Bring in 1.33 from FreeBSD-5:
[dragonfly.git] / sys / boot / i386 / btx / btx / btx.S
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1#
2# Copyright (c) 1998 Robert Nordier
3# All rights reserved.
4#
5# Redistribution and use in source and binary forms are freely
6# permitted provided that the above copyright notice and this
7# paragraph and the following disclaimer are duplicated in all
8# such forms.
9#
10# This software is provided "AS IS" and without any express or
11# implied warranties, including, without limitation, the implied
12# warranties of merchantability and fitness for a particular
13# purpose.
14#
15
5ee58eed 16# $FreeBSD: src/sys/boot/i386/btx/btx/btx.s,v 1.32 2002/10/08 18:19:02 jhb Exp $
8baa6c0b 17# $DragonFly: src/sys/boot/i386/btx/btx/Attic/btx.S,v 1.4 2004/06/24 23:31:06 dillon Exp $
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18
19#
20# Memory layout.
21#
22 .set MEM_BTX,0x1000 # Start of BTX memory
23 .set MEM_ESP0,0x1800 # Supervisor stack
24 .set MEM_BUF,0x1800 # Scratch buffer
25 .set MEM_ESP1,0x1e00 # Link stack
26 .set MEM_IDT,0x1e00 # IDT
27 .set MEM_TSS,0x1f98 # TSS
28 .set MEM_MAP,0x2000 # I/O bit map
29 .set MEM_DIR,0x4000 # Page directory
30 .set MEM_TBL,0x5000 # Page tables
31 .set MEM_ORG,0x9000 # BTX code
32 .set MEM_USR,0xa000 # Start of user memory
33#
34# Paging control.
35#
36 .set PAG_SIZ,0x1000 # Page size
37 .set PAG_CNT,0x1000 # Pages to map
38#
39# Segment selectors.
40#
41 .set SEL_SCODE,0x8 # Supervisor code
42 .set SEL_SDATA,0x10 # Supervisor data
43 .set SEL_RCODE,0x18 # Real mode code
44 .set SEL_RDATA,0x20 # Real mode data
45 .set SEL_UCODE,0x28|3 # User code
46 .set SEL_UDATA,0x30|3 # User data
47 .set SEL_TSS,0x38 # TSS
48#
49# Task state segment fields.
50#
51 .set TSS_ESP0,0x4 # PL 0 ESP
52 .set TSS_SS0,0x8 # PL 0 SS
53 .set TSS_ESP1,0xc # PL 1 ESP
54 .set TSS_MAP,0x66 # I/O bit map base
55#
56# System calls.
57#
58 .set SYS_EXIT,0x0 # Exit
59 .set SYS_EXEC,0x1 # Exec
60#
61# V86 constants.
62#
63 .set V86_FLG,0x208eff # V86 flag mask
64 .set V86_STK,0x400 # V86 stack allowance
65#
66# Dump format control bytes.
67#
68 .set DMP_X16,0x1 # Word
69 .set DMP_X32,0x2 # Long
70 .set DMP_MEM,0x4 # Memory
71 .set DMP_EOL,0x8 # End of line
72#
73# Screen defaults and assumptions.
74#
75 .set SCR_MAT,0x7 # Mode/attribute
76 .set SCR_COL,0x50 # Columns per row
77 .set SCR_ROW,0x19 # Rows per screen
78#
79# BIOS Data Area locations.
80#
81 .set BDA_MEM,0x413 # Free memory
82 .set BDA_KEYFLAGS,0x417 # Keyboard shift-state flags
83 .set BDA_SCR,0x449 # Video mode
84 .set BDA_POS,0x450 # Cursor position
85 .set BDA_BOOT,0x472 # Boot howto flag
86#
87# Derivations, for brevity.
88#
89 .set _ESP0H,MEM_ESP0>>0x8 # Byte 1 of ESP0
90 .set _ESP1H,MEM_ESP1>>0x8 # Byte 1 of ESP1
91 .set _TSSIO,MEM_MAP-MEM_TSS # TSS I/O base
92 .set _TSSLM,MEM_DIR-MEM_TSS-1 # TSS limit
93 .set _IDTLM,MEM_TSS-MEM_IDT-1 # IDT limit
94#
95# Code segment.
96#
97 .globl start
98 .code16
99start: # Start of code
100#
101# BTX header.
102#
103btx_hdr: .byte 0xeb # Machine ID
104 .byte 0xe # Header size
105 .ascii "BTX" # Magic
106 .byte 0x1 # Major version
107 .byte 0x1 # Minor version
108 .byte BTX_FLAGS # Flags
109 .word PAG_CNT-MEM_ORG>>0xc # Paging control
110 .word break-start # Text size
111 .long 0x0 # Entry address
112#
113# Initialization routine.
114#
115init: cli # Disable interrupts
116 xor %ax,%ax # Zero/segment
117 mov %ax,%ss # Set up
118 mov $MEM_ESP0,%sp # stack
119 mov %ax,%es # Address
120 mov %ax,%ds # data
121 pushl $0x2 # Clear
122 popfl # flags
123#
124# Initialize memory.
125#
126 mov $MEM_IDT,%di # Memory to initialize
127 mov $(MEM_ORG-MEM_IDT)/2,%cx # Words to zero
128 push %di # Save
129 rep # Zero-fill
130 stosw # memory
131 pop %di # Restore
132#
133# Create IDT.
134#
135 mov $idtctl,%si # Control string
136init.1: lodsb # Get entry
137 cbw # count
138 xchg %ax,%cx # as word
139 jcxz init.4 # If done
140 lodsb # Get segment
141 xchg %ax,%dx # P:DPL:type
142 lodsw # Get control
143 xchg %ax,%bx # set
144 lodsw # Get handler offset
145 mov $SEL_SCODE,%dh # Segment selector
146init.2: shr %bx # Handle this int?
147 jnc init.3 # No
148 mov %ax,(%di) # Set handler offset
149 mov %dh,0x2(%di) # and selector
150 mov %dl,0x5(%di) # Set P:DPL:type
151 add $0x4,%ax # Next handler
152init.3: lea 0x8(%di),%di # Next entry
153 loop init.2 # Till set done
154 jmp init.1 # Continue
155#
156# Initialize TSS.
157#
158init.4: movb $_ESP0H,TSS_ESP0+1(%di) # Set ESP0
159 movb $SEL_SDATA,TSS_SS0(%di) # Set SS0
160 movb $_ESP1H,TSS_ESP1+1(%di) # Set ESP1
161 movb $_TSSIO,TSS_MAP(%di) # Set I/O bit map base
162ifdef(`PAGING',`
163#
164# Create page directory.
165#
166 xor %edx,%edx # Page
167 mov $PAG_SIZ>>0x8,%dh # size
168 xor %eax,%eax # Zero
169 mov $MEM_DIR,%di # Page directory
170 mov $PAG_CNT>>0xa,%cl # Entries
171 mov $MEM_TBL|0x7,%ax # First entry
172init.5: stosl # Write entry
173 add %dx,%ax # To next
174 loop init.5 # Till done
175#
176# Create page tables.
177#
178 mov $MEM_TBL,%di # Page table
179 mov $PAG_CNT>>0x8,%ch # Entries
180 xor %ax,%ax # Start address
181init.6: mov $0x7,%al # Set U:W:P flags
182 cmp btx_hdr+0x8,%cx # Standard user page?
183 jb init.7 # Yes
184 cmp $PAG_CNT-MEM_BTX>>0xc,%cx # BTX memory?
185 jae init.7 # No or first page
186 and $~0x2,%al # Clear W flag
187 cmp $PAG_CNT-MEM_USR>>0xc,%cx # User page zero?
188 jne init.7 # No
189 testb $0x80,btx_hdr+0x7 # Unmap it?
190 jz init.7 # No
191 and $~0x1,%al # Clear P flag
192init.7: stosl # Set entry
193 add %edx,%eax # Next address
194 loop init.6 # Till done
195')
196#
197# Bring up the system.
198#
199 mov $0x2820,%bx # Set protected mode
200 callw setpic # IRQ offsets
201 lidt idtdesc # Set IDT
202ifdef(`PAGING',`
203 xor %eax,%eax # Set base
204 mov $MEM_DIR>>0x8,%ah # of page
205 mov %eax,%cr3 # directory
206')
207 lgdt gdtdesc # Set GDT
208 mov %cr0,%eax # Switch to protected
209ifdef(`PAGING',`
210 or $0x80000001,%eax # mode and enable paging
211',`
212 or $0x01,%eax # mode
213')
214 mov %eax,%cr0 #
215 ljmp $SEL_SCODE,$init.8 # To 32-bit code
216 .code32
217init.8: xorl %ecx,%ecx # Zero
218 movb $SEL_SDATA,%cl # To 32-bit
219 movw %cx,%ss # stack
220#
221# Launch user task.
222#
223 movb $SEL_TSS,%cl # Set task
224 ltr %cx # register
225 movl $MEM_USR,%edx # User base address
226 movzwl %ss:BDA_MEM,%eax # Get free memory
227 shll $0xa,%eax # To bytes
228 subl $0x1000,%eax # Less arg space
229 subl %edx,%eax # Less base
230 movb $SEL_UDATA,%cl # User data selector
231 pushl %ecx # Set SS
232 pushl %eax # Set ESP
233 push $0x202 # Set flags (IF set)
234 push $SEL_UCODE # Set CS
235 pushl btx_hdr+0xc # Set EIP
236 pushl %ecx # Set GS
237 pushl %ecx # Set FS
238 pushl %ecx # Set DS
239 pushl %ecx # Set ES
240 pushl %edx # Set EAX
241 movb $0x7,%cl # Set remaining
242init.9: push $0x0 # general
243 loop init.9 # registers
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244ifdef(`BTX_SERIAL',`
245 call sio_init # setup the serial console
246')
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247 popa # and initialize
248 popl %es # Initialize
249 popl %ds # user
250 popl %fs # segment
251 popl %gs # registers
252 iret # To user mode
253#
254# Exit routine.
255#
256exit: cli # Disable interrupts
257 movl $MEM_ESP0,%esp # Clear stack
258#
259# Turn off paging.
260#
261 movl %cr0,%eax # Get CR0
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262 andl $~0x80000000,%eax # Disable
263 movl %eax,%cr0 # paging
984263bc 264 xorl %ecx,%ecx # Zero
984263bc 265 movl %ecx,%cr3 # Flush TLB
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266#
267# Restore the GDT in case we caught a kernel trap.
268#
269 lgdt gdtdesc # Set GDT
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270#
271# To 16 bits.
272#
273 ljmpw $SEL_RCODE,$exit.1 # Reload CS
274 .code16
275exit.1: mov $SEL_RDATA,%cl # 16-bit selector
276 mov %cx,%ss # Reload SS
277 mov %cx,%ds # Load
278 mov %cx,%es # remaining
279 mov %cx,%fs # segment
280 mov %cx,%gs # registers
281#
282# To real-address mode.
283#
284 dec %ax # Switch to
285 mov %eax,%cr0 # real mode
286 ljmp $0x0,$exit.2 # Reload CS
287exit.2: xor %ax,%ax # Real mode segment
288 mov %ax,%ss # Reload SS
289 mov %ax,%ds # Address data
290 mov $0x7008,%bx # Set real mode
291 callw setpic # IRQ offsets
292 lidt ivtdesc # Set IVT
293#
294# Reboot or await reset.
295#
296 sti # Enable interrupts
297 testb $0x1,btx_hdr+0x7 # Reboot?
298exit.3: jz exit.3 # No
299 movw $0x1234, BDA_BOOT # Do a warm boot
8baa6c0b 300 ljmp $0xf000,$0xfff0 # reboot the machine
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301#
302# Set IRQ offsets by reprogramming 8259A PICs.
303#
304setpic: in $0x21,%al # Save master
305 push %ax # IMR
306 in $0xa1,%al # Save slave
307 push %ax # IMR
308 movb $0x11,%al # ICW1 to
309 outb %al,$0x20 # master,
310 outb %al,$0xa0 # slave
311 movb %bl,%al # ICW2 to
312 outb %al,$0x21 # master
313 movb %bh,%al # ICW2 to
314 outb %al,$0xa1 # slave
315 movb $0x4,%al # ICW3 to
316 outb %al,$0x21 # master
317 movb $0x2,%al # ICW3 to
318 outb %al,$0xa1 # slave
319 movb $0x1,%al # ICW4 to
320 outb %al,$0x21 # master,
321 outb %al,$0xa1 # slave
322 pop %ax # Restore slave
323 outb %al,$0xa1 # IMR
324 pop %ax # Restore master
325 outb %al,$0x21 # IMR
326 retw # To caller
327 .code32
328#
329# Initiate return from V86 mode to user mode.
330#
331inthlt: hlt # To supervisor mode
332#
333# Exception jump table.
334#
335intx00: push $0x0 # Int 0x0: #DE
336 jmp ex_noc # Divide error
337 push $0x1 # Int 0x1: #DB
338 jmp ex_noc # Debug
339 push $0x3 # Int 0x3: #BP
340 jmp ex_noc # Breakpoint
341 push $0x4 # Int 0x4: #OF
342 jmp ex_noc # Overflow
343 push $0x5 # Int 0x5: #BR
344 jmp ex_noc # BOUND range exceeded
345 push $0x6 # Int 0x6: #UD
346 jmp ex_noc # Invalid opcode
347 push $0x7 # Int 0x7: #NM
348 jmp ex_noc # Device not available
349 push $0x8 # Int 0x8: #DF
350 jmp except # Double fault
351 push $0xa # Int 0xa: #TS
352 jmp except # Invalid TSS
353 push $0xb # Int 0xb: #NP
354 jmp except # Segment not present
355 push $0xc # Int 0xc: #SS
356 jmp except # Stack segment fault
357 push $0xd # Int 0xd: #GP
358 jmp ex_v86 # General protection
359 push $0xe # Int 0xe: #PF
360 jmp except # Page fault
361intx10: push $0x10 # Int 0x10: #MF
362 jmp ex_noc # Floating-point error
363#
364# Handle #GP exception.
365#
366ex_v86: testb $0x2,0x12(%esp,1) # V86 mode?
367 jz except # No
368 jmp v86mon # To monitor
369#
370# Save a zero error code.
371#
372ex_noc: pushl (%esp,1) # Duplicate int no
373 movb $0x0,0x4(%esp,1) # Fake error code
374#
375# Handle exception.
376#
377except: cld # String ops inc
378 pushl %ds # Save
379 pushl %es # most
380 pusha # registers
381 movb $0x6,%al # Push loop count
382 testb $0x2,0x3a(%esp,1) # V86 mode?
383 jnz except.1 # Yes
384 pushl %gs # Set GS
385 pushl %fs # Set FS
386 pushl %ds # Set DS
387 pushl %es # Set ES
388 movb $0x2,%al # Push loop count
389 cmpw $SEL_SCODE,0x44(%esp,1) # Supervisor mode?
390 jne except.1 # No
391 pushl %ss # Set SS
392 leal 0x50(%esp,1),%eax # Set
393 pushl %eax # ESP
394 jmp except.2 # Join common code
395except.1: pushl 0x50(%esp,1) # Set GS, FS, DS, ES
396 decb %al # (if V86 mode), and
397 jne except.1 # SS, ESP
398except.2: push $SEL_SDATA # Set up
399 popl %ds # to
400 pushl %ds # address
401 popl %es # data
402 movl %esp,%ebx # Stack frame
403 movl $dmpfmt,%esi # Dump format string
404 movl $MEM_BUF,%edi # Buffer
405 pushl %edi # Dump to
406 call dump # buffer
407 popl %esi # and
408 call putstr # display
409 leal 0x18(%esp,1),%esp # Discard frame
410 popa # Restore
411 popl %es # registers
412 popl %ds # saved
413 cmpb $0x3,(%esp,1) # Breakpoint?
414 je except.3 # Yes
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415 cmpb $0x1,(%esp,1) # Debug?
416 jne except.2a # No
417 testl $0x100,0x10(%esp,1) # Trap flag set?
418 jnz except.3 # Yes
419except.2a: jmp exit # Exit
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420except.3: leal 0x8(%esp,1),%esp # Discard err, int no
421 iret # From interrupt
422#
423# Return to user mode from V86 mode.
424#
425intrtn: cld # String ops inc
426 pushl %ds # Address
427 popl %es # data
428 leal 0x3c(%ebp),%edx # V86 Segment registers
429 movl MEM_TSS+TSS_ESP1,%esi # Link stack pointer
430 lodsl # INT_V86 args pointer
431 movl %esi,%ebx # Saved exception frame
432 testl %eax,%eax # INT_V86 args?
433 jz intrtn.2 # No
434 movl $MEM_USR,%edi # User base
435 movl 0x1c(%esi),%ebx # User ESP
436 movl %eax,(%edi,%ebx,1) # Restore to user stack
437 leal 0x8(%edi,%eax,1),%edi # Arg segment registers
438 testb $0x4,-0x6(%edi) # Return flags?
439 jz intrtn.1 # No
440 movl 0x30(%ebp),%eax # Get V86 flags
441 movw %ax,0x18(%esi) # Set user flags
442intrtn.1: leal 0x10(%esi),%ebx # Saved exception frame
443 xchgl %edx,%esi # Segment registers
444 movb $0x4,%cl # Update seg regs
445 rep # in INT_V86
446 movsl # args
447intrtn.2: movl %edx,%esi # Segment registers
448 leal 0x28(%ebp),%edi # Set up seg
449 movb $0x4,%cl # regs for
450 rep # later
451 movsl # pop
452 movl %ebx,%esi # Restore exception
453 movb $0x5,%cl # frame to
454 rep # supervisor
455 movsl # stack
456 movl %esi,MEM_TSS+TSS_ESP1 # Link stack pointer
457 popa # Restore
458 leal 0x8(%esp,1),%esp # Discard err, int no
459 popl %es # Restore
460 popl %ds # user
461 popl %fs # segment
462 popl %gs # registers
463 iret # To user mode
464#
465# V86 monitor.
466#
467v86mon: cld # String ops inc
468 pushl $SEL_SDATA # Set up for
469 popl %ds # flat addressing
470 pusha # Save registers
471 movl %esp,%ebp # Address stack frame
472 movzwl 0x2c(%ebp),%edi # Load V86 CS
473 shll $0x4,%edi # To linear
474 movl 0x28(%ebp),%esi # Load V86 IP
475 addl %edi,%esi # Code pointer
476 xorl %ecx,%ecx # Zero
477 movb $0x2,%cl # 16-bit operands
478 xorl %eax,%eax # Zero
479v86mon.1: lodsb # Get opcode
480 cmpb $0x66,%al # Operand size prefix?
481 jne v86mon.2 # No
482 movb $0x4,%cl # 32-bit operands
483 jmp v86mon.1 # Continue
484v86mon.2: cmpb $0xf4,%al # HLT?
485 jne v86mon.3 # No
486 cmpl $inthlt+0x1,%esi # Is inthlt?
487 jne v86mon.7 # No (ignore)
488 jmp intrtn # Return to user mode
489v86mon.3: cmpb $0xf,%al # Prefixed instruction?
490 jne v86mon.4 # No
491 cmpb $0x09,(%esi) # Is it a WBINVD?
492 je v86wbinvd # Yes
493 cmpb $0x30,(%esi) # Is it a WRMSR?
494 je v86wrmsr # Yes
495 cmpb $0x32,(%esi) # Is it a RDMSR?
496 je v86rdmsr # Yes
497 cmpb $0x20,(%esi) # Is this a
498 jne v86mon.4 # MOV EAX,CR0
499 cmpb $0xc0,0x1(%esi) # instruction?
500 je v86mov # Yes
501v86mon.4: cmpb $0xfa,%al # CLI?
502 je v86cli # Yes
503 cmpb $0xfb,%al # STI?
504 je v86sti # Yes
505 movzwl 0x38(%ebp),%ebx # Load V86 SS
506 shll $0x4,%ebx # To offset
507 pushl %ebx # Save
508 addl 0x34(%ebp),%ebx # Add V86 SP
509 movl 0x30(%ebp),%edx # Load V86 flags
510 cmpb $0x9c,%al # PUSHF/PUSHFD?
511 je v86pushf # Yes
512 cmpb $0x9d,%al # POPF/POPFD?
513 je v86popf # Yes
514 cmpb $0xcd,%al # INT imm8?
515 je v86intn # Yes
516 cmpb $0xcf,%al # IRET/IRETD?
517 je v86iret # Yes
518 popl %ebx # Restore
519 popa # Restore
520 jmp except # Handle exception
521v86mon.5: movl %edx,0x30(%ebp) # Save V86 flags
522v86mon.6: popl %edx # V86 SS adjustment
523 subl %edx,%ebx # Save V86
524 movl %ebx,0x34(%ebp) # SP
525v86mon.7: subl %edi,%esi # From linear
526 movl %esi,0x28(%ebp) # Save V86 IP
527 popa # Restore
528 leal 0x8(%esp,1),%esp # Discard int no, error
529 iret # To V86 mode
530#
531# Emulate MOV EAX,CR0.
532#
533v86mov: movl %cr0,%eax # CR0 to
534 movl %eax,0x1c(%ebp) # saved EAX
535 incl %esi # Adjust IP
536#
537# Return from emulating a 0x0f prefixed instruction
538#
539v86preret: incl %esi # Adjust IP
540 jmp v86mon.7 # Finish up
541#
542# Emulate WBINVD
543#
544v86wbinvd: wbinvd # Write back and invalidate
545 # cache
546 jmp v86preret # Finish up
547#
548# Emulate WRMSR
549#
550v86wrmsr: movl 0x18(%ebp),%ecx # Get user's %ecx (MSR to write)
551 movl 0x14(%ebp),%edx # Load the value
552 movl 0x1c(%ebp),%eax # to write
553 wrmsr # Write MSR
554 jmp v86preret # Finish up
555#
556# Emulate RDMSR
557#
558v86rdmsr: movl 0x18(%ebp),%ecx # MSR to read
559 rdmsr # Read the MSR
560 movl %eax,0x1c(%ebp) # Return the value of
561 movl %edx,0x14(%ebp) # the MSR to the user
562 jmp v86preret # Finish up
563#
564# Emulate CLI.
565#
566v86cli: andb $~0x2,0x31(%ebp) # Clear IF
567 jmp v86mon.7 # Finish up
568#
569# Emulate STI.
570#
571v86sti: orb $0x2,0x31(%ebp) # Set IF
572 jmp v86mon.7 # Finish up
573#
574# Emulate PUSHF/PUSHFD.
575#
576v86pushf: subl %ecx,%ebx # Adjust SP
577 cmpb $0x4,%cl # 32-bit
578 je v86pushf.1 # Yes
579 data16 # 16-bit
580v86pushf.1: movl %edx,(%ebx) # Save flags
581 jmp v86mon.6 # Finish up
582#
583# Emulate IRET/IRETD.
584#
585v86iret: movzwl (%ebx),%esi # Load V86 IP
586 movzwl 0x2(%ebx),%edi # Load V86 CS
587 leal 0x4(%ebx),%ebx # Adjust SP
588 movl %edi,0x2c(%ebp) # Save V86 CS
589 xorl %edi,%edi # No ESI adjustment
590#
591# Emulate POPF/POPFD (and remainder of IRET/IRETD).
592#
593v86popf: cmpb $0x4,%cl # 32-bit?
594 je v86popf.1 # Yes
595 movl %edx,%eax # Initialize
596 data16 # 16-bit
597v86popf.1: movl (%ebx),%eax # Load flags
598 addl %ecx,%ebx # Adjust SP
599 andl $V86_FLG,%eax # Merge
600 andl $~V86_FLG,%edx # the
601 orl %eax,%edx # flags
602 jmp v86mon.5 # Finish up
603#
604# trap int 15, function 87
605# reads %es:%si from saved registers on stack to find a GDT containing
606# source and destination locations
607# reads count of words from saved %cx
608# returns success by setting %ah to 0
609#
610int15_87: pushl %eax # Save
611 pushl %ebx # some information
612 pushl %esi # onto the stack.
613 pushl %edi
614 xorl %eax,%eax # clean EAX
615 xorl %ebx,%ebx # clean EBX
616 movl 0x4(%ebp),%esi # Get user's ESI
617 movl 0x3C(%ebp),%ebx # store ES
618 movw %si,%ax # store SI
619 shll $0x4,%ebx # Make it a seg.
620 addl %eax,%ebx # ebx=(es<<4)+si
621 movb 0x14(%ebx),%al # Grab the
622 movb 0x17(%ebx),%ah # necessary
623 shll $0x10,%eax # information
624 movw 0x12(%ebx),%ax # from
625 movl %eax,%esi # the
626 movb 0x1c(%ebx),%al # GDT in order to
627 movb 0x1f(%ebx),%ah # have %esi offset
628 shll $0x10,%eax # of source and %edi
629 movw 0x1a(%ebx),%ax # of destination.
630 movl %eax,%edi
631 pushl %ds # Make:
632 popl %es # es = ds
633 pushl %ecx # stash ECX
634 xorl %ecx,%ecx # highw of ECX is clear
635 movw 0x18(%ebp),%cx # Get user's ECX
636 shll $0x1,%ecx # Convert from num words to num
637 # bytes
638 rep # repeat...
639 movsb # perform copy.
640 popl %ecx # Restore
641 popl %edi
642 popl %esi # previous
643 popl %ebx # register
644 popl %eax # values.
645 movb $0x0,0x1d(%ebp) # set ah = 0 to indicate
646 # success
647 andb $0xfe,%dl # clear CF
648 jmp v86mon.5 # Finish up
649
650#
651# Reboot the machine by setting the reboot flag and exiting
652#
653reboot: orb $0x1,btx_hdr+0x7 # Set the reboot flag
654 jmp exit # Terminate BTX and reboot
655
656#
657# Emulate INT imm8... also make sure to check if it's int 15/87
658#
659v86intn: lodsb # Get int no
660 cmpb $0x19,%al # is it int 19?
661 je reboot # yes, reboot the machine
662 cmpb $0x15,%al # is it int 15?
663 jne v86intn.3 # no, skip parse
664 pushl %eax # stash EAX
665 movl 0x1c(%ebp),%eax # user's saved EAX
666 cmpb $0x87,%ah # is it the memcpy subfunction?
667 jne v86intn.1 # no, keep checking
668 popl %eax # get the stack straight
669 jmp int15_87 # it's our cue
670v86intn.1: cmpw $0x4f53,%ax # is it the delete key callout?
671 jne v86intn.2 # no, handle the int normally
672 movb BDA_KEYFLAGS,%al # get the shift key state
673 andb $0xc,%al # mask off just Ctrl and Alt
674 cmpb $0xc,%al # are both Ctrl and Alt down?
675 jne v86intn.2 # no, handle the int normally
676 popl %eax # restore EAX
677 jmp reboot # reboot the machine
678v86intn.2: popl %eax # restore EAX
679v86intn.3: subl %edi,%esi # From
680 shrl $0x4,%edi # linear
681 movw %dx,-0x2(%ebx) # Save flags
682 movw %di,-0x4(%ebx) # Save CS
683 leal -0x6(%ebx),%ebx # Adjust SP
684 movw %si,(%ebx) # Save IP
685 shll $0x2,%eax # Scale
686 movzwl (%eax),%esi # Load IP
687 movzwl 0x2(%eax),%edi # Load CS
688 movl %edi,0x2c(%ebp) # Save CS
689 xorl %edi,%edi # No ESI adjustment
690 andb $~0x1,%dh # Clear TF
691 jmp v86mon.5 # Finish up
692#
693# Hardware interrupt jump table.
694#
695intx20: push $0x8 # Int 0x20: IRQ0
696 jmp int_hw # V86 int 0x8
697 push $0x9 # Int 0x21: IRQ1
698 jmp int_hw # V86 int 0x9
699 push $0xa # Int 0x22: IRQ2
700 jmp int_hw # V86 int 0xa
701 push $0xb # Int 0x23: IRQ3
702 jmp int_hw # V86 int 0xb
703 push $0xc # Int 0x24: IRQ4
704 jmp int_hw # V86 int 0xc
705 push $0xd # Int 0x25: IRQ5
706 jmp int_hw # V86 int 0xd
707 push $0xe # Int 0x26: IRQ6
708 jmp int_hw # V86 int 0xe
709 push $0xf # Int 0x27: IRQ7
710 jmp int_hw # V86 int 0xf
711 push $0x70 # Int 0x28: IRQ8
712 jmp int_hw # V86 int 0x70
713 push $0x71 # Int 0x29: IRQ9
714 jmp int_hw # V86 int 0x71
715 push $0x72 # Int 0x2a: IRQ10
716 jmp int_hw # V86 int 0x72
717 push $0x73 # Int 0x2b: IRQ11
718 jmp int_hw # V86 int 0x73
719 push $0x74 # Int 0x2c: IRQ12
720 jmp int_hw # V86 int 0x74
721 push $0x75 # Int 0x2d: IRQ13
722 jmp int_hw # V86 int 0x75
723 push $0x76 # Int 0x2e: IRQ14
724 jmp int_hw # V86 int 0x76
725 push $0x77 # Int 0x2f: IRQ15
726 jmp int_hw # V86 int 0x77
727#
728# Reflect hardware interrupts.
729#
730int_hw: testb $0x2,0xe(%esp,1) # V86 mode?
731 jz intusr # No
732 pushl $SEL_SDATA # Address
733 popl %ds # data
734 xchgl %eax,(%esp,1) # Swap EAX, int no
735 pushl %ebp # Address
736 movl %esp,%ebp # stack frame
737 pushl %ebx # Save
738 shll $0x2,%eax # Get int
739 movl (%eax),%eax # vector
740 subl $0x6,0x14(%ebp) # Adjust V86 ESP
741 movzwl 0x18(%ebp),%ebx # V86 SS
742 shll $0x4,%ebx # * 0x10
743 addl 0x14(%ebp),%ebx # + V86 ESP
744 xchgw %ax,0x8(%ebp) # Swap V86 IP
745 rorl $0x10,%eax # Swap words
746 xchgw %ax,0xc(%ebp) # Swap V86 CS
747 roll $0x10,%eax # Swap words
748 movl %eax,(%ebx) # CS:IP for IRET
749 movl 0x10(%ebp),%eax # V86 flags
750 movw %ax,0x4(%ebx) # Flags for IRET
751 andb $~0x3,0x11(%ebp) # Clear IF, TF
752 popl %ebx # Restore
753 popl %ebp # saved
754 popl %eax # registers
755 iret # To V86 mode
756#
757# Invoke V86 interrupt from user mode, with arguments.
758#
759intx31: stc # Have btx_v86
760 pushl %eax # Missing int no
761#
762# Invoke V86 interrupt from user mode.
763#
764intusr: std # String ops dec
765 pushl %eax # Expand
766 pushl %eax # stack
767 pushl %eax # frame
768 pusha # Save
769 pushl %gs # Save
770 movl %esp,%eax # seg regs
771 pushl %fs # and
772 pushl %ds # point
773 pushl %es # to them
774 push $SEL_SDATA # Set up
775 popl %ds # to
776 pushl %ds # address
777 popl %es # data
778 movl $MEM_USR,%ebx # User base
779 movl %ebx,%edx # address
780 jc intusr.1 # If btx_v86
781 xorl %edx,%edx # Control flags
782 xorl %ebp,%ebp # btx_v86 pointer
783intusr.1: leal 0x50(%esp,1),%esi # Base of frame
784 pushl %esi # Save
785 addl -0x4(%esi),%ebx # User ESP
786 movl MEM_TSS+TSS_ESP1,%edi # Link stack pointer
787 leal -0x4(%edi),%edi # Adjust for push
788 xorl %ecx,%ecx # Zero
789 movb $0x5,%cl # Push exception
790 rep # frame on
791 movsl # link stack
792 xchgl %eax,%esi # Saved seg regs
793 movl 0x40(%esp,1),%eax # Get int no
794 testl %edx,%edx # Have btx_v86?
795 jz intusr.2 # No
796 movl (%ebx),%ebp # btx_v86 pointer
797 movb $0x4,%cl # Count
798 addl %ecx,%ebx # Adjust for pop
799 rep # Push saved seg regs
800 movsl # on link stack
801 addl %ebp,%edx # Flatten btx_v86 ptr
802 leal 0x14(%edx),%esi # Seg regs pointer
803 movl 0x4(%edx),%eax # Get int no/address
804 movzwl 0x2(%edx),%edx # Get control flags
805intusr.2: movl %ebp,(%edi) # Push btx_v86 and
806 movl %edi,MEM_TSS+TSS_ESP1 # save link stack ptr
807 popl %edi # Base of frame
808 xchgl %eax,%ebp # Save intno/address
809 movl 0x48(%esp,1),%eax # Get flags
810 testb $0x2,%dl # Simulate CALLF?
811 jnz intusr.3 # Yes
812 decl %ebx # Push flags
813 decl %ebx # on V86
814 movw %ax,(%ebx) # stack
815intusr.3: movb $0x4,%cl # Count
816 subl %ecx,%ebx # Push return address
817 movl $inthlt,(%ebx) # on V86 stack
818 rep # Copy seg regs to
819 movsl # exception frame
820 xchgl %eax,%ecx # Save flags
821 movl %ebx,%eax # User ESP
822 subl $V86_STK,%eax # Less bytes
823 ja intusr.4 # to
824 xorl %eax,%eax # keep
825intusr.4: shrl $0x4,%eax # Gives segment
826 stosl # Set SS
827 shll $0x4,%eax # To bytes
828 xchgl %eax,%ebx # Swap
829 subl %ebx,%eax # Gives offset
830 stosl # Set ESP
831 xchgl %eax,%ecx # Get flags
832 btsl $0x11,%eax # Set VM
833 andb $~0x1,%ah # Clear TF
834 stosl # Set EFL
835 xchgl %eax,%ebp # Get int no/address
836 testb $0x1,%dl # Address?
837 jnz intusr.5 # Yes
838 shll $0x2,%eax # Scale
839 movl (%eax),%eax # Load int vector
840intusr.5: movl %eax,%ecx # Save
841 shrl $0x10,%eax # Gives segment
842 stosl # Set CS
843 movw %cx,%ax # Restore
844 stosl # Set EIP
845 leal 0x10(%esp,1),%esp # Discard seg regs
846 popa # Restore
847 iret # To V86 mode
848#
849# System Call.
850#
851intx30: cmpl $SYS_EXEC,%eax # Exec system call?
852 jne intx30.1 # No
853 pushl %ss # Set up
854 popl %es # all
855 pushl %es # segment
856 popl %ds # registers
857 pushl %ds # for the
858 popl %fs # program
859 pushl %fs # we're
860 popl %gs # invoking
861 movl $MEM_USR,%eax # User base address
862 addl 0xc(%esp,1),%eax # Change to user
863 leal 0x4(%eax),%esp # stack
864ifdef(`PAGING',`
865 movl %cr0,%eax # Turn
866 andl $~0x80000000,%eax # off
867 movl %eax,%cr0 # paging
868 xorl %eax,%eax # Flush
869 movl %eax,%cr3 # TLB
870')
871 popl %eax # Call
872 call *%eax # program
5ee58eed 873intx30.1: orb $0x1,%ss:btx_hdr+0x7 # Flag reboot
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874 jmp exit # Exit
875#
876# Dump structure [EBX] to [EDI], using format string [ESI].
877#
878dump.0: stosb # Save char
879dump: lodsb # Load char
880 testb %al,%al # End of string?
881 jz dump.10 # Yes
882 testb $0x80,%al # Control?
883 jz dump.0 # No
884 movb %al,%ch # Save control
885 movb $'=',%al # Append
886 stosb # '='
887 lodsb # Get offset
888 pushl %esi # Save
889 movsbl %al,%esi # To
890 addl %ebx,%esi # pointer
891 testb $DMP_X16,%ch # Dump word?
892 jz dump.1 # No
893 lodsw # Get and
894 call hex16 # dump it
895dump.1: testb $DMP_X32,%ch # Dump long?
896 jz dump.2 # No
897 lodsl # Get and
898 call hex32 # dump it
899dump.2: testb $DMP_MEM,%ch # Dump memory?
900 jz dump.8 # No
901 pushl %ds # Save
902 testb $0x2,0x52(%ebx) # V86 mode?
903 jnz dump.3 # Yes
904 verr 0x4(%esi) # Readable selector?
905 jnz dump.3 # No
906 ldsl (%esi),%esi # Load pointer
907 jmp dump.4 # Join common code
908dump.3: lodsl # Set offset
909 xchgl %eax,%edx # Save
910 lodsl # Get segment
911 shll $0x4,%eax # * 0x10
912 addl %edx,%eax # + offset
913 xchgl %eax,%esi # Set pointer
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914dump.4: movb $2,%dl # Num lines
915dump.4a: movb $0x10,%cl # Bytes to dump
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916dump.5: lodsb # Get byte and
917 call hex8 # dump it
918 decb %cl # Keep count
5ee58eed 919 jz dump.6a # If done
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920 movb $'-',%al # Separator
921 cmpb $0x8,%cl # Half way?
922 je dump.6 # Yes
923 movb $' ',%al # Use space
924dump.6: stosb # Save separator
925 jmp dump.5 # Continue
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926dump.6a: decb %dl # Keep count
927 jz dump.7 # If done
928 movb $0xa,%al # Line feed
929 stosb # Save one
930 movb $7,%cl # Leading
931 movb $' ',%al # spaces
932dump.6b: stosb # Dump
933 decb %cl # spaces
934 jnz dump.6b
935 jmp dump.4a # Next line
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936dump.7: popl %ds # Restore
937dump.8: popl %esi # Restore
938 movb $0xa,%al # Line feed
939 testb $DMP_EOL,%ch # End of line?
940 jnz dump.9 # Yes
941 movb $' ',%al # Use spaces
942 stosb # Save one
943dump.9: jmp dump.0 # Continue
944dump.10: stosb # Terminate string
945 ret # To caller
946#
947# Convert EAX, AX, or AL to hex, saving the result to [EDI].
948#
949hex32: pushl %eax # Save
950 shrl $0x10,%eax # Do upper
951 call hex16 # 16
952 popl %eax # Restore
953hex16: call hex16.1 # Do upper 8
954hex16.1: xchgb %ah,%al # Save/restore
955hex8: pushl %eax # Save
956 shrb $0x4,%al # Do upper
957 call hex8.1 # 4
958 popl %eax # Restore
959hex8.1: andb $0xf,%al # Get lower 4
960 cmpb $0xa,%al # Convert
961 sbbb $0x69,%al # to hex
962 das # digit
963 orb $0x20,%al # To lower case
964 stosb # Save char
965 ret # (Recursive)
966#
967# Output zero-terminated string [ESI] to the console.
968#
969putstr.0: call putchr # Output char
970putstr: lodsb # Load char
971 testb %al,%al # End of string?
972 jnz putstr.0 # No
973 ret # To caller
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974ifdef(`BTX_SERIAL',`
975 .set SIO_PRT,SIOPRT # Base port
976 .set SIO_FMT,SIOFMT # 8N1
977 .set SIO_DIV,(115200/SIOSPD) # 115200 / SPD
978
979# void sio_init(void)
980
981sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
982 movb $SIO_FMT|0x80,%al # Set format
983 outb %al,(%dx) # and DLAB
984 pushl %edx # Save
985 subb $0x3,%dl # Divisor latch reg
986 movw $SIO_DIV,%ax # Set
987 outw %ax,(%dx) # BPS
988 popl %edx # Restore
989 movb $SIO_FMT,%al # Clear
990 outb %al,(%dx) # DLAB
991 incl %edx # Modem control reg
992 movb $0x3,%al # Set RTS,
993 outb %al,(%dx) # DTR
994 incl %edx # Line status reg
995
996# void sio_flush(void)
997
998sio_flush.0: call sio_getc.1 # Get character
999sio_flush: call sio_ischar # Check for character
1000 jnz sio_flush.0 # Till none
1001 ret # To caller
1002
1003# void sio_putc(int c)
1004
1005sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg
1006 xor %ecx,%ecx # Timeout
1007 movb $0x40,%ch # counter
1008sio_putc.1: inb (%dx),%al # Transmitter
1009 testb $0x20,%al # buffer empty?
1010 loopz sio_putc.1 # No
1011 jz sio_putc.2 # If timeout
1012 movb 0x4(%esp,1),%al # Get character
1013 subb $0x5,%dl # Transmitter hold reg
1014 outb %al,(%dx) # Write character
1015sio_putc.2: ret $0x4 # To caller
1016
1017# int sio_getc(void)
1018
1019sio_getc: call sio_ischar # Character available?
1020 jz sio_getc # No
1021sio_getc.1: subb $0x5,%dl # Receiver buffer reg
1022 inb (%dx),%al # Read character
1023 ret # To caller
1024
1025# int sio_ischar(void)
1026
1027sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register
1028 xorl %eax,%eax # Zero
1029 inb (%dx),%al # Received data
1030 andb $0x1,%al # ready?
1031 ret # To caller
1032
1033#
1034# Output character AL to the serial console.
1035#
1036putchr: pusha # Save
1037 cmpb $10, %al # is it a newline?
1038 jne putchr.1 # no?, then leave
1039 push $13 # output a carriage
1040 call sio_putc # return first
1041 movb $10, %al # restore %al
1042putchr.1: pushl %eax # Push the character
1043 # onto the stack
1044 call sio_putc # Output the character
1045 popa # Restore
1046 ret # To caller
1047',`
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1048#
1049# Output character AL to the console.
1050#
1051putchr: pusha # Save
1052 xorl %ecx,%ecx # Zero for loops
1053 movb $SCR_MAT,%ah # Mode/attribute
1054 movl $BDA_POS,%ebx # BDA pointer
1055 movw (%ebx),%dx # Cursor position
1056 movl $0xb8000,%edi # Regen buffer (color)
1057 cmpb %ah,BDA_SCR-BDA_POS(%ebx) # Mono mode?
1058 jne putchr.1 # No
1059 xorw %di,%di # Regen buffer (mono)
1060putchr.1: cmpb $0xa,%al # New line?
1061 je putchr.2 # Yes
1062 xchgl %eax,%ecx # Save char
1063 movb $SCR_COL,%al # Columns per row
1064 mulb %dh # * row position
1065 addb %dl,%al # + column
1066 adcb $0x0,%ah # position
1067 shll %eax # * 2
1068 xchgl %eax,%ecx # Swap char, offset
1069 movw %ax,(%edi,%ecx,1) # Write attr:char
1070 incl %edx # Bump cursor
1071 cmpb $SCR_COL,%dl # Beyond row?
1072 jb putchr.3 # No
1073putchr.2: xorb %dl,%dl # Zero column
1074 incb %dh # Bump row
1075putchr.3: cmpb $SCR_ROW,%dh # Beyond screen?
1076 jb putchr.4 # No
1077 leal 2*SCR_COL(%edi),%esi # New top line
1078 movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
1079 rep # Scroll
1080 movsl # screen
5ee58eed 1081 movb $0x20,%al # Space
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1082 movb $SCR_COL,%cl # Columns to clear
1083 rep # Clear
1084 stosw # line
1085 movb $SCR_ROW-1,%dh # Bottom line
1086putchr.4: movw %dx,(%ebx) # Update position
1087 popa # Restore
1088 ret # To caller
5ee58eed 1089')
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1090
1091 .p2align 4
1092#
1093# Global descriptor table.
1094#
1095gdt: .word 0x0,0x0,0x0,0x0 # Null entry
1096 .word 0xffff,0x0,0x9a00,0xcf # SEL_SCODE
1097 .word 0xffff,0x0,0x9200,0xcf # SEL_SDATA
1098 .word 0xffff,0x0,0x9a00,0x0 # SEL_RCODE
1099 .word 0xffff,0x0,0x9200,0x0 # SEL_RDATA
1100 .word 0xffff,MEM_USR,0xfa00,0xcf# SEL_UCODE
1101 .word 0xffff,MEM_USR,0xf200,0xcf# SEL_UDATA
1102 .word _TSSLM,MEM_TSS,0x8900,0x0 # SEL_TSS
1103gdt.1:
1104#
1105# Pseudo-descriptors.
1106#
1107gdtdesc: .word gdt.1-gdt-1,gdt,0x0 # GDT
1108idtdesc: .word _IDTLM,MEM_IDT,0x0 # IDT
1109ivtdesc: .word 0x400-0x0-1,0x0,0x0 # IVT
1110#
1111# IDT construction control string.
1112#
1113idtctl: .byte 0x10, 0x8e # Int 0x0-0xf
1114 .word 0x7dfb,intx00 # (exceptions)
1115 .byte 0x10, 0x8e # Int 0x10
1116 .word 0x1, intx10 # (exception)
1117 .byte 0x10, 0x8e # Int 0x20-0x2f
1118 .word 0xffff,intx20 # (hardware)
1119 .byte 0x1, 0xee # int 0x30
1120 .word 0x1, intx30 # (system call)
1121 .byte 0x2, 0xee # Int 0x31-0x32
1122 .word 0x1, intx31 # (V86, null)
1123 .byte 0x0 # End of string
1124#
1125# Dump format string.
1126#
1127dmpfmt: .byte '\n' # "\n"
1128 .ascii "int" # "int="
1129 .byte 0x80|DMP_X32, 0x40 # "00000000 "
1130 .ascii "err" # "err="
1131 .byte 0x80|DMP_X32, 0x44 # "00000000 "
1132 .ascii "efl" # "efl="
1133 .byte 0x80|DMP_X32, 0x50 # "00000000 "
1134 .ascii "eip" # "eip="
1135 .byte 0x80|DMP_X32|DMP_EOL,0x48 # "00000000\n"
1136 .ascii "eax" # "eax="
1137 .byte 0x80|DMP_X32, 0x34 # "00000000 "
1138 .ascii "ebx" # "ebx="
1139 .byte 0x80|DMP_X32, 0x28 # "00000000 "
1140 .ascii "ecx" # "ecx="
1141 .byte 0x80|DMP_X32, 0x30 # "00000000 "
1142 .ascii "edx" # "edx="
1143 .byte 0x80|DMP_X32|DMP_EOL,0x2c # "00000000\n"
1144 .ascii "esi" # "esi="
1145 .byte 0x80|DMP_X32, 0x1c # "00000000 "
1146 .ascii "edi" # "edi="
1147 .byte 0x80|DMP_X32, 0x18 # "00000000 "
1148 .ascii "ebp" # "ebp="
1149 .byte 0x80|DMP_X32, 0x20 # "00000000 "
1150 .ascii "esp" # "esp="
1151 .byte 0x80|DMP_X32|DMP_EOL,0x0 # "00000000\n"
1152 .ascii "cs" # "cs="
1153 .byte 0x80|DMP_X16, 0x4c # "0000 "
1154 .ascii "ds" # "ds="
1155 .byte 0x80|DMP_X16, 0xc # "0000 "
1156 .ascii "es" # "es="
1157 .byte 0x80|DMP_X16, 0x8 # "0000 "
1158 .ascii " " # " "
1159 .ascii "fs" # "fs="
1160 .byte 0x80|DMP_X16, 0x10 # "0000 "
1161 .ascii "gs" # "gs="
1162 .byte 0x80|DMP_X16, 0x14 # "0000 "
1163 .ascii "ss" # "ss="
1164 .byte 0x80|DMP_X16|DMP_EOL,0x4 # "0000\n"
1165 .ascii "cs:eip" # "cs:eip="
1166 .byte 0x80|DMP_MEM|DMP_EOL,0x48 # "00 00 ... 00 00\n"
1167 .ascii "ss:esp" # "ss:esp="
1168 .byte 0x80|DMP_MEM|DMP_EOL,0x0 # "00 00 ... 00 00\n"
5ee58eed 1169 .asciz "BTX halted\n" # End
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1170#
1171# End of BTX memory.
1172#
1173 .p2align 4
1174break: