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;
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;
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; rmod - resident module of the SvarCOM command interpreter
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; rmod - resident module of the SvarCOM command interpreter (NASM code)
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;
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;
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; Copyright (C) 2021 Mateusz Viste
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; Copyright (C) 2021 Mateusz Viste
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; MIT license
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; MIT license
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;
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;
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; this is installed in memory by the transient part of SvarCOM. it has only
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; this is installed in memory by the transient part of SvarCOM. it has only
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; needs to be redirected (0xffff=no redirection)
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; needs to be redirected (0xffff=no redirection)
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REDIR_OUTFIL dw 0xffff    ; +EAh
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REDIR_OUTFIL dw 0xffff    ; +EAh
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REDIR_INFIL dw 0xffff     ; +ECh
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REDIR_INFIL dw 0xffff     ; +ECh
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REDIR_OUTAPPEND dw 0      ; +EEh
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REDIR_OUTAPPEND dw 0      ; +EEh
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; CTRL+BREAK (int 23h) handler
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; According to the TechHelp! Manual: "If you want to abort (exit to the parent
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; process), then set the carry flag and return via a FAR RET. This causes DOS
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; to perform normal cleanup and exit to the parent." (otherwise use iret)
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BREAK_HANDLER:            ; +F0h
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stc
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retf
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skipsig:         ; +F0h
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skipsig:                  ; +F2h
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; set up CS=DS=SS and point SP to my private stack buffer
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; set up CS=DS=SS and point SP to my private stack buffer
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mov ax, cs
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mov ax, cs
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mov ds, ax
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mov ds, ax
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mov es, ax
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mov es, ax
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mov ss, ax
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mov ss, ax
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mov sp, STACKPTR
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mov sp, STACKPTR
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; set up myself as break handler
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mov ax, 0x2523  ; set int vector 23h
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mov dx, BREAK_HANDLER
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int 0x21
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; revert stdin/stdout redirections (if any) to their initial state
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; revert stdin/stdout redirections (if any) to their initial state
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call REVERT_REDIR_IF_ANY
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call REVERT_REDIR_IF_ANY
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; redirect stdout if required
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; redirect stdout if required
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call REDIR_OUTFILE_IF_REQUIRED
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call REDIR_OUTFILE_IF_REQUIRED