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assemblyNewbie 14 Feb 2007, 10:20
Hi,
I normally write programs in java and have no experience with assembly or flat assembler. I need to write a program (quickly) which can create and write to files, I found the attatched segment of code at http://www.computing.dcu.ie/~ray/CA225.html#FILES%20AND%20HOW%20TO%20USE%20THEM, tried to run it but found many errors. Please could someone help me fix the problem. Apologies if this has been covered in a different thread.
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14 Feb 2007, 10:20 |
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shoorick 14 Feb 2007, 10:44
it is masm example. are you really need 16-bit executable?
----------- here fasm win32 console example for you
Last edited by shoorick on 14 Feb 2007, 10:52; edited 1 time in total |
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14 Feb 2007, 10:44 |
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assemblyNewbie 14 Feb 2007, 10:50
What I need is a program that will run under Windows XP (32-bit) which is capable of creating files and writing data to files.
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14 Feb 2007, 10:50 |
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shoorick 14 Feb 2007, 10:54
get example above (i have edited post)
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14 Feb 2007, 10:54 |
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shoorick 14 Feb 2007, 13:13
under win32 it is possible with kernel mode drivers, but it will need enough high skill on NT system work - i have no enough experience on this to help you.
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14 Feb 2007, 13:13 |
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assemblyNewbie 14 Feb 2007, 13:23
I've found this code (http://www.geocities.com/SiliconValley/2072/atapi.htm) that apparently sends ATA commands to the hard disk but its probably not written in fasm win32. I'd be grateful if someone could translate it for me (if possible) and let me know if it'd work with windows xp.
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14 Feb 2007, 13:23 |
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Dex4u 14 Feb 2007, 17:34
It will not work under XP, you will need to boot from a floppy or cd etc, to run such code.
Here some code that may help; http://www.dex4u.com/cdpod/cdpod.zip |
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14 Feb 2007, 17:34 |
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shoorick 15 Feb 2007, 05:32
it sounds like software protection attempt, so, there is not so simple I think
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15 Feb 2007, 05:32 |
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assemblyNewbie 15 Feb 2007, 10:09
Please could you explain why it won't work under xp. I'd also like to know why the code I attatched above wouldn't compile.
Dex4u - does your code work with xp? Does the code you provided send ATA commands to the disk? |
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15 Feb 2007, 10:09 |
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assemblyNewbie 15 Feb 2007, 10:57
Ok, I've found that I need to use the windows APIs instead of having direct access to the systems resources. I've searched the MSDN pages on the different I/O commands which can be used with the Device Input and Output Control (IOCTL).
However I haven't found a command which can read raw sectors from the disk. Does anyone know how to do this? Is there an IOCTL command which can send ATA commands to the disk? (this is less important than being able to read raw sectors) Sorry for asking so many questions which are probably obvious to all of you but its important that i find a way of doing this and i'm running out of time. |
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15 Feb 2007, 10:57 |
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shoorick 15 Feb 2007, 11:07
it would be clear if you were know some basics on cpu and os architecture. simply say, there are two modes of cpu: "real" and "protected". real present after cpu reset and let you use any instructions in your code. such mode can be found in bare ms dos. but this mode is unfriendly for multytasking, so, modern oses turn cpu into protected mode after loading. in this mode it is possible to assign security level to the excuted code and restrict some memory (read/write/execute) and i/o operations for each level. usualy system has "kernel" level ("0") and user applications have "user" ("3") level. it is impossible provide direct i/o operations from user level, to do this usually used intermediate drivers, which run in kernel mode.
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15 Feb 2007, 11:07 |
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assemblyNewbie 15 Feb 2007, 11:36
One more question (hopefully) - Using the ReadFile method described in the windows API (http://msdn2.microsoft.com/en-us/library/aa365467.aspx) is it possible to start reading the file, or disk, from a specific location. If so, how?
e.g If i wanted to read 512 bytes from the hard disk and write them to a file, then read the next 512 bytes and write them to the end of the file, etc. How would i use the readFile method to do it (you don't need to describe how to write to the file, i now know how to do this - sort of) Thanks for all yourr help so far |
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15 Feb 2007, 11:36 |
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shoorick 15 Feb 2007, 11:53
there is SetFilePointer function to set initial pointer position in file.
if you read 512 bytes from file next same reading will read next 512 bytes. |
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15 Feb 2007, 11:53 |
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tantrikwizard 15 Feb 2007, 14:31
assemblyNewbie wrote: One more question (hopefully) - Using the ReadFile method described in the windows API (http://msdn2.microsoft.com/en-us/library/aa365467.aspx) is it possible to start reading the file, or disk, from a specific location. If so, how? What youre trying to do is not so simple. IOCTL is the proper function to work directly with the HAL (hardware abstraction layer) and thus read absolute HDD sectors (if it is even possible). Use the standard file IO API to read & write files, not disk sectors. http://msdn2.microsoft.com/en-us/library/aa365470.aspx You cannot use IOCTL to read & write files (I dont think) IOCTL is for direct hardware interaction and the file system is an extra layer above the hardware. |
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15 Feb 2007, 14:31 |
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Dex4u 15 Feb 2007, 15:55
assemblyNewbie wrote:
No you can not use it under XP and yes that code can send ATA commands. I found this our to write to sectors in xp http://www.codeguru.com/Cpp/W-P/system/misc/article.php/c5765/ With out a OS you can do it like this, to read/write to hdd: Code: ; Reading the harddisk using ports!; +-------------------------------+ by qark;;; This took me months to get working but I finally managed it.;; This code only works for the 286+ so you must detect for 8088's somewhere; in your code.;; Technical Information on the ports:; Port Read/Write Misc; ------ ------------ -------------------------------------------------; 1f0 r/w data register, the bytes are written/read here; 1f1 r error register (look these values up yourself); 1f2 r/w sector count, how many sectors to read/write; 1f3 r/w sector number, the actual sector wanted; 1f4 r/w cylinder low, cylinders is 0-1024; 1f5 r/w cylinder high, this makes up the rest of the 1024; 1f6 r/w drive/head; bit 7 = 1; bit 6 = 0; bit 5 = 1; bit 4 = 0 drive 0 select; = 1 drive 1 select; bit 3-0 head select bits; 1f7 r status register; bit 7 = 1 controller is executing a command; bit 6 = 1 drive is ready; bit 5 = 1 write fault; bit 4 = 1 seek complete; bit 3 = 1 sector buffer requires servicing; bit 2 = 1 disk data read corrected; bit 1 = 1 index - set to 1 each revolution; bit 0 = 1 previous command ended in an error; 1f7 w command register; commands:; 50h format track; 20h read sectors with retry; 21h read sectors without retry; 22h read long with retry; 23h read long without retry; 30h write sectors with retry; 31h write sectors without retry; 32h write long with retry; 33h write long without retry;; Most of these should work on even non-IDE hard disks.; This code is for reading, the code for writing is the next article. mov dx,1f6h ;Drive and head port mov al,0a0h ;Drive 0, head 0 out dx,al mov dx,1f2h ;Sector count port mov al,1 ;Read one sector out dx,al mov dx,1f3h ;Sector number port mov al,1 ;Read sector one out dx,al mov dx,1f4h ;Cylinder low port mov al,0 ;Cylinder 0 out dx,al mov dx,1f5h ;Cylinder high port mov al,0 ;The rest of the cylinder 0 out dx,al mov dx,1f7h ;Command port mov al,20h ;Read with retry. out dx,alstill_going: in al,dx test al,8 ;This means the sector buffer requires ;servicing. jz still_going ;Don't continue until the sector buffer ;is ready. mov cx,512/2 ;One sector /2 mov di,offset buffer mov dx,1f0h ;Data port - data comes in and out of here. rep insw; ------ mov ax,201h ;Read using int13h then compare buffers. mov dx,80h mov cx,1 mov bx,offset buffer2 int 13h mov cx,512 mov si,offset buffer mov di,offset buffer2 repe cmpsb jne failure mov ah,9 mov dx,offset readmsg int 21h jmp good_exitfailure: mov ah,9 mov dx,offset failmsg int 21hgood_exit: mov ax,4c00h ;Exit the program int 21h readmsg db 'The buffers match. Hard disk read using ports.$' failmsg db 'The buffers do not match.$'buffer db 512 dup ('V')buffer2 db 512 dup ('L');; Writing to the hard disk using the ports! by qark; +---------------------------------------+;; The only differences between reading and writing using the ports is; that 30h is sent to the command register, and instead of INSW you; OUTSW. ; mov dx,1f6h ;Drive and head port mov al,0a0h ;Drive 0, head 0 out dx,al mov dx,1f2h ;Sector count port mov al,1 ;Write one sector out dx,al mov dx,1f3h ;Sector number port mov al,1 ;Wrote to sector one out dx,al mov dx,1f4h ;Cylinder low port mov al,0 ;Cylinder 0 out dx,al mov dx,1f5h ;Cylinder high port mov al,0 ;The rest of the cylinder 0 out dx,al mov dx,1f7h ;Command port mov al,30h ;Write with retry. out dx,aloogle: in al,dx test al,8 ;Wait for sector buffer ready. jz oogle mov cx,512/2 ;One sector /2 mov si,offset buffer mov dx,1f0h ;Data port - data comes in and out of here. rep outsw ;Send it.; ------------ mov ax,201h ;We'll read in sector 1 using mov bx,offset buffer2 ;int13h and see if we are successful. mov cx,1 mov dx,80h int 13h mov cx,512 mov si,offset buffer mov di,offset buffer2 repe cmpsb ;Compare the buffers. jne failure mov ah,9 mov dx,offset write_msg int 21h jmp w_exitfailure: mov ah,9 mov dx,offset fail int 21hw_exit: mov ax,4c00h ;Exit the program int 21h write_msg db 'Sector one written to using the ports, OH NO! there goes XP.$' fail db 'Writing using ports failed.$'buffer db 512 dup ('A')buffer2 db 512 dup ('D') NOTE: THE ABOVE CODE WILL OVER WRITE YOUR MBR, so do not run with above settings, and the dos bits would be replaced by none dos functions. |
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15 Feb 2007, 15:55 |
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assemblyNewbie 16 Feb 2007, 12:20
I'm not interested in using the IOCTL to read/write files as I'll use standard C/C++ functions to do this.
I found the attatched code which apparantly reads sectors directly from the hard disk. Its written in C or C++ but I haven't managed to compile it yet - as i only have a c compiler. I tried the example code on the MSDN website which should display information about the disk geometry. This doesn't compile either , please could someone tell me if its a problem with the code or if its something simple like the programs written in C++ not C.
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16 Feb 2007, 12:20 |
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assemblyNewbie 16 Feb 2007, 12:28
The code mentioned above is attatched here
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16 Feb 2007, 12:28 |
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shoorick 16 Feb 2007, 12:44
yes, it reads physical disks or partitions (running with admin privilege)
---------- you can run tt from attach in this way: tt \\.\c: d.txt
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16 Feb 2007, 12:44 |
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DOS386 17 Feb 2007, 01:16
Quote: Dex4u - does your code work with xp? NO. Why ? The IN and OUT instructions are crippled off in XP. (Except with some Admin/Driver deals maybe  , not present is this code)
INT $13 does'n work eihter  in XP
Quote: Does the code you provided send ATA commands to the disk? I hope yes, but ONLY in DOS or on no OS at all. Are you sure that you need to read sectors in XP ? You can't do much with the NTFS data anyway, except intentionally corrupt it  _________________ Bug Nr.: 12345 Title: Hello World program compiles to 100 KB !!! Status: Closed: NOT a Bug |
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17 Feb 2007, 01:16 |
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