WebSVN – Kolibri OS – Diff – /kernel/trunk/sec_loader/trunk/boot/fat32/bootsect.asm


; Copyright (c) 2008-2009, diamond
; All rights reserved.
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions are met:
;       * Redistributions of source code must retain the above copyright
;       notice, this list of conditions and the following disclaimer.
;       * Redistributions in binary form must reproduce the above copyright
;       notice, this list of conditions and the following disclaimer in the
;       documentation and/or other materials provided with the distribution.
;       * Neither the name of the  nor the
;       names of its contributors may be used to endorse or promote products
;       derived from this software without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka  ''AS IS'' AND ANY
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
; DISCLAIMED. IN NO EVENT SHALL  BE LIABLE FOR ANY
; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;*****************************************************************************
 
use_lba = 0
        org     0x7C00
        jmp     start
        nop
; FAT parameters, BPB
; they must be changed at install, replaced with real values
                rb      8       ; BS_OEMName, ignored
                dw      200h    ; BPB_BytsPerSec
BPB_SecsPerClus db      ?
BPB_RsvdSecCnt  dw      ?
BPB_NumFATs     db      ?
BPB_RootEntCnt  dw      ?
                dw      ?       ; BPB_TotSec16
                db      ?       ; BPB_Media
                dw      ?       ; BPB_FATSz16 = 0 for FAT32
BPB_SecPerTrk   dw      ?
BPB_NumHeads    dw      ?
BPB_HiddSec     dd      ?
                dd      ?       ; BPB_TotSec32
BPB_FATSz32     dd      ?
BPB_ExtFlags    dw      ?
                dw      ?       ; BPB_FSVer
BPB_RootClus    dd      ?
                dw      ?       ; BPB_FSInfo
BPB_BkBootSec   dw      ?
                rb      12      ; BPB_Reserved
BS_DrvNum       db      ?
                db      ?       ; BS_Reserved1
                db      ?       ; BS_BootSig
                dd      ?       ; BS_VolID
                rb      11      ; BS_VolLab
                rb      8       ;
 
curseg  dw      0x8000
 
start:
        xor     ax, ax
        mov     ss, ax
        mov     sp, 0x7C00
        mov     ds, ax
        mov     bp, sp
        cld
        sti
        push    dx      ; byte [bp-2] = boot drive
if use_lba
        mov     ah, 41h
        mov     bx, 55AAh
        int     13h
        mov     si, aNoLBA
        jc      err_
        cmp     bx, 0AA55h
        jnz     err_
        test    cl, 1
        jz      err_
else
        mov     ah, 8
        int     13h
        jc      @f
        movzx   ax, dh
        inc     ax
        mov     [bp+BPB_NumHeads-0x7C00], ax
        and     cx, 3Fh
        mov     [bp+BPB_SecPerTrk-0x7C00], cx
@@:
end if
; get FAT parameters
        xor     bx, bx
        movzx   eax, [bp+BPB_NumFATs-0x7C00]
        mul     [bp+BPB_FATSz32-0x7C00]
        movzx   ecx, [bp+BPB_RsvdSecCnt-0x7C00]
        push    ecx     ; FAT start = dword [bp-6]
        add     eax, ecx
        push    eax     ; data start = dword [bp-10]
        ;push   dword -1        ; dword [bp-14] = current sector for FAT cache
        db      66h
        push    -1      ; dword [bp-14] = current sector for FAT cache
        mov     eax, [bp+BPB_RootClus-0x7C00]
        mov     si, main_loader
        call    lookup_in_dir
        jnc     kordldr_ok
noloader:
        mov     si, aLoaderNotFound
err_:
        call    out_string
        mov     si, aPressAnyKey
        call    out_string
        xor     ax, ax
        int     16h
        int     18h
        jmp     $
kordldr_ok:
        mov     eax, [es:di+20-2]       ; hiword(eax) = hiword(cluster)
        mov     ax, [es:di+26]          ; loword(eax) = loword(cluster)
        mov     es, bx          ; es = 0
        mov     bx, 0x7E00
        push    bx      ; save return address: bx = 7E00
; fall through - 'ret' in read_cluster will return to 7E00
 
read_cluster:
; ss:bp = 0:7C00
; es:bx = pointer to data
; eax = cluster
        sub     eax, 2
        movzx   ecx, [bp+BPB_SecsPerClus-0x7C00]
        mul     ecx
 
read_sectors2:
; same as read_sectors32, but eax is relative to start of data
        add     eax, [bp-10]
read_sectors32:
; ss:bp = 0:7C00
; es:bx = pointer to data
; eax = first sector
; cx = number of sectors
; some high words of 32-bit registers are destroyed!
        pusha
        add     eax, [bp+BPB_HiddSec-0x7C00]
if use_lba
        push    ds
do_read_sectors:
        push    ax
        push    cx
        cmp     cx, 0x7F
        jbe     @f
        mov     cx, 0x7F
@@:
; create disk address packet on the stack
; dq starting LBA
        push    0
        push    0
        push    eax
; dd buffer
        push    es
        push    bx
; dw number of blocks to transfer (no more than 0x7F)
        push    cx
; dw packet size in bytes
        push    10h
; issue BIOS call
        push    ss
        pop     ds
        mov     si, sp
        mov     dl, [bp-2]
        mov     ah, 42h
        int     13h
        mov     si, aReadError
        jc      err_
; restore stack
        add     sp, 10h
; increase current sector & buffer; decrease number of sectors
        movzx   esi, cx
        mov     ax, es
        shl     cx, 5
        add     ax, cx
        mov     es, ax
        pop     cx
        pop     ax
        add     eax, esi
        sub     cx, si
        jnz     do_read_sectors
        pop     ds
        popa
        ret
else
do_read_sectors:
        pusha
        pop     edi     ; loword(edi) = di, hiword(edi) = si
        push    bx
 
; eax / (SectorsPerTrack) -> eax, remainder bx
        movzx   esi, [bp+BPB_SecPerTrk-0x7C00]
        xor     edx, edx
        div     esi
        mov     bx, dx          ; bx=sector-1
 
; eax -> dx:ax
        push    eax
        pop     ax
        pop     dx
; (dword in dx:ax) / (NumHeads) -> (word in ax), remainder dx
        div     [bp+BPB_NumHeads-0x7C00]
 
; number of sectors: read no more than to end of track
        sub     si, bx
        cmp     cx, si
        jbe     @f
        mov     cx, si
@@:
 
        inc     bx
; now ax=track, dl=head, dh=0, cl=number of sectors, ch=0, bl=sector; convert to int13 format
        movzx   edi, cx
        mov     dh, dl
        mov     dl, [bp-2]
        shl     ah, 6
        mov     ch, al
        mov     al, cl
        mov     cl, bl
        or      cl, ah
        pop     bx
        mov     si, 3
        mov     ah, 2
@@:
        push    ax
        int     13h
        jnc     @f
        xor     ax, ax
        int     13h     ; reset drive
        pop     ax
        dec     si
        jnz     @b
        mov     si, aReadError
        jmp     err_
@@:
        pop     ax
        mov     ax, es
        mov     cx, di
        shl     cx, 5
        add     ax, cx
        mov     es, ax
        push    edi
        popa
        add     eax, edi
        sub     cx, di
        jnz     do_read_sectors
        popa
        ret
end if
 
lookup_in_dir:
; in: ds:si -> 11-bytes FAT name
; in: eax = cluster
; in: bx = 0
; out: if found: CF=0, es:di -> directory entry
; out: if not found: CF=1
;       push    0x8000
;       pop     es
; read current cluster: first cluster goes to 8000:0000, others - to 8200:0000
        mov     es, [bp-7C00h + curseg]
        push    es
        push    eax
        call    read_cluster
        mov     ax, es
        cmp     ah, 82h
        jb      @f
        mov     ax, 8200h
@@:
        mov     [bp-7C00h + curseg], ax
        pop     eax
        pop     es
; scan for filename
        shl     cx, 4
        xor     di, di
sloop:
        cmp     byte [es:di], bl
        jz      snotfound
        test    byte [es:di+11], 8      ; volume label?
        jnz     scont                   ; ignore volume labels
        pusha
        mov     cx, 11
        repz    cmpsb
        popa
        jz      sdone
scont:
        add     di, 0x20
        loop    sloop
; next cluster
        push    0x6000
        pop     es
        push    es ax
        shr     eax, 7
        cmp     eax, [bp-14]
        mov     [bp-14], eax
        jz      @f
        add     eax, [bp-6]
        mov     cx, 1
        call    read_sectors32
@@:
        pop     di es
        and     di, 0x7F
        shl     di, 2
        and     byte [es:di+3], 0x0F
        mov     eax, [es:di]
        ;and    eax, 0x0FFFFFFF
        cmp     eax, 0x0FFFFFF7
        jb      lookup_in_dir
snotfound:
        stc
sdone:
        ret
 
out_string:
; in: ds:si -> ASCIIZ string
        lodsb
        test    al, al
        jz      sdone
        mov     ah, 0Eh
        mov     bx, 7
        int     10h
        jmp     out_string
 
aReadError      db      'Read error',0
if use_lba
aNoLBA          db      'The drive does not support LBA!',0
end if
aLoaderNotFound db      'Loader not found',0
aPressAnyKey    db      13,10,'Press any key...',13,10,0
main_loader     db      'KORDLDR F32'
 
        db      56h
; just to make file 512 bytes long :)
        db      'd' xor 'i' xor 'a' xor 'm' xor 'o' xor 'n' xor 'd'
 
; bootsector signature
        dw      0xAA55
 
; display offsets of all procedures used by kordldr.f12.asm
macro show [procedure]
{
        bits = 16
        display `procedure,' = '
        repeat bits/4
                d = '0' + procedure shr (bits - %*4) and 0Fh
                if d > '9'
                        d = d + 'A'-'9'-1
                end if
                display d
        end repeat
        display 13,10
}
 
show read_sectors32, read_sectors2, err_, noloader

Rev 1065	Rev 1132
1	; Copyright (c) 2008-2009, diamond	1	; Copyright (c) 2008-2009, diamond
2	; All rights reserved.	2	; All rights reserved.
3	;	3	;
4	; Redistribution and use in source and binary forms, with or without	4	; Redistribution and use in source and binary forms, with or without
5	; modification, are permitted provided that the following conditions are met:	5	; modification, are permitted provided that the following conditions are met:
6	; * Redistributions of source code must retain the above copyright	6	; * Redistributions of source code must retain the above copyright
7	; notice, this list of conditions and the following disclaimer.	7	; notice, this list of conditions and the following disclaimer.
8	; * Redistributions in binary form must reproduce the above copyright	8	; * Redistributions in binary form must reproduce the above copyright
9	; notice, this list of conditions and the following disclaimer in the	9	; notice, this list of conditions and the following disclaimer in the
10	; documentation and/or other materials provided with the distribution.	10	; documentation and/or other materials provided with the distribution.
11	; * Neither the name of the nor the	11	; * Neither the name of the nor the
12	; names of its contributors may be used to endorse or promote products	12	; names of its contributors may be used to endorse or promote products
13	; derived from this software without specific prior written permission.	13	; derived from this software without specific prior written permission.
14	;	14	;
15	; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka ''AS IS'' AND ANY	15	; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka ''AS IS'' AND ANY
16	; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED	16	; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17	; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE	17	; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18	; DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY	18	; DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY
19	; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES	19	; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
20	; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;	20	; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21	; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND	21	; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
22	; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	22	; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23	; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS	23	; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
24	; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	24	; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25	;*****************************************************************************	25	;*****************************************************************************
26		26
27	use_lba = 0	27	use_lba = 0
28	org 0x7C00	28	org 0x7C00
29	jmp start	29	jmp start
30	nop	30	nop
31	; FAT parameters, BPB	31	; FAT parameters, BPB
32	; they must be changed at install, replaced with real values	32	; they must be changed at install, replaced with real values
33	rb 8 ; BS_OEMName, ignored	33	rb 8 ; BS_OEMName, ignored
34	dw 200h ; BPB_BytsPerSec	34	dw 200h ; BPB_BytsPerSec
35	BPB_SecsPerClus db ?	35	BPB_SecsPerClus db ?
36	BPB_RsvdSecCnt dw ?	36	BPB_RsvdSecCnt dw ?
37	BPB_NumFATs db ?	37	BPB_NumFATs db ?
38	BPB_RootEntCnt dw ?	38	BPB_RootEntCnt dw ?
39	dw ? ; BPB_TotSec16	39	dw ? ; BPB_TotSec16
40	db ? ; BPB_Media	40	db ? ; BPB_Media
41	dw ? ; BPB_FATSz16 = 0 for FAT32	41	dw ? ; BPB_FATSz16 = 0 for FAT32
42	BPB_SecPerTrk dw ?	42	BPB_SecPerTrk dw ?
43	BPB_NumHeads dw ?	43	BPB_NumHeads dw ?
44	BPB_HiddSec dd ?	44	BPB_HiddSec dd ?
45	dd ? ; BPB_TotSec32	45	dd ? ; BPB_TotSec32
46	BPB_FATSz32 dd ?	46	BPB_FATSz32 dd ?
47	BPB_ExtFlags dw ?	47	BPB_ExtFlags dw ?
48	dw ? ; BPB_FSVer	48	dw ? ; BPB_FSVer
49	BPB_RootClus dd ?	49	BPB_RootClus dd ?
50	dw ? ; BPB_FSInfo	50	dw ? ; BPB_FSInfo
51	BPB_BkBootSec dw ?	51	BPB_BkBootSec dw ?
52	rb 12 ; BPB_Reserved	52	rb 12 ; BPB_Reserved
53	BS_DrvNum db ?	53	BS_DrvNum db ?
54	db ? ; BS_Reserved1	54	db ? ; BS_Reserved1
55	db ? ; BS_BootSig	55	db ? ; BS_BootSig
56	dd ? ; BS_VolID	56	dd ? ; BS_VolID
57	rb 11 ; BS_VolLab	57	rb 11 ; BS_VolLab
58	rb 8 ;	58	rb 8 ;
59		59
60	curseg dw 0x8000	60	curseg dw 0x8000
61		61
62	start:	62	start:
63	xor ax, ax	63	xor ax, ax
64	mov ss, ax	64	mov ss, ax
65	mov sp, 0x7C00	65	mov sp, 0x7C00
66	mov ds, ax	66	mov ds, ax
67	mov bp, sp	67	mov bp, sp
68	cld	68	cld
69	sti	69	sti
70	push dx ; byte [bp-2] = boot drive	70	push dx ; byte [bp-2] = boot drive
71	if use_lba	71	if use_lba
72	mov ah, 41h	72	mov ah, 41h
73	mov bx, 55AAh	73	mov bx, 55AAh
74	int 13h	74	int 13h
75	mov si, aNoLBA	75	mov si, aNoLBA
76	jc err	76	jc err_
77	cmp bx, 0AA55h	77	cmp bx, 0AA55h
78	jnz err	78	jnz err_
79	test cl, 1	79	test cl, 1
80	jz err	80	jz err_
81	else	81	else
82	mov ah, 8	82	mov ah, 8
83	int 13h	83	int 13h
84	jc @f	84	jc @f
85	movzx ax, dh	85	movzx ax, dh
86	inc ax	86	inc ax
87	mov [bp+BPB_NumHeads-0x7C00], ax	87	mov [bp+BPB_NumHeads-0x7C00], ax
88	and cx, 3Fh	88	and cx, 3Fh
89	mov [bp+BPB_SecPerTrk-0x7C00], cx	89	mov [bp+BPB_SecPerTrk-0x7C00], cx
90	@@:	90	@@:
91	end if	91	end if
92	; get FAT parameters	92	; get FAT parameters
93	xor bx, bx	93	xor bx, bx
94	movzx eax, [bp+BPB_NumFATs-0x7C00]	94	movzx eax, [bp+BPB_NumFATs-0x7C00]
95	mul [bp+BPB_FATSz32-0x7C00]	95	mul [bp+BPB_FATSz32-0x7C00]
96	movzx ecx, [bp+BPB_RsvdSecCnt-0x7C00]	96	movzx ecx, [bp+BPB_RsvdSecCnt-0x7C00]
97	push ecx ; FAT start = dword [bp-6]	97	push ecx ; FAT start = dword [bp-6]
98	add eax, ecx	98	add eax, ecx
99	push eax ; data start = dword [bp-10]	99	push eax ; data start = dword [bp-10]
100	;push dword -1 ; dword [bp-14] = current sector for FAT cache	100	;push dword -1 ; dword [bp-14] = current sector for FAT cache
101	db 66h	101	db 66h
102	push -1 ; dword [bp-14] = current sector for FAT cache	102	push -1 ; dword [bp-14] = current sector for FAT cache
103	mov eax, [bp+BPB_RootClus-0x7C00]	103	mov eax, [bp+BPB_RootClus-0x7C00]
104	mov si, main_loader	104	mov si, main_loader
105	call lookup_in_dir	105	call lookup_in_dir
106	jnc kordldr_ok	106	jnc kordldr_ok
107	noloader:	107	noloader:
108	mov si, aLoaderNotFound	108	mov si, aLoaderNotFound
109	err:	109	err_:
110	call out_string	110	call out_string
111	mov si, aPressAnyKey	111	mov si, aPressAnyKey
112	call out_string	112	call out_string
113	xor ax, ax	113	xor ax, ax
114	int 16h	114	int 16h
115	int 18h	115	int 18h
116	jmp $	116	jmp $
117	kordldr_ok:	117	kordldr_ok:
118	mov eax, [es:di+20-2] ; hiword(eax) = hiword(cluster)	118	mov eax, [es:di+20-2] ; hiword(eax) = hiword(cluster)
119	mov ax, [es:di+26] ; loword(eax) = loword(cluster)	119	mov ax, [es:di+26] ; loword(eax) = loword(cluster)
120	mov es, bx ; es = 0	120	mov es, bx ; es = 0
121	mov bx, 0x7E00	121	mov bx, 0x7E00
122	push bx ; save return address: bx = 7E00	122	push bx ; save return address: bx = 7E00
123	; fall through - 'ret' in read_cluster will return to 7E00	123	; fall through - 'ret' in read_cluster will return to 7E00
124		124
125	read_cluster:	125	read_cluster:
126	; ss:bp = 0:7C00	126	; ss:bp = 0:7C00
127	; es:bx = pointer to data	127	; es:bx = pointer to data
128	; eax = cluster	128	; eax = cluster
129	sub eax, 2	129	sub eax, 2
130	movzx ecx, [bp+BPB_SecsPerClus-0x7C00]	130	movzx ecx, [bp+BPB_SecsPerClus-0x7C00]
131	mul ecx	131	mul ecx
132		132
133	read_sectors2:	133	read_sectors2:
134	; same as read_sectors32, but eax is relative to start of data	134	; same as read_sectors32, but eax is relative to start of data
135	add eax, [bp-10]	135	add eax, [bp-10]
136	read_sectors32:	136	read_sectors32:
137	; ss:bp = 0:7C00	137	; ss:bp = 0:7C00
138	; es:bx = pointer to data	138	; es:bx = pointer to data
139	; eax = first sector	139	; eax = first sector
140	; cx = number of sectors	140	; cx = number of sectors
141	; some high words of 32-bit registers are destroyed!	141	; some high words of 32-bit registers are destroyed!
142	pusha	142	pusha
143	add eax, [bp+BPB_HiddSec-0x7C00]	143	add eax, [bp+BPB_HiddSec-0x7C00]
144	if use_lba	144	if use_lba
145	push ds	145	push ds
146	do_read_sectors:	146	do_read_sectors:
147	push ax	147	push ax
148	push cx	148	push cx
149	cmp cx, 0x7F	149	cmp cx, 0x7F
150	jbe @f	150	jbe @f
151	mov cx, 0x7F	151	mov cx, 0x7F
152	@@:	152	@@:
153	; create disk address packet on the stack	153	; create disk address packet on the stack
154	; dq starting LBA	154	; dq starting LBA
155	push 0	155	push 0
156	push 0	156	push 0
157	push eax	157	push eax
158	; dd buffer	158	; dd buffer
159	push es	159	push es
160	push bx	160	push bx
161	; dw number of blocks to transfer (no more than 0x7F)	161	; dw number of blocks to transfer (no more than 0x7F)
162	push cx	162	push cx
163	; dw packet size in bytes	163	; dw packet size in bytes
164	push 10h	164	push 10h
165	; issue BIOS call	165	; issue BIOS call
166	push ss	166	push ss
167	pop ds	167	pop ds
168	mov si, sp	168	mov si, sp
169	mov dl, [bp-2]	169	mov dl, [bp-2]
170	mov ah, 42h	170	mov ah, 42h
171	int 13h	171	int 13h
172	mov si, aReadError	172	mov si, aReadError
173	jc err	173	jc err_
174	; restore stack	174	; restore stack
175	add sp, 10h	175	add sp, 10h
176	; increase current sector & buffer; decrease number of sectors	176	; increase current sector & buffer; decrease number of sectors
177	movzx esi, cx	177	movzx esi, cx
178	mov ax, es	178	mov ax, es
179	shl cx, 5	179	shl cx, 5
180	add ax, cx	180	add ax, cx
181	mov es, ax	181	mov es, ax
182	pop cx	182	pop cx
183	pop ax	183	pop ax
184	add eax, esi	184	add eax, esi
185	sub cx, si	185	sub cx, si
186	jnz do_read_sectors	186	jnz do_read_sectors
187	pop ds	187	pop ds
188	popa	188	popa
189	ret	189	ret
190	else	190	else
191	do_read_sectors:	191	do_read_sectors:
192	pusha	192	pusha
193	pop edi ; loword(edi) = di, hiword(edi) = si	193	pop edi ; loword(edi) = di, hiword(edi) = si
194	push bx	194	push bx
195		195
196	; eax / (SectorsPerTrack) -> eax, remainder bx	196	; eax / (SectorsPerTrack) -> eax, remainder bx
197	movzx esi, [bp+BPB_SecPerTrk-0x7C00]	197	movzx esi, [bp+BPB_SecPerTrk-0x7C00]
198	xor edx, edx	198	xor edx, edx
199	div esi	199	div esi
200	mov bx, dx ; bx=sector-1	200	mov bx, dx ; bx=sector-1
201		201
202	; eax -> dx:ax	202	; eax -> dx:ax
203	push eax	203	push eax
204	pop ax	204	pop ax
205	pop dx	205	pop dx
206	; (dword in dx:ax) / (NumHeads) -> (word in ax), remainder dx	206	; (dword in dx:ax) / (NumHeads) -> (word in ax), remainder dx
207	div [bp+BPB_NumHeads-0x7C00]	207	div [bp+BPB_NumHeads-0x7C00]
208		208
209	; number of sectors: read no more than to end of track	209	; number of sectors: read no more than to end of track
210	sub si, bx	210	sub si, bx
211	cmp cx, si	211	cmp cx, si
212	jbe @f	212	jbe @f
213	mov cx, si	213	mov cx, si
214	@@:	214	@@:
215		215
216	inc bx	216	inc bx
217	; now ax=track, dl=head, dh=0, cl=number of sectors, ch=0, bl=sector; convert to int13 format	217	; now ax=track, dl=head, dh=0, cl=number of sectors, ch=0, bl=sector; convert to int13 format
218	movzx edi, cx	218	movzx edi, cx
219	mov dh, dl	219	mov dh, dl
220	mov dl, [bp-2]	220	mov dl, [bp-2]
221	shl ah, 6	221	shl ah, 6
222	mov ch, al	222	mov ch, al
223	mov al, cl	223	mov al, cl
224	mov cl, bl	224	mov cl, bl
225	or cl, ah	225	or cl, ah
226	pop bx	226	pop bx
227	mov si, 3	227	mov si, 3
228	mov ah, 2	228	mov ah, 2
229	@@:	229	@@:
230	push ax	230	push ax
231	int 13h	231	int 13h
232	jnc @f	232	jnc @f
233	xor ax, ax	233	xor ax, ax
234	int 13h ; reset drive	234	int 13h ; reset drive
235	pop ax	235	pop ax
236	dec si	236	dec si
237	jnz @b	237	jnz @b
238	mov si, aReadError	238	mov si, aReadError
239	jmp err	239	jmp err_
240	@@:	240	@@:
241	pop ax	241	pop ax
242	mov ax, es	242	mov ax, es
243	mov cx, di	243	mov cx, di
244	shl cx, 5	244	shl cx, 5
245	add ax, cx	245	add ax, cx
246	mov es, ax	246	mov es, ax
247	push edi	247	push edi
248	popa	248	popa
249	add eax, edi	249	add eax, edi
250	sub cx, di	250	sub cx, di
251	jnz do_read_sectors	251	jnz do_read_sectors
252	popa	252	popa
253	ret	253	ret
254	end if	254	end if
255		255
256	lookup_in_dir:	256	lookup_in_dir:
257	; in: ds:si -> 11-bytes FAT name	257	; in: ds:si -> 11-bytes FAT name
258	; in: eax = cluster	258	; in: eax = cluster
259	; in: bx = 0	259	; in: bx = 0
260	; out: if found: CF=0, es:di -> directory entry	260	; out: if found: CF=0, es:di -> directory entry
261	; out: if not found: CF=1	261	; out: if not found: CF=1
262	; push 0x8000	262	; push 0x8000
263	; pop es	263	; pop es
264	; read current cluster: first cluster goes to 8000:0000, others - to 8200:0000	264	; read current cluster: first cluster goes to 8000:0000, others - to 8200:0000
265	mov es, [bp-7C00h + curseg]	265	mov es, [bp-7C00h + curseg]
266	push es	266	push es
267	push eax	267	push eax
268	call read_cluster	268	call read_cluster
269	mov ax, es	269	mov ax, es
270	cmp ah, 82h	270	cmp ah, 82h
271	jb @f	271	jb @f
272	mov ax, 8200h	272	mov ax, 8200h
273	@@:	273	@@:
274	mov [bp-7C00h + curseg], ax	274	mov [bp-7C00h + curseg], ax
275	pop eax	275	pop eax
276	pop es	276	pop es
277	; scan for filename	277	; scan for filename
278	shl cx, 4	278	shl cx, 4
279	xor di, di	279	xor di, di
280	sloop:	280	sloop:
281	cmp byte [es:di], bl	281	cmp byte [es:di], bl
282	jz snotfound	282	jz snotfound
283	test byte [es:di+11], 8 ; volume label?	283	test byte [es:di+11], 8 ; volume label?
284	jnz scont ; ignore volume labels	284	jnz scont ; ignore volume labels
285	pusha	285	pusha
286	mov cx, 11	286	mov cx, 11
287	repz cmpsb	287	repz cmpsb
288	popa	288	popa
289	jz sdone	289	jz sdone
290	scont:	290	scont:
291	add di, 0x20	291	add di, 0x20
292	loop sloop	292	loop sloop
293	; next cluster	293	; next cluster
294	push 0x6000	294	push 0x6000
295	pop es	295	pop es
296	push es ax	296	push es ax
297	shr eax, 7	297	shr eax, 7
298	cmp eax, [bp-14]	298	cmp eax, [bp-14]
299	mov [bp-14], eax	299	mov [bp-14], eax
300	jz @f	300	jz @f
301	add eax, [bp-6]	301	add eax, [bp-6]
302	mov cx, 1	302	mov cx, 1
303	call read_sectors32	303	call read_sectors32
304	@@:	304	@@:
305	pop di es	305	pop di es
306	and di, 0x7F	306	and di, 0x7F
307	shl di, 2	307	shl di, 2
308	and byte [es:di+3], 0x0F	308	and byte [es:di+3], 0x0F
309	mov eax, [es:di]	309	mov eax, [es:di]
310	;and eax, 0x0FFFFFFF	310	;and eax, 0x0FFFFFFF
311	cmp eax, 0x0FFFFFF7	311	cmp eax, 0x0FFFFFF7
312	jb lookup_in_dir	312	jb lookup_in_dir
313	snotfound:	313	snotfound:
314	stc	314	stc
315	sdone:	315	sdone:
316	ret	316	ret
317		317
318	out_string:	318	out_string:
319	; in: ds:si -> ASCIIZ string	319	; in: ds:si -> ASCIIZ string
320	lodsb	320	lodsb
321	test al, al	321	test al, al
322	jz sdone	322	jz sdone
323	mov ah, 0Eh	323	mov ah, 0Eh
324	mov bx, 7	324	mov bx, 7
325	int 10h	325	int 10h
326	jmp out_string	326	jmp out_string
327		327
328	aReadError db 'Read error',0	328	aReadError db 'Read error',0
329	if use_lba	329	if use_lba
330	aNoLBA db 'The drive does not support LBA!',0	330	aNoLBA db 'The drive does not support LBA!',0
331	end if	331	end if
332	aLoaderNotFound db 'Loader not found',0	332	aLoaderNotFound db 'Loader not found',0
333	aPressAnyKey db 13,10,'Press any key...',13,10,0	333	aPressAnyKey db 13,10,'Press any key...',13,10,0
334	main_loader db 'KORDLDR F32'	334	main_loader db 'KORDLDR F32'
335		335
336	db 56h	336	db 56h
337	; just to make file 512 bytes long :)	337	; just to make file 512 bytes long :)
338	db 'd' xor 'i' xor 'a' xor 'm' xor 'o' xor 'n' xor 'd'	338	db 'd' xor 'i' xor 'a' xor 'm' xor 'o' xor 'n' xor 'd'
339		339
340	; bootsector signature	340	; bootsector signature
341	dw 0xAA55	341	dw 0xAA55
342		342
343	; display offsets of all procedures used by kordldr.f12.asm	343	; display offsets of all procedures used by kordldr.f12.asm
344	macro show [procedure]	344	macro show [procedure]
345	{	345	{
346	bits = 16	346	bits = 16
347	display `procedure,' = '	347	display `procedure,' = '
348	repeat bits/4	348	repeat bits/4
349	d = '0' + procedure shr (bits - %*4) and 0Fh	349	d = '0' + procedure shr (bits - %*4) and 0Fh
350	if d > '9'	350	if d > '9'
351	d = d + 'A'-'9'-1	351	d = d + 'A'-'9'-1
352	end if	352	end if
353	display d	353	display d
354	end repeat	354	end repeat
355	display 13,10	355	display 13,10
356	}	356	}
357		357
358	show read_sectors32, read_sectors2, err, noloader	358	show read_sectors32, read_sectors2, err_, noloader

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(root)/kernel/trunk/sec_loader/trunk/boot/fat32/bootsect.asm – Rev 1065 → 1132