Index
> OS Construction > Input/Output And Device Drivers |
| Author |
|
|
DJ Mauretto
ok i'll try to reply
in digital electronics the only one language is 1 or 0 , every card has inside electronic chip that you program with signal that perform something.... example: i have this string of bit 0000 ( 4 zero ) if you apply this to ALU ( Arithmetic and Logic Unit ) says that perform addition,now if we intend to do subtraction ,can expand our circuit and add our ALU another control signal and therefore one bit says 0001. ok now we have 2 function 0000 addition 0001 subtraction when you program card you set this bit and send to register |
|||
21 Jul 2007, 18:49 |
|
|
Dark Dude
Ok, yea, so I'm guessing you'd send that to the device like so:
mov ax, 0110000001000111b out 4, ax Which would send 0110000001000111 to the device located on IO Port 4... But how/where would I find out what bit does what to the device? For example, I know there's something you do to retrieve the mouse position and stuff, but I cant find documentations on the bits or anything |
|||
|
21 Jul 2007, 19:39 |
|
|
DJ Mauretto
ok
you must learn datasheet of your device...but not always manufacturer release free document ,sometimes you must pay ,sometimes are secret  see ATI
sometimes you'll find on this forum ( read FAQ ) sometimes on google ,sometimes you can ask to people of forum ..... |
|||
|
21 Jul 2007, 20:39 |
|
|
Dex4u
Heres a basic guide to making a FM801 sound card driver, all gather round.
Step 1. First you write a function to read PCI , we will start with dos . Code: ;===============================================================; 8/16/32bit PCI reader;; Entry: EAX=PCI Bus/Device/fn/register number; BIT30 set if 32 bit access requested; BIT29 set if 16 bit access requested; otherwise defaults to 8bit read;; Exit: DL,DX,EDX register data depending on requested read size;; Note: this routine is meant to be called via pciRegRead8, pciRegread16,; or pciRegRead32, listed below.;; Note2: don't attempt to read 32bits of data from a non dword aligned reg; number. Likewise, don't do 16bit reads from non word aligned reg #;BIT30 EQU 40000000hBIT31 EQU 80000000hPCI_INDEX_PORT EQU 0CF8hPCI_DATA_PORT EQU 0CFChPCI32 EQU BIT31 ; bitflag to signal 32bit accessPCI16 EQU BIT30 ; bitflag for 16bit accessVIA_VID equ 1319h ; VIAPCI vendor IDVIA_DID equ 0801h ; VIA device IDpciRegRead: push ebx push cx mov ebx, eax ; save eax, dh mov cl, dh and eax, NOT PCI32+PCI16 ; clear out data size request or eax, BIT31 ; make a PCI access request and al, NOT 3 ; force index to be dword mov dx, PCI_INDEX_PORT out dx, eax ; write PCI selector mov dx, PCI_DATA_PORT mov al, bl and al, 3 ; figure out which port to add dl, al ; read to in eax, dx ; do 32bit read test ebx, PCI32 jz @f mov edx, eax ; return 32bits of data@@: mov dx, ax ; return 16bits of data test ebx, PCI32+PCI16 jnz @f mov dh, cl ; restore dh for 8 bit read@@: mov eax, ebx ; restore eax and eax, NOT PCI32+PCI16 ; clear out data size request pop cx pop ebx retpciRegRead8: and eax, NOT PCI16+PCI32 ; set up 8 bit read size jmp pciRegRead ; call generic PCI accesspciRegRead16: and eax, NOT PCI16+PCI32 ; set up 16 bit read size or eax, PCI16 ; call generic PCI access jmp pciRegReadpciRegRead32: and eax, NOT PCI16+PCI32 ; set up 32 bit read size or eax, PCI32 ; call generic PCI access jmp pciRegRead Step 2. we fill in the vendor id and device id to see it is on the pc, to do that we need a function to scan through pci space to look for vendor+device id like this. Code: ;===============================================================; PCIFindDevice: scan through PCI space looking for a device+vendor ID;; Entry: EAX=Device+vendor ID;; Exit: EAX=PCI address if device found; CY clear if found, set if not found. EAX invalid if CY set.;; [old stackless] Destroys: ebx, edx, esi, edi, cl;pciFindDevice: push cx push edx push esi push edi mov esi, eax ; save off vend+device ID mov edi, (80000000h - 100h) ; start with bus 0, dev 0 func 0nextPCIdevice: add edi, 100h cmp edi, 80fff800h ; scanned all devices? stc jz PCIscanExit ; not found mov eax, edi ; read PCI registers call pciRegRead32 cmp edx, esi ; found device? jnz nextPCIDevice clcPCIScanExit: pushf mov eax, edi ; return found PCI address and eax, NOT BIT31 ; return only bus/dev/fn # popf pop edi pop esi pop edx pop cx retEnd Step 3. we need to put it together and call the above functions. Code: mov eax, (VIA_DID shl 16) + VIA_VID call pciFindDevice jnc @f; couldn't find the audio device! lea dx, noVIAMsg mov ah, 9 int 21h jmp $ ; if run from dos replace this with, the normal dos returnnoVIAMsg db "Error: Unable to find FM801 audio device!",CR,LF,"$"VIAMsg db "Found FM801 audio device!",CR,LF,"$"@@: lea dx, VIAMsg mov ah, 9 int 21h jmp $ ; if run from dos replace this with, the normal dos return Step 4. put the above code in to a com file (adding org 100h, etc) and boot it from dos, MiniDos or bootprog you can get it here: http://alexfru.chat.ru/epm.html Print one message for found and one for not found. Note: It returns PCI address of device, if device found, and togeather with info you can find in here: http://alsa.cybermirror.org/datasheets/forte_media/FM801-AU-Data.PDF see page 18 in the manual, is how you write a driver. Your should find the info you need on vendor/device ID here. http://www.pcidatabase.com/#notice Step 5. well i think that enough for now, tune in for the next installment of basic sound card basics, only joking i do not want to bore you. |
|||
|
22 Jul 2007, 02:08 |
|
< Last Thread | Next Thread > |
Forum Rules:
|