1 /* $NetBSD: position.c,v 1.3 1998/02/04 11:09:05 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1988 Mark Nudleman 5 * Copyright (c) 1988, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 #ifndef lint 39 #if 0 40 static char sccsid[] = "@(#)position.c 8.1 (Berkeley) 6/6/93"; 41 #else 42 __RCSID("$NetBSD: position.c,v 1.3 1998/02/04 11:09:05 christos Exp $"); 43 #endif 44 #endif /* not lint */ 45 46 /* 47 * Routines dealing with the "position" table. 48 * This is a table which tells the position (in the input file) of the 49 * first char on each currently displayed line. 50 * 51 * {{ The position table is scrolled by moving all the entries. 52 * Would be better to have a circular table 53 * and just change a couple of pointers. }} 54 */ 55 56 #include <sys/types.h> 57 #include <stdlib.h> 58 59 #include "less.h" 60 #include "extern.h" 61 62 static off_t *table; /* The position table */ 63 static int tablesize; 64 65 /* 66 * Return the starting file position of a line displayed on the screen. 67 * The line may be specified as a line number relative to the top 68 * of the screen, but is usually one of these special cases: 69 * the top (first) line on the screen 70 * the second line on the screen 71 * the bottom line on the screen 72 * the line after the bottom line on the screen 73 */ 74 off_t 75 position(where) 76 int where; 77 { 78 switch (where) 79 { 80 case BOTTOM: 81 where = sc_height - 2; 82 break; 83 case BOTTOM_PLUS_ONE: 84 where = sc_height - 1; 85 break; 86 case MIDDLE: 87 where = sc_height / 2; 88 } 89 return (table[where]); 90 } 91 92 /* 93 * Add a new file position to the bottom of the position table. 94 */ 95 void 96 add_forw_pos(pos) 97 off_t pos; 98 { 99 int i; 100 101 /* 102 * Scroll the position table up. 103 */ 104 for (i = 1; i < sc_height; i++) 105 table[i-1] = table[i]; 106 table[sc_height - 1] = pos; 107 } 108 109 /* 110 * Add a new file position to the top of the position table. 111 */ 112 void 113 add_back_pos(pos) 114 off_t pos; 115 { 116 int i; 117 118 /* 119 * Scroll the position table down. 120 */ 121 for (i = sc_height - 1; i > 0; i--) 122 table[i] = table[i-1]; 123 table[0] = pos; 124 } 125 126 void 127 copytable() 128 { 129 int a, b; 130 131 for (a = 0; a < sc_height && table[a] == NULL_POSITION; a++); 132 for (b = 0; a < sc_height; a++, b++) { 133 table[b] = table[a]; 134 table[a] = NULL_POSITION; 135 } 136 } 137 138 /* 139 * Initialize the position table, done whenever we clear the screen. 140 */ 141 void 142 pos_clear() 143 { 144 int i; 145 146 if (table == 0) { 147 tablesize = sc_height > 25 ? sc_height : 25; 148 table = (off_t *)malloc(tablesize * sizeof *table); 149 } else if (sc_height >= tablesize) { 150 tablesize = sc_height; 151 table = (off_t *)realloc(table, tablesize * sizeof *table); 152 } 153 154 for (i = 0; i < sc_height; i++) 155 table[i] = NULL_POSITION; 156 } 157 158 /* 159 * See if the byte at a specified position is currently on the screen. 160 * Check the position table to see if the position falls within its range. 161 * Return the position table entry if found, -1 if not. 162 */ 163 int 164 onscreen(pos) 165 off_t pos; 166 { 167 int i; 168 169 if (pos < table[0]) 170 return (-1); 171 for (i = 1; i < sc_height; i++) 172 if (pos < table[i]) 173 return (i-1); 174 return (-1); 175 } 176