xdma.lst

DOS下的dma读写驱动

   325 000000CB 91                      	xchg	ax,cx		;CHS -- save request code and sectors.
   326 000000CC 31FF                    	xor	di,di		;Reset upper LBA address bits.
   327 000000CE BE3F00                  	mov	si,0003Fh	;Set SI-reg. to starting sector.
   328 000000D1 21C6                    	and	si,ax
   329 000000D3 4E                      	dec	si
   330 000000D4 C0E806                  	shr	al,6		;Set AX-reg. to starting cylinder.
   331 000000D7 86C4                    	xchg	al,ah
   332 000000D9 92                      	xchg	ax,dx		     ;Swap cylinder & head values.
   333 000000DA 2E8A463C                	mov	al,[cs:bp+CHSSec-@]  ;Get disk CHS sectors/head value.
   334 000000DE 08C0                    	or	al,al		     ;Were disk CHS values legitimate?
   335 000000E0 74CF                    	jz	Pass		     ;No?  Let BIOS do this request!
   336 000000E2 50                      	push	ax		     ;Save CHS sectors/head value.
   337 000000E3 F6E4                    	mul	ah		     ;Convert head to sectors.
   338 000000E5 01C6                    	add	si,ax		     ;Add result to starting sector.
   339 000000E7 58                      	pop	ax		     ;Reload CHS sectors/head value.
   340 000000E8 2EF66640                	mul	byte [cs:bp+CHSHd-@] ;Convert cylinder to sectors.
   341 000000EC F7E2                    	mul	dx
   342 000000EE 01C6                    	add	si,ax		;Add to head/sector value.
   343 000000F0 11FA                    	adc	dx,di
   344 000000F2 93                      	xchg	ax,bx		;Get buffer offset in AX-register.
   345 000000F3 91                      	xchg	ax,cx		;Swap offset with request/sectors.
   346 000000F4 1E                      SaveSeg	push	ds		;Save CPU segment registers.
   347 000000F5 06                      	push	es
   348 000000F6 0E                      	push	cs		;Set this driver's DS-register.
   349 000000F7 1F                      	pop	ds
   350 000000F8 31DB                    	xor	bx,bx		;Zero BX-reg. for relative commands.
   351 000000FA 88571F                  	mov	[bx+LBA+2-@],dl	;Save LBA bits 16-23, to free DL-reg.
   352 000000FD 8A5713                  	mov	dl,[bx+ReqBF-@]	;Set driver & channel "busy" flags
   353 00000100 085712                  	or	[bx+Flags-@],dl	;  so other IDE drivers will WAIT!
   354 00000103 FB                      	sti			;Re-enable CPU interrupts.
   355 00000104 89771D                  	mov	[bx+LBA-@],si	;Save LBA bits 0-15 and 24-47.
   356 00000107 887719                  	mov	[bx+LBA2-@],dh
   357 0000010A 897F1A                  	mov	[bx+LBA2+1-@],di
   358 0000010D 894F28                  	mov	[bx+VDSOf-@],cx	;Save 32-bit user buffer address.
   359 00000110 895F2A                  	mov	[bx+VDSOf+2-@],bx
   360 00000113 8C472C                  	mov	[bx+VDSSg-@],es	;Save 16-bit user buffer segment.
   361 00000116 C1EA0C                  	shr	dx,12		;Shift out LBA bits 16-27.
   362 00000119 09D7                    	or	di,dx		;Anything in LBA bits 28-47?
   363 0000011B 7508                    	jnz	LBA48		;Yes, use LBA48 read/write command.
   364 0000011D 867719                  	xchg	dh,[bx+LBA2-@]	;LBA28 -- reload & reset bits 24-27.
   365 00000120 80CCC9                  	or	ah,(DRCMD+1)	;Get LBA28 read/write command + 5.
   366 00000123 EB03                    	jmp	short GetAdr	;Go get IDE and LBA address bytes.
   367 00000125 C0E403                  LBA48	shl	ah,3		;LBA48 -- get command as 020h/030h.
   368 00000128 B207                    GetAdr	mov	dl,(LBABITS/32)	;Initialize LBA command bits.
   369 0000012A BFF600                  	mov	di,(CDSEL-100h)	;Get primary device-address bytes.
   370                                  @DMALo1	equ	$-1		;(Lower DMA command address, Init set).
   371 0000012D D1ED                    	shr	bp,1		;Is this a primary-channel request?
   372 0000012F 7403                    	jz	DevAdr		;Yes, set IDE & PCI address bytes.
   373 00000131 BF7608                  	mov	di,(CDSEL+680h)	;Get secondary device-address bytes.
   374                                  @DMALo2	equ	$-1		;(Lower DMA command address, Init set).
   375 00000134 897F07                  DevAdr	mov	[bx+IDEAd-@],di ;Set current IDE & PCI address bytes.
   376 00000137 C0D205                  	rcl	dl,5		;Shift disk-select into LBA commands.
   377 0000013A 08F2                    	or	dl,dh		;"Or" in LBA28 bits 24-27 (if any).
   378 0000013C B605                    	mov	dh,005h		;Get final IDE command byte.
   379 0000013E 30E6                    	xor	dh,ah		;(LBA28 = C8h/CAh, LBA48 = 25h/35h).
   380 00000140 895720                  	mov	[bx+DSCmd-@],dx	;Set LBA and IDE command bytes.
   381 00000143 88471C                  	mov	[bx+SecCt-@],al	;Set I-O sector count.
   382 00000146 B400                    	mov	ah,0		;Set VDS/XMS and DMA buffer lengths.
   383 00000148 D1E0                    	shl	ax,1
   384 0000014A 894725                  	mov	[bx+VDSLn+1-@],ax
   385 0000014D 894735                  	mov	[bx+IOLen+1-@],ax
   386 00000150 F6C600                  	test	dh,0			   ;Overlap output request?
   387                                  @Ovlp1	equ	$-1			   ;(012h if overlap enabled).
   388 00000153 7578                    	jnz	BufIO			   ;Yes, do buffered output.
   389 00000155 66834F30FF              	or	dword [bx+IOAdr-@],byte -1 ;Invalidate VDS address.
   390 0000015A B80381                  	mov	ax,08103h		   ;VDS "lock" user buffer.
   391 0000015D BA0C00                  	mov	dx,0000Ch
   392 00000160 E8AF00                  	call	VDLock
   393 00000163 7268                    	jc	BufIO			   ;Error -- do buffered I-O.
   394 00000165 8B4730                  	mov	ax,[bx+IOAdr-@]		   ;Get lower VDS address.
   395 00000168 66837F30FF              	cmp	dword [bx+IOAdr-@],byte -1 ;Is VDS address valid?
   396 0000016D 7211                    	jb	SetVLF			   ;Yes, set VDS "lock" flag.
   397 0000016F B81000                  	mov	ax,16		;No VDS -- get 20-bit buffer segment.
   398 00000172 F7672C                  	mul	word [bx+VDSSg-@]
   399 00000175 034728                  	add	ax,[bx+VDSOf-@]	;Add in buffer offset value.
   400 00000178 11DA                    	adc	dx,bx
   401 0000017A 894730                  	mov	[bx+IOAdr-@],ax	;Set 20-bit user buffer address.
   402 0000017D 895732                  	mov	[bx+IOAdr+2-@],dx
   403 00000180 105F11                  SetVLF	adc	[bx+VLF-@],bl	;Set VDS "lock" flag from carry bit.
   404 00000183 A803                    	test	al,003h		;Is user I-O buffer 32-bit aligned?
   405 00000185 7543                    	jnz	NoLock		;No, use buffered I-O routines below.
   406 00000187 8B4F34                  	mov	cx,[bx+IOLen-@]	;Get lower ending DMA address.
   407 0000018A 49                      	dec	cx		;(IOLen - 1 + IOAdr).
   408 0000018B 01C8                    	add	ax,cx		;Would this I-O cross a 64K boundary?
   409 0000018D 723B                    	jc	NoLock		;Yes, use buffered I-O routines below.
   410 0000018F 837F32FF                	cmp	word [bx+IOAdr+2-@],byte -1  ;DMA I-O above our limit?
   411                                  @DMALmt	equ	$-1		;(If 640K limit, set to 009h by Init).
   412 00000193 7735                    	ja	NoLock		;Yes, use buffered I-O routines below.
   413 00000195 E89000                  	call	DoDMA		;Do direct DMA I-O with user's buffer.
   414 00000198 89E5                    Done	mov	bp,sp		;Done -- point to saved registers.
   415 0000019A 884613                  	mov	[bp+19],al	;Set error code in exiting AH-reg.
   416 0000019D 9C                      	pushf			;Save error flag (carry bit).
   417 0000019E E86700                  	call	VDUnlk		;If needed, "unlock" user I-O buffer.
   418 000001A1 FA                      	cli			;Disable CPU interrupts.
   419 000001A2 8A4713                  	mov	al,[bx+ReqBF-@]	;Reset driver & channel "busy" flags
   420 000001A5 F6D0                    	not	al		;  so other IDE drivers may proceed!
   421 000001A7 204712                  	and	[bx+Flags-@],al
   422 000001AA 58                      	pop	ax		;Reload error flag into carry bit.
   423 000001AB D1E8                    	shr	ax,1
   424 000001AD 07                      	pop	es		;Reload all CPU registers.
   425 000001AE 1F                      	pop	ds
   426 000001AF 61                      	popa
   427 000001B0 2E0FB226[4400]          	lss	sp,[cs:CStack]	;Switch back to caller's stack.
   428 000001B6 89E5                    GetOut	mov	bp,sp		;Point to caller's saved BP-reg.
   429 000001B8 D05E06                  	rcr	byte [bp+6],1	;Set error flag in exiting carry
   430 000001BB D04606                  	rol	byte [bp+6],1	;  bit, in flags saved by Int 13h.
   431 000001BE 5D                      	pop	bp		;Reload BP-register and exit.
   432 000001BF CF                      	iret
   433 000001C0 E81F00                  BufOut	call	XMSMov		;Buffered output -- move data to XMS.
   434 000001C3 72D3                    	jc	Done		;If error, post return code & exit!
   435 000001C5 E85800                  	call	BufDMA		;Output all data from XMS buffer.
   436 000001C8 EBCE                    	jmp	short Done	;Done -- post any return code & exit.
   437 000001CA E83B00                  NoLock	call	VDUnlk		;Buffered I-O -- "unlock" user buffer.
   438 000001CD 66C1672810              BufIO	shl	dword [bx+VDSOf-@],16  ;Convert to XMS handle & offset.
   439 000001D2 F6472112                	test	byte [bx+IOCmd-@],012h ;Is this a write request?
   440 000001D6 75E8                    	jnz	BufOut		;Yes, use output routine above.
   441 000001D8 E84500                  	call	BufDMA		;Input all data to driver XMS buffer.
   442 000001DB 72BB                    	jc	Done		;If error, post return code & exit!
   443 000001DD E80200                  	call	XMSMov		;Move XMS data to user input buffer.
   444 000001E0 EBB6                    	jmp	short Done	;Done -- post any return code & exit.
   445                                  ;
   446                                  ; Subroutine to move data to or from the driver's XMS buffer.
   447                                  ;
   448 000001E2 0E                      XMSMov	push	cs		;Point ES-reg. to our data.
   449 000001E3 07                      	pop	es
   450 000001E4 BF[2E00]                	mov	di,XMSDH	;Point to XMS destination field.
   451 000001E7 7508                    	jnz	XMSet		;If output, just set XMS destination!
   452 000001E9 BE[2800]                	mov	si,XMSSH	;Point to XMS user-buffer address.
   453 000001EC 56                      	push	si
   454 000001ED A5                      	movsw			;Move user-buffer address from
   455 000001EE A5                      	movsw			;  XMS source to XMS destination.
   456 000001EF A5                      	movsw
   457 000001F0 5F                      	pop	di		;Point to XMS source field.
   458 000001F1 BE[2200]                XMSet	mov	si,XMOfs	;Set XMS handle and buffer offset as
   459 000001F4 B80000                  	mov	ax,0		;  input source or output destination.
   460                                  @XMHdl	equ	$-2		;(XMS memory "handle", set by Init).
   461 000001F7 AB                      	stosw
   462 000001F8 A5                      	movsw
   463 000001F9 891D                    	mov	[di],bx
   464 000001FB B40B                    	mov	ah,00Bh		;Get XMS "move data" request code.
   465 000001FD 53                      	push	bx		;Save BX-reg. and execute XMS request.
   466 000001FE 9A                      	db	09Ah		;(SI-reg. points to IOLen after move).
   467 000001FF 00000000                @XEntry dd	0		;(XMS "entry" address, set by Init).
   468 00000203 48                      	dec	ax		;Return 0 if success, -1 if error.
   469 00000204 D1F8                    	sar	ax,1		;If error, set carry flag on.
   470 00000206 EB12                    	jmp	short VDDone	;Go restore driver settings and exit.
   471                                  ;
   472                                  ; Subroutine to do a VDS "lock" or "unlock".
   473                                  ;
   474 00000208 D06F11                  VDUnlk	shr	byte [bx+VLF-@],1  ;Was I-O buffer "locked" by VDS?
   475 0000020B 7312                    	jnc	VDExit		;No, just exit below.
   476 0000020D B80481                  VDUnlX	mov	ax,08104h	;Get VDS "unlock" parameters.
   477 00000210 31D2                    	xor	dx,dx
   478 00000212 BF[2400]                VDLock	mov	di,VDSLn	;Point to VDS parameter block.
   479 00000215 0E                      	push	cs
   480 00000216 07                      	pop	es
   481 00000217 53                      	push	bx		;Save BX-reg. and execute VDS request.
   482 00000218 CD4B                    	int	04Bh
   483 0000021A 5B                      VDDone	pop	bx		;Reload our BX-register.
   484 0000021B FB                      	sti			;RESTORE all critical driver settings!
   485 0000021C FC                      	cld			;(Never-NEVER "trust" external code!).
   486 0000021D 0E                      	push	cs