| Line 17... |
Line 17... |
| 17 |
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17 |
|
| 18 |
; offset
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18 |
; offset
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| 19 |
SIG1 dw 0x1983 ; +0
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19 |
SIG1 dw 0x1983 ; +0
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| 20 |
SIG2 dw 0x1985 ; +2
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20 |
SIG2 dw 0x1985 ; +2
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| 21 |
SIG3 dw 0x2017 ; +4
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21 |
SIG3 dw 0x2017 ; +4
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| 22 |
SIG4 dw 0x2019 ; +6
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22 |
SIG4 dw 0x2019 ; +6 this acts also as a guardval to detect stack overflows
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| 23 |
|
23 |
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| - |
|
24 |
; DOS int 21h functions that I use require at least 40 bytes of stack under
|
| - |
|
25 |
; DOS-C (FreeDOS) kernel, so here I reserve 64 bytes juste to be sure
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| - |
|
26 |
STACKBUF db "XXX SVARCOM RMOD BY MATEUSZ VISTE XXXXXXXXXXXXXXXXXXXXXXXXXXXX"
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| 24 |
FFU_UNUSED dw 0 ; +8
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27 |
STACKPTR dw 0
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| 25 |
|
28 |
|
| 26 |
; exit code of last application
|
29 |
; exit code of last application
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| 27 |
LEXCODE dw 0 ; +0Ah
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30 |
LEXCODE dw 0 ; +4Ah
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| 28 |
|
31 |
|
| 29 |
; offset of the COMSPEC variable in the environment block, 0 means "use
|
32 |
; offset of the COMSPEC variable in the environment block, 0 means "use
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| 30 |
; boot drive". this value is patched by the transient part of COMMAND.COM
|
33 |
; boot drive". this value is patched by the transient part of COMMAND.COM
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| 31 |
COMSPECPTR dw 0 ; +0Ch
|
34 |
COMSPECPTR dw 0 ; +4Ch
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| 32 |
|
35 |
|
| 33 |
; fallback COMSPEC string used if no COMPSEC is present in the environment
|
36 |
; fallback COMSPEC string used if no COMPSEC is present in the environment
|
| 34 |
; drive. drive is patched by the transient part of COMMAND.COM
|
37 |
; drive. drive is patched by the transient part of COMMAND.COM
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| 35 |
COMSPECBOOT db "@:\COMMAND.COM", 0 ; +0Eh
|
38 |
COMSPECBOOT db "@:\COMMAND.COM", 0 ; +4Eh
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| 36 |
|
39 |
|
| 37 |
; ExecParamRec used by INT 21h, AX=4b00 (load and execute program), 14 bytes:
|
40 |
; ExecParamRec used by INT 21h, AX=4b00 (load and execute program), 14 bytes:
|
| 38 |
; offset size content
|
41 |
; offset size content
|
| 39 |
; +0 2 segment of environment for child (0 = current)
|
42 |
; +0 2 segment of environment for child (0 = current)
|
| 40 |
; +2 4 address of command line to place at PSP:0080
|
43 |
; +2 4 address of command line to place at PSP:0080
|
| 41 |
; +6 4 address of an FCB to be placed at PSP:005c
|
44 |
; +6 4 address of an FCB to be placed at PSP:005c
|
| 42 |
; +0Ah 4 address of an FCB to be placed at PSP:006c
|
45 |
; +0Ah 4 address of an FCB to be placed at PSP:006c
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| 43 |
EXEC_PARAM_REC db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ; +1Dh
|
46 |
EXEC_PARAM_REC db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ; +5Dh
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| 44 |
|
47 |
|
| 45 |
; Program to execute, preset by SvarCOM (128 bytes, ASCIIZ) ; +2Bh
|
48 |
; Program to execute, preset by SvarCOM (128 bytes, ASCIIZ) ; +6Bh
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| 46 |
EXECPROG dd 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
|
49 |
EXECPROG dd 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
|
| 47 |
|
50 |
|
| 48 |
skipsig: ; +ABh
|
51 |
skipsig: ; +EBh
|
| 49 |
|
52 |
|
| 50 |
; set up CS=DS=SS and point SP to my private stack buffer
|
53 |
; set up CS=DS=SS and point SP to my private stack buffer
|
| 51 |
mov ax, cs
|
54 |
mov ax, cs
|
| 52 |
mov ds, ax
|
55 |
mov ds, ax
|
| 53 |
mov es, ax
|
56 |
mov es, ax
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| Line 143... |
Line 146... |
| 143 |
; called as respawn (as opposed to being invoked as a normal application)
|
146 |
; called as respawn (as opposed to being invoked as a normal application)
|
| 144 |
; this allows multiple copies of SvarCOM to stack upon each other.
|
147 |
; this allows multiple copies of SvarCOM to stack upon each other.
|
| 145 |
CMDTAIL db 0x01, 0x0A, 0x0D
|
148 |
CMDTAIL db 0x01, 0x0A, 0x0D
|
| 146 |
|
149 |
|
| 147 |
ERRLOAD db "ERR x, FAILED TO LOAD COMMAND.COM", 13, 10, '$'
|
150 |
ERRLOAD db "ERR x, FAILED TO LOAD COMMAND.COM", 13, 10, '$'
|
| 148 |
|
- |
|
| 149 |
; DOS int 21h functions that I use require at least 32 bytes of stack, here I
|
- |
|
| 150 |
; allocate 64 bytes to be sure
|
- |
|
| 151 |
STACKBUF db "0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF"
|
- |
|
| 152 |
STACKPTR db "xx"
|
- |
|