scrollback.c revision 50027b5b 
1/* $XTermId: scrollback.c,v 1.23 2022/03/09 00:38:51 tom Exp $ */
2
3/*
4 * Copyright 2009-2020,2022 by Thomas E. Dickey
5 *
6 *                         All Rights Reserved
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a
9 * copy of this software and associated documentation files (the
10 * "Software"), to deal in the Software without restriction, including
11 * without limitation the rights to use, copy, modify, merge, publish,
12 * distribute, sublicense, and/or sell copies of the Software, and to
13 * permit persons to whom the Software is furnished to do so, subject to
14 * the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included
17 * in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
21 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
22 * IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
23 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
24 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
25 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * Except as contained in this notice, the name(s) of the above copyright
28 * holders shall not be used in advertising or otherwise to promote the
29 * sale, use or other dealings in this Software without prior written
30 * authorization.
31 */
32
33#include <xterm.h>
34
35#define REAL_ROW(screen, row) ((row) + (screen)->saved_fifo)
36#define ROW2FIFO(screen, row) \
37	(unsigned) (REAL_ROW(screen, row) % (screen)->savelines)
38
39/*
40 * Given a row-number, find the corresponding data for the line in the VT100
41 * widget's saved-line FIFO.  The row-number (from getLineData) is negative.
42 * So we just count backwards from the last saved line.
43 */
44LineData *
45getScrollback(TScreen *screen, int row)
46{
47    LineData *result = 0;
48
49    if (screen->saved_fifo > 0 && REAL_ROW(screen, row) >= 0) {
50	unsigned which = ROW2FIFO(screen, row);
51	ScrnBuf where = scrnHeadAddr(screen, screen->saveBuf_index, which);
52	result = (LineData *) where;
53    }
54
55    TRACE(("getScrollback %d -> %d -> %p\n",
56	   row, ROW2FIFO(screen, row),
57	   (void *) result));
58    return result;
59}
60
61/*
62 * Allocate a new row in the scrollback FIFO, returning a pointer to it.
63 */
64LineData *
65addScrollback(TScreen *screen)
66{
67    ScrnBuf where = 0;
68    unsigned ncols = (unsigned) MaxCols(screen);
69
70    if (screen->saveBuf_index != 0 && screen->savelines != 0) {
71	unsigned which;
72	Char *block;
73
74	TRACE(("addScrollback %lu\n", screen->saved_fifo));
75
76	/* first, see which index we'll use */
77	which = (unsigned) (screen->saved_fifo % screen->savelines);
78	where = scrnHeadAddr(screen, screen->saveBuf_index, which);
79
80	/* discard any obsolete index data */
81	if (screen->saved_fifo > screen->savelines) {
82	    LineData *prior = (LineData *) where;
83	    /*
84	     * setupLineData uses the attribs as the first address used from the
85	     * data block.
86	     */
87	    if (prior->attribs != 0) {
88		TRACE(("...freeing prior FIFO data in slot %d: %p->%p\n",
89		       which, (void *) prior, (void *) prior->attribs));
90		FreeAndNull(prior->attribs);
91	    }
92	    if (screen->saved_fifo > 2 * screen->savelines) {
93		screen->saved_fifo -= screen->savelines;
94	    }
95	}
96
97	/* allocate the new data */
98	block = allocScrnData(screen, 1, ncols, False);
99
100	/* record the new data in the index */
101	setupLineData(screen, where, (Char *) block, 1, ncols, False);
102
103	TRACE(("...storing new FIFO data in slot %d: %p->%p\n",
104	       which, (void *) where, block));
105
106	screen->saved_fifo++;
107    }
108    return (LineData *) where;
109}
110
111void
112deleteScrollback(TScreen *screen)
113{
114    unsigned which = ROW2FIFO(screen, -1);
115    ScrnBuf where = scrnHeadAddr(screen, screen->saveBuf_index, which);
116    LineData *prior = (LineData *) where;
117    /*
118     * setupLineData uses the attribs as the first address used from the
119     * data block.
120     */
121    if (prior->attribs != 0) {
122	TRACE(("...freeing prior FIFO data in slot %d: %p->%p\n",
123	       which, (void *) prior, (void *) prior->attribs));
124	FreeAndNull(prior->attribs);
125    }
126    screen->saved_fifo--;
127}
128