libdrawtext

annotate src/font.c @ 57:7b01e04c9c8b

find changesets by author, revision, files, or words in the commit message
added copyright notices
author John Tsiombikas <nuclear@mutantstargoat.com>
date Fri, 16 Sep 2011 08:42:07 +0300
parents fe0c54e574ae
children 7e0c702f1223
rev   line source
nuclear@5 1 /*
nuclear@5 2 libdrawtext - a simple library for fast text rendering in OpenGL
nuclear@5 3 Copyright (C) 2011 John Tsiombikas <nuclear@member.fsf.org>
nuclear@5 4
nuclear@5 5 This program is free software: you can redistribute it and/or modify
nuclear@5 6 it under the terms of the GNU Lesser General Public License as published by
nuclear@5 7 the Free Software Foundation, either version 3 of the License, or
nuclear@5 8 (at your option) any later version.
nuclear@5 9
nuclear@5 10 This program is distributed in the hope that it will be useful,
nuclear@5 11 but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@5 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
nuclear@5 13 GNU Lesser General Public License for more details.
nuclear@5 14
nuclear@5 15 You should have received a copy of the GNU Lesser General Public License
nuclear@5 16 along with this program. If not, see <http://www.gnu.org/licenses/>.
nuclear@5 17 */
nuclear@0 18 #ifndef NO_FREETYPE
nuclear@0 19 #define USE_FREETYPE
nuclear@0 20 #endif
nuclear@0 21
nuclear@0 22 #include <stdio.h>
nuclear@0 23 #include <stdlib.h>
nuclear@0 24 #include <string.h>
nuclear@0 25 #include <limits.h>
nuclear@0 26 #include <ctype.h>
nuclear@0 27 #include <errno.h>
nuclear@0 28 #ifdef USE_FREETYPE
nuclear@0 29 #include <ft2build.h>
nuclear@0 30 #include FT_FREETYPE_H
nuclear@0 31 #endif
nuclear@0 32 #include "drawtext.h"
nuclear@0 33 #include "drawtext_impl.h"
nuclear@0 34
nuclear@0 35 #define FTSZ_TO_PIXELS(x) ((x) / 64)
nuclear@0 36 #define MAX_IMG_WIDTH 4096
nuclear@0 37
nuclear@0 38
nuclear@0 39 #ifdef USE_FREETYPE
nuclear@0 40 static int init_freetype(void);
nuclear@0 41 static void cleanup(void);
nuclear@0 42
nuclear@0 43 static void calc_best_size(int total_width, int max_glyph_height, int padding, int pow2, int *imgw, int *imgh);
nuclear@0 44 static int next_pow2(int x);
nuclear@0 45
nuclear@0 46 static FT_Library ft;
nuclear@0 47
nuclear@0 48
nuclear@0 49 static int init_done;
nuclear@0 50
nuclear@0 51 static int init_freetype(void)
nuclear@0 52 {
nuclear@0 53 if(!init_done) {
nuclear@0 54 if(FT_Init_FreeType(&ft) != 0) {
nuclear@0 55 return -1;
nuclear@0 56 }
nuclear@0 57 atexit(cleanup);
nuclear@0 58 init_done = 1;
nuclear@0 59 }
nuclear@0 60 return 0;
nuclear@0 61 }
nuclear@0 62
nuclear@0 63 static void cleanup(void)
nuclear@0 64 {
nuclear@0 65 if(init_done) {
nuclear@0 66 FT_Done_FreeType(ft);
nuclear@0 67 }
nuclear@0 68 }
nuclear@0 69
nuclear@0 70 struct dtx_font *dtx_open_font(const char *fname, int sz)
nuclear@0 71 {
nuclear@0 72 struct dtx_font *fnt;
nuclear@0 73
nuclear@0 74 init_freetype();
nuclear@0 75
nuclear@0 76 if(!(fnt = calloc(1, sizeof *fnt))) {
nuclear@0 77 fperror("failed to allocate font structure");
nuclear@0 78 return 0;
nuclear@0 79 }
nuclear@0 80
nuclear@0 81 if(FT_New_Face(ft, fname, 0, (FT_Face*)&fnt->face) != 0) {
nuclear@0 82 fprintf(stderr, "failed to open font file: %s\n", fname);
nuclear@0 83 return 0;
nuclear@0 84 }
nuclear@0 85
nuclear@0 86 /* pre-create the extended ASCII range glyphmap */
nuclear@0 87 if(sz) {
nuclear@0 88 dtx_prepare_range(fnt, sz, 0, 256);
nuclear@0 89 }
nuclear@0 90
nuclear@0 91 return fnt;
nuclear@0 92 }
nuclear@0 93
nuclear@0 94 void dtx_close_font(struct dtx_font *fnt)
nuclear@0 95 {
nuclear@0 96 if(!fnt) return;
nuclear@0 97
nuclear@0 98 FT_Done_Face(fnt->face);
nuclear@0 99
nuclear@0 100 /* destroy the glyphmaps */
nuclear@0 101 while(fnt->gmaps) {
nuclear@0 102 void *tmp = fnt->gmaps;
nuclear@0 103 fnt->gmaps = fnt->gmaps->next;
nuclear@0 104 dtx_free_glyphmap(tmp);
nuclear@0 105 }
nuclear@0 106
nuclear@0 107 free(fnt);
nuclear@0 108 }
nuclear@0 109
nuclear@0 110 void dtx_prepare(struct dtx_font *fnt, int sz)
nuclear@0 111 {
nuclear@0 112 dtx_get_font_glyphmap_range(fnt, sz, 0, 256);
nuclear@0 113 }
nuclear@0 114
nuclear@0 115 void dtx_prepare_range(struct dtx_font *fnt, int sz, int cstart, int cend)
nuclear@0 116 {
nuclear@0 117 dtx_get_font_glyphmap_range(fnt, sz, cstart, cend);
nuclear@0 118 }
nuclear@0 119
nuclear@0 120 struct dtx_glyphmap *dtx_get_font_glyphmap(struct dtx_font *fnt, int sz, int code)
nuclear@0 121 {
nuclear@0 122 struct dtx_glyphmap *gm;
nuclear@0 123
nuclear@0 124 /* check to see if the last we've given out fits the bill */
nuclear@0 125 if(fnt->last_gmap && code >= fnt->last_gmap->cstart && code < fnt->last_gmap->cend && fnt->last_gmap->ptsize == sz) {
nuclear@0 126 return fnt->last_gmap;
nuclear@0 127 }
nuclear@0 128
nuclear@0 129 /* otherwise search for the appropriate glyphmap */
nuclear@0 130 gm = fnt->gmaps;
nuclear@0 131 while(gm) {
nuclear@0 132 if(code >= gm->cstart && code < gm->cend && sz == gm->ptsize) {
nuclear@0 133 fnt->last_gmap = gm;
nuclear@0 134 return gm;
nuclear@0 135 }
nuclear@0 136 gm = gm->next;
nuclear@0 137 }
nuclear@0 138 return 0;
nuclear@0 139 }
nuclear@0 140
nuclear@0 141 struct dtx_glyphmap *dtx_get_font_glyphmap_range(struct dtx_font *fnt, int sz, int cstart, int cend)
nuclear@0 142 {
nuclear@0 143 struct dtx_glyphmap *gm;
nuclear@0 144
nuclear@0 145 /* search the available glyphmaps to see if we've got one that includes
nuclear@0 146 * the requested range
nuclear@0 147 */
nuclear@0 148 gm = fnt->gmaps;
nuclear@0 149 while(gm) {
nuclear@0 150 if(gm->cstart <= cstart && gm->cend >= cend && gm->ptsize == sz) {
nuclear@0 151 return gm;
nuclear@0 152 }
nuclear@0 153 gm = gm->next;
nuclear@0 154 }
nuclear@0 155
nuclear@0 156 /* not found, create one and add it to the list */
nuclear@0 157 if(!(gm = dtx_create_glyphmap_range(fnt, sz, cstart, cend))) {
nuclear@0 158 return 0;
nuclear@0 159 }
nuclear@0 160 return gm;
nuclear@0 161 }
nuclear@0 162
nuclear@0 163 struct dtx_glyphmap *dtx_create_glyphmap_range(struct dtx_font *fnt, int sz, int cstart, int cend)
nuclear@0 164 {
nuclear@0 165 FT_Face face = fnt->face;
nuclear@0 166 struct dtx_glyphmap *gmap;
nuclear@0 167 int i, j;
nuclear@0 168 int gx, gy;
nuclear@0 169 int padding = 4;
nuclear@0 170 int total_width = padding;
nuclear@0 171 int max_height = 0;
nuclear@0 172
nuclear@0 173 FT_Set_Char_Size(fnt->face, 0, sz * 64, 72, 72);
nuclear@0 174
nuclear@3 175 if(!(gmap = calloc(1, sizeof *gmap))) {
nuclear@0 176 return 0;
nuclear@0 177 }
nuclear@0 178
nuclear@0 179 gmap->ptsize = sz;
nuclear@0 180 gmap->cstart = cstart;
nuclear@0 181 gmap->cend = cend;
nuclear@0 182 gmap->crange = cend - cstart;
nuclear@0 183 gmap->line_advance = FTSZ_TO_PIXELS((float)face->size->metrics.height);
nuclear@0 184
nuclear@0 185 if(!(gmap->glyphs = malloc(gmap->crange * sizeof *gmap->glyphs))) {
nuclear@0 186 free(gmap);
nuclear@0 187 return 0;
nuclear@0 188 }
nuclear@0 189
nuclear@0 190 for(i=0; i<gmap->crange; i++) {
nuclear@0 191 int h;
nuclear@0 192
nuclear@0 193 FT_Load_Char(face, i + cstart, 0);
nuclear@0 194 h = FTSZ_TO_PIXELS(face->glyph->metrics.height);
nuclear@0 195
nuclear@0 196 if(h > max_height) {
nuclear@0 197 max_height = h;
nuclear@0 198 }
nuclear@0 199 total_width += FTSZ_TO_PIXELS(face->glyph->metrics.width) + padding;
nuclear@0 200 }
nuclear@0 201
nuclear@0 202 calc_best_size(total_width, max_height, padding, 1, &gmap->xsz, &gmap->ysz);
nuclear@0 203
nuclear@0 204 if(!(gmap->pixels = malloc(gmap->xsz * gmap->ysz))) {
nuclear@0 205 free(gmap->glyphs);
nuclear@0 206 free(gmap);
nuclear@0 207 return 0;
nuclear@0 208 }
nuclear@0 209 memset(gmap->pixels, 0, gmap->xsz * gmap->ysz);
nuclear@0 210
nuclear@0 211 gx = padding;
nuclear@0 212 gy = padding;
nuclear@0 213
nuclear@0 214 for(i=0; i<gmap->crange; i++) {
nuclear@0 215 float gwidth, gheight;
nuclear@0 216 unsigned char *src, *dst;
nuclear@0 217 FT_GlyphSlot glyph;
nuclear@0 218
nuclear@0 219 FT_Load_Char(face, i + cstart, FT_LOAD_RENDER);
nuclear@0 220 glyph = face->glyph;
nuclear@0 221 gwidth = FTSZ_TO_PIXELS((float)glyph->metrics.width);
nuclear@0 222 gheight = FTSZ_TO_PIXELS((float)glyph->metrics.height);
nuclear@0 223
nuclear@0 224 if(gx > gmap->xsz - gwidth - padding) {
nuclear@0 225 gx = padding;
nuclear@0 226 gy += max_height + padding;
nuclear@0 227 }
nuclear@0 228
nuclear@0 229 src = glyph->bitmap.buffer;
nuclear@0 230 dst = gmap->pixels + gy * gmap->xsz + gx;
nuclear@0 231
nuclear@0 232 for(j=0; j<glyph->bitmap.rows; j++) {
nuclear@0 233 memcpy(dst, src, glyph->bitmap.width);
nuclear@0 234 dst += gmap->xsz;
nuclear@0 235 src += glyph->bitmap.pitch;
nuclear@0 236 }
nuclear@0 237
nuclear@0 238 gmap->glyphs[i].code = i;
nuclear@0 239 gmap->glyphs[i].x = gx - 1;
nuclear@0 240 gmap->glyphs[i].y = gy - 1;
nuclear@0 241 gmap->glyphs[i].width = gwidth + 2;
nuclear@0 242 gmap->glyphs[i].height = gheight + 2;
nuclear@0 243 gmap->glyphs[i].orig_x = -FTSZ_TO_PIXELS((float)glyph->metrics.horiBearingX) + 1;
nuclear@0 244 gmap->glyphs[i].orig_y = FTSZ_TO_PIXELS((float)glyph->metrics.height - glyph->metrics.horiBearingY) + 1;
nuclear@0 245 gmap->glyphs[i].advance = FTSZ_TO_PIXELS((float)glyph->metrics.horiAdvance);
nuclear@0 246 /* also precalc normalized */
nuclear@0 247 gmap->glyphs[i].nx = (float)gmap->glyphs[i].x / (float)gmap->xsz;
nuclear@0 248 gmap->glyphs[i].ny = (float)gmap->glyphs[i].y / (float)gmap->ysz;
nuclear@0 249 gmap->glyphs[i].nwidth = (float)gmap->glyphs[i].width / (float)gmap->xsz;
nuclear@0 250 gmap->glyphs[i].nheight = (float)gmap->glyphs[i].height / (float)gmap->ysz;
nuclear@0 251
nuclear@0 252 gx += gwidth + padding;
nuclear@0 253 }
nuclear@0 254
nuclear@0 255 /* add it to the glyphmaps list of the font */
nuclear@0 256 gmap->next = fnt->gmaps;
nuclear@0 257 fnt->gmaps = gmap;
nuclear@0 258
nuclear@0 259 return gmap;
nuclear@0 260 }
nuclear@0 261 #endif /* USE_FREETYPE */
nuclear@0 262
nuclear@0 263 void dtx_free_glyphmap(struct dtx_glyphmap *gmap)
nuclear@0 264 {
nuclear@0 265 if(gmap) {
nuclear@0 266 free(gmap->pixels);
nuclear@0 267 free(gmap->glyphs);
nuclear@0 268 free(gmap);
nuclear@0 269 }
nuclear@0 270 }
nuclear@0 271
nuclear@0 272 unsigned char *dtx_get_glyphmap_pixels(struct dtx_glyphmap *gmap)
nuclear@0 273 {
nuclear@0 274 return gmap->pixels;
nuclear@0 275 }
nuclear@0 276
nuclear@0 277 int dtx_get_glyphmap_width(struct dtx_glyphmap *gmap)
nuclear@0 278 {
nuclear@0 279 return gmap->xsz;
nuclear@0 280 }
nuclear@0 281
nuclear@0 282 int dtx_get_glyphmap_height(struct dtx_glyphmap *gmap)
nuclear@0 283 {
nuclear@0 284 return gmap->ysz;
nuclear@0 285 }
nuclear@0 286
nuclear@0 287 struct dtx_glyphmap *dtx_load_glyphmap(const char *fname)
nuclear@0 288 {
nuclear@0 289 FILE *fp;
nuclear@0 290 struct dtx_glyphmap *gmap;
nuclear@0 291
nuclear@0 292 if(!(fp = fopen(fname, "r"))) {
nuclear@0 293 return 0;
nuclear@0 294 }
nuclear@0 295 gmap = dtx_load_glyphmap_stream(fp);
nuclear@0 296 fclose(fp);
nuclear@0 297 return gmap;
nuclear@0 298 }
nuclear@0 299
nuclear@0 300 struct dtx_glyphmap *dtx_load_glyphmap_stream(FILE *fp)
nuclear@0 301 {
nuclear@0 302 char buf[512];
nuclear@0 303 int hdr_lines = 0;
nuclear@0 304 struct dtx_glyphmap *gmap;
nuclear@0 305 struct glyph *glyphs = 0;
nuclear@0 306 int min_code = INT_MAX;
nuclear@0 307 int max_code = INT_MIN;
nuclear@0 308 int i, max_pixval, num_pixels;
nuclear@0 309
nuclear@0 310 if(!(gmap = calloc(1, sizeof *gmap))) {
nuclear@0 311 fperror("failed to allocate glyphmap");
nuclear@0 312 return 0;
nuclear@0 313 }
nuclear@0 314
nuclear@0 315 while(hdr_lines < 3) {
nuclear@0 316 char *line = buf;
nuclear@0 317 if(!fgets(buf, sizeof buf, fp)) {
nuclear@0 318 fperror("unexpected end of file");
nuclear@0 319 goto err;
nuclear@0 320 }
nuclear@0 321
nuclear@0 322 while(isspace(*line)) {
nuclear@0 323 line++;
nuclear@0 324 }
nuclear@0 325
nuclear@0 326 if(line[0] == '#') {
nuclear@0 327 struct glyph *g;
nuclear@0 328 int c;
nuclear@0 329 float x, y, xsz, ysz, res;
nuclear@0 330
nuclear@0 331 res = sscanf(line + 1, "%d: %fx%f+%f+%f\n", &c, &xsz, &ysz, &x, &y);
nuclear@0 332 if(res != 5) {
nuclear@0 333 fprintf(stderr, "%s: invalid glyph info line\n", __func__);
nuclear@0 334 goto err;
nuclear@0 335 }
nuclear@0 336
nuclear@0 337 if(!(g = malloc(sizeof *g))) {
nuclear@0 338 fperror("failed to allocate glyph");
nuclear@0 339 goto err;
nuclear@0 340 }
nuclear@0 341 g->code = c;
nuclear@0 342 g->x = x;
nuclear@0 343 g->y = y;
nuclear@0 344 g->width = xsz;
nuclear@0 345 g->height = ysz;
nuclear@0 346 g->next = glyphs;
nuclear@0 347 glyphs = g;
nuclear@0 348
nuclear@0 349 if(c < min_code) {
nuclear@0 350 min_code = c;
nuclear@0 351 }
nuclear@0 352 if(c > max_code) {
nuclear@0 353 max_code = c;
nuclear@0 354 }
nuclear@0 355 } else {
nuclear@0 356 switch(hdr_lines) {
nuclear@0 357 case 0:
nuclear@0 358 if(0[line] != 'P' || 1[line] != '6') {
nuclear@0 359 fprintf(stderr, "%s: invalid file format (magic)\n", __func__);
nuclear@0 360 goto err;
nuclear@0 361 }
nuclear@0 362 break;
nuclear@0 363
nuclear@0 364 case 1:
nuclear@0 365 if(sscanf(line, "%d %d", &gmap->xsz, &gmap->ysz) != 2) {
nuclear@0 366 fprintf(stderr, "%s: invalid file format (dim)\n", __func__);
nuclear@0 367 goto err;
nuclear@0 368 }
nuclear@0 369 break;
nuclear@0 370
nuclear@0 371 case 2:
nuclear@0 372 {
nuclear@0 373 char *endp;
nuclear@0 374 max_pixval = strtol(line, &endp, 10);
nuclear@0 375 if(endp == line) {
nuclear@0 376 fprintf(stderr, "%s: invalid file format (maxval)\n", __func__);
nuclear@0 377 goto err;
nuclear@0 378 }
nuclear@0 379 }
nuclear@0 380 break;
nuclear@0 381
nuclear@0 382 default:
nuclear@0 383 break; /* can't happen */
nuclear@0 384 }
nuclear@0 385 hdr_lines++;
nuclear@0 386 }
nuclear@0 387 }
nuclear@0 388
nuclear@0 389 num_pixels = gmap->xsz * gmap->ysz;
nuclear@0 390 if(!(gmap->pixels = malloc(num_pixels))) {
nuclear@0 391 fperror("failed to allocate pixels");
nuclear@0 392 goto err;
nuclear@0 393 }
nuclear@0 394
nuclear@0 395 for(i=0; i<num_pixels; i++) {
nuclear@0 396 long c = fgetc(fp);
nuclear@0 397 if(c == -1) {
nuclear@0 398 fprintf(stderr, "unexpected end of file while reading pixels\n");
nuclear@0 399 goto err;
nuclear@0 400 }
nuclear@0 401 gmap->pixels[i] = 255 * c / max_pixval;
nuclear@0 402 fseek(fp, 2, SEEK_CUR);
nuclear@0 403 }
nuclear@0 404
nuclear@0 405 gmap->cstart = min_code;
nuclear@0 406 gmap->cend = max_code + 1;
nuclear@0 407 gmap->crange = gmap->cend - gmap->cstart;
nuclear@0 408
nuclear@0 409 if(!(gmap->glyphs = calloc(gmap->crange, sizeof *gmap->glyphs))) {
nuclear@0 410 fperror("failed to allocate glyph info");
nuclear@0 411 goto err;
nuclear@0 412 }
nuclear@0 413
nuclear@0 414 while(glyphs) {
nuclear@0 415 struct glyph *g = glyphs;
nuclear@0 416 glyphs = glyphs->next;
nuclear@0 417
nuclear@0 418 gmap->glyphs[g->code - gmap->cstart] = *g;
nuclear@0 419 free(g);
nuclear@0 420 }
nuclear@0 421 return gmap;
nuclear@0 422
nuclear@0 423 err:
nuclear@0 424 dtx_free_glyphmap(gmap);
nuclear@0 425 while(glyphs) {
nuclear@0 426 void *tmp = glyphs;
nuclear@0 427 glyphs = glyphs->next;
nuclear@0 428 free(tmp);
nuclear@0 429 }
nuclear@0 430 return 0;
nuclear@0 431 }
nuclear@0 432
nuclear@0 433 int dtx_save_glyphmap(const char *fname, const struct dtx_glyphmap *gmap)
nuclear@0 434 {
nuclear@0 435 FILE *fp;
nuclear@0 436 int res;
nuclear@0 437
nuclear@0 438 if(!(fp = fopen(fname, "wb"))) {
nuclear@0 439 fprintf(stderr, "%s: failed to open file: %s: %s\n", __func__, fname, strerror(errno));
nuclear@0 440 return -1;
nuclear@0 441 }
nuclear@0 442 res = dtx_save_glyphmap_stream(fp, gmap);
nuclear@0 443 fclose(fp);
nuclear@0 444 return res;
nuclear@0 445 }
nuclear@0 446
nuclear@0 447 int dtx_save_glyphmap_stream(FILE *fp, const struct dtx_glyphmap *gmap)
nuclear@0 448 {
nuclear@0 449 int i, num_pixels;
nuclear@0 450 struct glyph *g = gmap->glyphs;
nuclear@0 451
nuclear@0 452 fprintf(fp, "P6\n%d %d\n", gmap->xsz, gmap->ysz);
nuclear@0 453 for(i=0; i<gmap->crange; i++) {
nuclear@0 454 fprintf(fp, "# %d: %fx%f+%f+%f\n", g->code, g->width, g->height, g->x, g->y);
nuclear@0 455 g++;
nuclear@0 456 }
nuclear@0 457 fprintf(fp, "255\n");
nuclear@0 458
nuclear@0 459 num_pixels = gmap->xsz * gmap->ysz;
nuclear@0 460 for(i=0; i<num_pixels; i++) {
nuclear@0 461 int c = gmap->pixels[i];
nuclear@0 462 fputc(c, fp);
nuclear@0 463 fputc(c, fp);
nuclear@0 464 fputc(c, fp);
nuclear@0 465 }
nuclear@0 466 return 0;
nuclear@0 467 }
nuclear@0 468
nuclear@0 469
nuclear@0 470 static void calc_best_size(int total_width, int max_glyph_height, int padding, int pow2, int *imgw, int *imgh)
nuclear@0 471 {
nuclear@0 472 int xsz, ysz, num_rows;
nuclear@0 473 float aspect;
nuclear@0 474
nuclear@0 475 for(xsz=2; xsz<=MAX_IMG_WIDTH; xsz *= 2) {
nuclear@0 476 num_rows = total_width / xsz + 1;
nuclear@0 477
nuclear@0 478 /* take into account the one extra padding for each row after the first */
nuclear@0 479 num_rows = (total_width + padding * (num_rows - 1)) / xsz + 1;
nuclear@0 480
nuclear@0 481 ysz = num_rows * (max_glyph_height + padding) + padding;
nuclear@0 482 if(pow2) {
nuclear@0 483 ysz = next_pow2(ysz);
nuclear@0 484 }
nuclear@0 485 aspect = (float)xsz / (float)ysz;
nuclear@0 486
nuclear@0 487 if(aspect >= 1.0) {
nuclear@0 488 break;
nuclear@0 489 }
nuclear@0 490 }
nuclear@0 491
nuclear@0 492 if(xsz > MAX_IMG_WIDTH) {
nuclear@0 493 xsz = MAX_IMG_WIDTH;
nuclear@0 494 }
nuclear@0 495
nuclear@0 496 *imgw = xsz;
nuclear@0 497 *imgh = ysz;
nuclear@0 498 }
nuclear@0 499
nuclear@0 500
nuclear@0 501 static int next_pow2(int x)
nuclear@0 502 {
nuclear@0 503 x--;
nuclear@0 504 x = (x >> 1) | x;
nuclear@0 505 x = (x >> 2) | x;
nuclear@0 506 x = (x >> 4) | x;
nuclear@0 507 x = (x >> 8) | x;
nuclear@0 508 x = (x >> 16) | x;
nuclear@0 509 return x + 1;
nuclear@0 510 }