From 09a405d8f652b56944c93ebf5c673cdfe5319b04 Mon Sep 17 00:00:00 2001 From: Lorry Tar Creator Date: Sat, 21 Jul 2012 20:40:00 +0000 Subject: Imported from /srv/lorry/lorry-area/less/less-451.tar.gz. --- position.c | 231 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) create mode 100755 position.c (limited to 'position.c') diff --git a/position.c b/position.c new file mode 100755 index 0000000..9518307 --- /dev/null +++ b/position.c @@ -0,0 +1,231 @@ +/* + * Copyright (C) 1984-2012 Mark Nudelman + * + * You may distribute under the terms of either the GNU General Public + * License or the Less License, as specified in the README file. + * + * For more information, see the README file. + */ + + +/* + * 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 "less.h" +#include "position.h" + +static POSITION *table = NULL; /* The position table */ +static int table_size; + +extern int sc_width, 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 + */ + public POSITION +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 - 1) / 2; + } + return (table[where]); +} + +/* + * Add a new file position to the bottom of the position table. + */ + public void +add_forw_pos(pos) + POSITION 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. + */ + public void +add_back_pos(pos) + POSITION 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; +} + +/* + * Initialize the position table, done whenever we clear the screen. + */ + public void +pos_clear() +{ + register int i; + + for (i = 0; i < sc_height; i++) + table[i] = NULL_POSITION; +} + +/* + * Allocate or reallocate the position table. + */ + public void +pos_init() +{ + struct scrpos scrpos; + + if (sc_height <= table_size) + return; + /* + * If we already have a table, remember the first line in it + * before we free it, so we can copy that line to the new table. + */ + if (table != NULL) + { + get_scrpos(&scrpos); + free((char*)table); + } else + scrpos.pos = NULL_POSITION; + table = (POSITION *) ecalloc(sc_height, sizeof(POSITION)); + table_size = sc_height; + pos_clear(); + if (scrpos.pos != NULL_POSITION) + table[scrpos.ln-1] = scrpos.pos; +} + +/* + * 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. + */ + public int +onscreen(pos) + POSITION 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); +} + +/* + * See if the entire screen is empty. + */ + public int +empty_screen() +{ + return (empty_lines(0, sc_height-1)); +} + + public int +empty_lines(s, e) + int s; + int e; +{ + register int i; + + for (i = s; i <= e; i++) + if (table[i] != NULL_POSITION) + return (0); + return (1); +} + +/* + * Get the current screen position. + * The screen position consists of both a file position and + * a screen line number where the file position is placed on the screen. + * Normally the screen line number is 0, but if we are positioned + * such that the top few lines are empty, we may have to set + * the screen line to a number > 0. + */ + public void +get_scrpos(scrpos) + struct scrpos *scrpos; +{ + register int i; + + /* + * Find the first line on the screen which has something on it, + * and return the screen line number and the file position. + */ + for (i = 0; i < sc_height; i++) + if (table[i] != NULL_POSITION) + { + scrpos->ln = i+1; + scrpos->pos = table[i]; + return; + } + /* + * The screen is empty. + */ + scrpos->pos = NULL_POSITION; +} + +/* + * Adjust a screen line number to be a simple positive integer + * in the range { 0 .. sc_height-2 }. + * (The bottom line, sc_height-1, is reserved for prompts, etc.) + * The given "sline" may be in the range { 1 .. sc_height-1 } + * to refer to lines relative to the top of the screen (starting from 1), + * or it may be in { -1 .. -(sc_height-1) } to refer to lines + * relative to the bottom of the screen. + */ + public int +adjsline(sline) + int sline; +{ + /* + * Negative screen line number means + * relative to the bottom of the screen. + */ + if (sline < 0) + sline += sc_height; + /* + * Can't be less than 1 or greater than sc_height-1. + */ + if (sline <= 0) + sline = 1; + if (sline >= sc_height) + sline = sc_height - 1; + /* + * Return zero-based line number, not one-based. + */ + return (sline-1); +} -- cgit v1.2.1