source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH2h_HRead.asm@ 3

Last change on this file since 3 was 3, checked in by Tomi Tilli, 15 years ago
File size: 2.0 KB
Line 
1; File name : AH2h_HRead.asm
2; Project name : IDE BIOS
3; Created date : 27.9.2007
4; Last update : 12.4.2010
5; Author : Tomi Tilli
6; Description : Int 13h function AH=2h, Read Disk Sectors.
7
8; Section containing code
9SECTION .text
10
11;--------------------------------------------------------------------
12; Int 13h function AH=2h, Read Disk Sectors.
13;
14; AH2h_HandlerForReadDiskSectors
15; Parameters:
16; AH: Bios function 2h
17; AL: Number of sectors to read (1...255)
18; CH: Cylinder number, bits 7...0
19; CL: Bits 7...6: Cylinder number bits 9 and 8
20; Bits 5...0: Starting sector number (1...63)
21; DH: Starting head number (0...255)
22; DL: Drive number (8xh)
23; ES:BX: Pointer to buffer recieving data
24; Parameters loaded by Int13h_Jump:
25; DS: RAMVARS segment
26; Returns:
27; AH: Int 13h/40h floppy return status
28; AL: Burst error length if AH=11h, undefined otherwise
29; CF: 0 if successfull, 1 if error
30; IF: 1
31; Corrupts registers:
32; Flags
33;--------------------------------------------------------------------
34ALIGN JUMP_ALIGN
35AH2h_HandlerForReadDiskSectors:
36 test al, al ; Invalid sector count?
37 jz SHORT AH2h_ZeroCntErr ; If so, return with error
38
39 ; Save registers
40 push dx
41 push cx
42 push bx
43 push ax
44
45 ; Select sector or block mode command
46 call FindDPT_ForDriveNumber ; DS:DI now points to DPT
47 mov ah, HCMD_READ_SECT ; Load sector mode command
48 cmp BYTE [di+DPT.bSetBlock], 1 ; Block mode enabled?
49 jbe SHORT .XferData ; If not, jump to transfer
50 mov ah, HCMD_READ_MUL ; Load block mode command
51
52 ; Transfer data
53ALIGN JUMP_ALIGN
54.XferData:
55 call HCommand_OutputCountAndLCHSandCommand
56 jc SHORT .Return ; Return if error
57 call HPIO_ReadBlock ; Read data from IDE-controller
58.Return:
59 jmp Int13h_PopXRegsAndReturn
60
61; Invalid sector count (also for AH=3h and AH=4h)
62AH2h_ZeroCntErr:
63 mov ah, RET_HD_INVALID ; Invalid value passed
64 stc ; Set CF since error
65 jmp Int13h_PopDiDsAndReturn
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