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|
include MSBDS.INC ;include BDS struc ;an000; dms;
;=========================================================================
; I13_Handler - This routine is the main driver of the
; INT 13h hook.
;=========================================================================
I13_Handler proc far ; ;an000; dms;
jmp I13_Handler_Start
I13_Max_Head db ? ;max head count on drive ;an000; dms;
I13_SPT db ? ;max sectors/track count ;an000; dms;
I13_BPS dw ? ;max number bytes/sector ;an000; dms;
I13_Bytes_Per_Para dw 10h ;number of bytes per paragraph ;an000; dms;
I13_Bytes_Per_EMS_Page dw 4000h ;bytes per EMS page ;an000; dms;
I13_Paras_Per_Sector dw ? ;paras per sector ;an000; dms;
I13_DD_Per_Sector dw ? ;double words per sector ;an000; dms;
I13_Operation db ? ;INT 13h function ;an000; dms;
I13_Sector_Count db ? ;sector count ;an000; dms;
I13_Track_Number dw ? ;track number ;an000; dms;
I13_Sector_Number db ? ;sector number ;an000; dms;
I13_Head_Number db ? ;head number ;an000; dms;
I13_Drive_Number db ? ;drive number ;an000; dms;
I13_Sectors_To_Trf db 1 ;current sectors to trf ;an000; dms;
I13_Curr_Trf_Cnt db ? ;total transfer count in secs ;an000; dms;
I13_Trf_Off dw ? ;current address for trf ;an000; dms;
I13_Trf_Seg dw ? ;an000; dms;
I13_512_Byte_Buffer db 512 dup(0) ;buffer for sector ;an000; dms;
I13_Handler_Start:
sti ;ints on ;an000; dms;
cmp ah,02h ;read operation? ;an000; dms;
je I13_Handler_Get_Parms ;yes - get drive parms ;an000; dms;
cmp ah,03h ;write operation? ;an000; dms;
je I13_Handler_Get_Parms ;yes - get drive parms ;an000; dms;
jmp cs:IntV13 ;neither - go to old INT 13h ;an000; dms;
I13_Handler_Get_Parms:
call I13_Get_Dev_Parms ;get device parms for this drive;an000; dms;
jnc I13_Handler_Range_Ck ;we have device data ;an000; dms;
jmp cs:IntV13 ;go to old INT 13h vector ;an000; dms;
I13_Handler_Range_Ck:
call I13_Target_Source_Range_Ck ;crosses the 640k boundary? ;an000; dms;
jc I13_Handler_Request_Break ;break up the request ;an000; dms;
jmp cs:IntV13 ;go to old INT 13h vector ;an000; dms;
I13_Handler_Request_Break:
call I13_Request_Break_Up ;break up I13 request ;an000; dms;
ret 2 ;return to caller ;an000; dms;
;clear the flags from the stack
; and pass back ours
I13_Handler endp ; ;an000; dms;
;=========================================================================
; I13_Target_Source_Range_Ck - This routine determines if the
; target or source resides in an EMS
; page.
;
; Inputs : ES:BX - Source/target address
;
; Outputs : CY - if address resides in an EMS page
; NC - address not in an EMS page
;=========================================================================
I13_Target_Source_Range_Ck proc near ; ;an000; dms;
push ax ;save regs ;an000; dms;
push bx ; ;an000; dms;
push cx ; ;an000; dms;
push si ; ;an000; dms;
push ds ; ;an000; dms;
mov ax,cs ;get cs addressibility ;an000; dms;
mov ds,ax ; ;an000; dms;
mov si,offset cs:Map_Table ;point to the map table ;an000; dms;
mov cx,cs:Map_Count ;get the number of phys. pages ;an000; dms;
I13_Target_Source_Loop:
cmp cx,0 ;at end? ;an000; dms;
je I13_Target_Source_Not_EMS_Page ;yes - source/target not in pg ;an000; dms;
mov ax,ds:[si].Phys_Page_Segment ;get the segment value ;an000; dms;
mov bx,es ; ;an000; dms;
cmp bx,ax ;source/target > EMS page? ;an000; dms;
jb I13_Target_Source_Not_EMS_Page ;no - we are OK for old INT 13 ;an000; dms;
;must be >= EMS page
add ax,400h ;get end address of EMS page ;an000; dms;
cmp bx,ax ;source/target < end of EMS pg? ;an000; dms;
jb I13_Target_Source_In_EMS_Page ;yes - we are in a page ;an000; dms;
add si,type Mappable_Phys_Page_Struct ;adjust pointer to next page ;an000; dms;
dec cx ;dec counter ;an000; dms;
jmp I13_Target_Source_Loop ;continue loop ;an000; dms;
I13_Target_Source_Not_EMS_Page:
clc ;flag not in EMS page ;an000; dms;
jmp I13_Target_Source_Exit ;exit routine ;an000; dms;
I13_Target_Source_In_EMS_Page:
stc ;flag in an EMS page ;an000; dms;
I13_Target_Source_Exit:
pop ds ;restore regs ;an000; dms;
pop si ; ;an000; dms;
pop cx ; ;an000; dms;
pop bx ; ;an000; dms;
pop ax ; ;an000; dms;
ret ; ;an000; dms;
I13_Target_Source_Range_Ck endp ; ;an000; dms;
;=========================================================================
; I13_Request_Break_Up - Break up the INT 13h request onto 16k
; boundaries.
;
; Inputs : AH - 02 (Read)
; 03 (Write)
; AL - Sector count
; CH - Track number
; CL - Sector number
; DH - Head number
; DL - Drive number
; ES:BX - Buffer address
;
; Outputs : Data transferred
;=========================================================================
I13_Request_Break_Up proc near ; ;an000; dms;
push bx ;save regs ;an000; dms;
push cx ; ;an000; dms;
push dx ; ;an000; dms;
push di ; ;an000; dms;
push si ; ;an000; dms;
push ds ; ;an000; dms;
push es ; ;an000; dms;
mov cs:I13_Trf_Seg,es ;save segment ;an000; dms;
mov cs:I13_Trf_Off,bx ;save offset ;an000; dms;
mov cs:I13_Curr_Trf_Cnt,0 ;init transfer count ;an000; dms;
mov cs:I13_Operation,ah ;save operation ;an000; dms;
mov cs:I13_Sector_Count,al ;save sector count ;an000; dms;
mov byte ptr cs:I13_Track_Number,ch ;save starting track number ;an000; dms;
mov ch,cl ;xchg bytes ;an000; dms;
shr ch,1 ;shift 6 bits ;an000; dms;
shr ch,1 ; ;an000; dms;
shr ch,1 ; ;an000; dms;
shr ch,1 ; ;an000; dms;
shr ch,1 ; ;an000; dms;
shr ch,1 ; ;an000; dms;
mov byte ptr cs:I13_Track_Number[+1],ch ;high byte for cylinder ;an000; dms;
and cl,00111111b ;get bits 0-5 for sector number ;an000; dms;
mov cs:I13_Sector_Number,cl ;save starting sector number ;an000; dms;
mov cs:I13_Head_Number,dh ;save starting head number ;an000; dms;
mov cs:I13_Drive_Number,dl ;save drive number ;an000; dms;
mov cl,cs:I13_Sector_Count ;while sectors ;an000; dms;
cmp cs:I13_Operation,02h ;read? ;an000; dms;
jne I13_Request_Write ;must be a write ;an000; dms;
I13_Request_Read:
cmp cl,0 ;at end? ;an000; dms;
je I13_Request_Success ;exit we are done ;an000; dms;
lea bx,cs:I13_512_Byte_Buffer ;point to 512 byte buffer ;an000; dms;
mov ax,cs ;pass cs to es ;an000; dms;
mov es,ax ; ;an000; dms;
call I13_Invoke ;do the INT 13h to our buffer ;an000; dms;
jc I13_Request_Failed ;signal failure ;an000; dms;
mov ax,cs ;point to our buffer to the ;an000; dms;
mov ds,ax ; transfer ;an000; dms;
mov si,offset cs:I13_512_Byte_Buffer; ;an000; dms;
mov es,cs:I13_Trf_Seg ;restore seg to target ;an000; dms;
mov di,cs:I13_Trf_Off ;restore off to target ;an000; dms;
push cx ;save cx across move ;an000; dms;
cld ;do a forward move ;an000; dms;
mov cx,cs:I13_DD_Per_Sector ; for 128 dd's ;an000; dms;
db 66h ;op code for dd word move ;an000; dms;
rep movsw ;do the move - wow that was fast;an000; dms;
pop cx ;restore it ;an000; dms;
call I13_Adjust ;adjust our pointers ;an000; dms;
dec cl ;decrease sector counter ;an000; dms;
jmp I13_Request_Read ;continue loop ;an000; dms;
I13_Request_Write:
cmp cl,0 ;at end? ;an000; dms;
je I13_Request_Success ;exit we are done ;an000; dms;
mov ax,cs ;point to 512 byte buffer ;an000; dms;
mov es,ax ; ;an000; dms;
mov di,offset cs:I13_512_Byte_Buffer; ;an000; dms;
mov ds,cs:I13_Trf_Seg ;get source segment ;an000; dms;
mov si,cs:I13_Trf_Off ;get source offset ;an000; dms;
push cx ;save cx across move ;an000; dms;
cld ;do a forward move ;an000; dms;
mov cx,cs:I13_DD_Per_Sector ; for 128 dd's ;an000; dms;
db 66h ;op code for dd word move ;an000; dms;
rep movsw ;do the move - wow that was fast;an000; dms;
pop cx ;restore it ;an000; dms;
lea bx,cs:I13_512_Byte_Buffer ;point to 512 byte buffer ;an000; dms;
mov ax,cs ;pass cs to es ;an000; dms;
mov es,ax ; ;an000; dms;
call I13_Invoke ;do the INT 13h to our buffer ;an000; dms;
jc I13_Request_Failed ;signal failure ;an000; dms;
call I13_Adjust ;adjust our pointers ;an000; dms;
dec cl ;decrease sector counter ;an000; dms;
jmp I13_Request_Write ;continue loop ;an000; dms;
I13_Request_Failed:
jmp I13_Request_Exit ;exit on error ;an000; dms;
I13_Request_Success:
xor ax,ax ;clear status byte ;an000; dms;
I13_Request_Exit:
pop es ;restore regs ;an000; dms;
pop ds ; ;an000; dms;
pop si ; ;an000; dms;
pop di ; ;an000; dms;
pop dx ; ;an000; dms;
pop cx ; ;an000; dms;
pop bx ; ;an000; dms;
ret ; ;an000; dms;
I13_Request_Break_Up endp ; ;an000; dms;
;=========================================================================
; I13_Adjust - This routine adjusts the needed fields for
; the next iteration of INT 13h.
;
; Inputs : I13_Sectors_To_Trf - Sectors just read/written
; I13_Sector_Number - Starting sector number for trf
; I13_Head_Number - Starting head number for trf
; I13_Track_Number - Starting track number for trf
;
; Outputs : I13_Sector_Number - New starting sector for trf
; I13_Head_Number - New starting head for trf
; I13_Track_Number - New starting track for trf
;=========================================================================
I13_Adjust proc near ;adjust values ;an000; dms;
push ax ;save regs ;an000; dms;
inc cs:I13_Sector_Number ;next sector ;an000; dms;
mov al,cs:I13_Sector_Number ; ;an000; dms;
cmp al,cs:I13_SPT ;> sectors on track? ;an000; dms;
jna I13_Adjust_Exit ;no ;an000; dms;
mov cs:I13_Sector_Number,1 ;yes - start at next ;an000; dms;
inc cs:I13_Head_Number ;next head ;an000; dms;
mov al,cs:I13_Head_Number ; ;an000; dms;
cmp al,cs:I13_Max_Head ;> head count ;an000; dms;
jb I13_Adjust_Exit ;no ;an000; dms;
mov cs:I13_Head_Number,0 ;yes - head 0 ;an000; dms;
inc cs:I13_Track_Number ;next track ;an000; dms;
I13_Adjust_Exit:
mov ax,cs:I13_Paras_Per_Sector ;get bytes per sector ;an000; dms;
add cs:I13_Trf_Seg,ax ;adjust segment ;an000; dms;
pop ax ;restore regs ;an000; dms;
ret ; ;an000; dms;
I13_Adjust endp ; ;an000; dms;
;=========================================================================
; I13_Invoke - This routine sets up the regs for the INT 13h
; and invokes it for the sector we need.
;
; Inputs : I13_Operation - read/write
; I13_Track_Number - cylinder to read/write
; I13_Sector_Number - starting sector for read/write
; I13_Head_Number - starting head
; I13_Drive_Number - starting drive
;
; Outputs : NC - good read/write
; CY - bad read/write
;=========================================================================
I13_Invoke proc near ;invoke INT 13h ;an000; dms;
push bx ;save regs ;an000; dms;
push cx ; ;an000; dms;
push dx ; ;an000; dms;
mov ah,cs:I13_Operation ;get function call ;an000; dms;
mov al,cs:I13_Sectors_To_Trf ;get sectors to transfer ;an000; dms;
mov ch,byte ptr cs:I13_Track_Number ;get track number ;an000; dms;
mov cl,byte ptr cs:I13_Track_Number[+1] ;get high 2 bits ;an000; dms;
shl cl,1 ;put bit is positions 6&7 ;an000; dms;
shl cl,1 ; ;an000; dms;
shl cl,1 ; ;an000; dms;
shl cl,1 ; ;an000; dms;
shl cl,1 ; ;an000; dms;
shl cl,1 ; ;an000; dms;
or cl,cs:I13_Sector_Number ;place the sector number in cl ;an000; dms;
mov dh,cs:I13_Head_Number ;get head number ;an000; dms;
mov dl,cs:I13_Drive_Number ;get drive number ;an000; dms;
pushf
call cs:IntV13 ;go to old vector ;an000; dms;
inc cs:I13_Curr_Trf_Cnt ;increment counter ;an000; dms;
pop dx ;restore regs ;an000; dms;
pop cx ; ;an000; dms;
pop bx ; ;an000; dms;
ret ; ;an000; dms;
I13_Invoke endp ; ;an000; dms;
;=========================================================================
; I13_Get_Dev_Parms - This routine obtains the device parameters for
; the drive being accessed for the INT 13h.
;
; Inputs : DL - drive number
;
; Outputs : I13_Max_Head - max head count on drive
; I13_SPT - max sectors/track count for drive
; CY - error
; NC - no error
;=========================================================================
I13_Get_Dev_Parms proc near ;get sectors/track & head cnt. ;an000; dms;
push ax ;save regs ;an000; dms;
push bx ; ;an000; dms;
push cx ; ;an000; dms;
push dx ; ;an000; dms;
push di ; ;an000; dms;
push ds ; ;an000; dms;
mov ax,0803h ;get the BDS table ;an000; dms;
int 2fh ; ;an000; dms;
I13_Get_Dev_Next_Entry:
cmp ds:[di].Drivenum,dl ;do we have our drive? ;an000; dms;
je I13_Get_Dev_Save_Parms ;yes get data ;an000; dms;
cmp word ptr ds:[di].Link[+0],-1 ;last entry in list? ;an000; dms;
je I13_Get_Dev_Parms_Error_Exit ;yes - did not find drive ;an000; dms;
mov ax,word ptr ds:[di].Link[+0] ;get offset of next entry ;an000; dms;
mov bx,word ptr ds:[di].Link[+2] ;get segment of next entry ;an000; dms;
mov ds,bx ;stuff into ds:di ;an000; dms;
mov di,ax ; ;an000; dms;
jmp I13_Get_Dev_Next_Entry ;continue ;an000; dms;
I13_Get_Dev_Save_Parms:
mov ax,ds:[di].BytePerSec ;get byte count per sector ;an000; dms;
mov cs:I13_BPS,ax ; ;an000; dms;
xor dx,dx ;clear high word ;an000; dms;
div cs:I13_Bytes_Per_Para ;get number of paras in sector ;an000; dms;
mov cs:I13_Paras_Per_Sector,ax ;save it ;an000; dms;
shl ax,1 ;get DD's per sector ;an000; dms;
shl ax,1 ; ;an000; dms;
mov cs:I13_DD_Per_Sector,ax ; ;an000; dms;
mov ax,ds:[di].SecLim ;get sectors per track ;an000; dms;
mov cs:I13_SPT,al ; ;an000; dms;
mov ax,ds:[di].HdLim ;get max head count ;an000; dms;
mov cs:I13_Max_Head,al ; ;an000; dms;
clc ;flag data found ;an000; dms;
jmp I13_Get_Dev_Parms_Exit ; ;an000; dms;
I13_Get_Dev_Parms_Error_Exit:
stc ;flag no data found ;an000; dms;
I13_Get_Dev_Parms_Exit:
pop ds ;restore regs ;an000; dms;
pop di ; ;an000; dms;
pop dx ; ;an000; dms;
pop cx ; ;an000; dms;
pop bx ; ;an000; dms;
pop ax ; ;an000; dms;
ret ; ;an000; dms;
I13_Get_Dev_Parms endp ; ;an000; dms;
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