--- /dev/null
+/*
+ * Copyright (C) 1984-2011 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 about less, or for information on how to
+ * contact the author, 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);
+}
projects / apitrace / blobdiff