rev |
line source |
pascal@24476
|
1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
2 ;; ;;
|
pascal@24476
|
3 ;; "BootProg" Loader v 1.5 by Alexey Frunze (c) 2000-2015 ;;
|
pascal@24476
|
4 ;; 2-clause BSD license. ;;
|
pascal@24476
|
5 ;; ;;
|
pascal@24476
|
6 ;; ;;
|
pascal@24476
|
7 ;; How to Compile: ;;
|
pascal@24476
|
8 ;; ~~~~~~~~~~~~~~~ ;;
|
pascal@24476
|
9 ;; nasm boot32.asm -f bin -o boot32.bin ;;
|
pascal@24476
|
10 ;; ;;
|
pascal@24476
|
11 ;; ;;
|
pascal@24476
|
12 ;; Features: ;;
|
pascal@24476
|
13 ;; ~~~~~~~~~ ;;
|
pascal@24535
|
14 ;; - FAT32 supported using BIOS int 13h function 42h (IOW, it will only ;;
|
pascal@24535
|
15 ;; work with modern BIOSes supporting HDDs bigger than 8 GB) ;;
|
pascal@24476
|
16 ;; ;;
|
pascal@24476
|
17 ;; - Loads a 16-bit executable file in the MS-DOS .COM or .EXE format ;;
|
pascal@24476
|
18 ;; from the root directory of a disk and transfers control to it ;;
|
pascal@24476
|
19 ;; (the "ProgramName" variable holds the name of the file to be loaded) ;;
|
pascal@25460
|
20 ;; Its maximum size can be up to 637KB without Extended BIOS Data area. ;;
|
pascal@24476
|
21 ;; ;;
|
pascal@24476
|
22 ;; - Prints an error if the file isn't found or couldn't be read ;;
|
pascal@24476
|
23 ;; ("File not found" or "Read error") ;;
|
pascal@24476
|
24 ;; and waits for a key to be pressed, then executes the Int 19h ;;
|
pascal@24476
|
25 ;; instruction and lets the BIOS continue bootstrap. ;;
|
pascal@24476
|
26 ;; ;;
|
pascal@24476
|
27 ;; ;;
|
pascal@24476
|
28 ;; Known Bugs: ;;
|
pascal@24476
|
29 ;; ~~~~~~~~~~~ ;;
|
pascal@24476
|
30 ;; - All bugs are fixed as far as I know. The boot sector has been tested ;;
|
pascal@24476
|
31 ;; on my HDD and an 8GB USB stick. ;;
|
pascal@24476
|
32 ;; ;;
|
pascal@24476
|
33 ;; ;;
|
pascal@24476
|
34 ;; Memory Layout: ;;
|
pascal@24476
|
35 ;; ~~~~~~~~~~~~~~ ;;
|
pascal@24476
|
36 ;; The diagram below shows the typical memory layout. The actual location ;;
|
pascal@24476
|
37 ;; of the boot sector and its stack may be lower than A0000H if the BIOS ;;
|
pascal@24476
|
38 ;; reserves memory for its Extended BIOS Data Area just below A0000H and ;;
|
pascal@24476
|
39 ;; reports less than 640 KB of RAM via its Int 12H function. ;;
|
pascal@24476
|
40 ;; ;;
|
pascal@24476
|
41 ;; physical address ;;
|
pascal@24476
|
42 ;; +------------------------+ 00000H ;;
|
pascal@24476
|
43 ;; | Interrupt Vector Table | ;;
|
pascal@24476
|
44 ;; +------------------------+ 00400H ;;
|
pascal@24476
|
45 ;; | BIOS Data Area | ;;
|
pascal@24476
|
46 ;; +------------------------+ 00500H ;;
|
pascal@24476
|
47 ;; | PrtScr Status / Unused | ;;
|
pascal@24476
|
48 ;; +------------------------+ 00600H ;;
|
pascal@24476
|
49 ;; | Loaded Image | ;;
|
pascal@24476
|
50 ;; +------------------------+ nnnnnH ;;
|
pascal@24476
|
51 ;; | Available Memory | ;;
|
pascal@25460
|
52 ;; +------------------------+ A0000H - 1KB ;;
|
pascal@24476
|
53 ;; | Boot Sector | ;;
|
pascal@25460
|
54 ;; +------------------------+ A0000H - 0.5KB ;;
|
pascal@25460
|
55 ;; | 0.5KB Boot Stack | ;;
|
pascal@24476
|
56 ;; +------------------------+ A0000H ;;
|
pascal@24476
|
57 ;; | Video RAM | ;;
|
pascal@24476
|
58 ;; ;;
|
pascal@24476
|
59 ;; ;;
|
pascal@24476
|
60 ;; Boot Image Startup (register values): ;;
|
pascal@24476
|
61 ;; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ;;
|
pascal@24945
|
62 ;; ax = 0ffffh (both FCB in the PSP don't have a valid drive identifier), ;;
|
pascal@25454
|
63 ;; bx = 0, dl = BIOS boot drive number (e.g. 0, 80H) ;;
|
pascal@24476
|
64 ;; cs:ip = program entry point ;;
|
pascal@24476
|
65 ;; ss:sp = program stack (don't confuse with boot sector's stack) ;;
|
pascal@24476
|
66 ;; COM program defaults: cs = ds = es = ss = 50h, sp = 0, ip = 100h ;;
|
pascal@24476
|
67 ;; EXE program defaults: ds = es = EXE data - 10h (fake MS-DOS psp), ;;
|
pascal@24476
|
68 ;; cs:ip and ss:sp depends on EXE header ;;
|
pascal@24476
|
69 ;; Magic numbers: ;;
|
pascal@24476
|
70 ;; si = 16381 (prime number 2**14-3) ;;
|
pascal@24476
|
71 ;; di = 32749 (prime number 2**15-19) ;;
|
pascal@24476
|
72 ;; bp = 65521 (prime number 2**16-15) ;;
|
pascal@24476
|
73 ;; The magic numbers let the program know whether it has been loaded by ;;
|
pascal@24476
|
74 ;; this boot sector or by MS-DOS, which may be handy for universal, bare- ;;
|
pascal@24476
|
75 ;; metal and MS-DOS programs. ;;
|
pascal@24945
|
76 ;; The command line contains no arguments. ;;
|
pascal@24476
|
77 ;; ;;
|
pascal@24476
|
78 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
79
|
pascal@24491
|
80 %define bx(label) bx+label-boot
|
pascal@25449
|
81 %define si(label) si+label-boot
|
pascal@25485
|
82 ExtraBootSector equ 1
|
pascal@25449
|
83 ClusterMask equ 1 ; +9 bytes
|
pascal@25460
|
84 NullEntryCheck equ 1 ; +5 bytes
|
pascal@25485
|
85 CheckAttrib equ 1 ; +6 bytes
|
pascal@25485
|
86 NonMirroredFATs equ 1 ; +18 bytes
|
pascal@25449
|
87 ReadRetry equ 1 ; +7 bytes
|
pascal@25458
|
88 LBA48bits equ 1 ; +15 bytes
|
pascal@25485
|
89 CHSsupport equ 1 ; +27 bytes max 16MB, 32MB or 8GB
|
pascal@25485
|
90 CHSupTo32MB equ 1 ; +6 bytes
|
pascal@25485
|
91 CHSupTo8GB equ 1 ; +14 bytes
|
pascal@25485
|
92 SectorOf512Bytes equ 0 ; -5 bytes
|
pascal@25458
|
93 Always2FATs equ 0 ; -4 bytes
|
pascal@24491
|
94
|
pascal@24476
|
95 [BITS 16]
|
pascal@24476
|
96
|
pascal@24478
|
97 ImageLoadSeg equ 60h ; <=07Fh because of "push byte ImageLoadSeg" instructions
|
pascal@25460
|
98 StackSize equ 512
|
pascal@24476
|
99
|
pascal@24476
|
100 [SECTION .text]
|
pascal@24476
|
101 [ORG 0]
|
pascal@24476
|
102
|
pascal@24476
|
103 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
104 ;; Boot sector starts here ;;
|
pascal@24476
|
105 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
106
|
pascal@24491
|
107 boot:
|
pascal@25458
|
108 DriveNumber equ boot+0
|
pascal@25458
|
109 HiLBA equ boot+2
|
pascal@24476
|
110 jmp short start ; MS-DOS/Windows checks for this jump
|
pascal@24476
|
111 nop
|
pascal@24476
|
112 bsOemName DB "BootProg" ; 0x03
|
pascal@24476
|
113
|
pascal@24476
|
114 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
115 ;; BPB1 starts here ;;
|
pascal@24476
|
116 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
117
|
pascal@24479
|
118 bpbBytesPerSector DW 0 ; 0x0B
|
pascal@24479
|
119 bpbSectorsPerCluster DB 0 ; 0x0D
|
pascal@24479
|
120 bpbReservedSectors DW 0 ; 0x0E
|
pascal@24479
|
121 bpbNumberOfFATs DB 0 ; 0x10
|
pascal@24479
|
122 bpbRootEntries DW 0 ; 0x11
|
pascal@24479
|
123 bpbTotalSectors DW 0 ; 0x13
|
pascal@24479
|
124 bpbMedia DB 0 ; 0x15
|
pascal@24479
|
125 bpbSectorsPerFAT DW 0 ; 0x16
|
pascal@24479
|
126 bpbSectorsPerTrack DW 0 ; 0x18
|
pascal@24479
|
127 bpbHeadsPerCylinder DW 0 ; 0x1A
|
pascal@24479
|
128 bpbHiddenSectors DD 0 ; 0x1C
|
pascal@24479
|
129 bpbTotalSectorsBig DD 0 ; 0x20
|
pascal@24476
|
130
|
pascal@24476
|
131 ;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
132 ;; BPB1 ends here ;;
|
pascal@24476
|
133 ;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
134
|
pascal@24476
|
135 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
136 ;; BPB2 starts here ;;
|
pascal@24476
|
137 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
138
|
pascal@24479
|
139 bsSectorsPerFAT32 DD 0 ; 0x24
|
pascal@24479
|
140 bsExtendedFlags DW 0 ; 0x28
|
pascal@24479
|
141 bsFSVersion DW 0 ; 0x2A
|
pascal@24479
|
142 bsRootDirectoryClusterNo DD 0 ; 0x2C
|
pascal@24479
|
143 bsFSInfoSectorNo DW 0 ; 0x30
|
pascal@24479
|
144 bsBackupBootSectorNo DW 0 ; 0x32
|
pascal@24479
|
145 bsreserved times 12 DB 0 ; 0x34
|
pascal@24479
|
146 bsDriveNumber DB 0 ; 0x40
|
pascal@24479
|
147 bsreserved1 DB 0 ; 0x41
|
pascal@24479
|
148 bsExtendedBootSignature DB 0 ; 0x42
|
pascal@24479
|
149 bsVolumeSerialNumber DD 0 ; 0x43
|
pascal@25458
|
150 bsVolumeLabel times 11 DB " " ; 0x47 "NO NAME "
|
pascal@25458
|
151 bsFileSystemName times 8 DB " " ; 0x52 "FAT32 "
|
pascal@24476
|
152
|
pascal@24476
|
153 ;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
154 ;; BPB2 ends here ;;
|
pascal@24476
|
155 ;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
156
|
pascal@24476
|
157 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
158 ;; Boot sector code starts here ;;
|
pascal@24476
|
159 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
160
|
pascal@24476
|
161 start:
|
pascal@24476
|
162 cld
|
pascal@24476
|
163
|
pascal@24476
|
164 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
165 ;; How much RAM is there? ;;
|
pascal@24476
|
166 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
167
|
pascal@24476
|
168 int 12h ; get conventional memory size (in KBs)
|
pascal@25460
|
169 dec ax ; reserve 1K bytes for the code and the stack
|
pascal@24525
|
170 mov cx, 106h
|
pascal@24525
|
171 shl ax, cl ; and convert it to 16-byte paragraphs
|
pascal@24476
|
172
|
pascal@24476
|
173 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
174 ;; Reserve memory for the boot sector and its stack ;;
|
pascal@24476
|
175 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
176
|
pascal@24525
|
177 mov es, ax ; cs:0 = ds:0 = ss:0 -> top - 512 - StackSize
|
pascal@25485
|
178 %if ExtraBootSector == 0
|
pascal@24525
|
179 mov ss, ax
|
pascal@24525
|
180 mov sp, 512+StackSize ; bytes 0-511 are reserved for the boot code
|
pascal@25485
|
181 %endif
|
pascal@24476
|
182
|
pascal@24476
|
183 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
184 ;; Copy ourselves to top of memory ;;
|
pascal@24476
|
185 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
186
|
pascal@24476
|
187 mov si, 7C00h
|
pascal@24476
|
188 xor di, di
|
pascal@24476
|
189 mov ds, di
|
pascal@25449
|
190 push es
|
pascal@25449
|
191 mov [si(DriveNumber)], dx ; store BIOS boot drive number
|
pascal@24478
|
192 rep movsw
|
pascal@24476
|
193
|
pascal@24476
|
194 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
195 ;; Jump to the copy ;;
|
pascal@24476
|
196 ;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
197
|
pascal@25450
|
198 push byte main
|
pascal@25485
|
199 push es
|
pascal@25485
|
200 pop ds
|
pascal@24476
|
201 retf
|
pascal@24476
|
202
|
pascal@24476
|
203 main:
|
pascal@25449
|
204 xor ebx, ebx
|
pascal@25485
|
205 %if ExtraBootSector != 0
|
pascal@25485
|
206 add al, 32
|
pascal@25485
|
207 mov es, ax
|
pascal@25485
|
208 mov eax, [bx(bpbHiddenSectors)]
|
pascal@25485
|
209 inc eax
|
pascal@25485
|
210 %if LBA48bits != 0
|
pascal@25485
|
211 mov [bx(HiLBA)], bx
|
pascal@25485
|
212 %endif
|
pascal@25485
|
213 call ReadSectorBoot
|
pascal@25485
|
214 push ds
|
pascal@25485
|
215 pop ss
|
pascal@25485
|
216 mov sp, 512+StackSize ; bytes 0-511 are reserved for the boot code
|
pascal@25485
|
217 %endif
|
pascal@24476
|
218
|
pascal@25449
|
219 %if ClusterMask != 0
|
pascal@24491
|
220 and byte [bx(bsRootDirectoryClusterNo+3)], 0Fh ; mask cluster value
|
pascal@25449
|
221 %endif
|
pascal@24491
|
222 mov esi, [bx(bsRootDirectoryClusterNo)] ; esi=cluster # of root dir
|
pascal@24476
|
223
|
pascal@24478
|
224 push byte ImageLoadSeg
|
pascal@24478
|
225 pop es
|
pascal@25449
|
226
|
pascal@25449
|
227 RootDirReadContinue:
|
pascal@25458
|
228 call ReadClusterSector ; read one sector of the root dir
|
pascal@24476
|
229
|
pascal@24476
|
230 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
231 ;; Look for the COM/EXE file to load and run ;;
|
pascal@24476
|
232 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
233
|
pascal@24476
|
234 xor di, di ; es:di -> root entries array
|
pascal@24476
|
235
|
pascal@24476
|
236 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
237 ;; Looks for a file/dir by its name ;;
|
pascal@24476
|
238 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
239 ;; Input: DS:SI -> file name (11 chars) ;;
|
pascal@24478
|
240 ;; ES:DI -> root directory array ;;
|
pascal@24525
|
241 ;; BP = paragraphs in sector ;;
|
pascal@24476
|
242 ;; Output: ESI = cluster number ;;
|
pascal@24476
|
243 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
244
|
pascal@24476
|
245 FindNameCycle:
|
pascal@25449
|
246 %if NullEntryCheck != 0
|
pascal@24525
|
247 cmp byte [es:di], bh
|
pascal@24478
|
248 je ErrFind ; end of root directory (NULL entry found)
|
pascal@25449
|
249 %endif
|
pascal@24478
|
250 pusha
|
pascal@25454
|
251 mov cl, NameLength
|
pascal@24525
|
252 mov si, ProgramName ; ds:si -> program name
|
pascal@24476
|
253 repe cmpsb
|
pascal@25467
|
254 %if CheckAttrib != 0
|
pascal@25467
|
255 VolumeLabel equ 8
|
pascal@25467
|
256 SubDirectory equ 10h
|
pascal@25467
|
257 jnz SkipFindName
|
pascal@25467
|
258 test byte [es:di], VolumeLabel+SubDirectory
|
pascal@25467
|
259 SkipFindName:
|
pascal@25467
|
260 %endif
|
pascal@24525
|
261 je FindNameFound
|
pascal@24478
|
262 popa
|
pascal@24525
|
263 add di, byte 32
|
pascal@24476
|
264 dec bp
|
pascal@24476
|
265 dec bp
|
pascal@24476
|
266 jnz FindNameCycle ; next root entry
|
pascal@25458
|
267 loop RootDirReadContinue ; next sector in cluster
|
pascal@25458
|
268 cmp esi, 0FFFFFF6h ; carry=0 if last cluster, and carry=1 otherwise
|
pascal@25458
|
269 jnc RootDirReadContinue ; continue to the next root dir cluster
|
pascal@24478
|
270 ErrFind:
|
pascal@24478
|
271 call Error ; end of root directory (dir end reached)
|
pascal@24476
|
272 db "File not found."
|
pascal@24476
|
273 FindNameFound:
|
pascal@24525
|
274 push word [es:di+14h-11]
|
pascal@24525
|
275 push word [es:di+1Ah-11]
|
pascal@24478
|
276 pop esi ; esi = cluster no. cx = 0
|
pascal@24476
|
277
|
pascal@24525
|
278 dec dword [es:di+1Ch-11] ; load ((n - 1)/256)*16 +1 paragraphs
|
pascal@24525
|
279 imul di, [es:di+1Ch+1-11], byte 16 ; file size in paragraphs (full pages)
|
pascal@24476
|
280
|
pascal@24476
|
281 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
282 ;; Load the entire file ;;
|
pascal@24476
|
283 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
284
|
pascal@24476
|
285 push es
|
pascal@24476
|
286 FileReadContinue:
|
pascal@24476
|
287 push di
|
pascal@25458
|
288 call ReadClusterSector ; read one sector of the boot file
|
pascal@25458
|
289 dec cx
|
pascal@24476
|
290 mov di, es
|
pascal@24478
|
291 add di, bp
|
pascal@24478
|
292 mov es, di ; es:bx updated
|
pascal@24476
|
293 pop di
|
pascal@24478
|
294
|
pascal@24476
|
295 sub di, bp
|
pascal@24476
|
296 jae FileReadContinue
|
pascal@24943
|
297 xor ax, ax
|
pascal@24476
|
298 pop bp
|
pascal@24476
|
299
|
pascal@24476
|
300 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
301 ;; Type detection, .COM or .EXE? ;;
|
pascal@24476
|
302 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
303
|
pascal@24476
|
304 mov ds, bp ; bp=ds=seg the file is loaded to
|
pascal@24535
|
305
|
pascal@24476
|
306 add bp, [bx+08h] ; bp = image base
|
pascal@24476
|
307 mov di, [bx+18h] ; di = reloc table pointer
|
pascal@24476
|
308
|
pascal@24476
|
309 cmp word [bx], 5A4Dh ; "MZ" signature?
|
pascal@24476
|
310 je RelocateEXE ; yes, it's an EXE program
|
pascal@24476
|
311
|
pascal@24476
|
312 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
313 ;; Setup and run a .COM program ;;
|
pascal@24535
|
314 ;; Set CS=DS=ES=SS SP=0 IP=100h ;;
|
pascal@25454
|
315 ;; AX=0ffffh BX=0 DX=drive and ;;
|
pascal@25454
|
316 ;; cmdline=void ;;
|
pascal@24476
|
317 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
318
|
pascal@24535
|
319 mov di, 100h ; ip
|
pascal@24476
|
320 mov bp, ImageLoadSeg-10h ; "org 100h" stuff :)
|
pascal@24476
|
321 mov ss, bp
|
pascal@24476
|
322 xor sp, sp
|
pascal@24476
|
323 push bp ; cs, ds and es
|
pascal@25485
|
324 %if ExtraBootSector != 0
|
pascal@25485
|
325 jmp Run
|
pascal@25485
|
326 %macro BootFileName 0
|
pascal@25485
|
327 %else
|
pascal@24476
|
328 jmp short Run
|
pascal@25485
|
329 %endif
|
pascal@24476
|
330
|
pascal@24476
|
331 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
332 ;; Relocate, setup and run a .EXE program ;;
|
pascal@24476
|
333 ;; Set CS:IP, SS:SP, DS, ES and AX according ;;
|
pascal@24476
|
334 ;; to wiki.osdev.org/MZ#Initial_Program_State ;;
|
pascal@25454
|
335 ;; AX=0ffffh BX=0 DX=drive cmdline=void ;;
|
pascal@24476
|
336 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
337
|
pascal@24476
|
338 ReloCycle:
|
pascal@24476
|
339 add [di+2], bp ; item seg (abs)
|
pascal@24476
|
340 les si, [di] ; si = item ofs, es = item seg
|
pascal@24476
|
341 add [es:si], bp ; fixup
|
pascal@24525
|
342 scasw ; di += 2
|
pascal@24525
|
343 scasw ; point to next entry
|
pascal@24476
|
344
|
pascal@24476
|
345 RelocateEXE:
|
pascal@24942
|
346 dec word [bx+06h] ; reloc items, 32768 max (128KB table)
|
pascal@24942
|
347 jns ReloCycle
|
pascal@24942
|
348
|
pascal@24945
|
349 les si, [bx+0Eh]
|
pascal@24945
|
350 add si, bp
|
pascal@24945
|
351 mov ss, si ; ss for EXE
|
pascal@24945
|
352 mov sp, es ; sp for EXE
|
pascal@24476
|
353
|
pascal@24476
|
354 lea si, [bp-10h] ; ds and es both point to the segment
|
pascal@24476
|
355 push si ; containing the PSP structure
|
pascal@24476
|
356
|
pascal@24476
|
357 add bp, [bx+16h] ; cs for EXE
|
pascal@24535
|
358 mov di, [bx+14h] ; ip for EXE
|
pascal@24476
|
359 Run:
|
pascal@24476
|
360 pop ds
|
pascal@24476
|
361 push bp
|
pascal@24535
|
362 push di
|
pascal@24476
|
363 push ds
|
pascal@24476
|
364 pop es
|
pascal@24942
|
365 mov [80h], ax ; clear cmdline
|
pascal@24942
|
366 dec ax ; both FCB in the PSP don't have a valid drive identifier
|
pascal@24476
|
367
|
pascal@24476
|
368 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
369 ;; Set the magic numbers so the program knows that it ;;
|
pascal@24476
|
370 ;; has been loaded by this bootsector and not by MS-DOS ;;
|
pascal@24476
|
371 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
372 mov si, 16381 ; prime number 2**14-3
|
pascal@24476
|
373 mov di, 32749 ; prime number 2**15-19
|
pascal@24476
|
374 mov bp, 65521 ; prime number 2**16-15
|
pascal@24476
|
375
|
pascal@24476
|
376 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
377 ;; All done, transfer control to the program now ;;
|
pascal@24476
|
378 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
379 retf
|
pascal@25485
|
380 %if ExtraBootSector != 0
|
pascal@25485
|
381 %endm
|
pascal@25485
|
382 %endif
|
pascal@24476
|
383
|
pascal@25458
|
384 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
385 ;; Error Messaging Code ;;
|
pascal@25458
|
386 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
387
|
pascal@25458
|
388 Error:
|
pascal@25458
|
389 pop si
|
pascal@25458
|
390 puts:
|
pascal@25458
|
391 mov ah, 0Eh
|
pascal@25458
|
392 mov bl, 7
|
pascal@25458
|
393 lodsb
|
pascal@25458
|
394 int 10h
|
pascal@25458
|
395 cmp al, '.'
|
pascal@25458
|
396 jne puts
|
pascal@25458
|
397 cbw
|
pascal@25458
|
398 int 16h ; wait for a key...
|
pascal@25458
|
399 int 19h ; bootstrap
|
pascal@25458
|
400
|
pascal@25458
|
401 Stop:
|
pascal@25458
|
402 hlt
|
pascal@25458
|
403 jmp short Stop
|
pascal@25458
|
404
|
pascal@25458
|
405 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
406 ;; Reads a FAT32 sector ;;
|
pascal@25458
|
407 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
408 ;; Inout: ES:BX -> buffer ;;
|
pascal@25458
|
409 ;; EAX = prev sector ;;
|
pascal@25458
|
410 ;; CX = rem sectors in cluster ;;
|
pascal@25458
|
411 ;; ESI = next cluster ;;
|
pascal@25458
|
412 ;; Output: EAX = current sector ;;
|
pascal@25458
|
413 ;; CX = rem sectors in cluster ;;
|
pascal@25458
|
414 ;; ESI = next cluster ;;
|
pascal@25458
|
415 ;; BP -> para / sector ;;
|
pascal@25458
|
416 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
417
|
pascal@25458
|
418 ReadClusterSector:
|
pascal@25458
|
419 %if SectorOf512Bytes != 0
|
pascal@25458
|
420 mov bp, 32 ; bp = paragraphs per sector
|
pascal@25458
|
421 %else
|
pascal@24525
|
422 mov bp, [bx(bpbBytesPerSector)]
|
pascal@24525
|
423 shr bp, 4 ; bp = paragraphs per sector
|
pascal@25458
|
424 %endif
|
pascal@25449
|
425 mov dx, 1 ; adjust LBA for next sector
|
pascal@24525
|
426 inc cx
|
pascal@24525
|
427 loop ReadSectorLBA
|
pascal@24525
|
428
|
pascal@25449
|
429 mul ebx ; edx:eax = 0
|
pascal@25458
|
430 %if SectorOf512Bytes != 0
|
pascal@25458
|
431 mov al, 128 ; ax=# of FAT32 entries per sector
|
pascal@25458
|
432 %else
|
pascal@24945
|
433 imul ax, bp, byte 4 ; ax=# of FAT32 entries per sector
|
pascal@25458
|
434 %endif
|
pascal@24525
|
435 lea edi, [esi-2] ; esi=cluster #
|
pascal@24476
|
436 xchg eax, esi
|
pascal@24478
|
437 div esi ; eax=FAT sector #, edx=entry # in sector
|
pascal@24476
|
438
|
pascal@24525
|
439 imul si, dx, byte 4 ; si=entry # in sector, clear C
|
pascal@25485
|
440 %if NonMirroredFATs != 0
|
pascal@25485
|
441 cwde
|
pascal@25485
|
442 or dl, byte [bx(bsExtendedFlags)]
|
pascal@25485
|
443 jns MirroredFATs ; Non-mirrored FATs ?
|
pascal@25485
|
444 and dl, 0Fh
|
pascal@25485
|
445 imul edx, dword [bx(bsSectorsPerFAT32)] ; we need to read the active one
|
pascal@25485
|
446 add eax, edx
|
pascal@25485
|
447 MirroredFATs:
|
pascal@25485
|
448 cwde
|
pascal@25485
|
449 %else
|
pascal@25485
|
450 %if LBA48bits != 0
|
pascal@25458
|
451 xor dx, dx
|
pascal@25485
|
452 %endif
|
pascal@25449
|
453 %endif
|
pascal@25458
|
454 call ReadSectorLBAfromFAT ; read 1 FAT32 sector
|
pascal@24476
|
455
|
pascal@25449
|
456 %if ClusterMask != 0
|
pascal@24478
|
457 and byte [es:si+3], 0Fh ; mask cluster value
|
pascal@25449
|
458 %endif
|
pascal@24478
|
459 mov esi, [es:si] ; esi=next cluster #
|
pascal@24476
|
460
|
pascal@25458
|
461 %if Always2FATs != 0
|
pascal@25458
|
462 imul eax, dword [bx(bsSectorsPerFAT32)], 2
|
pascal@25458
|
463 %else
|
pascal@24525
|
464 movzx eax, byte [bx(bpbNumberOfFATs)]
|
pascal@24525
|
465 mul dword [bx(bsSectorsPerFAT32)]
|
pascal@25458
|
466 %endif
|
pascal@24525
|
467
|
pascal@24525
|
468 xchg eax, edi
|
pascal@25454
|
469 movzx ecx, byte [bx(bpbSectorsPerCluster)] ; 8..128
|
pascal@24945
|
470 mul ecx ; edx:eax=sector number in data area
|
pascal@24525
|
471 add eax, edi
|
pascal@25458
|
472 %if LBA48bits != 0
|
pascal@25458
|
473 adc dx, bx
|
pascal@25458
|
474 %endif
|
pascal@24476
|
475
|
pascal@25458
|
476 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
477 ;; Reads a sector form the start of FAT ;;
|
pascal@25458
|
478 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@25458
|
479
|
pascal@25458
|
480 ReadSectorLBAfromFAT:
|
pascal@25458
|
481 add eax, [bx(bpbHiddenSectors)]
|
pascal@25449
|
482 %if LBA48bits != 0
|
pascal@25449
|
483 adc dx, bx
|
pascal@25449
|
484 mov word [bx(HiLBA)], dx
|
pascal@25449
|
485 %endif
|
pascal@25454
|
486 mov dx, [bx(bpbReservedSectors)]
|
pascal@24476
|
487
|
pascal@24478
|
488 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
489 ;; Reads a sector using BIOS Int 13h fn 42h ;;
|
pascal@24478
|
490 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24478
|
491 ;; Input: EAX = LBA ;;
|
pascal@24478
|
492 ;; CX = sector count ;;
|
pascal@24478
|
493 ;; ES:BX -> buffer address ;;
|
pascal@24478
|
494 ;; Output: CF = 0 if no more sectors ;;
|
pascal@24478
|
495 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
496
|
pascal@24476
|
497 ReadSectorLBA:
|
pascal@25449
|
498 add eax, edx
|
pascal@25449
|
499 %if LBA48bits != 0
|
pascal@24535
|
500 adc word [bx(HiLBA)], bx
|
pascal@25449
|
501 %endif
|
pascal@25485
|
502 ReadSectorBoot:
|
pascal@25449
|
503 mov dx, [bx(DriveNumber)] ; restore BIOS boot drive number
|
pascal@24476
|
504 pusha
|
pascal@24476
|
505
|
pascal@24478
|
506 push bx
|
pascal@25449
|
507 %if LBA48bits != 0
|
pascal@24491
|
508 push word [bx(HiLBA)] ; 48-bit LBA
|
pascal@25449
|
509 %else
|
pascal@25449
|
510 push bx
|
pascal@25449
|
511 %endif
|
pascal@24478
|
512 push eax
|
pascal@24476
|
513 push es
|
pascal@24476
|
514 push bx
|
pascal@24478
|
515 push byte 1 ; sector count word = 1
|
pascal@24525
|
516 push byte 16 ; packet size byte = 16, reserved byte = 0
|
pascal@24525
|
517
|
pascal@25449
|
518 %if CHSsupport != 0
|
pascal@25458
|
519 %if CHSupTo8GB != 0
|
pascal@25449
|
520 push eax
|
pascal@25449
|
521 pop cx ; save low LBA
|
pascal@25449
|
522 pop ax ; get high LBA
|
pascal@25449
|
523 cwd ; clear dx (assume LBA offset <1TB)
|
pascal@25449
|
524 idiv word [bx(bpbSectorsPerTrack)] ; up to 8GB disks, avoid divide error
|
pascal@25449
|
525
|
pascal@25449
|
526 xchg ax, cx ; restore low LBA, save high LBA / SPT
|
pascal@25458
|
527 %else
|
pascal@25449
|
528 ; Busybox mkdosfs creates fat32 for floppies.
|
pascal@25449
|
529 ; Floppies may support CHS only.
|
pascal@25458
|
530 %if CHSupTo32MB != 0
|
pascal@25458
|
531 xor dx, dx ; clear dx (LBA offset <32MB)
|
pascal@25458
|
532 %else
|
pascal@25449
|
533 cwd ; clear dx (LBA offset <16MB)
|
pascal@25458
|
534 %endif
|
pascal@25450
|
535 xor cx, cx ; high LBA / SPT = 0
|
pascal@25458
|
536 %endif
|
pascal@25449
|
537 idiv word [bx(bpbSectorsPerTrack)]
|
pascal@25449
|
538 ; ax = LBA / SPT
|
pascal@25449
|
539 ; dx = LBA % SPT = sector - 1
|
pascal@25449
|
540 inc dx
|
pascal@25449
|
541
|
pascal@25449
|
542 xchg cx, dx ; restore high LBA / SPT, save sector no.
|
pascal@25450
|
543 idiv word [bx(bpbHeadsPerCylinder)]
|
pascal@25449
|
544 ; ax = (LBA / SPT) / HPC = cylinder
|
pascal@25449
|
545 ; dx = (LBA / SPT) % HPC = head
|
pascal@25449
|
546
|
pascal@25458
|
547 xchg ch, al ; clear al
|
pascal@25449
|
548 ; ch = LSB 0...7 of cylinder no.
|
pascal@25458
|
549 %if CHSupTo8GB != 0 || CHSupTo32MB != 0
|
pascal@25458
|
550 shr ax, 2
|
pascal@25458
|
551 or cl, al
|
pascal@25449
|
552 ; cl = MSB 8...9 of cylinder no. + sector no.
|
pascal@25458
|
553 %endif
|
pascal@25449
|
554 mov dh, dl
|
pascal@25449
|
555 ; dh = head no.
|
pascal@25449
|
556 mov dl, [bx(DriveNumber)] ; restore BIOS boot drive number
|
pascal@25449
|
557 %endif
|
pascal@25449
|
558
|
pascal@25454
|
559 ReadSectorRetry:
|
pascal@24525
|
560 mov si, sp
|
pascal@24478
|
561 mov ah, 42h ; ah = 42h = extended read function no.
|
pascal@24478
|
562 int 13h ; extended read sectors (DL, DS:SI)
|
pascal@24478
|
563 jnc ReadSuccess ; CF = 0 if no error
|
pascal@24476
|
564
|
pascal@25449
|
565 %if CHSsupport != 0
|
pascal@25449
|
566 mov ax, 201h ; al = sector count = 1
|
pascal@25449
|
567 ; ah = 2 = read function no.
|
pascal@25449
|
568 int 13h ; read sectors (AL, CX, DX, ES:BX)
|
pascal@25449
|
569
|
pascal@25449
|
570 jnc ReadSuccess ; CF = 0 if no error
|
pascal@25449
|
571 %endif
|
pascal@25449
|
572 %if ReadRetry != 0
|
pascal@25458
|
573 %if CHSsupport != 0
|
pascal@25449
|
574 cbw ; ah = 0 = reset function
|
pascal@25458
|
575 %else
|
pascal@24945
|
576 xor ax, ax ; ah = 0 = reset function
|
pascal@25458
|
577 %endif
|
pascal@24476
|
578 int 13h ; reset drive (DL)
|
pascal@24476
|
579
|
pascal@25457
|
580 dec bp ; up to 32 retries
|
pascal@25454
|
581 jnz ReadSectorRetry
|
pascal@25449
|
582 %endif
|
pascal@24525
|
583
|
pascal@24476
|
584 call Error
|
pascal@24476
|
585 db "Read error."
|
pascal@24476
|
586
|
pascal@24478
|
587 ReadSuccess:
|
pascal@24476
|
588
|
pascal@24476
|
589 popa ; sp += 16
|
pascal@24478
|
590 popa
|
pascal@24476
|
591 ret
|
pascal@24476
|
592
|
pascal@24942
|
593 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24942
|
594 ;; Fill free space with zeroes ;;
|
pascal@24942
|
595 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24942
|
596
|
pascal@25458
|
597 times (512-13-($-$$)) db 0
|
pascal@24476
|
598
|
pascal@24476
|
599 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
600 ;; Name of the file to load and run ;;
|
pascal@24476
|
601 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
602
|
pascal@25463
|
603 NameLength equ 11
|
pascal@25463
|
604 ProgramName times NameLength db 0 ; name and extension
|
pascal@24476
|
605
|
pascal@24476
|
606 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
607 ;; End of the sector ID ;;
|
pascal@24476
|
608 ;;;;;;;;;;;;;;;;;;;;;;;;;;
|
pascal@24476
|
609
|
pascal@24476
|
610 dw 0AA55h ; BIOS checks for this ID
|
pascal@25485
|
611
|
pascal@25485
|
612 %if ExtraBootSector != 0
|
pascal@25485
|
613 dd 61415252h ; "RRaA"
|
pascal@25485
|
614 BootFileName
|
pascal@25485
|
615 times (996-($-$$)) db 0
|
pascal@25485
|
616 ; dd 41617272h ; "rrAa"
|
pascal@25485
|
617 %endif
|