;; ;; done in FindSmiddyOS). ;; ;; ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; MOV DL,[CDDriveNumber] ; Set it up again MOV AH,42h ; Read from drive function MOV SI,DiskAddressPacket ; Load SI with address of the DAP INT 13h ; Call read sector from drive JC Failure ; Nope, hosed, get out MOV ES,[DiskAddressPacket.Segment] ; Sets up so we can analyze the data MOV DI,[DiskAddressPacket.Offset] ; Sets up so we can analyze the data MOV BX,40 ; Load BX with Volume Label offset ; (Check CDROM.ASM or ISO 9660) VolumeLabelLoop: MOV CL,[ES:DI+BX] ; Grab a letter CMP CL,' ' ; Is it a space? (Assumes end of ; string is space, may run out) JE .VolumeLabelDone ; Yes, we are done MOV [VolumeLabel+BX-40],CL INC BX JMP VolumeLabelLoop ; Need to compare BX to length of ; Volume Label on CD (32?) .VolumeLabelDone: MOV byte [VolumeLabel+BX-40],0 ; End the string MOV EAX,[ES:DI+158] ; LBA of root directory, where all ; things start. MOV [DiskAddressPacket.End],EAX ; Load packet with new address on CD of ; the root directory MOV DL,[CDDriveNumber] ; Set it up again MOV AH,42h ; Read from drive function MOV SI,DiskAddressPacket ; Load SI with address of the DAP INT 13h ; Call read sector from drive JC Failure ; Nope, hosed, get out CALL FindSmiddyOS MOV AH,0FEh ; If the FindSmiddyOS makes it back ; here, then the file was not found ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Failure: Displays failure with an error code number. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Failure: mov AL,AH ; Put the error into lowest bits mov cl,8 ; only 8 bits call ToHex ; Get what is in the XX to display MOV SI,FailureMessage ; reboot message CALL PrintString mov si,HexBuffer CALL PrintString MOV SI,AddTheHAtTheEnd CALL PrintString MOV SI,TheEndOfTheLine CALL PrintString mov SI,PressAnyKeyMessage CALL PrintString MOV AH,0 ; Reboot on error INT 16h ; BIOS GetKey INT 19h ; BIOS Reboot ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; FindSmiddyOS: Locates SmiddyOS in the root directory of the CD/DVD/BD and ;; ;; launchs it if it finds it. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; NumberOfSectorsToRead: dd 0 FindSmiddyOS: MOV ES,[DiskAddressPacket.Segment] MOV DI,[DiskAddressPacket.Offset] CMP byte [VolumeLabel],0 JE .NoLabel JMP .LabelDone .NoLabel: ; MOV SI,HasNoLabel ; CALL PrintString .LabelDone: ; MOV SI,TheEndOfTheLine ; CALL PrintString ; MOV SI,TheEndOfTheLine ; CALL PrintString .GrabDirectoryEntry: MOV AL,[ES:DI] ; Length of the current directory entry MOV [DirectoryEntrySize],AL MOV EAX,[ES:DI+2] ; Starting sector of directory entry MOV [FileSector],EAX MOV EAX,[ES:DI+10] ; Size of directory entry on CD/DVD/BD MOV [FileSize],EAX MOV AL,[ES:DI+32] ; File's name length (see El Torito of ; ISO:9660 or CDROM.ASM) MOV [FileNameLength],AL XOR BX,BX ; Initialize BX XOR CX,CX ; Initialize CX MOV SI,DI ADD SI,33 MOV BX,FileNameEntry MOV AL,[FileNameLength] CMP AL,1 ; Check to see if a dot or dotdot entry JE .DotAndDotDotEntries .LoopFileNameEntry: ; Capture the filename entry for later ; manipulation MOV AL,[ES:SI] MOV [DS:BX],AL INC BX INC CX INC SI XOR AX,AX MOV AL,[FileNameLength] CMP CX,AX JB .LoopFileNameEntry MOV byte [DS:BX],0 JMP .FileNameEntryDisplay .DotAndDotDotEntries: MOV AL,[FileEntryNumber] CMP AL,0 JA .DoDotDotEntry MOV word [FileNameEntry],'.' ; First directory entry MOV byte [FileNameEntry+1],0 ; End the string with a termination JMP .FileNameEntryDisplay .DoDotDotEntry: MOV word [FileNameEntry],'..' ; Second directory entry MOV byte [FileNameEntry+2],0 ; End the string with a termination .FileNameEntryDisplay: MOV SI,FileNameEntry PUSH DI MOV DI,FileName CALL StringCompare POP DI JC .EndOfTheLine MOV EAX,[FileSector] MOV [DiskAddressPacket.End],EAX ; Save the starting sector into DAP MOV EAX,[FileSize] XOR EDX,EDX MOV EBX,2048 DIV EBX INC EAX MOV [NumberOfSectorsToRead],EAX ; This is the absolute number of ; sectors to be read. CMP AX,32 JA .UpdateSectorsToRead MOV [DiskAddressPacket.SectorsToRead],AX ; Save number of sectors to read JMP .PassedTheUpdate .UpdateSectorsToRead: MOV [DiskAddressPacket.SectorsToRead],word 32 SUB [NumberOfSectorsToRead],dword 32 .PassedTheUpdate: .ReadTheSectorsLoop: MOV DL,[CDDriveNumber] ; Set it up again MOV AH,42h ; Read from drive function MOV SI,DiskAddressPacket ; Load SI with address of the DAP INT 13h ; Call read sector from drive JC Failure ; Nope, hosed, get out CMP [NumberOfSectorsToRead], dword 0 JE .StartTheOperatingSystem MOV EAX,[DiskAddressPacket.SectorsToRead] ; Add sectors read (32) to it, ; for the new starting sector ADD [DiskAddressPacket.End],EAX ; Update sector to start reading from ; on CD/DVD/BD MOV EBX,2048 MUL EBX ; Update EAX with amount of space used SHR EAX,4 ; Shift it right to update the segment ; to load next ADD [DiskAddressPacket.Segment], AX ; Segment to load next in memory CMP [NumberOfSectorsToRead],dword 32 ; Is this still too big (greater than ; 64k barrier? JAE .UpdateSectorsToRead ; If so, need to load another 32 ; sectors MOV EAX,[NumberOfSectorsToRead] ; Else MOV [DiskAddressPacket.SectorsToRead],AX ; We load what is left MOV [NumberOfSectorsToRead],dword 0 ; Zero out this bad boi! JMP .ReadTheSectorsLoop .StartTheOperatingSystem: MOV DL,[CDDriveNumber] ; Drive into DL for booting JMP 0202h:0h ; Start SmiddyOS (For standard DOS ; executeable) .EndOfTheLine: XOR CX,CX ; Prepare CX to do math for DI MOV CL,[DirectoryEntrySize] ; Get the size of the directory entry ADD DI,CX ; Add that size to the DI to get to the ; next record CMP byte [ES:DI],0 ; Is the next entry = 0? JE .End ; If so, we're at the end of the ; directory, move on XOR CX,CX MOV BX,FileNameEntry .ClearFileNameEntry: MOV byte [DS:BX],0 ; Erase the begining of the ; FileNameEntry INC BX INC CX CMP CX,254 JB .ClearFileNameEntry MOV byte [DS:BX],0 INC byte [FileEntryNumber] JMP .GrabDirectoryEntry ; If not, we have more processing to do .End: RET ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; PrintString ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; PrintString: PUSHA ; Save Registers .Loop: LODSB ; Load SI into AL, increment SI one ; byte OR AL,AL ; AL = 0? JZ .Done ; If yes, get out MOV AH,0Eh MOV BH,0 MOV BL,7 ; character attribute INT 10h ; Display character in AL JMP .Loop ; Do it again .Done: POPA ; Replace registers RET ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; ToHex ;; ;; Loads HexBuffer with ASCII corresponding to 8, 16, or 32 bit interger in ;; ;; hex. ;; ;; Requires interger in AL, AX, or EAX depending on bit size ;; ;; Requires the number of bits in the CL ;; ;; Returns a full buffer or an empty buffer on error ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ToHex: pusha MOV BX,0 ; Load BX with pointer offset MOV [TheEAX],EAX ; Save the EAX MOV [TheCL],CL ; Save the CL CMP CL,8 ; Check for 8 bits JNE .Check16 JMP .Loop1 ; Start loading the buffer .Check16: CMP CL,10h ; Check for 16 bits JNE .Check32 JMP .Loop1 ; Start loading the buffer .Check32: CMP CL,20h ; Check for 32 bits JNE .ErrorBits .Loop1: MOV EAX,[TheEAX] ; Reload EAX with the converter SUB CL,4 ; Lower bit count by 4 bits SHR EAX,CL AND AL,0Fh ADD AL,'0' CMP AL,'9' JBE .LoadBuff1 ADD AL,'A'-'0'-10 ; Convert to "A" to "F" JMP .LoadBuff1 .Loop2: MOV EAX,[TheEAX] ; Reload EAX again SUB CL,4 ; Lower bit count by 8 bits SHR EAX,CL AND AL,0Fh ADD AL,'0' CMP AL,'9' JBE .LoadBuff2 ADD AL,'A'-'0'-10 ; Convert A,B,C,D,E,F JMP .LoadBuff2 .LoadBuff1: MOV [HexBuffer+BX],AL ; Load buffer with AL INC BX ; Increment buffer pointer JMP .Loop2 ; Do next byte .LoadBuff2: MOV [HexBuffer+BX],AL ; Load buffer with AL INC BX ; Increment buffer pointer CMP CL,0 ; Check if we're done JNE .Loop1 ; Do next Byte .ErrorBits: MOV AL,0 MOV [HexBuffer+BX],AL ; End the string with a zero popa RET ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; StringCompare ;; ;; ;; ;; Compares the equality of two strings, loaded in SI and DI. ;; ;; ;; ;; Sets the CF if not the same. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; StringCompare: PUSH SI ; Save SI to be restored at the end PUSH DI ; Save DI to be restored at the end .Loop: MOV AL,[SI] ; Grab byte from SI MOV BL,[DI] ; Grab byte from DI CMP AL,BL ; Compare if they are equal JNE .NotEqual ; They aren't equal CMP AL,0 ; Both bytes are null JE .Done INC DI ; Increment DI INC SI ; Increment SI JMP .Loop ; Start looping .NotEqual: STC ; Set the carry flag to indicate ; failure JMP .End .Done: CLC ; Clear the carry flag to indicate ; success .End: POP DI ; Restore DI before returning to caller POP SI ; Restore SI before returning to caller RET ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; StringLength ;; ;; ;; ;; Checks the length of the string in the SI and returns it in the AX. ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; StringLength: PUSH BX XOR BX,BX .Loop: CMP byte [SI+BX],0 JE .End INC BX JMP .Loop .End: MOV AX,BX POP BX RET ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Program Data ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; DirectoryEntrySize: db 0 FileSector: dd 0 FileSize: dd 0 FileNameLength: db 0 FileNameEntry: TIMES 255 db ' ' FileEntryNumber: db 0 DriveDisplayMessage: db 'Volume in drive: ',0 ; Get label from Primary ; Volume Descriptor ; (loaded first) HasNoLabel: db 'no label',0 FileNamePointer: dw 0 DataSector: DW 0 CDDriveNumber: db 0 RootDirectorySector dd 0 FileName: DB 'SMIDDYOS.EXE',0 ; FAT Filename, 8.3, or ; 11 characters WelcomeMessage: db 13,10,'smiddy OS CD boot v1.00',225,13,10,0 ; Version of CD-Boot FailureMessage: db 'Failure: ',0 DriveNumberReported: db 'Drive number reported: ',0 PressAnyKeyMessage: db 'Press any key to reboot...',13,10,0 AddTheHAtTheEnd: db 'h',0 TheEndOfTheLine: db 13,10,0 ; Used to print the end of the line ; string SizeOfPacketInBytes: db 'The size of packet in bytes: ',0 BootMediaType: db 'The boot media type: ',0 DriveNumberFromPacket: db 'Drive number from packet: ',0 VolumeLabel: TIMES 33 db 0 ; Where the volume label ; is stored DiskAddressPacket: db 16,0 ; a.k.a. DAP .SectorsToRead: dw 1 ; Number of sectors to read (read size ; of OS) .Offset: dw 0 ; Offset :0000 .Segment: dw 0200h ; Segment 0200: currerntly, will change ; to 0200:0000 for loading SmiddyOS .End: dq 16 ; Sector 16 or 10h on CD-ROM DiskResultsBuffer: times 30 db 0 ; Return buffer from int 13h ah=48h HexBuffer: DB 0,0,0,0,0,0,0,0,0 ; Buffer for hex text string TheEAX: dd 0 ; Saves EAX TheCL: db 0 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; 512 Byte Code Boot Signature ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; TIMES 2046-($-BootSector) DB 0 DW 0AA55h ; Bootloading sector signature (for ; CD/DVD/BD) I am not sure this is ; needed for optical media booting. Please, there are a lot of folks who helped to put this together, and I likely used code off the web, so be kind and give credit where you should. I put this out here for your use as you will, hopefully others will learn from it as I have. |
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07 Dec 2014, 04:41 |
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