summaryrefslogtreecommitdiff
path: root/DuetPkg/BootSector/start16.S
blob: be525b6f307a0c31637b08403b8ad7add9407cd6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
#------------------------------------------------------------------------------
#*
#*   Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
#*   This program and the accompanying materials                          
#*   are licensed and made available under the terms and conditions of the BSD License         
#*   which accompanies this distribution.  The full text of the license may be found at        
#*   http://opensource.org/licenses/bsd-license.php                                            
#*                                                                                             
#*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
#*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             
#*   
#*    start16.asm
#*  
#*   Abstract:
#*
#------------------------------------------------------------------------------

        #.MODEL small
        .stack: 
        .486p: 
        .code: 

.equ                        FAT_DIRECTORY_ENTRY_SIZE,   0x0020
.equ                        FAT_DIRECTORY_ENTRY_SHIFT,  5
.equ                        BLOCK_SIZE,                 0x0200
.equ                        BLOCK_MASK,                 0x01ff
.equ                        BLOCK_SHIFT,                9

        .org 0x00

.global _start
_start:

Ia32Jump: 
  jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  nop

OemId:             .ascii  "INTEL   "    # OemId               - 8 bytes

SectorSize:        .word  0              # Sector Size         - 16 bits
SectorsPerCluster: .byte  0              # Sector Per Cluster  - 8 bits
ReservedSectors:   .word  0              # Reserved Sectors    - 16 bits
NoFats:            .byte  0              # Number of FATs      - 8 bits
RootEntries:       .word  0              # Root Entries        - 16 bits
Sectors:           .word  0              # Number of Sectors   - 16 bits
Media:             .byte  0              # Media               - 8 bits  - ignored
SectorsPerFat:     .word  0              # Sectors Per FAT     - 16 bits
SectorsPerTrack:   .word  0              # Sectors Per Track   - 16 bits - ignored
Heads:             .word  0              # Heads               - 16 bits - ignored
HiddenSectors:     .long  0              # Hidden Sectors      - 32 bits - ignored
LargeSectors:      .long  0              # Large Sectors       - 32 bits 
PhysicalDrive:     .byte  0              # PhysicalDriveNumber - 8 bits  - ignored
CurrentHead:       .byte  0              # Current Head        - 8 bits
Signature:         .byte  0              # Signature           - 8 bits  - ignored
VolId:             .ascii  "    "        # Volume Serial Number- 4 bytes
FatLabel:          .ascii  "           " # Label               - 11 bytes
SystemId:          .ascii  "FAT16   "    # SystemId            - 8 bytes

BootSectorEntryPoint: 
        #ASSUME ds:@code
        #ASSUME ss:@code
      # ds = 1000, es = 2000 + x (size of first cluster >> 4)
      # cx = Start Cluster of EfiLdr
      # dx = Start Cluster of Efivar.bin

# Re use the BPB data stored in Boot Sector
        movw    $0x7c00, %bp

        pushw   %cx
# Read Efivar.bin
#       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
        movw    $0x1900, %ax
        movw    %ax, %es
        testw   %dx, %dx
        jnz     CheckVarStoreSize

        movb    $1, %al
NoVarStore: 
        pushw   %es
# Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
        movb    %al, %es:4
        jmp     SaveVolumeId

CheckVarStoreSize: 
        movw    %dx, %di
        cmpl    $0x4000, %ds:2(%di)
        movb    $2, %al
        jne     NoVarStore

LoadVarStore: 
        movb    $0, %al
        movb    %al, %es:4
        movw    (%di), %cx
#       ES:DI = 1500:0
        xorw    %di, %di
        pushw   %es
        movw    $0x1500, %ax
        movw    %ax, %es
        call    ReadFile
SaveVolumeId: 
        popw    %es
        movw    VolId(%bp), %ax
        movw    %ax, %es:0                      # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
        movw    VolId+2(%bp), %ax
        movw    %ax, %es:2

# Read Efildr
        popw    %cx
#       cx    = Start Cluster of Efildr -> BS.com has filled already
#       ES:DI = 2000:0, first cluster will be read again
        xorw    %di, %di                            # di = 0
        movw    $0x2000, %ax
        movw    %ax, %es
        call    ReadFile
        movw    %cs, %ax
        movw    %ax, %cs:JumpSegment

JumpFarInstruction: 
        .byte   0xea
JumpOffset: 
        .word   0x200
JumpSegment: 
        .word   0x2000



# ****************************************************************************
# ReadFile
#
# Arguments:
#   CX    = Start Cluster of File
#   ES:DI = Buffer to store file content read from disk
#
# Return:
#   (ES << 4 + DI) = end of file content Buffer
#
# ****************************************************************************
ReadFile: 
# si      = NumberOfClusters
# cx      = ClusterNumber
# dx      = CachedFatSectorNumber
# ds:0000 = CacheFatSectorBuffer
# es:di   = Buffer to load file
# bx      = NextClusterNumber
        pusha
        movw    $1, %si                             # NumberOfClusters = 1
        pushw   %cx                                 # Push Start Cluster onto stack
        movw    $0xfff, %dx                         # CachedFatSectorNumber = 0xfff
FatChainLoop: 
        movw    %cx, %ax                            # ax = ClusterNumber    
        andw    $0xfff8, %ax                        # ax = ax & 0xfff8
        cmpw    $0xfff8, %ax                        # See if this is the last cluster
        je      FoundLastCluster                    # Jump if last cluster found
        movw    %cx, %ax                            # ax = ClusterNumber
        shlw    %ax                                 # FatOffset = ClusterNumber * 2
        pushw   %si                                 # Save si
        movw    %ax, %si                            # si = FatOffset
        shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
        addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
        andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
        cmpw    %dx, %ax                            # Compare FatSectorNumber to CachedFatSectorNumber
        je      SkipFatRead
        movw    $2, %bx
        pushw   %es
        pushw   %ds
        popw    %es
        call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
        popw    %es
        movw    %ax, %dx                            # CachedFatSectorNumber = FatSectorNumber
SkipFatRead: 
        movw    (%si), %bx                          # bx = NextClusterNumber
        movw    %cx, %ax                            # ax = ClusterNumber
        popw    %si                                 # Restore si
        decw    %bx                                 # bx = NextClusterNumber - 1
        cmpw    %cx, %bx                            # See if (NextClusterNumber-1)==ClusterNumber
        jne     ReadClusters
        incw    %bx                                 # bx = NextClusterNumber
        incw    %si                                 # NumberOfClusters++
        movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
        jmp     FatChainLoop
ReadClusters: 
        incw    %bx
        popw    %ax                                 # ax = StartCluster
        pushw   %bx                                 # StartCluster = NextClusterNumber
        movw    %bx, %cx                            # ClusterNumber = NextClusterNumber
        subw    $2, %ax                             # ax = StartCluster - 2
        xorb    %bh, %bh
        movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
        mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
        addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
        pushw   %ax                                 # save start sector
        movw    %si, %ax                            # ax = NumberOfClusters
        mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
        movw    %ax, %bx                            # bx = Number of Sectors
        popw    %ax                                 # ax = Start Sector
        call    ReadBlocks
        movw    $1, %si                             # NumberOfClusters = 1
        jmp     FatChainLoop
FoundLastCluster: 
        popw    %cx
        popa
        ret


# ****************************************************************************
# ReadBlocks - Reads a set of blocks from a block device
#
# AX    = Start LBA
# BX    = Number of Blocks to Read
# ES:DI = Buffer to store sectors read from disk
# ****************************************************************************

# cx = Blocks
# bx = NumberOfBlocks
# si = StartLBA

ReadBlocks: 
        pusha
        addl    LBAOffsetForBootSector(%bp), %eax            # Add LBAOffsetForBootSector to Start LBA
        addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
        movl    %eax, %esi                          # esi = Start LBA
        movw    %bx, %cx                            # cx = Number of blocks to read
ReadCylinderLoop: 
        movw    $0x7bfc, %bp                        # bp = 0x7bfc
        movl    %esi, %eax                          # eax = Start LBA
        xorl    %edx, %edx                          # edx = 0
        movzwl  (%bp), %ebx                         # bx = MaxSector
        divl    %ebx                                # ax = StartLBA / MaxSector
        incw    %dx                                 # dx = (StartLBA % MaxSector) + 1

        movw    (%bp), %bx                          # bx = MaxSector
        subw    %dx, %bx                            # bx = MaxSector - Sector
        incw    %bx                                 # bx = MaxSector - Sector + 1
        cmpw    %bx, %cx                            # Compare (Blocks) to (MaxSector - Sector + 1)
        jg      LimitTransfer
        movw    %cx, %bx                            # bx = Blocks
LimitTransfer: 
        pushw   %ax                                 # save ax
        movw    %es, %ax                            # ax = es
        shrw    $(BLOCK_SHIFT-4), %ax               # ax = Number of blocks into mem system
        andw    $0x7f, %ax                          # ax = Number of blocks into current seg
        addw    %bx, %ax                            # ax = End Block number of transfer
        cmpw    $0x80, %ax                          # See if it crosses a 64K boundry
        jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
        subw    $0x80, %ax                          # ax = Number of blocks past 64K boundry
        subw    %ax, %bx                            # Decrease transfer size by block overage
NotCrossing64KBoundry: 
        popw    %ax                                 # restore ax

        pushw   %cx
        movb    %dl, %cl                            # cl = (StartLBA % MaxSector) + 1 = Sector
        xorw    %dx, %dx                            # dx = 0
        divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder  
                                                    # dx = ax % (MaxHead + 1) = Head

        pushw   %bx                                 # Save number of blocks to transfer
        movb    %dl, %dh                            # dh = Head
        movw    $0x7c00, %bp                        # bp = 0x7c00
        movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
        movb    %al, %ch                            # ch = Cylinder
        movb    %bl, %al                            # al = Blocks
        movb    $2, %ah                             # ah = Function 2
        movw    %di, %bx                            # es:bx = Buffer address
        int     $0x13
        jc      DiskError
        popw    %bx
        popw    %cx
        movzwl  %bx, %ebx
        addl    %ebx, %esi                          # StartLBA = StartLBA + NumberOfBlocks
        subw    %bx, %cx                            # Blocks = Blocks - NumberOfBlocks
        movw    %es, %ax
        shlw    $(BLOCK_SHIFT-4), %bx
        addw    %bx, %ax
        movw    %ax, %es                            # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
        cmpw    $0, %cx
        jne     ReadCylinderLoop
        popa
        ret

DiskError: 
        pushw %cs
        popw %ds
        leaw ErrorString, %si
        movw $7, %cx
        jmp  PrintStringAndHalt

PrintStringAndHalt: 
        movw $0xb800, %ax
        movw %ax, %es
        movw $160, %di
        rep
        movsw
Halt: 
        jmp   Halt

ErrorString: 
        .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c

        # .org     0x01fa # Just for passing build.
LBAOffsetForBootSector: 
        .long   0x0

        # .org     0x01fe # Just for passing build.
        .word   0xaa55

#******************************************************************************
#******************************************************************************
#******************************************************************************

.equ                 DELAY_PORT,            0x0ed     # Port to use for 1uS delay
.equ                 KBD_CONTROL_PORT,      0x060     # 8042 control port     
.equ                 KBD_STATUS_PORT,       0x064     # 8042 status port      
.equ                 WRITE_DATA_PORT_CMD,   0x0d1     # 8042 command to write the data port
.equ                 ENABLE_A20_CMD,        0x0df     # 8042 command to enable A20

        # .org     0x0200 # Just for passing build.
        jmp start
Em64String: 
        .byte 'E', 0x0c, 'm', 0x0c, '6', 0x0c, '4', 0x0c, 'T', 0x0c, ' ', 0x0c, 'U', 0x0c, 'n', 0x0c, 's', 0x0c, 'u', 0x0c, 'p', 0x0c, 'p', 0x0c, 'o', 0x0c, 'r', 0x0c, 't', 0x0c, 'e', 0x0c, 'd', 0x0c, '!', 0x0c

start:  
        movw %cs, %ax
        movw %ax, %ds
        movw %ax, %es
        movw %ax, %ss
        movw $MyStack, %sp

#        mov ax,0b800h
#        mov es,ax
#        mov byte ptr es:[160],'a'
#        mov ax,cs
#        mov es,ax

        movl $0, %ebx
        leal MemoryMap, %edi
MemMapLoop: 
        movl $0xe820, %eax
        movl $20, %ecx
        movl $0x534d4150, %edx  # 0x534d4150  stands for 'SMAP'
        int $0x15
        jc  MemMapDone
        addl $20, %edi
        cmpl $0, %ebx
        je  MemMapDone
        jmp MemMapLoop
MemMapDone: 
        leal MemoryMap, %eax
        subl %eax, %edi                     # Get the address of the memory map
        movl %edi, MemoryMapSize            # Save the size of the memory map

        xorl    %ebx, %ebx
        movw    %cs, %bx                    # BX=segment
        shll    $4, %ebx                    # BX="linear" address of segment base
        leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
        movl    %eax, gdtr + 2              # Put address of gdt into the gdtr
        leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
        movl    %eax, idtr + 2              # Put address of idt into the idtr
        leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map

        addl $0x1000, %ebx                  # Source of EFI32
        movl %ebx, JUMP+2
        addl $0x1000, %ebx
        movl %ebx, %esi                     # Source of EFILDR32

#        mov ax,0b800h
#        mov es,ax
#        mov byte ptr es:[162],'b'
#        mov ax,cs
#        mov es,ax

#
# Enable A20 Gate 
#

        movw $0x2401, %ax                   # Enable A20 Gate
        int $0x15
        jnc A20GateEnabled                  # Jump if it suceeded

#
# If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
#

        call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
        jnz     Timeout8042                 # Jump if the 8042 timed out
        outw    %ax, $DELAY_PORT            # Delay 1 uS
        movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
        outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
        call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
        jnz     Timeout8042                 # Jump if the 8042 timed out
        movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
        outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
        call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
        movw    $25, %cx                    # Delay 25 uS for the command to complete on the 8042
Delay25uS: 
        outw    %ax, $DELAY_PORT            # Delay 1 uS
        loop    Delay25uS
Timeout8042: 


A20GateEnabled: 

#
# DISABLE INTERRUPTS - Entering Protected Mode
#

        cli

#        mov ax,0b800h
#        mov es,ax
#        mov byte ptr es:[164],'c'
#        mov ax,cs
#        mov es,ax

        .byte   0x66
        lgdt    gdtr
        .byte   0x66
        lidt    idtr

        movl    %cr0, %eax
        orb     $1, %al
        movl    %eax, %cr0

        movl $0x008, %eax                   # Flat data descriptor
        movl $0x00400000, %ebp              # Destination of EFILDR32
        movl $0x00070000, %ebx              # Length of copy

JUMP: 
# jmp far 0010:00020000
        .byte 0x66
        .byte 0xea
        .long 0x00020000
        .word 0x0010

Empty8042InputBuffer: 
        movw $0, %cx
Empty8042Loop: 
        outw    %ax, $DELAY_PORT            # Delay 1us
        inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
        andb    $0x2, %al                   # Check the Input Buffer Full Flag
        loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
        ret

##############################################################################
# data
##############################################################################

        .p2align 1

gdtr:   .word  GDT_END - GDT_BASE - 1       # GDT limit
        .long 0                             # (GDT base gets set above)
##############################################################################
#   global descriptor table (GDT)
##############################################################################

        .p2align 1

GDT_BASE: 
# null descriptor
.equ                NULL_SEL, .-GDT_BASE
        .word 0         # limit 15:0
        .word 0         # base 15:0
        .byte 0         # base 23:16
        .byte 0         # type
        .byte 0         # limit 19:16, flags
        .byte 0         # base 31:24

# linear data segment descriptor
.equ            LINEAR_SEL, .-GDT_BASE
        .word 0xFFFF    # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0x92      # present, ring 0, data, expand-up, writable
        .byte 0xCF              # page-granular, 32-bit
        .byte 0

# linear code segment descriptor
.equ            LINEAR_CODE_SEL, .-GDT_BASE
        .word 0xFFFF    # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0x9A      # present, ring 0, data, expand-up, writable
        .byte 0xCF              # page-granular, 32-bit
        .byte 0

# system data segment descriptor
.equ            SYS_DATA_SEL, .-GDT_BASE
        .word 0xFFFF    # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0x92      # present, ring 0, data, expand-up, writable
        .byte 0xCF              # page-granular, 32-bit
        .byte 0

# system code segment descriptor
.equ            SYS_CODE_SEL, .-GDT_BASE
        .word 0xFFFF    # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0x9A      # present, ring 0, data, expand-up, writable
        .byte 0xCF              # page-granular, 32-bit
        .byte 0

# spare segment descriptor
.equ        SPARE3_SEL, .-GDT_BASE
        .word 0         # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0         # present, ring 0, data, expand-up, writable
        .byte 0         # page-granular, 32-bit
        .byte 0

# spare segment descriptor
.equ        SPARE4_SEL, .-GDT_BASE
        .word 0         # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0         # present, ring 0, data, expand-up, writable
        .byte 0         # page-granular, 32-bit
        .byte 0

# spare segment descriptor
.equ        SPARE5_SEL, .-GDT_BASE
        .word 0         # limit 0xFFFFF
        .word 0         # base 0
        .byte 0
        .byte 0         # present, ring 0, data, expand-up, writable
        .byte 0         # page-granular, 32-bit
        .byte 0

GDT_END: 

        .p2align 1



idtr:   .word IDT_END - IDT_BASE - 1  # IDT limit
        .long 0                       # (IDT base gets set above)
##############################################################################
#   interrupt descriptor table (IDT)
#
#   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
#       mappings.  This implementation only uses the system timer and all other
#       IRQs will remain masked.  The descriptors for vectors 33+ are provided
#       for convenience.
##############################################################################

#idt_tag db "IDT",0     
        .p2align 1

IDT_BASE: 
# divide by zero (INT 0)
.equ                DIV_ZERO_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# debug exception (INT 1)
.equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# NMI (INT 2)
.equ                NMI_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# soft breakpoint (INT 3)
.equ                BREAKPOINT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# overflow (INT 4)
.equ                OVERFLOW_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# bounds check (INT 5)
.equ                BOUNDS_CHECK_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# invalid opcode (INT 6)
.equ                INVALID_OPCODE_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# device not available (INT 7)
.equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# double fault (INT 8)
.equ                DOUBLE_FAULT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# Coprocessor segment overrun - reserved (INT 9)
.equ                RSVD_INTR_SEL1, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# invalid TSS (INT 0ah)
.equ                INVALID_TSS_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# segment not present (INT 0bh)
.equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# stack fault (INT 0ch)
.equ                STACK_FAULT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# general protection (INT 0dh)
.equ                GP_FAULT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# page fault (INT 0eh)
.equ                PAGE_FAULT_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# Intel reserved - do not use (INT 0fh)
.equ                RSVD_INTR_SEL2, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# floating point error (INT 10h)
.equ                FLT_POINT_ERR_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# alignment check (INT 11h)
.equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# machine check (INT 12h)
.equ                MACHINE_CHECK_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# SIMD floating-point exception (INT 13h)
.equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
        .fill  85 * 8, 1, 0

# IRQ 0 (System timer) - (INT 68h)
.equ                IRQ0_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 1 (8042 Keyboard controller) - (INT 69h)
.equ                IRQ1_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
.equ                IRQ2_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 3 (COM 2) - (INT 6bh)
.equ                IRQ3_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 4 (COM 1) - (INT 6ch)
.equ                IRQ4_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 5 (LPT 2) - (INT 6dh)
.equ                IRQ5_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 6 (Floppy controller) - (INT 6eh)
.equ                IRQ6_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 7 (LPT 1) - (INT 6fh)
.equ                IRQ7_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 8 (RTC Alarm) - (INT 70h)
.equ                IRQ8_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 9 - (INT 71h)
.equ                IRQ9_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 10 - (INT 72h)
.equ                 IRQ10_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 11 - (INT 73h)
.equ                 IRQ11_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 12 (PS/2 mouse) - (INT 74h)
.equ                 IRQ12_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 13 (Floating point error) - (INT 75h)
.equ                 IRQ13_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 14 (Secondary IDE) - (INT 76h)
.equ                 IRQ14_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

# IRQ 15 (Primary IDE) - (INT 77h)
.equ                 IRQ15_SEL, .-IDT_BASE
        .word 0             # offset 15:0
        .word SYS_CODE_SEL  # selector 15:0
        .byte 0             # 0 for interrupt gate
        .byte 0x0e | 0x80  # (10001110)type = 386 interrupt gate, present
        .word 0             # offset 31:16

IDT_END: 

        .p2align 1

MemoryMapSize:  .long 0
MemoryMap:  .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0

        .long 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
        .long 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

        .org 0x0fe0
MyStack:    
        # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
        #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
        #    known low address (20f00) so it can be set up by PlMapIrqToVect in
        #    8259.c

        int $8
        iret

        int $9
        iret

        int $10
        iret

        int $11
        iret

        int $12
        iret

        int $13
        iret

        int $14
        iret

        int $15
        iret


        .org 0x0ffe
BlockSignature: 
        .word 0xaa55