--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/miscellany/less-177/screen.c	Mon Apr 18 23:46:02 2005 +0900
@@ -0,0 +1,704 @@
+/*
+ * Routines which deal with the characteristics of the terminal.
+ * Uses termcap to be as terminal-independent as possible.
+ *
+ * {{ Someday this should be rewritten to use curses. }}
+ */
+
+#include "less.h"
+#if XENIX
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#endif
+
+#if TERMIO
+#include <termio.h>
+#else
+#include <sgtty.h>
+#endif
+
+#if !TERMIO && defined(TIOCGWINSZ)
+#include <sys/ioctl.h>
+#else
+/*
+ * For the Unix PC (ATT 7300 & 3B1):
+ * Since WIOCGETD is defined in sys/window.h, we can't use that to decide
+ * whether to include sys/window.h.  Use SIGPHONE from signal.h instead.
+ */
+#include <signal.h>
+#ifdef SIGPHONE
+#include <sys/window.h>
+#endif
+#endif
+
+#if NEED_PTEM_H && defined(TIOCGWINSZ)
+/*
+ * All this just to get struct winsize.  Sigh.
+ */
+#include <sys/types.h>
+#include <sys/stream.h>
+#include <sys/ptem.h>
+#endif
+
+/*
+ * Strings passed to tputs() to do various terminal functions.
+ */
+static char
+	*sc_pad,		/* Pad string */
+	*sc_home,		/* Cursor home */
+	*sc_addline,		/* Add line, scroll down following lines */
+	*sc_lower_left,		/* Cursor to last line, first column */
+	*sc_move,		/* General cursor positioning */
+	*sc_clear,		/* Clear screen */
+	*sc_eol_clear,		/* Clear to end of line */
+	*sc_s_in,		/* Enter standout (highlighted) mode */
+	*sc_s_out,		/* Exit standout mode */
+	*sc_u_in,		/* Enter underline mode */
+	*sc_u_out,		/* Exit underline mode */
+	*sc_b_in,		/* Enter bold mode */
+	*sc_b_out,		/* Exit bold mode */
+	*sc_bl_in,		/* Enter blink mode */
+	*sc_bl_out,		/* Exit blink mode */
+	*sc_visual_bell,	/* Visual bell (flash screen) sequence */
+	*sc_backspace,		/* Backspace cursor */
+	*sc_init,		/* Startup terminal initialization */
+	*sc_deinit;		/* Exit terminal de-initialization */
+
+static int init_done = 0;
+
+public int auto_wrap;		/* Terminal does \r\n when write past margin */
+public int ignaw;		/* Terminal ignores \n immediately after wrap */
+public int erase_char, kill_char; /* The user's erase and line-kill chars */
+public int sc_width, sc_height;	/* Height & width of screen */
+public int bo_s_width, bo_e_width;	/* Printing width of boldface seq */
+public int ul_s_width, ul_e_width;	/* Printing width of underline seq */
+public int so_s_width, so_e_width;	/* Printing width of standout seq */
+public int bl_s_width, bl_e_width;	/* Printing width of blink seq */
+
+static char *cheaper();
+
+/*
+ * These two variables are sometimes defined in,
+ * and needed by, the termcap library.
+ * It may be necessary on some systems to declare them extern here.
+ */
+/*extern*/ short ospeed;	/* Terminal output baud rate */
+/*extern*/ char PC;		/* Pad character */
+
+extern int quiet;		/* If VERY_QUIET, use visual bell for bell */
+extern int know_dumb;		/* Don't complain about a dumb terminal */
+extern int back_scroll;
+extern int swindow;
+extern char *tgetstr();
+extern char *tgoto();
+extern char *getenv();
+
+
+/*
+ * Change terminal to "raw mode", or restore to "normal" mode.
+ * "Raw mode" means 
+ *	1. An outstanding read will complete on receipt of a single keystroke.
+ *	2. Input is not echoed.  
+ *	3. On output, \n is mapped to \r\n.
+ *	4. \t is NOT expanded into spaces.
+ *	5. Signal-causing characters such as ctrl-C (interrupt),
+ *	   etc. are NOT disabled.
+ * It doesn't matter whether an input \n is mapped to \r, or vice versa.
+ */
+	public void
+raw_mode(on)
+	int on;
+{
+	static int curr_on = 0;
+
+	if (on == curr_on)
+		return;
+#if TERMIO
+    {
+	struct termio s;
+	static struct termio save_term;
+
+	if (on)
+	{
+		/*
+		 * Get terminal modes.
+		 */
+		ioctl(2, TCGETA, &s);
+
+		/*
+		 * Save modes and set certain variables dependent on modes.
+		 */
+		save_term = s;
+		ospeed = s.c_cflag & CBAUD;
+		erase_char = s.c_cc[VERASE];
+		kill_char = s.c_cc[VKILL];
+
+		/*
+		 * Set the modes to the way we want them.
+		 */
+		s.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
+		s.c_oflag |=  (OPOST|ONLCR|TAB3);
+		s.c_oflag &= ~(OCRNL|ONOCR|ONLRET);
+		s.c_cc[VMIN] = 1;
+		s.c_cc[VTIME] = 0;
+	} else
+	{
+		/*
+		 * Restore saved modes.
+		 */
+		s = save_term;
+	}
+	ioctl(2, TCSETAW, &s);
+    }
+#else
+    {
+	struct sgttyb s;
+	static struct sgttyb save_term;
+
+	if (on)
+	{
+		/*
+		 * Get terminal modes.
+		 */
+		ioctl(2, TIOCGETP, &s);
+
+		/*
+		 * Save modes and set certain variables dependent on modes.
+		 */
+		save_term = s;
+		ospeed = s.sg_ospeed;
+		erase_char = s.sg_erase;
+		kill_char = s.sg_kill;
+
+		/*
+		 * Set the modes to the way we want them.
+		 */
+		s.sg_flags |= CBREAK;
+		s.sg_flags &= ~(ECHO|XTABS);
+	} else
+	{
+		/*
+		 * Restore saved modes.
+		 */
+		s = save_term;
+	}
+	ioctl(2, TIOCSETN, &s);
+    }
+#endif
+	curr_on = on;
+}
+
+	static void
+cannot(s)
+	char *s;
+{
+	PARG parg;
+
+	if (know_dumb)
+		/* 
+		 * User knows this is a dumb terminal, so don't tell him.
+		 */
+		return;
+
+	parg.p_string = s;
+	error("WARNING: terminal cannot %s", &parg);
+}
+
+/*
+ * Get size of the output screen.
+ */
+	public void
+scrsize(p_height, p_width)
+	int *p_height;
+	int *p_width;
+{
+	register char *s;
+#ifdef TIOCGWINSZ
+	struct winsize w;
+#else
+#ifdef WIOCGETD
+	struct uwdata w;
+#endif
+#endif
+
+#ifdef TIOCGWINSZ
+	if (ioctl(2, TIOCGWINSZ, &w) == 0 && w.ws_row > 0)
+		*p_height = w.ws_row;
+	else
+#else
+#ifdef WIOCGETD
+	if (ioctl(2, WIOCGETD, &w) == 0 && w.uw_height > 0)
+		*p_height = w.uw_height/w.uw_vs;
+	else
+#endif
+#endif
+	if ((s = getenv("LINES")) != NULL)
+		*p_height = atoi(s);
+	else
+ 		*p_height = tgetnum("li");
+
+	if (*p_height <= 0)
+		*p_height = 24;
+
+#ifdef TIOCGWINSZ
+ 	if (ioctl(2, TIOCGWINSZ, &w) == 0 && w.ws_col > 0)
+		*p_width = w.ws_col;
+	else
+#ifdef WIOCGETD
+	if (ioctl(2, WIOCGETD, &w) == 0 && w.uw_width > 0)
+		*p_width = w.uw_width/w.uw_hs;
+	else
+#endif
+#endif
+	if ((s = getenv("COLUMNS")) != NULL)
+		*p_width = atoi(s);
+	else
+ 		*p_width = tgetnum("co");
+
+ 	if (*p_width <= 0)
+  		*p_width = 80;
+}
+
+/*
+ * Get terminal capabilities via termcap.
+ */
+	public void
+get_term()
+{
+	char *sp;
+	register char *t1, *t2;
+	register int hard;
+	char *term;
+	char termbuf[2048];
+
+	static char sbuf[1024];
+
+	/*
+	 * Find out what kind of terminal this is.
+	 */
+ 	if ((term = getenv("TERM")) == NULL)
+ 		term = "unknown";
+ 	if (tgetent(termbuf, term) <= 0)
+ 		strcpy(termbuf, "dumb:hc:");
+
+ 	hard = tgetflag("hc");
+
+	/*
+	 * Get size of the screen.
+	 */
+	scrsize(&sc_height, &sc_width);
+	pos_init();
+	if (swindow < 0)
+		swindow = sc_height - 1;
+
+	auto_wrap = tgetflag("am");
+	ignaw = tgetflag("xn");
+
+	/*
+	 * Assumes termcap variable "sg" is the printing width of:
+	 * the standout sequence, the end standout sequence,
+	 * the underline sequence, the end underline sequence,
+	 * the boldface sequence, and the end boldface sequence.
+	 */
+	if ((so_s_width = tgetnum("sg")) < 0)
+		so_s_width = 0;
+	so_e_width = so_s_width;
+
+	bo_s_width = bo_e_width = so_s_width;
+	ul_s_width = ul_e_width = so_s_width;
+	bl_s_width = bl_e_width = so_s_width;
+
+	/*
+	 * Get various string-valued capabilities.
+	 */
+	sp = sbuf;
+
+	sc_pad = tgetstr("pc", &sp);
+	if (sc_pad != NULL)
+		PC = *sc_pad;
+
+	sc_init = tgetstr("ti", &sp);
+	if (sc_init == NULL)
+		sc_init = "";
+
+	sc_deinit= tgetstr("te", &sp);
+	if (sc_deinit == NULL)
+		sc_deinit = "";
+
+	sc_eol_clear = tgetstr("ce", &sp);
+	if (hard || sc_eol_clear == NULL || *sc_eol_clear == '\0')
+	{
+		cannot("clear to end of line");
+		sc_eol_clear = "";
+	}
+
+	sc_clear = tgetstr("cl", &sp);
+	if (hard || sc_clear == NULL || *sc_clear == '\0')
+	{
+		cannot("clear screen");
+		sc_clear = "\n\n";
+	}
+
+	sc_move = tgetstr("cm", &sp);
+	if (hard || sc_move == NULL || *sc_move == '\0')
+	{
+		/*
+		 * This is not an error here, because we don't 
+		 * always need sc_move.
+		 * We need it only if we don't have home or lower-left.
+		 */
+		sc_move = "";
+	}
+
+	sc_s_in = tgetstr("so", &sp);
+	if (hard || sc_s_in == NULL)
+		sc_s_in = "";
+
+	sc_s_out = tgetstr("se", &sp);
+	if (hard || sc_s_out == NULL)
+		sc_s_out = "";
+
+	sc_u_in = tgetstr("us", &sp);
+	if (hard || sc_u_in == NULL)
+		sc_u_in = sc_s_in;
+
+	sc_u_out = tgetstr("ue", &sp);
+	if (hard || sc_u_out == NULL)
+		sc_u_out = sc_s_out;
+
+	sc_b_in = tgetstr("md", &sp);
+	if (hard || sc_b_in == NULL)
+	{
+		sc_b_in = sc_s_in;
+		sc_b_out = sc_s_out;
+	} else
+	{
+		sc_b_out = tgetstr("me", &sp);
+		if (hard || sc_b_out == NULL)
+			sc_b_out = "";
+	}
+
+	sc_bl_in = tgetstr("mb", &sp);
+	if (hard || sc_bl_in == NULL)
+	{
+		sc_bl_in = sc_s_in;
+		sc_bl_out = sc_s_out;
+	} else
+	{
+		sc_bl_out = sc_b_out;
+	}
+
+	sc_visual_bell = tgetstr("vb", &sp);
+	if (hard || sc_visual_bell == NULL)
+		sc_visual_bell = "";
+
+	if (tgetflag("bs"))
+		sc_backspace = "\b";
+	else
+	{
+		sc_backspace = tgetstr("bc", &sp);
+		if (sc_backspace == NULL || *sc_backspace == '\0')
+			sc_backspace = "\b";
+	}
+
+	/*
+	 * Choose between using "ho" and "cm" ("home" and "cursor move")
+	 * to move the cursor to the upper left corner of the screen.
+	 */
+	t1 = tgetstr("ho", &sp);
+	if (hard || t1 == NULL)
+		t1 = "";
+	if (*sc_move == '\0')
+		t2 = "";
+	else
+	{
+		strcpy(sp, tgoto(sc_move, 0, 0));
+		t2 = sp;
+		sp += strlen(sp) + 1;
+	}
+	sc_home = cheaper(t1, t2, "home cursor", "|\b^");
+
+	/*
+	 * Choose between using "ll" and "cm"  ("lower left" and "cursor move")
+	 * to move the cursor to the lower left corner of the screen.
+	 */
+	t1 = tgetstr("ll", &sp);
+	if (hard || t1 == NULL)
+		t1 = "";
+	if (*sc_move == '\0')
+		t2 = "";
+	else
+	{
+		strcpy(sp, tgoto(sc_move, 0, sc_height-1));
+		t2 = sp;
+		sp += strlen(sp) + 1;
+	}
+	sc_lower_left = cheaper(t1, t2,
+		"move cursor to lower left of screen", "\r");
+
+	/*
+	 * Choose between using "al" or "sr" ("add line" or "scroll reverse")
+	 * to add a line at the top of the screen.
+	 */
+	t1 = tgetstr("al", &sp);
+	if (hard || t1 == NULL)
+		t1 = "";
+	t2 = tgetstr("sr", &sp);
+	if (hard || t2 == NULL)
+		t2 = "";
+	sc_addline = cheaper(t1, t2, "scroll backwards", "");
+	if (*sc_addline == '\0')
+	{
+		/*
+		 * Force repaint on any backward movement.
+		 */
+		back_scroll = 0;
+	}
+}
+
+/*
+ * Return the cost of displaying a termcap string.
+ * We use the trick of calling tputs, but as a char printing function
+ * we give it inc_costcount, which just increments "costcount".
+ * This tells us how many chars would be printed by using this string.
+ * {{ Couldn't we just use strlen? }}
+ */
+static int costcount;
+
+/*ARGSUSED*/
+	static void
+inc_costcount(c)
+	int c;
+{
+	costcount++;
+}
+
+	static int
+cost(t)
+	char *t;
+{
+	costcount = 0;
+	tputs(t, sc_height, inc_costcount);
+	return (costcount);
+}
+
+/*
+ * Return the "best" of the two given termcap strings.
+ * The best, if both exist, is the one with the lower 
+ * cost (see cost() function).
+ */
+	static char *
+cheaper(t1, t2, doit, def)
+	char *t1, *t2;
+	char *doit;
+	char *def;
+{
+	if (*t1 == '\0' && *t2 == '\0')
+	{
+		cannot(doit);
+		return (def);
+	}
+	if (*t1 == '\0')
+		return (t2);
+	if (*t2 == '\0')
+		return (t1);
+	if (cost(t1) < cost(t2))
+		return (t1);
+	return (t2);
+}
+
+
+/*
+ * Below are the functions which perform all the 
+ * terminal-specific screen manipulation.
+ */
+
+
+/*
+ * Initialize terminal
+ */
+	public void
+init()
+{
+	tputs(sc_init, sc_height, putchr);
+	init_done = 1;
+}
+
+/*
+ * Deinitialize terminal
+ */
+	public void
+deinit()
+{
+	if (!init_done)
+		return;
+	tputs(sc_deinit, sc_height, putchr);
+	init_done = 0;
+}
+
+/*
+ * Home cursor (move to upper left corner of screen).
+ */
+	public void
+home()
+{
+	tputs(sc_home, 1, putchr);
+}
+
+/*
+ * Add a blank line (called with cursor at home).
+ * Should scroll the display down.
+ */
+	public void
+add_line()
+{
+	tputs(sc_addline, sc_height, putchr);
+}
+
+/*
+ * Move cursor to lower left corner of screen.
+ */
+	public void
+lower_left()
+{
+	tputs(sc_lower_left, 1, putchr);
+}
+
+/*
+ * Ring the terminal bell.
+ */
+	public void
+bell()
+{
+	if (quiet == VERY_QUIET)
+		vbell();
+	else
+		putchr('\7');
+}
+
+/*
+ * Output the "visual bell", if there is one.
+ */
+	public void
+vbell()
+{
+	if (*sc_visual_bell == '\0')
+		return;
+	tputs(sc_visual_bell, sc_height, putchr);
+}
+
+/*
+ * Clear the screen.
+ */
+	public void
+clear()
+{
+	tputs(sc_clear, sc_height, putchr);
+}
+
+/*
+ * Clear from the cursor to the end of the cursor's line.
+ * {{ This must not move the cursor. }}
+ */
+	public void
+clear_eol()
+{
+	tputs(sc_eol_clear, 1, putchr);
+}
+
+/*
+ * Begin "standout" (bold, underline, or whatever).
+ */
+	public void
+so_enter()
+{
+	tputs(sc_s_in, 1, putchr);
+}
+
+/*
+ * End "standout".
+ */
+	public void
+so_exit()
+{
+	tputs(sc_s_out, 1, putchr);
+}
+
+/*
+ * Begin "underline" (hopefully real underlining, 
+ * otherwise whatever the terminal provides).
+ */
+	public void
+ul_enter()
+{
+	tputs(sc_u_in, 1, putchr);
+}
+
+/*
+ * End "underline".
+ */
+	public void
+ul_exit()
+{
+	tputs(sc_u_out, 1, putchr);
+}
+
+/*
+ * Begin "bold"
+ */
+	public void
+bo_enter()
+{
+	tputs(sc_b_in, 1, putchr);
+}
+
+/*
+ * End "bold".
+ */
+	public void
+bo_exit()
+{
+	tputs(sc_b_out, 1, putchr);
+}
+
+/*
+ * Begin "blink"
+ */
+	public void
+bl_enter()
+{
+	tputs(sc_bl_in, 1, putchr);
+}
+
+/*
+ * End "blink".
+ */
+	public void
+bl_exit()
+{
+	tputs(sc_bl_out, 1, putchr);
+}
+
+/*
+ * Erase the character to the left of the cursor 
+ * and move the cursor left.
+ */
+	public void
+backspace()
+{
+	/* 
+	 * Try to erase the previous character by overstriking with a space.
+	 */
+	tputs(sc_backspace, 1, putchr);
+	putchr(' ');
+	tputs(sc_backspace, 1, putchr);
+}
+
+/*
+ * Output a plain backspace, without erasing the previous char.
+ */
+	public void
+putbs()
+{
+	tputs(sc_backspace, 1, putchr);
+}