1 /* $OpenBSD: hardscroll.c,v 1.7 2010/01/12 23:22:07 nicm Exp $ */ 2 3 /**************************************************************************** 4 * Copyright (c) 1998-2007,2008 Free Software Foundation, Inc. * 5 * * 6 * Permission is hereby granted, free of charge, to any person obtaining a * 7 * copy of this software and associated documentation files (the * 8 * "Software"), to deal in the Software without restriction, including * 9 * without limitation the rights to use, copy, modify, merge, publish, * 10 * distribute, distribute with modifications, sublicense, and/or sell * 11 * copies of the Software, and to permit persons to whom the Software is * 12 * furnished to do so, subject to the following conditions: * 13 * * 14 * The above copyright notice and this permission notice shall be included * 15 * in all copies or substantial portions of the Software. * 16 * * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * 18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * 19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * 20 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * 21 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * 22 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * 23 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * 24 * * 25 * Except as contained in this notice, the name(s) of the above copyright * 26 * holders shall not be used in advertising or otherwise to promote the * 27 * sale, use or other dealings in this Software without prior written * 28 * authorization. * 29 ****************************************************************************/ 30 31 /**************************************************************************** 32 * Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 * 33 * and: Eric S. Raymond <esr@snark.thyrsus.com> * 34 * and: Thomas E. Dickey 1996-on * 35 * and: Alexander V Lukyanov 1997-1998 * 36 ****************************************************************************/ 37 38 /****************************************************************************** 39 40 NAME 41 hardscroll.c -- hardware-scrolling optimization for ncurses 42 43 SYNOPSIS 44 void _nc_scroll_optimize(void) 45 46 DESCRIPTION 47 OVERVIEW 48 49 This algorithm for computes optimum hardware scrolling to transform an 50 old screen (curscr) into a new screen (newscr) via vertical line moves. 51 52 Because the screen has a `grain' (there are insert/delete/scroll line 53 operations but no insert/delete/scroll column operations), it is efficient 54 break the update algorithm into two pieces: a first stage that does only line 55 moves, optimizing the end product of user-invoked insertions, deletions, and 56 scrolls; and a second phase (corresponding to the present doupdate code in 57 ncurses) that does only line transformations. 58 59 The common case we want hardware scrolling for is to handle line insertions 60 and deletions in screen-oriented text-editors. This two-stage approach will 61 accomplish that at a low computation and code-size cost. 62 63 LINE-MOVE COMPUTATION 64 65 Now, to a discussion of the line-move computation. 66 67 For expository purposes, consider the screen lines to be represented by 68 integers 0..23 (with the understanding that the value of 23 may vary). 69 Let a new line introduced by insertion, scrolling, or at the bottom of 70 the screen following a line delete be given the index -1. 71 72 Assume that the real screen starts with lines 0..23. Now, we have 73 the following possible line-oriented operations on the screen: 74 75 Insertion: inserts a line at a given screen row, forcing all lines below 76 to scroll forward. The last screen line is lost. For example, an insertion 77 at line 5 would produce: 0..4 -1 5..23. 78 79 Deletion: deletes a line at a given screen row, forcing all lines below 80 to scroll forward. The last screen line is made new. For example, a deletion 81 at line 7 would produce: 0..6 8..23 -1. 82 83 Scroll up: move a range of lines up 1. The bottom line of the range 84 becomes new. For example, scrolling up the region from 9 to 14 will 85 produce 0..8 10..14 -1 15..23. 86 87 Scroll down: move a range of lines down 1. The top line of the range 88 becomes new. For example, scrolling down the region from 12 to 16 will produce 89 0..11 -1 12..15 17..23. 90 91 Now, an obvious property of all these operations is that they preserve the 92 order of old lines, though not their position in the sequence. 93 94 The key trick of this algorithm is that the original line indices described 95 above are actually maintained as _line[].oldindex fields in the window 96 structure, and stick to each line through scroll and insert/delete operations. 97 98 Thus, it is possible at update time to look at the oldnum fields and compute 99 an optimal set of il/dl/scroll operations that will take the real screen 100 lines to the virtual screen lines. Once these vertical moves have been done, 101 we can hand off to the second stage of the update algorithm, which does line 102 transformations. 103 104 Note that the move computation does not need to have the full generality 105 of a diff algorithm (which it superficially resembles) because lines cannot 106 be moved out of order. 107 108 THE ALGORITHM 109 110 The scrolling is done in two passes. The first pass is from top to bottom 111 scroling hunks UP. The second one is from bottom to top scrolling hunks DOWN. 112 Obviously enough, no lines to be scrolled will be destroyed. (lav) 113 114 HOW TO TEST THIS: 115 116 Use the following production: 117 118 hardscroll: hardscroll.c 119 $(CC) -g -DSCROLLDEBUG hardscroll.c -o hardscroll 120 121 Then just type scramble vectors and watch. The following test loads are 122 a representative sample of cases: 123 124 ----------------------------- CUT HERE ------------------------------------ 125 # No lines moved 126 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 127 # 128 # A scroll up 129 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 -1 130 # 131 # A scroll down 132 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 133 # 134 # An insertion (after line 12) 135 0 1 2 3 4 5 6 7 8 9 10 11 12 -1 13 14 15 16 17 18 19 20 21 22 136 # 137 # A simple deletion (line 10) 138 0 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 20 21 22 23 -1 139 # 140 # A more complex case 141 -1 -1 -1 -1 -1 3 4 5 6 7 -1 -1 8 9 10 11 12 13 14 15 16 17 -1 -1 142 ----------------------------- CUT HERE ------------------------------------ 143 144 AUTHOR 145 Eric S. Raymond <esr@snark.thyrsus.com>, November 1994 146 New algorithm by Alexander V. Lukyanov <lav@yars.free.net>, Aug 1997 147 148 *****************************************************************************/ 149 150 #include <curses.priv.h> 151 152 MODULE_ID("$Id: hardscroll.c,v 1.7 2010/01/12 23:22:07 nicm Exp $") 153 154 #if defined(SCROLLDEBUG) || defined(HASHDEBUG) 155 156 # undef screen_lines 157 # define screen_lines MAXLINES 158 NCURSES_EXPORT_VAR(int) 159 oldnums[MAXLINES]; 160 # define OLDNUM(n) oldnums[n] 161 # define _tracef printf 162 # undef TR 163 # define TR(n, a) if (_nc_tracing & (n)) { _tracef a ; putchar('\n'); } 164 165 extern NCURSES_EXPORT_VAR(unsigned) _nc_tracing; 166 167 #else /* no debug */ 168 169 /* OLDNUM(n) indicates which line will be shifted to the position n. 170 if OLDNUM(n) == _NEWINDEX, then the line n in new, not shifted from 171 somewhere. */ 172 NCURSES_EXPORT_VAR(int *) 173 _nc_oldnums = 0; /* obsolete: keep for ABI compat */ 174 175 # if USE_HASHMAP 176 # define oldnums SP->_oldnum_list 177 # define OLDNUM(n) oldnums[n] 178 # else /* !USE_HASHMAP */ 179 # define OLDNUM(n) newscr->_line[n].oldindex 180 # endif /* !USE_HASHMAP */ 181 182 #define OLDNUM_SIZE SP->_oldnum_size 183 184 #endif /* defined(SCROLLDEBUG) || defined(HASHDEBUG) */ 185 186 NCURSES_EXPORT(void) 187 _nc_scroll_optimize(void) 188 /* scroll optimization to transform curscr to newscr */ 189 { 190 int i; 191 int start, end, shift; 192 193 TR(TRACE_ICALLS, (T_CALLED("_nc_scroll_optimize"))); 194 195 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 196 #if USE_HASHMAP 197 /* get enough storage */ 198 if (OLDNUM_SIZE < screen_lines) { 199 int *new_oldnums = typeRealloc(int, screen_lines, oldnums); 200 if (!new_oldnums) 201 return; 202 oldnums = new_oldnums; 203 OLDNUM_SIZE = screen_lines; 204 } 205 /* calculate the indices */ 206 _nc_hash_map(); 207 #endif 208 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 209 210 #ifdef TRACE 211 if (USE_TRACEF(TRACE_UPDATE | TRACE_MOVE)) { 212 _nc_linedump(); 213 _nc_unlock_global(tracef); 214 } 215 #endif /* TRACE */ 216 217 /* pass 1 - from top to bottom scrolling up */ 218 for (i = 0; i < screen_lines;) { 219 while (i < screen_lines && (OLDNUM(i) == _NEWINDEX || OLDNUM(i) <= i)) 220 i++; 221 if (i >= screen_lines) 222 break; 223 224 shift = OLDNUM(i) - i; /* shift > 0 */ 225 start = i; 226 227 i++; 228 while (i < screen_lines && OLDNUM(i) != _NEWINDEX && OLDNUM(i) - i 229 == shift) 230 i++; 231 end = i - 1 + shift; 232 233 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 234 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 235 if (_nc_scrolln(shift, start, end, screen_lines - 1) == ERR) { 236 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 237 continue; 238 } 239 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 240 } 241 242 /* pass 2 - from bottom to top scrolling down */ 243 for (i = screen_lines - 1; i >= 0;) { 244 while (i >= 0 && (OLDNUM(i) == _NEWINDEX || OLDNUM(i) >= i)) 245 i--; 246 if (i < 0) 247 break; 248 249 shift = OLDNUM(i) - i; /* shift < 0 */ 250 end = i; 251 252 i--; 253 while (i >= 0 && OLDNUM(i) != _NEWINDEX && OLDNUM(i) - i == shift) 254 i--; 255 start = i + 1 - (-shift); 256 257 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 258 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 259 if (_nc_scrolln(shift, start, end, screen_lines - 1) == ERR) { 260 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 261 continue; 262 } 263 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 264 } 265 TR(TRACE_ICALLS, (T_RETURN(""))); 266 } 267 268 #if defined(TRACE) || defined(SCROLLDEBUG) || defined(HASHDEBUG) 269 NCURSES_EXPORT(void) 270 _nc_linedump(void) 271 /* dump the state of the real and virtual oldnum fields */ 272 { 273 int n; 274 char *buf = 0; 275 size_t want = (screen_lines + 1) * 4; 276 277 if ((buf = typeMalloc(char, want)) != 0) { 278 279 (void) strlcpy(buf, "virt", want); 280 for (n = 0; n < screen_lines; n++) 281 (void) snprintf(buf + strlen(buf), want - strlen(buf), " %02d", OLDNUM(n)); 282 TR(TRACE_UPDATE | TRACE_MOVE, (buf)); 283 free(buf); 284 } 285 } 286 #endif /* defined(TRACE) || defined(SCROLLDEBUG) */ 287 288 #ifdef SCROLLDEBUG 289 290 int 291 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED) 292 { 293 char line[BUFSIZ], *st, *last; 294 295 #ifdef TRACE 296 _nc_tracing = TRACE_MOVE; 297 #endif 298 for (;;) { 299 int n; 300 301 for (n = 0; n < screen_lines; n++) 302 oldnums[n] = _NEWINDEX; 303 304 /* grab the test vector */ 305 if (fgets(line, sizeof(line), stdin) == (char *) NULL) 306 exit(EXIT_SUCCESS); 307 308 /* parse it */ 309 n = 0; 310 if (line[0] == '#') { 311 (void) fputs(line, stderr); 312 continue; 313 } 314 st = strtok_r(line, " ", &last); 315 do { 316 oldnums[n++] = atoi(st); 317 } while 318 ((st = strtok_r((char *) NULL, " ", &last)) != 0); 319 320 /* display it */ 321 (void) fputs("Initial input:\n", stderr); 322 _nc_linedump(); 323 324 _nc_scroll_optimize(); 325 } 326 } 327 328 #endif /* SCROLLDEBUG */ 329 330 /* hardscroll.c ends here */ 331