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libncurses: updated to 6.0
[tomato.git] / release / src / router / libncurses / ncurses / tty / hardscroll.c
blobd6f28d67f97d7a87c1065452724072d41f9105a2
1 /****************************************************************************
2 * Copyright (c) 1998-2012,2015 Free Software Foundation, Inc. *
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12 * The above copyright notice and this permission notice shall be included *
13 * in all copies or substantial portions of the Software. *
14 * *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
16 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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27 ****************************************************************************/
28
29 /****************************************************************************
30 * Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 *
31 * and: Eric S. Raymond <esr@snark.thyrsus.com> *
32 * and: Thomas E. Dickey 1996-on *
33 * and: Alexander V Lukyanov 1997-1998 *
34 ****************************************************************************/
35
36 /******************************************************************************
37
38 NAME
39 hardscroll.c -- hardware-scrolling optimization for ncurses
40
41 SYNOPSIS
42 void _nc_scroll_optimize(void)
43
44 DESCRIPTION
45 OVERVIEW
46
47 This algorithm for computes optimum hardware scrolling to transform an
48 old screen (curscr) into a new screen (newscr) via vertical line moves.
49
50 Because the screen has a `grain' (there are insert/delete/scroll line
51 operations but no insert/delete/scroll column operations), it is efficient
52 break the update algorithm into two pieces: a first stage that does only line
53 moves, optimizing the end product of user-invoked insertions, deletions, and
54 scrolls; and a second phase (corresponding to the present doupdate code in
55 ncurses) that does only line transformations.
56
57 The common case we want hardware scrolling for is to handle line insertions
58 and deletions in screen-oriented text-editors. This two-stage approach will
59 accomplish that at a low computation and code-size cost.
60
61 LINE-MOVE COMPUTATION
62
63 Now, to a discussion of the line-move computation.
64
65 For expository purposes, consider the screen lines to be represented by
66 integers 0..23 (with the understanding that the value of 23 may vary).
67 Let a new line introduced by insertion, scrolling, or at the bottom of
68 the screen following a line delete be given the index -1.
69
70 Assume that the real screen starts with lines 0..23. Now, we have
71 the following possible line-oriented operations on the screen:
72
73 Insertion: inserts a line at a given screen row, forcing all lines below
74 to scroll forward. The last screen line is lost. For example, an insertion
75 at line 5 would produce: 0..4 -1 5..23.
76
77 Deletion: deletes a line at a given screen row, forcing all lines below
78 to scroll forward. The last screen line is made new. For example, a deletion
79 at line 7 would produce: 0..6 8..23 -1.
80
81 Scroll up: move a range of lines up 1. The bottom line of the range
82 becomes new. For example, scrolling up the region from 9 to 14 will
83 produce 0..8 10..14 -1 15..23.
84
85 Scroll down: move a range of lines down 1. The top line of the range
86 becomes new. For example, scrolling down the region from 12 to 16 will produce
87 0..11 -1 12..15 17..23.
88
89 Now, an obvious property of all these operations is that they preserve the
90 order of old lines, though not their position in the sequence.
91
92 The key trick of this algorithm is that the original line indices described
93 above are actually maintained as _line[].oldindex fields in the window
94 structure, and stick to each line through scroll and insert/delete operations.
95
96 Thus, it is possible at update time to look at the oldnum fields and compute
97 an optimal set of il/dl/scroll operations that will take the real screen
98 lines to the virtual screen lines. Once these vertical moves have been done,
99 we can hand off to the second stage of the update algorithm, which does line
100 transformations.
101
102 Note that the move computation does not need to have the full generality
103 of a diff algorithm (which it superficially resembles) because lines cannot
104 be moved out of order.
105
106 THE ALGORITHM
107
108 The scrolling is done in two passes. The first pass is from top to bottom
109 scroling hunks UP. The second one is from bottom to top scrolling hunks DOWN.
110 Obviously enough, no lines to be scrolled will be destroyed. (lav)
111
112 HOW TO TEST THIS:
113
114 Use the following production:
115
116 hardscroll: hardscroll.c
117 $(CC) -g -DSCROLLDEBUG hardscroll.c -o hardscroll
118
119 Then just type scramble vectors and watch. The following test loads are
120 a representative sample of cases:
121
122 ----------------------------- CUT HERE ------------------------------------
123 # No lines moved
124 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
125 #
126 # A scroll up
127 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 -1
128 #
129 # A scroll down
130 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
131 #
132 # An insertion (after line 12)
133 0 1 2 3 4 5 6 7 8 9 10 11 12 -1 13 14 15 16 17 18 19 20 21 22
134 #
135 # A simple deletion (line 10)
136 0 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 20 21 22 23 -1
137 #
138 # A more complex case
139 -1 -1 -1 -1 -1 3 4 5 6 7 -1 -1 8 9 10 11 12 13 14 15 16 17 -1 -1
140 ----------------------------- CUT HERE ------------------------------------
141
142 AUTHOR
143 Eric S. Raymond <esr@snark.thyrsus.com>, November 1994
144 New algorithm by Alexander V. Lukyanov <lav@yars.free.net>, Aug 1997
145
146 *****************************************************************************/
147
148 #include <curses.priv.h>
149
150 MODULE_ID("$Id: hardscroll.c,v 1.52 2015/07/25 20:13:07 tom Exp $")
151
152 #if defined(SCROLLDEBUG) || defined(HASHDEBUG)
153
154 # undef screen_lines
155 # define screen_lines(sp) MAXLINES
156 NCURSES_EXPORT_VAR (int)
157 oldnums[MAXLINES];
158 # define OLDNUM(sp,n) oldnums[n]
159 # define _tracef printf
160 # undef TR
161 # define TR(n, a) if (_nc_tracing & (n)) { _tracef a ; putchar('\n'); }
162
163 extern NCURSES_EXPORT_VAR(unsigned) _nc_tracing;
164
165 #else /* no debug */
166
167 /* OLDNUM(n) indicates which line will be shifted to the position n.
168 if OLDNUM(n) == _NEWINDEX, then the line n in new, not shifted from
169 somewhere. */
170 NCURSES_EXPORT_VAR (int *)
171 _nc_oldnums = 0; /* obsolete: keep for ABI compat */
172
173 # if USE_HASHMAP
174 # define oldnums(sp) (sp)->_oldnum_list
175 # define OLDNUM(sp,n) oldnums(sp)[n]
176 # else /* !USE_HASHMAP */
177 # define OLDNUM(sp,n) NewScreen(sp)->_line[n].oldindex
178 # endif /* !USE_HASHMAP */
179
180 #define OLDNUM_SIZE(sp) (sp)->_oldnum_size
181
182 #endif /* defined(SCROLLDEBUG) || defined(HASHDEBUG) */
183
184 NCURSES_EXPORT(void)
185 NCURSES_SP_NAME(_nc_scroll_optimize) (NCURSES_SP_DCL0)
186 /* scroll optimization to transform curscr to newscr */
187 {
188 int i;
189 int start, end, shift;
190
191 TR(TRACE_ICALLS, (T_CALLED("_nc_scroll_optimize(%p)"), (void *) SP_PARM));
192
193 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG)
194 #if USE_HASHMAP
195 /* get enough storage */
196 assert(OLDNUM_SIZE(SP_PARM) >= 0);
197 assert(screen_lines(SP_PARM) > 0);
198 if ((oldnums(SP_PARM) == 0)
199 || (OLDNUM_SIZE(SP_PARM) < screen_lines(SP_PARM))) {
200 int need_lines = ((OLDNUM_SIZE(SP_PARM) < screen_lines(SP_PARM))
201 ? screen_lines(SP_PARM)
202 : OLDNUM_SIZE(SP_PARM));
203 int *new_oldnums = typeRealloc(int,
204 (size_t) need_lines,
205 oldnums(SP_PARM));
206 if (!new_oldnums)
207 return;
208 oldnums(SP_PARM) = new_oldnums;
209 OLDNUM_SIZE(SP_PARM) = need_lines;
210 }
211 /* calculate the indices */
212 NCURSES_SP_NAME(_nc_hash_map) (NCURSES_SP_ARG);
213 #endif
214 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */
215
216 #ifdef TRACE
217 if (USE_TRACEF(TRACE_UPDATE | TRACE_MOVE)) {
218 NCURSES_SP_NAME(_nc_linedump) (NCURSES_SP_ARG);
219 _nc_unlock_global(tracef);
220 }
221 #endif /* TRACE */
222
223 /* pass 1 - from top to bottom scrolling up */
224 for (i = 0; i < screen_lines(SP_PARM);) {
225 while (i < screen_lines(SP_PARM)
226 && (OLDNUM(SP_PARM, i) == _NEWINDEX || OLDNUM(SP_PARM, i) <= i))
227 i++;
228 if (i >= screen_lines(SP_PARM))
229 break;
230
231 shift = OLDNUM(SP_PARM, i) - i; /* shift > 0 */
232 start = i;
233
234 i++;
235 while (i < screen_lines(SP_PARM)
236 && OLDNUM(SP_PARM, i) != _NEWINDEX
237 && OLDNUM(SP_PARM, i) - i == shift)
238 i++;
239 end = i - 1 + shift;
240
241 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift));
242 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG)
243 if (NCURSES_SP_NAME(_nc_scrolln) (NCURSES_SP_ARGx
244 shift,
245 start,
246 end,
247 screen_lines(SP_PARM) - 1) == ERR) {
248 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll"));
249 continue;
250 }
251 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */
252 }
253
254 /* pass 2 - from bottom to top scrolling down */
255 for (i = screen_lines(SP_PARM) - 1; i >= 0;) {
256 while (i >= 0
257 && (OLDNUM(SP_PARM, i) == _NEWINDEX
258 || OLDNUM(SP_PARM, i) >= i)) {
259 i--;
260 }
261 if (i < 0)
262 break;
263
264 shift = OLDNUM(SP_PARM, i) - i; /* shift < 0 */
265 end = i;
266
267 i--;
268 while (i >= 0
269 && OLDNUM(SP_PARM, i) != _NEWINDEX
270 && OLDNUM(SP_PARM, i) - i == shift) {
271 i--;
272 }
273 start = i + 1 - (-shift);
274
275 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift));
276 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG)
277 if (NCURSES_SP_NAME(_nc_scrolln) (NCURSES_SP_ARGx
278 shift,
279 start,
280 end,
281 screen_lines(SP_PARM) - 1) == ERR) {
282 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll"));
283 continue;
284 }
285 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */
286 }
287 TR(TRACE_ICALLS, (T_RETURN("")));
288 }
289
290 #if NCURSES_SP_FUNCS
291 NCURSES_EXPORT(void)
292 _nc_scroll_optimize(void)
293 {
294 NCURSES_SP_NAME(_nc_scroll_optimize) (CURRENT_SCREEN);
295 }
296 #endif
297
298 #if defined(TRACE) || defined(SCROLLDEBUG) || defined(HASHDEBUG)
299 NCURSES_EXPORT(void)
300 NCURSES_SP_NAME(_nc_linedump) (NCURSES_SP_DCL0)
301 /* dump the state of the real and virtual oldnum fields */
302 {
303 int n;
304 char *buf = 0;
305 size_t want = ((size_t) screen_lines(SP_PARM) + 1) * 4;
306 (void) SP_PARM;
307
308 if ((buf = typeMalloc(char, want)) != 0) {
309
310 *buf = '\0';
311 for (n = 0; n < screen_lines(SP_PARM); n++)
312 _nc_SPRINTF(buf + strlen(buf),
313 _nc_SLIMIT(want - strlen(buf))
314 " %02d", OLDNUM(SP_PARM, n));
315 TR(TRACE_UPDATE | TRACE_MOVE, ("virt %s", buf));
316 free(buf);
317 }
318 }
319
320 #if NCURSES_SP_FUNCS
321 NCURSES_EXPORT(void)
322 _nc_linedump(void)
323 {
324 NCURSES_SP_NAME(_nc_linedump) (CURRENT_SCREEN);
325 }
326 #endif
327
328 #endif /* defined(TRACE) || defined(SCROLLDEBUG) */
329
330 #ifdef SCROLLDEBUG
331
332 int
333 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED)
334 {
335 char line[BUFSIZ], *st;
336
337 #ifdef TRACE
338 _nc_tracing = TRACE_MOVE;
339 #endif
340 for (;;) {
341 int n;
342
343 for (n = 0; n < screen_lines(sp); n++)
344 oldnums[n] = _NEWINDEX;
345
346 /* grab the test vector */
347 if (fgets(line, sizeof(line), stdin) == (char *) NULL)
348 exit(EXIT_SUCCESS);
349
350 /* parse it */
351 n = 0;
352 if (line[0] == '#') {
353 (void) fputs(line, stderr);
354 continue;
355 }
356 st = strtok(line, " ");
357 do {
358 oldnums[n++] = atoi(st);
359 } while
360 ((st = strtok((char *) NULL, " ")) != 0);
361
362 /* display it */
363 (void) fputs("Initial input:\n", stderr);
364 _nc_linedump();
365
366 _nc_scroll_optimize();
367 }
368 }
369
370 #endif /* SCROLLDEBUG */
371
372 /* hardscroll.c ends here */
Tomato firmware and modifications.