1 /**************************************************************************** 2 * Copyright (c) 1998-2009,2010 Free Software Foundation, Inc. * 3 * * 4 * Permission is hereby granted, free of charge, to any person obtaining a * 5 * copy of this software and associated documentation files (the * 6 * "Software"), to deal in the Software without restriction, including * 7 * without limitation the rights to use, copy, modify, merge, publish, * 8 * distribute, distribute with modifications, sublicense, and/or sell * 9 * copies of the Software, and to permit persons to whom the Software is * 10 * furnished to do so, subject to the following conditions: * 11 * * 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 * 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * 18 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * 19 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * 20 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * 21 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * 22 * * 23 * Except as contained in this notice, the name(s) of the above copyright * 24 * holders shall not be used in advertising or otherwise to promote the * 25 * sale, use or other dealings in this Software without prior written * 26 * authorization. * 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 1.47 2010/04/24 23:46:47 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 if (OLDNUM_SIZE(SP_PARM) < screen_lines(SP_PARM)) { 197 int *new_oldnums = typeRealloc(int, 198 (size_t) screen_lines(SP_PARM), 199 oldnums(SP_PARM)); 200 if (!new_oldnums) 201 return; 202 oldnums(SP_PARM) = new_oldnums; 203 OLDNUM_SIZE(SP_PARM) = screen_lines(SP_PARM); 204 } 205 /* calculate the indices */ 206 NCURSES_SP_NAME(_nc_hash_map) (NCURSES_SP_ARG); 207 #endif 208 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 209 210 #ifdef TRACE 211 if (USE_TRACEF(TRACE_UPDATE | TRACE_MOVE)) { 212 NCURSES_SP_NAME(_nc_linedump) (NCURSES_SP_ARG); 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(SP_PARM);) { 219 while (i < screen_lines(SP_PARM) 220 && (OLDNUM(SP_PARM, i) == _NEWINDEX || OLDNUM(SP_PARM, i) <= i)) 221 i++; 222 if (i >= screen_lines(SP_PARM)) 223 break; 224 225 shift = OLDNUM(SP_PARM, i) - i; /* shift > 0 */ 226 start = i; 227 228 i++; 229 while (i < screen_lines(SP_PARM) 230 && OLDNUM(SP_PARM, i) != _NEWINDEX 231 && OLDNUM(SP_PARM, i) - i == shift) 232 i++; 233 end = i - 1 + shift; 234 235 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 236 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 237 if (NCURSES_SP_NAME(_nc_scrolln) (NCURSES_SP_ARGx 238 shift, 239 start, 240 end, 241 screen_lines(SP_PARM) - 1) == ERR) { 242 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 243 continue; 244 } 245 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 246 } 247 248 /* pass 2 - from bottom to top scrolling down */ 249 for (i = screen_lines(SP_PARM) - 1; i >= 0;) { 250 while (i >= 0 251 && (OLDNUM(SP_PARM, i) == _NEWINDEX 252 || OLDNUM(SP_PARM, i) >= i)) { 253 i--; 254 } 255 if (i < 0) 256 break; 257 258 shift = OLDNUM(SP_PARM, i) - i; /* shift < 0 */ 259 end = i; 260 261 i--; 262 while (i >= 0 263 && OLDNUM(SP_PARM, i) != _NEWINDEX 264 && OLDNUM(SP_PARM, i) - i == shift) { 265 i--; 266 } 267 start = i + 1 - (-shift); 268 269 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 270 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 271 if (NCURSES_SP_NAME(_nc_scrolln) (NCURSES_SP_ARGx 272 shift, 273 start, 274 end, 275 screen_lines(SP_PARM) - 1) == ERR) { 276 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 277 continue; 278 } 279 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 280 } 281 TR(TRACE_ICALLS, (T_RETURN(""))); 282 } 283 284 #if NCURSES_SP_FUNCS 285 NCURSES_EXPORT(void) 286 _nc_scroll_optimize(void) 287 { 288 NCURSES_SP_NAME(_nc_scroll_optimize) (CURRENT_SCREEN); 289 } 290 #endif 291 292 #if defined(TRACE) || defined(SCROLLDEBUG) || defined(HASHDEBUG) 293 NCURSES_EXPORT(void) 294 NCURSES_SP_NAME(_nc_linedump) (NCURSES_SP_DCL0) 295 /* dump the state of the real and virtual oldnum fields */ 296 { 297 int n; 298 char *buf = 0; 299 size_t want = ((size_t) screen_lines(SP_PARM) + 1) * 4; 300 301 if ((buf = typeMalloc(char, want)) != 0) { 302 303 *buf = '\0'; 304 for (n = 0; n < screen_lines(SP_PARM); n++) 305 (void) sprintf(buf + strlen(buf), " %02d", OLDNUM(SP_PARM, n)); 306 TR(TRACE_UPDATE | TRACE_MOVE, ("virt %s", buf)); 307 free(buf); 308 } 309 } 310 311 #if NCURSES_SP_FUNCS 312 NCURSES_EXPORT(void) 313 _nc_linedump(void) 314 { 315 NCURSES_SP_NAME(_nc_linedump) (CURRENT_SCREEN); 316 } 317 #endif 318 319 #endif /* defined(TRACE) || defined(SCROLLDEBUG) */ 320 321 #ifdef SCROLLDEBUG 322 323 int 324 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED) 325 { 326 char line[BUFSIZ], *st; 327 328 #ifdef TRACE 329 _nc_tracing = TRACE_MOVE; 330 #endif 331 for (;;) { 332 int n; 333 334 for (n = 0; n < screen_lines; n++) 335 oldnums[n] = _NEWINDEX; 336 337 /* grab the test vector */ 338 if (fgets(line, sizeof(line), stdin) == (char *) NULL) 339 exit(EXIT_SUCCESS); 340 341 /* parse it */ 342 n = 0; 343 if (line[0] == '#') { 344 (void) fputs(line, stderr); 345 continue; 346 } 347 st = strtok(line, " "); 348 do { 349 oldnums[n++] = atoi(st); 350 } while 351 ((st = strtok((char *) NULL, " ")) != 0); 352 353 /* display it */ 354 (void) fputs("Initial input:\n", stderr); 355 _nc_linedump(); 356 357 _nc_scroll_optimize(); 358 } 359 } 360 361 #endif /* SCROLLDEBUG */ 362 363 /* hardscroll.c ends here */ 364