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mateuszvis |
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/* This file is part of the SvarCOM project and is published under the terms
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* of the MIT license.
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*
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mateusz.vi |
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* Copyright (C) 2021-2022 Mateusz Viste
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mateuszvis |
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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mateuszvis |
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/*
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* cls
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*/
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mateuszvis |
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static enum cmd_result cmd_cls(struct cmd_funcparam *p) {
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unsigned char screenw, screenh;
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const char *ansiesc = "\x1B[2J$";
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if (cmd_ishlp(p)) {
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mateusz.vi |
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nls_outputnl(10,0); /* "Clears the screen" */
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outputnl("");
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outputnl("CLS");
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mateuszvis |
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return(CMD_OK);
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}
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screenw = screen_getwidth();
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screenh = screen_getheight();
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_asm {
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/* output an ANSI ESC code for "clear screen" in case the console is
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* some kind of terminal */
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mov ah, 0x09 /* write $-terminated string to stdout */
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mov dx, ansiesc
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int 0x21
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/* check what stdout is set to */
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mov ax, 0x4400 /* IOCTL query device/flags flags */
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mov bx, 1 /* file handle (1 = stdout) */
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int 0x21 /* CF set on error, otherwise DX set with flags */
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jc DONE /* abort on error */
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/* DX = 10000010
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| |||
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| ||+--- indicates standard output
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| |+---- set if NUL device
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| +----- set if CLOCK device
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+--------- set if handle is a device (ie. not a file)
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in other words, DL & 10001110 (8Eh) should result in 10000010 (82h)
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*/
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and dl, 0x8e
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cmp dl, 0x82
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jne DONE /* abort on error */
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/* scroll vram out of screen */
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mov ax, 0x0600 /* scroll up entire rectangle */
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mov bh, 0x07 /* fill screen with white-on-black */
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xor cx, cx /* upper left location in CH,CL (0,0) */
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/* DX is bottom right location of rectangle (DH=row, DL=column) */
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mov dh, [screenh]
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dec dh
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mov dl, [screenw]
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dec dl
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int 0x10
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/* set cursor to top left corner (0,0) of the screen */
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mov ah, 0x02 /* set cursor position */
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xor bh, bh /* page number */
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xor dx, dx /* location in DH,DL */
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int 0x10
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DONE:
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}
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mateuszvis |
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return(CMD_OK);
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mateuszvis |
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}
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