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Diffstat (limited to 'usr.bin/more/position.c')
| -rw-r--r-- | usr.bin/more/position.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/usr.bin/more/position.c b/usr.bin/more/position.c new file mode 100644 index 0000000..8564be0 --- /dev/null +++ b/usr.bin/more/position.c @@ -0,0 +1,163 @@ +/* + * Copyright (c) 1988 Mark Nudleman + * Copyright (c) 1988, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef lint +static char sccsid[] = "@(#)position.c 8.1 (Berkeley) 6/6/93"; +#endif /* not lint */ + +/* + * Routines dealing with the "position" table. + * This is a table which tells the position (in the input file) of the + * first char on each currently displayed line. + * + * {{ The position table is scrolled by moving all the entries. + * Would be better to have a circular table + * and just change a couple of pointers. }} + */ + +#include <sys/types.h> +#include <less.h> + +static off_t *table; /* The position table */ +static int tablesize; + +extern int sc_height; + +/* + * Return the starting file position of a line displayed on the screen. + * The line may be specified as a line number relative to the top + * of the screen, but is usually one of these special cases: + * the top (first) line on the screen + * the second line on the screen + * the bottom line on the screen + * the line after the bottom line on the screen + */ +off_t +position(where) + int where; +{ + switch (where) + { + case BOTTOM: + where = sc_height - 2; + break; + case BOTTOM_PLUS_ONE: + where = sc_height - 1; + break; + case MIDDLE: + where = sc_height / 2; + } + return (table[where]); +} + +/* + * Add a new file position to the bottom of the position table. + */ +add_forw_pos(pos) + off_t pos; +{ + register int i; + + /* + * Scroll the position table up. + */ + for (i = 1; i < sc_height; i++) + table[i-1] = table[i]; + table[sc_height - 1] = pos; +} + +/* + * Add a new file position to the top of the position table. + */ +add_back_pos(pos) + off_t pos; +{ + register int i; + + /* + * Scroll the position table down. + */ + for (i = sc_height - 1; i > 0; i--) + table[i] = table[i-1]; + table[0] = pos; +} + +copytable() +{ + register int a, b; + + for (a = 0; a < sc_height && table[a] == NULL_POSITION; a++); + for (b = 0; a < sc_height; a++, b++) { + table[b] = table[a]; + table[a] = NULL_POSITION; + } +} + +/* + * Initialize the position table, done whenever we clear the screen. + */ +pos_clear() +{ + register int i; + extern char *malloc(), *realloc(); + + if (table == 0) { + tablesize = sc_height > 25 ? sc_height : 25; + table = (off_t *)malloc(tablesize * sizeof *table); + } else if (sc_height >= tablesize) { + tablesize = sc_height; + table = (off_t *)realloc(table, tablesize * sizeof *table); + } + + for (i = 0; i < sc_height; i++) + table[i] = NULL_POSITION; +} + +/* + * See if the byte at a specified position is currently on the screen. + * Check the position table to see if the position falls within its range. + * Return the position table entry if found, -1 if not. + */ +onscreen(pos) + off_t pos; +{ + register int i; + + if (pos < table[0]) + return (-1); + for (i = 1; i < sc_height; i++) + if (pos < table[i]) + return (i-1); + return (-1); +} |
