/****************************************************************/ /* */ /* break.c */ /* FreeDOS */ /* */ /* Control Break detection and handling */ /* */ /* Copyright (c) 1999 */ /* Steffen Kaiser */ /* All Rights Reserved */ /* */ /* This file is part of DOS-C. */ /* */ /* DOS-C is free software; you can redistribute it and/or */ /* modify it under the terms of the GNU General Public License */ /* as published by the Free Software Foundation; either version */ /* 2, or (at your option) any later version. */ /* */ /* DOS-C is distributed in the hope that it will be useful, but */ /* WITHOUT ANY WARRANTY; without even the implied warranty of */ /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */ /* the GNU General Public License for more details. */ /* */ /* You should have received a copy of the GNU General Public */ /* License along with DOS-C; see the file COPYING. If not, */ /* write to the Free Software Foundation, 675 Mass Ave, */ /* Cambridge, MA 02139, USA. */ /****************************************************************/ #include "portab.h" #include "globals.h" #include "proto.h" #ifdef VERSION_STRINGS static BYTE *RcsId = "$Id: break.c,v 1.17 2004/04/14 15:40:50 bartoldeman Exp $"; #endif #define CB_FLG *(UBYTE FAR*)MK_FP(0x0, 0x471) #define CB_MSK 0x80 /* Check for ^Break/^C. * Three sources are available: * 1) flag at 40:71 bit 7 * 2) syscon stream (usually CON:) * 3) i/o stream (if unequal to syscon, e.g. AUX) */ unsigned char ctrl_break_pressed(void) { return CB_FLG & CB_MSK; } unsigned char check_handle_break(struct dhdr FAR **pdev) { unsigned char c = CTL_C; if (!ctrl_break_pressed()) c = (unsigned char)ndread(&syscon); if (c != CTL_C && *pdev != syscon) c = (unsigned char)ndread(pdev); if (c == CTL_C) handle_break(pdev, -1); return c; } /* * Handles a ^Break state * * Actions: * 1) clear the ^Break flag * 2) clear the STDIN stream * 3) echo ^C to sft_out or pdev if sft_out==-1 * 4) decrease the InDOS flag as the kernel drops back to user space * 5) invoke INT-23 and never come back */ void handle_break(struct dhdr FAR **pdev, int sft_out) { char *buf = "^C\r\n"; CB_FLG &= ~CB_MSK; /* reset the ^Break flag */ con_flush(pdev); if (sft_out == -1) cooked_write(pdev, 4, buf); else DosRWSft(sft_out, 4, buf, XFR_FORCE_WRITE); if (!ErrorMode) /* within int21_handler, InDOS is not incremented */ if (InDOS) --InDOS; /* fail-safe */ spawn_int23(); /* invoke user INT-23 and never come back */ }
