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source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/FindDPT.asm@ 198

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Last change on this file since 198 was 181, checked in by krille_n_@…, 13 years ago

Changes to all parts of the project:

Size optimizations.
Added a define (EXCLUDE_FROM_XTIDECFG) to exclude unused library code from XTIDECFG.
Tried to minimize time spent with interrupts disabled.
Some minor attempts to improve speed (reordering instructions etc).
Tried to improve readability, did some cleanup and fixed some errors in comments.

File size: 5.4 KB

Rev	Line
[150]	1	; Project name : XTIDE Universal BIOS
[3]	2	; Description : Functions for finding Disk Parameter Table.
	3
	4	; Section containing code
	5	SECTION .text
	6
	7	;--------------------------------------------------------------------
	8	; Finds pointer to first unused Disk Parameter Table.
	9	;
[150]	10	; FindDPT_ForNewDriveToDSDI
[3]	11	; Parameters:
	12	; DS: RAMVARS segment
	13	; Returns:
	14	; DS:DI: Ptr to first unused DPT
	15	; Corrupts registers:
[150]	16	; DL
	17	;--------------------------------------------------------------------
	18	ALIGN JUMP_ALIGN
	19	FindDPT_ForNewDriveToDSDI:
	20	mov dl, [RAMVARS.bFirstDrv]
	21	add dl, [RAMVARS.bDrvCnt]
	22	; Fall to FindDPT_ForDriveNumber
	23
	24
	25	;--------------------------------------------------------------------
	26	; Finds Disk Parameter Table for drive number.
	27	; IDE Base Port address will be stored to RAMVARS if correct DPT is found.
	28	;
	29	; FindDPT_ForDriveNumber
	30	; Parameters:
	31	; DL: Drive number
	32	; DS: RAMVARS segment
	33	; Returns:
	34	; DS:DI: Ptr to DPT
	35	; Corrupts registers:
[3]	36	; Nothing
	37	;--------------------------------------------------------------------
	38	ALIGN JUMP_ALIGN
[150]	39	FindDPT_ForDriveNumber:
	40	push dx
[161]	41	xchg di, ax ; Save the contents of AX in DI
[3]	42
[150]	43	mov al, LARGEST_DPT_SIZE
	44	sub dl, [RAMVARS.bFirstDrv]
	45	mul dl
	46	add ax, BYTE RAMVARS_size
[3]	47
[161]	48	xchg di, ax ; Restore AX and put result in DI
[150]	49	pop dx
	50	ret
	51
	52
[3]	53	;--------------------------------------------------------------------
	54	; Finds Disk Parameter Table for
	55	; Master or Slave drive at wanted port.
	56	;
[150]	57	; FindDPT_ToDSDIForIdeMasterAtPortDX
	58	; FindDPT_ToDSDIForIdeSlaveAtPortDX
[3]	59	; Parameters:
	60	; DX: IDE Base Port address
	61	; DS: RAMVARS segment
	62	; Returns:
	63	; DL: Drive number (if DPT found)
	64	; DS:DI: Ptr to DPT
	65	; CF: Set if wanted DPT found
	66	; Cleared if DPT not found
	67	; Corrupts registers:
[150]	68	; SI
[3]	69	;--------------------------------------------------------------------
	70	ALIGN JUMP_ALIGN
[150]	71	FindDPT_ToDSDIForIdeMasterAtPortDX:
[152]	72	mov si, IterateToMasterAtPortCallback
[150]	73	jmp SHORT IterateAllDPTs
[3]	74
	75	ALIGN JUMP_ALIGN
[150]	76	FindDPT_ToDSDIForIdeSlaveAtPortDX:
[152]	77	mov si, IterateToSlaveAtPortCallback
[150]	78	jmp SHORT IterateAllDPTs
[3]	79
	80	;--------------------------------------------------------------------
	81	; Iteration callback for finding DPT using
	82	; IDE base port for Master or Slave drive.
	83	;
[152]	84	; IterateToSlaveAtPortCallback
	85	; IterateToMasterAtPortCallback
[3]	86	; Parameters:
[150]	87	; CH: Drive number
[3]	88	; DX: IDE Base Port address
	89	; DS:DI: Ptr to DPT to examine
	90	; Returns:
	91	; DL: Drive number if correct DPT
	92	; CF: Set if wanted DPT found
	93	; Cleared if wrong DPT
	94	; Corrupts registers:
	95	; Nothing
	96	;--------------------------------------------------------------------
	97	ALIGN JUMP_ALIGN
[152]	98	IterateToSlaveAtPortCallback:
[158]	99	test BYTE [di+DPT.bFlagsLow], FLGL_DPT_SLAVE ; Clears CF
[150]	100	jnz SHORT CompareBasePortAddress
	101	ret ; Wrong DPT
[3]	102
	103	ALIGN JUMP_ALIGN
[152]	104	IterateToMasterAtPortCallback:
[158]	105	test BYTE [di+DPT.bFlagsLow], FLGL_DPT_SLAVE
[150]	106	jnz SHORT ReturnWrongDPT ; Return if slave drive
[3]	107
[150]	108	CompareBasePortAddress:
[3]	109	push bx
[150]	110	eMOVZX bx, BYTE [di+DPT.bIdevarsOffset] ; CS:BX now points to IDEVARS
	111	cmp dx, [cs:bx+IDEVARS.wPort] ; Wanted port?
[3]	112	pop bx
[150]	113	jne SHORT ReturnWrongDPT
	114	mov dl, ch ; Return drive number in DL
	115	stc ; Set CF since wanted DPT
[3]	116	ret
[152]	117
	118
	119	;--------------------------------------------------------------------
	120	; IterateToDptWithInterruptInServiceFlagSet
	121	; Parameters:
	122	; DS:DI: Ptr to DPT to examine
	123	; Returns:
	124	; CF: Set if wanted DPT found
	125	; Cleared if wrong DPT
	126	; Corrupts registers:
	127	; Nothing
	128	;--------------------------------------------------------------------
	129	ALIGN JUMP_ALIGN
	130	IterateToDptWithInterruptInServiceFlagSet:
[158]	131	test BYTE [di+DPT.bFlagsHigh], FLGH_DPT_INTERRUPT_IN_SERVICE
[152]	132	jz SHORT ReturnWrongDPT
	133	stc ; Set CF since wanted DPT
	134	ret
[150]	135	ReturnWrongDPT:
[152]	136	clc ; Clear CF since wrong DPT
[3]	137	ret
	138
	139
	140	;--------------------------------------------------------------------
[161]	141	; FindDPT_ToDSDIforInterruptInService
	142	; Parameters:
	143	; DS: RAMVARS segment
	144	; Returns:
	145	; DS:DI: Ptr to DPT
	146	; CF: Set if wanted DPT found
	147	; Cleared if DPT not found
	148	; Corrupts registers:
	149	; SI
	150	;--------------------------------------------------------------------
	151	ALIGN JUMP_ALIGN
	152	FindDPT_ToDSDIforInterruptInService:
	153	mov si, IterateToDptWithInterruptInServiceFlagSet
	154	; Fall to IterateAllDPTs
	155
	156
	157	;--------------------------------------------------------------------
[3]	158	; Iterates all Disk Parameter Tables.
	159	;
[150]	160	; IterateAllDPTs
[3]	161	; Parameters:
[152]	162	; AX,BX,DX: Parameters to callback function
	163	; CS:SI: Ptr to callback function
	164	; DS: RAMVARS segment
[3]	165	; Returns:
[152]	166	; DS:DI: Ptr to wanted DPT (if found)
	167	; CF: Set if wanted DPT found
	168	; Cleared if DPT not found
[181]	169	; Unchanged if no drives
[3]	170	; Corrupts registers:
[150]	171	; Nothing unless corrupted by callback function
[3]	172	;--------------------------------------------------------------------
	173	ALIGN JUMP_ALIGN
[150]	174	IterateAllDPTs:
[3]	175	push cx
[150]	176	mov cx, [RAMVARS.wDrvCntAndFirst]
	177	jcxz .AllDptsIterated ; Return if no drives
[152]	178	mov di, RAMVARS_size ; Point DS:DI to first DPT
[3]	179	ALIGN JUMP_ALIGN
	180	.LoopWhileDPTsLeft:
	181	call si ; Is wanted DPT?
[150]	182	jc SHORT .AllDptsIterated ; If so, return
	183	inc ch ; Increment drive number
	184	add di, BYTE LARGEST_DPT_SIZE ; Point to next DPT
	185	dec cl ; Decrement drives left
	186	jnz SHORT .LoopWhileDPTsLeft
[3]	187	clc ; Clear CF since DPT not found
	188	ALIGN JUMP_ALIGN
[150]	189	.AllDptsIterated:
[3]	190	pop cx
	191	ret

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