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| 1 | # |
1 | # |
| 2 | # Copyright (C) 2001-2004 Jakub Jermar |
2 | # Copyright (C) 2001-2004 Jakub Jermar |
| 3 | # All rights reserved. |
3 | # All rights reserved. |
| 4 | # |
4 | # |
| 5 | # Redistribution and use in source and binary forms, with or without |
5 | # Redistribution and use in source and binary forms, with or without |
| 6 | # modification, are permitted provided that the following conditions |
6 | # modification, are permitted provided that the following conditions |
| 7 | # are met: |
7 | # are met: |
| 8 | # |
8 | # |
| 9 | # - Redistributions of source code must retain the above copyright |
9 | # - Redistributions of source code must retain the above copyright |
| 10 | # notice, this list of conditions and the following disclaimer. |
10 | # notice, this list of conditions and the following disclaimer. |
| 11 | # - Redistributions in binary form must reproduce the above copyright |
11 | # - Redistributions in binary form must reproduce the above copyright |
| 12 | # notice, this list of conditions and the following disclaimer in the |
12 | # notice, this list of conditions and the following disclaimer in the |
| 13 | # documentation and/or other materials provided with the distribution. |
13 | # documentation and/or other materials provided with the distribution. |
| 14 | # - The name of the author may not be used to endorse or promote products |
14 | # - The name of the author may not be used to endorse or promote products |
| 15 | # derived from this software without specific prior written permission. |
15 | # derived from this software without specific prior written permission. |
| 16 | # |
16 | # |
| 17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | # |
27 | # |
| 28 | 28 | ||
| 29 | # This is a very primitive boot.s |
29 | # This is a very primitive boot.s |
| 30 | 30 | ||
| 31 | # It assumes that the first sector of the kernel image is found |
31 | # It assumes that the first sector of the kernel image is found |
| 32 | # on head 0, track 0, sector 2 of the first floppy drive (1440K). |
32 | # on head 0, track 0, sector 2 of the first floppy drive (1440K). |
| 33 | # Next kernel sectors follow on disk sector 3, 4, ... |
33 | # Next kernel sectors follow on disk sector 3, 4, ... |
| 34 | # |
34 | # |
| 35 | 35 | ||
| 36 | 36 | ||
| - | 37 | # KERNEL_SIZE is passed from the outside to the preprocessor |
|
| - | 38 | #if (KERNEL_SIZE%512>0) |
|
| - | 39 | #define TAIL 1 |
|
| - | 40 | #else |
|
| - | 41 | #define TAIL 0 |
|
| - | 42 | #endif |
|
| - | 43 | ||
| - | 44 | #define SECTORS (KERNEL_SIZE/512+TAIL) |
|
| - | 45 | ||
| 37 | .text |
46 | .text |
| 38 | .global _start_0x7c00 |
47 | .global _start_0x7c00 |
| 39 | 48 | ||
| 40 | .code16 |
49 | .code16 |
| 41 | _start_0x7c00: |
50 | _start_0x7c00: |
| 42 | xorw %ax,%ax # reset, %al will be used below |
51 | xorw %ax,%ax # reset, %al will be used below |
| 43 | movw %ax,%dx # fd0, %dh and %dl will be used below |
52 | movw %ax,%dx # fd0, %dh and %dl will be used below |
| 44 | int $0x13 |
- | |
| 45 | jc stop_trying |
53 | movw %dx,%ds |
| 46 | 54 | ||
| 47 | movb $2,%ah # read |
- | |
| 48 | incb %al # one sector |
- | |
| 49 | movb %ah,%cl # from disk sector 2 |
55 | movw %dx,%ss # initialize stack |
| 50 | movw %dx,%es |
56 | movw $stack,%sp |
| - | 57 | ||
| 51 | movw $0x8000,%bx # at %es:%bx |
58 | int $0x13 # reset floppy |
| 52 | int $0x13 |
- | |
| 53 | jc stop_trying |
59 | jc stop_trying |
| 54 | 60 | ||
| 55 | pushw $('.') |
- | |
| 56 | call echo_mark |
- | |
| 57 | add $2,%sp |
- | |
| 58 | - | ||
| 59 | movw %dx,%ds |
61 | movw %dx,%ds |
| - | 62 | movw %dx,%ss |
|
| - | 63 | movw $0x7c00,%sp |
|
| - | 64 | movw $0xffe0,%si # after next increment, %si will become 0x0000 |
|
| - | 65 | movw %si,%es |
|
| - | 66 | movw $0x8000,%bx # at %es:%bx |
|
| 60 | 67 | ||
| 61 | # KERNEL_SIZE is passed from the outside to the preprocessor |
- | |
| 62 | movl $(KERNEL_SIZE),%edi |
68 | movl $(SECTORS),%edi |
| 63 | 69 | ||
| 64 | shrl $9,%edi # number of sectors that kernel occupies (%edi div 512) |
- | |
| 65 | - | ||
| 66 | read_next: |
70 | read_next: |
| 67 | test %edi,%edi |
71 | test %edi,%edi |
| 68 | jnz read_sectors |
72 | jnz read_sectors |
| 69 | 73 | ||
| 70 | movb $12,%al |
74 | movb $12,%al |
| 71 | movw $0x3f2,%dx |
75 | movw $0x3f2,%dx |
| 72 | outb %al,%dx |
76 | outb %al,%dx |
| 73 | 77 | ||
| 74 | pushw $('$') |
78 | movb $('$'),%al |
| 75 | call echo_mark |
79 | call echo_mark |
| 76 | add $2,%sp |
- | |
| 77 | 80 | ||
| 78 | jmpl $0,$0x8000 |
81 | jmpl $0,$0x8000 |
| 79 | 82 | ||
| 80 | read_sectors: |
83 | read_sectors: |
| 81 | pushw $('.') |
84 | movb $('.'),%al |
| 82 | call echo_mark |
85 | call echo_mark |
| 83 | add $2,%sp |
- | |
| 84 | 86 | ||
| 85 | decl %edi |
87 | decl %edi |
| 86 | incw logical_sector |
88 | incw logical_sector |
| 87 | movw %es,%si |
89 | movw %es,%si |
| 88 | addw $0x20,%si |
90 | addw $0x20,%si |
| 89 | movw %si,%es |
91 | movw %si,%es |
| 90 | 92 | ||
| 91 | movw logical_sector,%ax |
93 | movw logical_sector,%ax |
| 92 | divb sectors |
94 | divb sectors |
| 93 | 95 | ||
| 94 | movb %ah,%cl |
96 | movb %ah,%cl |
| 95 | incb %cl # sector |
97 | incb %cl # sector |
| 96 | 98 | ||
| 97 | movb %al,%ch |
99 | movb %al,%ch |
| 98 | shrb $1,%ch # track |
100 | shrb $1,%ch # track |
| 99 | 101 | ||
| 100 | movb %al,%dh |
102 | movb %al,%dh |
| 101 | andb $1,%dh # head |
103 | andb $1,%dh # head |
| 102 | 104 | ||
| 103 | movw $0x0201,%ax |
105 | movw $0x0201,%ax |
| 104 | int $0x13 |
106 | int $0x13 |
| 105 | jnc read_next |
107 | jnc read_next |
| 106 | 108 | ||
| 107 | pushw $('R') |
109 | movb $('R'),%al |
| 108 | call echo_mark |
110 | call echo_mark |
| 109 | add $2,%sp |
- | |
| 110 | 111 | ||
| 111 | xorw %ax,%ax # try to reset |
112 | xorw %ax,%ax # try to reset |
| 112 | movw %ax,%dx # fd0 |
113 | movw %ax,%dx # fd0 |
| 113 | int $0x13 |
114 | int $0x13 |
| 114 | jnc read_next |
115 | jnc read_next |
| 115 | 116 | ||
| 116 | stop_trying: |
117 | stop_trying: |
| 117 | pushw $('F') |
118 | movb $('F'),%al |
| 118 | call echo_mark |
119 | call echo_mark |
| 119 | add $2,%sp |
- | |
| 120 | 120 | ||
| 121 | cli |
121 | cli |
| 122 | hlt |
122 | hlt |
| 123 | 123 | ||
| 124 | CH=4 |
124 | CH=4 |
| 125 | echo_mark: |
125 | echo_mark: |
| 126 | push %bp |
126 | push %bp |
| 127 | movw %sp,%bp |
127 | movw %sp,%bp |
| 128 | pusha |
128 | pusha |
| 129 | 129 | ||
| 130 | movw CH(%bp),%ax |
- | |
| 131 | movb $0xe,%ah |
130 | movb $0xe,%ah |
| 132 | movb $7,%bl |
131 | movb $7,%bl |
| 133 | int $0x10 |
132 | int $0x10 |
| 134 | 133 | ||
| 135 | popa |
134 | popa |
| 136 | pop %bp |
135 | pop %bp |
| 137 | ret |
136 | ret |
| 138 | 137 | ||
| 139 | # current logical sector from the beginning of the disk |
138 | # current logical sector from the beginning of the disk |
| 140 | logical_sector: |
139 | logical_sector: |
| 141 | .word 1 |
140 | .word 0 |
| 142 | 141 | ||
| 143 | # number of sectors per track on 1440 floppy |
142 | # number of sectors per track on 1440 floppy |
| 144 | sectors: |
143 | sectors: |
| 145 | .byte 18 |
144 | .byte 18 |
| 146 | 145 | ||
| 147 | - | ||
| 148 | # boot floppy signature |
146 | # boot floppy signature |
| 149 | .org 0x1fe |
147 | .org 0x1fe |
| 150 | boot_floppy_signature: |
148 | boot_floppy_signature: |
| 151 | .byte 0x55 |
149 | .byte 0x55 |
| 152 | .byte 0xaa |
150 | .byte 0xaa |
| - | 151 | stack: |
|
| 153 | 152 | ||