102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
/*
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* Copyright (c) 2001
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <types.h>
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#include <lib.h>
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/*
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* Do a backspace in typed input.
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* We overwrite the current character with a space in case we're on
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* a terminal where backspace is nondestructive.
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*/
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static void backsp(void) {
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putch('\b');
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putch(' ');
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putch('\b');
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}
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/*
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* Read a string off the console. Support a few of the more useful
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* common control characters. Do not include the terminating newline
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* in the buffer passed back.
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*/
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void kgets(char *buf, size_t maxlen) {
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size_t pos = 0;
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int ch;
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while (1) {
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ch = getch();
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if (ch == '\n' || ch == '\r') {
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putch('\n');
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break;
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}
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/* Only allow the normal 7-bit ascii */
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if (ch >= 32 && ch < 127 && pos < maxlen - 1) {
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putch(ch);
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buf[pos++] = ch;
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} else if ((ch == '\b' || ch == 127) && pos > 0) {
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/* backspace */
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backsp();
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pos--;
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} else if (ch == 3) {
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/* ^C - return empty string */
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putch('^');
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putch('C');
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putch('\n');
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pos = 0;
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break;
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} else if (ch == 18) {
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/* ^R - reprint input */
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buf[pos] = 0;
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kprintf("^R\n%s", buf);
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} else if (ch == 21) {
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/* ^U - erase line */
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while (pos > 0) {
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backsp();
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pos--;
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}
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} else if (ch == 23) {
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/* ^W - erase word */
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while (pos > 0 && buf[pos - 1] == ' ') {
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backsp();
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pos--;
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}
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while (pos > 0 && buf[pos - 1] != ' ') {
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backsp();
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pos--;
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}
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} else {
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beep();
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}
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}
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buf[pos] = 0;
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}
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