1 /**************************************************************************** 2 * Copyright (c) 1998-2012,2015 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 1.52 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 */ 373