1 /**************************************************************************** 2 * Copyright (c) 1998 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 ****************************************************************************/ 33 34 35 /****************************************************************************** 36 37 NAME 38 hardscroll.c -- hardware-scrolling optimization for ncurses 39 40 SYNOPSIS 41 void _nc_scroll_optimize(void) 42 43 DESCRIPTION 44 OVERVIEW 45 46 This algorithm for computes optimum hardware scrolling to transform an 47 old screen (curscr) into a new screen (newscr) via vertical line moves. 48 49 Because the screen has a `grain' (there are insert/delete/scroll line 50 operations but no insert/delete/scroll column operations), it is efficient 51 break the update algorithm into two pieces: a first stage that does only line 52 moves, optimizing the end product of user-invoked insertions, deletions, and 53 scrolls; and a second phase (corresponding to the present doupdate code in 54 ncurses) that does only line transformations. 55 56 The common case we want hardware scrolling for is to handle line insertions 57 and deletions in screen-oriented text-editors. This two-stage approach will 58 accomplish that at a low computation and code-size cost. 59 60 LINE-MOVE COMPUTATION 61 62 Now, to a discussion of the line-move computation. 63 64 For expository purposes, consider the screen lines to be represented by 65 integers 0..23 (with the understanding that the value of 23 may vary). 66 Let a new line introduced by insertion, scrolling, or at the bottom of 67 the screen following a line delete be given the index -1. 68 69 Assume that the real screen starts with lines 0..23. Now, we have 70 the following possible line-oriented operations on the screen: 71 72 Insertion: inserts a line at a given screen row, forcing all lines below 73 to scroll forward. The last screen line is lost. For example, an insertion 74 at line 5 would produce: 0..4 -1 5..23. 75 76 Deletion: deletes a line at a given screen row, forcing all lines below 77 to scroll forward. The last screen line is made new. For example, a deletion 78 at line 7 would produce: 0..6 8..23 -1. 79 80 Scroll up: move a range of lines up 1. The bottom line of the range 81 becomes new. For example, scrolling up the region from 9 to 14 will 82 produce 0..8 10..14 -1 15..23. 83 84 Scroll down: move a range of lines down 1. The top line of the range 85 becomes new. For example, scrolling down the region from 12 to 16 will produce 86 0..11 -1 12..15 17..23. 87 88 Now, an obvious property of all these operations is that they preserve the 89 order of old lines, though not their position in the sequence. 90 91 The key trick of this algorithm is that the original line indices described 92 above are actually maintained as _line[].oldindex fields in the window 93 structure, and stick to each line through scroll and insert/delete operations. 94 95 Thus, it is possible at update time to look at the oldnum fields and compute 96 an optimal set of il/dl/scroll operations that will take the real screen 97 lines to the virtual screen lines. Once these vertical moves have been done, 98 we can hand off to the second stage of the update algorithm, which does line 99 transformations. 100 101 Note that the move computation does not need to have the full generality 102 of a diff algorithm (which it superficially resembles) because lines cannot 103 be moved out of order. 104 105 THE ALGORITHM 106 107 The scrolling is done in two passes. The first pass is from top to bottom 108 scroling hunks UP. The second one is from bottom to top scrolling hunks DOWN. 109 Obviously enough, no lines to be scrolled will be destroyed. (lav) 110 111 HOW TO TEST THIS: 112 113 Use the following production: 114 115 hardscroll: hardscroll.c 116 $(CC) -g -DSCROLLDEBUG hardscroll.c -o hardscroll 117 118 Then just type scramble vectors and watch. The following test loads are 119 a representative sample of cases: 120 121 ----------------------------- CUT HERE ------------------------------------ 122 # No lines moved 123 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 124 # 125 # A scroll up 126 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 -1 127 # 128 # A scroll down 129 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 130 # 131 # An insertion (after line 12) 132 0 1 2 3 4 5 6 7 8 9 10 11 12 -1 13 14 15 16 17 18 19 20 21 22 133 # 134 # A simple deletion (line 10) 135 0 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 20 21 22 23 -1 136 # 137 # A more complex case 138 -1 -1 -1 -1 -1 3 4 5 6 7 -1 -1 8 9 10 11 12 13 14 15 16 17 -1 -1 139 ----------------------------- CUT HERE ------------------------------------ 140 141 AUTHOR 142 Eric S. Raymond <esr@snark.thyrsus.com>, November 1994 143 New algorithm by Alexander V. Lukyanov <lav@yars.free.net>, Aug 1997 144 145 *****************************************************************************/ 146 147 #include <curses.priv.h> 148 149 MODULE_ID("$Id: hardscroll.c,v 1.33 1999/02/27 20:01:29 tom Exp $") 150 151 #if defined(SCROLLDEBUG) || defined(HASHDEBUG) 152 153 # undef screen_lines 154 # define screen_lines MAXLINES 155 int oldnums[MAXLINES]; 156 # define OLDNUM(n) oldnums[n] 157 # define _tracef printf 158 # undef TR 159 # define TR(n, a) if (_nc_tracing & (n)) { _tracef a ; putchar('\n'); } 160 161 #else /* no debug */ 162 163 /* OLDNUM(n) indicates which line will be shifted to the position n. 164 if OLDNUM(n) == _NEWINDEX, then the line n in new, not shifted from 165 somewhere. */ 166 # if USE_HASHMAP 167 int *_nc_oldnums = 0; 168 static int oldnums_allocated = 0; 169 # define oldnums _nc_oldnums 170 # define OLDNUM(n) oldnums[n] 171 # else /* !USE_HASHMAP */ 172 # define OLDNUM(n) newscr->_line[n].oldindex 173 # endif /* !USE_HASHMAP */ 174 175 #endif /* defined(SCROLLDEBUG) || defined(HASHDEBUG) */ 176 177 178 void _nc_scroll_optimize(void) 179 /* scroll optimization to transform curscr to newscr */ 180 { 181 int i; 182 int start, end, shift; 183 184 TR(TRACE_ICALLS, ("_nc_scroll_optimize() begins")); 185 186 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 187 #if USE_HASHMAP 188 /* get enough storage */ 189 if (oldnums_allocated < screen_lines) 190 { 191 int *new_oldnums = typeRealloc(int, screen_lines, oldnums); 192 if (!new_oldnums) 193 return; 194 oldnums = new_oldnums; 195 oldnums_allocated = screen_lines; 196 } 197 /* calculate the indices */ 198 _nc_hash_map(); 199 #endif 200 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 201 202 #ifdef TRACE 203 if (_nc_tracing & (TRACE_UPDATE | TRACE_MOVE)) 204 _nc_linedump(); 205 #endif /* TRACE */ 206 207 /* pass 1 - from top to bottom scrolling up */ 208 for (i = 0; i < screen_lines; ) 209 { 210 while (i < screen_lines && (OLDNUM(i) == _NEWINDEX || OLDNUM(i) <= i)) 211 i++; 212 if (i >= screen_lines) 213 break; 214 215 shift = OLDNUM(i) - i; /* shift > 0 */ 216 start = i; 217 218 i++; 219 while (i < screen_lines && OLDNUM(i) != _NEWINDEX && OLDNUM(i) - i == shift) 220 i++; 221 end = i-1 + shift; 222 223 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 224 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 225 if (_nc_scrolln(shift, start, end, screen_lines - 1) == ERR) 226 { 227 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 228 continue; 229 } 230 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 231 } 232 233 /* pass 2 - from bottom to top scrolling down */ 234 for (i = screen_lines-1; i >= 0; ) 235 { 236 while (i >= 0 && (OLDNUM(i) == _NEWINDEX || OLDNUM(i) >= i)) 237 i--; 238 if (i < 0) 239 break; 240 241 shift = OLDNUM(i) - i; /* shift < 0 */ 242 end = i; 243 244 i--; 245 while (i >= 0 && OLDNUM(i) != _NEWINDEX && OLDNUM(i) - i == shift) 246 i--; 247 start = i+1 - (-shift); 248 249 TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", start, end, shift)); 250 #if !defined(SCROLLDEBUG) && !defined(HASHDEBUG) 251 if (_nc_scrolln(shift, start, end, screen_lines - 1) == ERR) 252 { 253 TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll")); 254 continue; 255 } 256 #endif /* !defined(SCROLLDEBUG) && !defined(HASHDEBUG) */ 257 } 258 } 259 260 #if defined(TRACE) || defined(SCROLLDEBUG) || defined(HASHDEBUG) 261 void _nc_linedump(void) 262 /* dump the state of the real and virtual oldnum fields */ 263 { 264 static size_t have; 265 static char *buf; 266 267 int n; 268 size_t want = (screen_lines + 1) * 4; 269 270 if (have < want) 271 buf = typeMalloc(char, have = want); 272 273 (void) strcpy(buf, "virt"); 274 for (n = 0; n < screen_lines; n++) 275 (void) sprintf(buf + strlen(buf), " %02d", OLDNUM(n)); 276 TR(TRACE_UPDATE | TRACE_MOVE, (buf)); 277 #if NO_LEAKS 278 free(buf); 279 have = 0; 280 #endif 281 } 282 #endif /* defined(TRACE) || defined(SCROLLDEBUG) */ 283 284 #ifdef SCROLLDEBUG 285 286 int 287 main(int argc GCC_UNUSED, char *argv[] GCC_UNUSED) 288 { 289 char line[BUFSIZ], *st; 290 291 #ifdef TRACE 292 _nc_tracing = TRACE_MOVE; 293 #endif 294 for (;;) 295 { 296 int n; 297 298 for (n = 0; n < screen_lines; n++) 299 oldnums[n] = _NEWINDEX; 300 301 /* grab the test vector */ 302 if (fgets(line, sizeof(line), stdin) == (char *)NULL) 303 exit(EXIT_SUCCESS); 304 305 /* parse it */ 306 n = 0; 307 if (line[0] == '#') 308 { 309 (void) fputs(line, stderr); 310 continue; 311 } 312 st = strtok(line, " "); 313 do { 314 oldnums[n++] = atoi(st); 315 } while 316 ((st = strtok((char *)NULL, " ")) != 0); 317 318 /* display it */ 319 (void) fputs("Initial input:\n", stderr); 320 _nc_linedump(); 321 322 _nc_scroll_optimize(); 323 } 324 } 325 326 #endif /* SCROLLDEBUG */ 327 328 /* hardscroll.c ends here */ 329