src/mesa/main/imports.c

   1 /**
   2  * \file imports.c
   3  * Standard C library function wrappers.
   4  *
   5  * Imports are services which the device driver or window system or
   6  * operating system provides to the core renderer.  The core renderer (Mesa)
   7  * will call these functions in order to do memory allocation, simple I/O,
   8  * etc.
   9  *
  10  * Some drivers will want to override/replace this file with something
  11  * specialized, but that'll be rare.
  12  *
  13  * Eventually, I want to move roll the glheader.h file into this.
  14  *
  15  * \todo Functions still needed:
  16  * - scanf
  17  * - qsort
  18  * - rand and RAND_MAX
  19  */
  20
  21 /*
  22  * Mesa 3-D graphics library
  23  * Version:  7.1
  24  *
  25  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
  26  *
  27  * Permission is hereby granted, free of charge, to any person obtaining a
  28  * copy of this software and associated documentation files (the "Software"),
  29  * to deal in the Software without restriction, including without limitation
  30  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  31  * and/or sell copies of the Software, and to permit persons to whom the
  32  * Software is furnished to do so, subject to the following conditions:
  33  *
  34  * The above copyright notice and this permission notice shall be included
  35  * in all copies or substantial portions of the Software.
  36  *
  37  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  38  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  39  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  40  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  41  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  42  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  43  */
  44
  45
  46
  47 #include "imports.h"
  48 #include "context.h"
  49 #include "version.h"
  50
  51
  52 #define MAXSTRING 4000  /* for vsnprintf() */
  53
  54 #ifdef WIN32
  55 #define vsnprintf _vsnprintf
  56 #elif defined(__IBMC__) || defined(__IBMCPP__) || ( defined(__VMS) && __CRTL_VER < 70312000 )
  57 extern int vsnprintf(char *str, size_t count, const char *fmt, va_list arg);
  58 #ifdef __VMS
  59 #include "vsnprintf.c"
  60 #endif
  61 #endif
  62
  63 /**********************************************************************/
  64 /** \name Memory */
  65 /*@{*/
  66
  67 /** Wrapper around malloc() */
  68 void *
  69 _mesa_malloc(size_t bytes)
  70 {
  71    return malloc(bytes);
  72 }
  73
  74 /** Wrapper around calloc() */
  75 void *
  76 _mesa_calloc(size_t bytes)
  77 {
  78    return calloc(1, bytes);
  79 }
  80
  81 /** Wrapper around free() */
  82 void
  83 _mesa_free(void *ptr)
  84 {
  85    free(ptr);
  86 }
  87
  88 /**
  89  * Allocate aligned memory.
  90  *
  91  * \param bytes number of bytes to allocate.
  92  * \param alignment alignment (must be greater than zero).
  93  *
  94  * Allocates extra memory to accommodate rounding up the address for
  95  * alignment and to record the real malloc address.
  96  *
  97  * \sa _mesa_align_free().
  98  */
  99 void *
 100 _mesa_align_malloc(size_t bytes, unsigned long alignment)
 101 {
 102 #if defined(HAVE_POSIX_MEMALIGN)
 103    void *mem;
 104
 105    (void) posix_memalign(& mem, alignment, bytes);
 106    return mem;
 107 #elif defined(_WIN32) && defined(_MSC_VER)
 108    return _aligned_malloc(bytes, alignment);
 109 #else
 110    uintptr_t ptr, buf;
 111
 112    ASSERT( alignment > 0 );
 113
 114    ptr = (uintptr_t) _mesa_malloc(bytes + alignment + sizeof(void *));
 115    if (!ptr)
 116       return NULL;
 117
 118    buf = (ptr + alignment + sizeof(void *)) & ~(uintptr_t)(alignment - 1);
 119    *(uintptr_t *)(buf - sizeof(void *)) = ptr;
 120
 121 #ifdef DEBUG
 122    /* mark the non-aligned area */
 123    while ( ptr < buf - sizeof(void *) ) {
 124       *(unsigned long *)ptr = 0xcdcdcdcd;
 125       ptr += sizeof(unsigned long);
 126    }
 127 #endif
 128
 129    return (void *) buf;
 130 #endif /* defined(HAVE_POSIX_MEMALIGN) */
 131 }
 132
 133 /**
 134  * Same as _mesa_align_malloc(), but using _mesa_calloc() instead of
 135  * _mesa_malloc()
 136  */
 137 void *
 138 _mesa_align_calloc(size_t bytes, unsigned long alignment)
 139 {
 140 #if defined(HAVE_POSIX_MEMALIGN)
 141    void *mem;
 142
 143    mem = _mesa_align_malloc(bytes, alignment);
 144    if (mem != NULL) {
 145       (void) memset(mem, 0, bytes);
 146    }
 147
 148    return mem;
 149 #elif defined(_WIN32) && defined(_MSC_VER)
 150    void *mem;
 151
 152    mem = _aligned_malloc(bytes, alignment);
 153    if (mem != NULL) {
 154       (void) memset(mem, 0, bytes);
 155    }
 156
 157    return mem;
 158 #else
 159    uintptr_t ptr, buf;
 160
 161    ASSERT( alignment > 0 );
 162
 163    ptr = (uintptr_t) _mesa_calloc(bytes + alignment + sizeof(void *));
 164    if (!ptr)
 165       return NULL;
 166
 167    buf = (ptr + alignment + sizeof(void *)) & ~(uintptr_t)(alignment - 1);
 168    *(uintptr_t *)(buf - sizeof(void *)) = ptr;
 169
 170 #ifdef DEBUG
 171    /* mark the non-aligned area */
 172    while ( ptr < buf - sizeof(void *) ) {
 173       *(unsigned long *)ptr = 0xcdcdcdcd;
 174       ptr += sizeof(unsigned long);
 175    }
 176 #endif
 177
 178    return (void *)buf;
 179 #endif /* defined(HAVE_POSIX_MEMALIGN) */
 180 }
 181
 182 /**
 183  * Free memory which was allocated with either _mesa_align_malloc()
 184  * or _mesa_align_calloc().
 185  * \param ptr pointer to the memory to be freed.
 186  * The actual address to free is stored in the word immediately before the
 187  * address the client sees.
 188  */
 189 void
 190 _mesa_align_free(void *ptr)
 191 {
 192 #if defined(HAVE_POSIX_MEMALIGN)
 193    free(ptr);
 194 #elif defined(_WIN32) && defined(_MSC_VER)
 195    _aligned_free(ptr);
 196 #else
 197    void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
 198    void *realAddr = *cubbyHole;
 199    _mesa_free(realAddr);
 200 #endif /* defined(HAVE_POSIX_MEMALIGN) */
 201 }
 202
 203 /**
 204  * Reallocate memory, with alignment.
 205  */
 206 void *
 207 _mesa_align_realloc(void *oldBuffer, size_t oldSize, size_t newSize,
 208                     unsigned long alignment)
 209 {
 210 #if defined(_WIN32) && defined(_MSC_VER)
 211    (void) oldSize;
 212    return _aligned_realloc(oldBuffer, newSize, alignment);
 213 #else
 214    const size_t copySize = (oldSize < newSize) ? oldSize : newSize;
 215    void *newBuf = _mesa_align_malloc(newSize, alignment);
 216    if (newBuf && oldBuffer && copySize > 0) {
 217       _mesa_memcpy(newBuf, oldBuffer, copySize);
 218    }
 219    if (oldBuffer)
 220       _mesa_align_free(oldBuffer);
 221    return newBuf;
 222 #endif
 223 }
 224
 225
 226
 227 /** Reallocate memory */
 228 void *
 229 _mesa_realloc(void *oldBuffer, size_t oldSize, size_t newSize)
 230 {
 231    const size_t copySize = (oldSize < newSize) ? oldSize : newSize;
 232    void *newBuffer = _mesa_malloc(newSize);
 233    if (newBuffer && oldBuffer && copySize > 0)
 234       _mesa_memcpy(newBuffer, oldBuffer, copySize);
 235    if (oldBuffer)
 236       _mesa_free(oldBuffer);
 237    return newBuffer;
 238 }
 239
 240 /** memcpy wrapper */
 241 void *
 242 _mesa_memcpy(void *dest, const void *src, size_t n)
 243 {
 244 #if defined(SUNOS4)
 245    return memcpy((char *) dest, (char *) src, (int) n);
 246 #else
 247    return memcpy(dest, src, n);
 248 #endif
 249 }
 250
 251 /** Wrapper around memset() */
 252 void
 253 _mesa_memset( void *dst, int val, size_t n )
 254 {
 255 #if defined(SUNOS4)
 256    memset( (char *) dst, (int) val, (int) n );
 257 #else
 258    memset(dst, val, n);
 259 #endif
 260 }
 261
 262 /**
 263  * Fill memory with a constant 16bit word.
 264  * \param dst destination pointer.
 265  * \param val value.
 266  * \param n number of words.
 267  */
 268 void
 269 _mesa_memset16( unsigned short *dst, unsigned short val, size_t n )
 270 {
 271    while (n-- > 0)
 272       *dst++ = val;
 273 }
 274
 275 /** Wrapper around either memset() or bzero() */
 276 void
 277 _mesa_bzero( void *dst, size_t n )
 278 {
 279 #if defined(__FreeBSD__)
 280    bzero( dst, n );
 281 #else
 282    memset( dst, 0, n );
 283 #endif
 284 }
 285
 286 /** Wrapper around memcmp() */
 287 int
 288 _mesa_memcmp( const void *s1, const void *s2, size_t n )
 289 {
 290 #if defined(SUNOS4)
 291    return memcmp( (char *) s1, (char *) s2, (int) n );
 292 #else
 293    return memcmp(s1, s2, n);
 294 #endif
 295 }
 296
 297 /*@}*/
 298
 299
 300 /**********************************************************************/
 301 /** \name Math */
 302 /*@{*/
 303
 304 /** Wrapper around sin() */
 305 double
 306 _mesa_sin(double a)
 307 {
 308    return sin(a);
 309 }
 310
 311 /** Single precision wrapper around sin() */
 312 float
 313 _mesa_sinf(float a)
 314 {
 315    return (float) sin((double) a);
 316 }
 317
 318 /** Wrapper around cos() */
 319 double
 320 _mesa_cos(double a)
 321 {
 322    return cos(a);
 323 }
 324
 325 /** Single precision wrapper around asin() */
 326 float
 327 _mesa_asinf(float x)
 328 {
 329    return (float) asin((double) x);
 330 }
 331
 332 /** Single precision wrapper around atan() */
 333 float
 334 _mesa_atanf(float x)
 335 {
 336    return (float) atan((double) x);
 337 }
 338
 339 /** Wrapper around sqrt() */
 340 double
 341 _mesa_sqrtd(double x)
 342 {
 343    return sqrt(x);
 344 }
 345
 346
 347 /*
 348  * A High Speed, Low Precision Square Root
 349  * by Paul Lalonde and Robert Dawson
 350  * from "Graphics Gems", Academic Press, 1990
 351  *
 352  * SPARC implementation of a fast square root by table
 353  * lookup.
 354  * SPARC floating point format is as follows:
 355  *
 356  * BIT 31       30      23      22      0
 357  *     sign     exponent        mantissa
 358  */
 359 static short sqrttab[0x100];    /* declare table of square roots */
 360
 361 void
 362 _mesa_init_sqrt_table(void)
 363 {
 364 #if defined(USE_IEEE) && !defined(DEBUG)
 365    unsigned short i;
 366    fi_type fi;     /* to access the bits of a float in  C quickly  */
 367                    /* we use a union defined in glheader.h         */
 368
 369    for(i=0; i<= 0x7f; i++) {
 370       fi.i = 0;
 371
 372       /*
 373        * Build a float with the bit pattern i as mantissa
 374        * and an exponent of 0, stored as 127
 375        */
 376
 377       fi.i = (i << 16) | (127 << 23);
 378       fi.f = _mesa_sqrtd(fi.f);
 379
 380       /*
 381        * Take the square root then strip the first 7 bits of
 382        * the mantissa into the table
 383        */
 384
 385       sqrttab[i] = (fi.i & 0x7fffff) >> 16;
 386
 387       /*
 388        * Repeat the process, this time with an exponent of
 389        * 1, stored as 128
 390        */
 391
 392       fi.i = 0;
 393       fi.i = (i << 16) | (128 << 23);
 394       fi.f = sqrt(fi.f);
 395       sqrttab[i+0x80] = (fi.i & 0x7fffff) >> 16;
 396    }
 397 #else
 398    (void) sqrttab;  /* silence compiler warnings */
 399 #endif /*HAVE_FAST_MATH*/
 400 }
 401
 402
 403 /**
 404  * Single precision square root.
 405  */
 406 float
 407 _mesa_sqrtf( float x )
 408 {
 409 #if defined(USE_IEEE) && !defined(DEBUG)
 410    fi_type num;
 411                                 /* to access the bits of a float in C
 412                                  * we use a union from glheader.h     */
 413
 414    short e;                     /* the exponent */
 415    if (x == 0.0F) return 0.0F;  /* check for square root of 0 */
 416    num.f = x;
 417    e = (num.i >> 23) - 127;     /* get the exponent - on a SPARC the */
 418                                 /* exponent is stored with 127 added */
 419    num.i &= 0x7fffff;           /* leave only the mantissa */
 420    if (e & 0x01) num.i |= 0x800000;
 421                                 /* the exponent is odd so we have to */
 422                                 /* look it up in the second half of  */
 423                                 /* the lookup table, so we set the   */
 424                                 /* high bit                                */
 425    e >>= 1;                     /* divide the exponent by two */
 426                                 /* note that in C the shift */
 427                                 /* operators are sign preserving */
 428                                 /* for signed operands */
 429    /* Do the table lookup, based on the quaternary mantissa,
 430     * then reconstruct the result back into a float
 431     */
 432    num.i = ((sqrttab[num.i >> 16]) << 16) | ((e + 127) << 23);
 433
 434    return num.f;
 435 #else
 436    return (float) _mesa_sqrtd((double) x);
 437 #endif
 438 }
 439
 440
 441 /**
 442  inv_sqrt - A single precision 1/sqrt routine for IEEE format floats.
 443  written by Josh Vanderhoof, based on newsgroup posts by James Van Buskirk
 444  and Vesa Karvonen.
 445 */
 446 float
 447 _mesa_inv_sqrtf(float n)
 448 {
 449 #if defined(USE_IEEE) && !defined(DEBUG)
 450         float r0, x0, y0;
 451         float r1, x1, y1;
 452         float r2, x2, y2;
 453 #if 0 /* not used, see below -BP */
 454         float r3, x3, y3;
 455 #endif
 456         union { float f; unsigned int i; } u;
 457         unsigned int magic;
 458
 459         /*
 460          Exponent part of the magic number -
 461
 462          We want to:
 463          1. subtract the bias from the exponent,
 464          2. negate it
 465          3. divide by two (rounding towards -inf)
 466          4. add the bias back
 467
 468          Which is the same as subtracting the exponent from 381 and dividing
 469          by 2.
 470
 471          floor(-(x - 127) / 2) + 127 = floor((381 - x) / 2)
 472         */
 473
 474         magic = 381 << 23;
 475
 476         /*
 477          Significand part of magic number -
 478
 479          With the current magic number, "(magic - u.i) >> 1" will give you:
 480
 481          for 1 <= u.f <= 2: 1.25 - u.f / 4
 482          for 2 <= u.f <= 4: 1.00 - u.f / 8
 483
 484          This isn't a bad approximation of 1/sqrt.  The maximum difference from
 485          1/sqrt will be around .06.  After three Newton-Raphson iterations, the
 486          maximum difference is less than 4.5e-8.  (Which is actually close
 487          enough to make the following bias academic...)
 488
 489          To get a better approximation you can add a bias to the magic
 490          number.  For example, if you subtract 1/2 of the maximum difference in
 491          the first approximation (.03), you will get the following function:
 492
 493          for 1 <= u.f <= 2:    1.22 - u.f / 4
 494          for 2 <= u.f <= 3.76: 0.97 - u.f / 8
 495          for 3.76 <= u.f <= 4: 0.72 - u.f / 16
 496          (The 3.76 to 4 range is where the result is < .5.)
 497
 498          This is the closest possible initial approximation, but with a maximum
 499          error of 8e-11 after three NR iterations, it is still not perfect.  If
 500          you subtract 0.0332281 instead of .03, the maximum error will be
 501          2.5e-11 after three NR iterations, which should be about as close as
 502          is possible.
 503
 504          for 1 <= u.f <= 2:    1.2167719 - u.f / 4
 505          for 2 <= u.f <= 3.73: 0.9667719 - u.f / 8
 506          for 3.73 <= u.f <= 4: 0.7167719 - u.f / 16
 507
 508         */
 509
 510         magic -= (int)(0.0332281 * (1 << 25));
 511
 512         u.f = n;
 513         u.i = (magic - u.i) >> 1;
 514
 515         /*
 516          Instead of Newton-Raphson, we use Goldschmidt's algorithm, which
 517          allows more parallelism.  From what I understand, the parallelism
 518          comes at the cost of less precision, because it lets error
 519          accumulate across iterations.
 520         */
 521         x0 = 1.0f;
 522         y0 = 0.5f * n;
 523         r0 = u.f;
 524
 525         x1 = x0 * r0;
 526         y1 = y0 * r0 * r0;
 527         r1 = 1.5f - y1;
 528
 529         x2 = x1 * r1;
 530         y2 = y1 * r1 * r1;
 531         r2 = 1.5f - y2;
 532
 533 #if 1
 534         return x2 * r2;  /* we can stop here, and be conformant -BP */
 535 #else
 536         x3 = x2 * r2;
 537         y3 = y2 * r2 * r2;
 538         r3 = 1.5f - y3;
 539
 540         return x3 * r3;
 541 #endif
 542 #else
 543         return (float) (1.0 / sqrt(n));
 544 #endif
 545 }
 546
 547
 548 /** Wrapper around pow() */
 549 double
 550 _mesa_pow(double x, double y)
 551 {
 552    return pow(x, y);
 553 }
 554
 555
 556 /**
 557  * Find the first bit set in a word.
 558  */
 559 int
 560 _mesa_ffs(int i)
 561 {
 562 #if (defined(_WIN32) ) || defined(__IBMC__) || defined(__IBMCPP__)
 563    register int bit = 0;
 564    if (i != 0) {
 565       if ((i & 0xffff) == 0) {
 566          bit += 16;
 567          i >>= 16;
 568       }
 569       if ((i & 0xff) == 0) {
 570          bit += 8;
 571          i >>= 8;
 572       }
 573       if ((i & 0xf) == 0) {
 574          bit += 4;
 575          i >>= 4;
 576       }
 577       while ((i & 1) == 0) {
 578          bit++;
 579          i >>= 1;
 580       }
 581       bit++;
 582    }
 583    return bit;
 584 #else
 585    return ffs(i);
 586 #endif
 587 }
 588
 589
 590 /**
 591  * Find position of first bit set in given value.
 592  * XXX Warning: this function can only be used on 64-bit systems!
 593  * \return  position of least-significant bit set, starting at 1, return zero
 594  *          if no bits set.
 595  */
 596 int
 597 #ifdef __MINGW32__
 598 _mesa_ffsll(long val)
 599 #else
 600 _mesa_ffsll(long long val)
 601 #endif
 602 {
 603 #ifdef ffsll
 604    return ffsll(val);
 605 #else
 606    int bit;
 607
 608    assert(sizeof(val) == 8);
 609
 610    bit = _mesa_ffs(val);
 611    if (bit != 0)
 612       return bit;
 613
 614    bit = _mesa_ffs(val >> 32);
 615    if (bit != 0)
 616       return 32 + bit;
 617
 618    return 0;
 619 #endif
 620 }
 621
 622
 623 /**
 624  * Return number of bits set in given GLuint.
 625  */
 626 unsigned int
 627 _mesa_bitcount(unsigned int n)
 628 {
 629    unsigned int bits;
 630    for (bits = 0; n > 0; n = n >> 1) {
 631       bits += (n & 1);
 632    }
 633    return bits;
 634 }
 635
 636
 637 /**
 638  * Convert a 4-byte float to a 2-byte half float.
 639  * Based on code from:
 640  * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
 641  */
 642 GLhalfARB
 643 _mesa_float_to_half(float val)
 644 {
 645    const int flt = *((int *) (void *) &val);
 646    const int flt_m = flt & 0x7fffff;
 647    const int flt_e = (flt >> 23) & 0xff;
 648    const int flt_s = (flt >> 31) & 0x1;
 649    int s, e, m = 0;
 650    GLhalfARB result;
 651
 652    /* sign bit */
 653    s = flt_s;
 654
 655    /* handle special cases */
 656    if ((flt_e == 0) && (flt_m == 0)) {
 657       /* zero */
 658       /* m = 0; - already set */
 659       e = 0;
 660    }
 661    else if ((flt_e == 0) && (flt_m != 0)) {
 662       /* denorm -- denorm float maps to 0 half */
 663       /* m = 0; - already set */
 664       e = 0;
 665    }
 666    else if ((flt_e == 0xff) && (flt_m == 0)) {
 667       /* infinity */
 668       /* m = 0; - already set */
 669       e = 31;
 670    }
 671    else if ((flt_e == 0xff) && (flt_m != 0)) {
 672       /* NaN */
 673       m = 1;
 674       e = 31;
 675    }
 676    else {
 677       /* regular number */
 678       const int new_exp = flt_e - 127;
 679       if (new_exp < -24) {
 680          /* this maps to 0 */
 681          /* m = 0; - already set */
 682          e = 0;
 683       }
 684       else if (new_exp < -14) {
 685          /* this maps to a denorm */
 686          unsigned int exp_val = (unsigned int) (-14 - new_exp); /* 2^-exp_val*/
 687          e = 0;
 688          switch (exp_val) {
 689             case 0:
 690                _mesa_warning(NULL,
 691                    "float_to_half: logical error in denorm creation!\n");
 692                /* m = 0; - already set */
 693                break;
 694             case 1: m = 512 + (flt_m >> 14); break;
 695             case 2: m = 256 + (flt_m >> 15); break;
 696             case 3: m = 128 + (flt_m >> 16); break;
 697             case 4: m = 64 + (flt_m >> 17); break;
 698             case 5: m = 32 + (flt_m >> 18); break;
 699             case 6: m = 16 + (flt_m >> 19); break;
 700             case 7: m = 8 + (flt_m >> 20); break;
 701             case 8: m = 4 + (flt_m >> 21); break;
 702             case 9: m = 2 + (flt_m >> 22); break;
 703             case 10: m = 1; break;
 704          }
 705       }
 706       else if (new_exp > 15) {
 707          /* map this value to infinity */
 708          /* m = 0; - already set */
 709          e = 31;
 710       }
 711       else {
 712          /* regular */
 713          e = new_exp + 15;
 714          m = flt_m >> 13;
 715       }
 716    }
 717
 718    result = (s << 15) | (e << 10) | m;
 719    return result;
 720 }
 721
 722
 723 /**
 724  * Convert a 2-byte half float to a 4-byte float.
 725  * Based on code from:
 726  * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
 727  */
 728 float
 729 _mesa_half_to_float(GLhalfARB val)
 730 {
 731    /* XXX could also use a 64K-entry lookup table */
 732    const int m = val & 0x3ff;
 733    const int e = (val >> 10) & 0x1f;
 734    const int s = (val >> 15) & 0x1;
 735    int flt_m, flt_e, flt_s, flt;
 736    float result;
 737
 738    /* sign bit */
 739    flt_s = s;
 740
 741    /* handle special cases */
 742    if ((e == 0) && (m == 0)) {
 743       /* zero */
 744       flt_m = 0;
 745       flt_e = 0;
 746    }
 747    else if ((e == 0) && (m != 0)) {
 748       /* denorm -- denorm half will fit in non-denorm single */
 749       const float half_denorm = 1.0f / 16384.0f; /* 2^-14 */
 750       float mantissa = ((float) (m)) / 1024.0f;
 751       float sign = s ? -1.0f : 1.0f;
 752       return sign * mantissa * half_denorm;
 753    }
 754    else if ((e == 31) && (m == 0)) {
 755       /* infinity */
 756       flt_e = 0xff;
 757       flt_m = 0;
 758    }
 759    else if ((e == 31) && (m != 0)) {
 760       /* NaN */
 761       flt_e = 0xff;
 762       flt_m = 1;
 763    }
 764    else {
 765       /* regular */
 766       flt_e = e + 112;
 767       flt_m = m << 13;
 768    }
 769
 770    flt = (flt_s << 31) | (flt_e << 23) | flt_m;
 771    result = *((float *) (void *) &flt);
 772    return result;
 773 }
 774
 775 /*@}*/
 776
 777
 778 /**********************************************************************/
 779 /** \name Sort & Search */
 780 /*@{*/
 781
 782 /**
 783  * Wrapper for bsearch().
 784  */
 785 void *
 786 _mesa_bsearch( const void *key, const void *base, size_t nmemb, size_t size,
 787                int (*compar)(const void *, const void *) )
 788 {
 789 #if defined(_WIN32_WCE)
 790    void *mid;
 791    int cmp;
 792    while (nmemb) {
 793       nmemb >>= 1;
 794       mid = (char *)base + nmemb * size;
 795       cmp = (*compar)(key, mid);
 796       if (cmp == 0)
 797          return mid;
 798       if (cmp > 0) {
 799          base = (char *)mid + size;
 800          --nmemb;
 801       }
 802    }
 803    return NULL;
 804 #else
 805    return bsearch(key, base, nmemb, size, compar);
 806 #endif
 807 }
 808
 809 /*@}*/
 810
 811
 812 /**********************************************************************/
 813 /** \name Environment vars */
 814 /*@{*/
 815
 816 /**
 817  * Wrapper for getenv().
 818  */
 819 char *
 820 _mesa_getenv( const char *var )
 821 {
 822 #if defined(_XBOX) || defined(_WIN32_WCE)
 823    return NULL;
 824 #else
 825    return getenv(var);
 826 #endif
 827 }
 828
 829 /*@}*/
 830
 831
 832 /**********************************************************************/
 833 /** \name String */
 834 /*@{*/
 835
 836 /** Wrapper around strstr() */
 837 char *
 838 _mesa_strstr( const char *haystack, const char *needle )
 839 {
 840    return strstr(haystack, needle);
 841 }
 842
 843 /** Wrapper around strncat() */
 844 char *
 845 _mesa_strncat( char *dest, const char *src, size_t n )
 846 {
 847    return strncat(dest, src, n);
 848 }
 849
 850 /** Wrapper around strcpy() */
 851 char *
 852 _mesa_strcpy( char *dest, const char *src )
 853 {
 854    return strcpy(dest, src);
 855 }
 856
 857 /** Wrapper around strncpy() */
 858 char *
 859 _mesa_strncpy( char *dest, const char *src, size_t n )
 860 {
 861    return strncpy(dest, src, n);
 862 }
 863
 864 /** Wrapper around strlen() */
 865 size_t
 866 _mesa_strlen( const char *s )
 867 {
 868    return strlen(s);
 869 }
 870
 871 /** Wrapper around strcmp() */
 872 int
 873 _mesa_strcmp( const char *s1, const char *s2 )
 874 {
 875    return strcmp(s1, s2);
 876 }
 877
 878 /** Wrapper around strncmp() */
 879 int
 880 _mesa_strncmp( const char *s1, const char *s2, size_t n )
 881 {
 882    return strncmp(s1, s2, n);
 883 }
 884
 885 /**
 886  * Implemented using _mesa_malloc() and _mesa_strcpy.
 887  * Note that NULL is handled accordingly.
 888  */
 889 char *
 890 _mesa_strdup( const char *s )
 891 {
 892    if (s) {
 893       size_t l = _mesa_strlen(s);
 894       char *s2 = (char *) _mesa_malloc(l + 1);
 895       if (s2)
 896          _mesa_strcpy(s2, s);
 897       return s2;
 898    }
 899    else {
 900       return NULL;
 901    }
 902 }
 903
 904 /** Wrapper around atoi() */
 905 int
 906 _mesa_atoi(const char *s)
 907 {
 908    return atoi(s);
 909 }
 910
 911 /** Wrapper around strtod() */
 912 double
 913 _mesa_strtod( const char *s, char **end )
 914 {
 915    return strtod(s, end);
 916 }
 917
 918 /*@}*/
 919
 920
 921 /**********************************************************************/
 922 /** \name I/O */
 923 /*@{*/
 924
 925 /** Wrapper around vsprintf() */
 926 int
 927 _mesa_sprintf( char *str, const char *fmt, ... )
 928 {
 929    int r;
 930    va_list args;
 931    va_start( args, fmt );
 932    r = vsprintf( str, fmt, args );
 933    va_end( args );
 934    return r;
 935 }
 936
 937 /** Wrapper around vsnprintf() */
 938 int
 939 _mesa_snprintf( char *str, size_t size, const char *fmt, ... )
 940 {
 941    int r;
 942    va_list args;
 943    va_start( args, fmt );
 944    r = vsnprintf( str, size, fmt, args );
 945    va_end( args );
 946    return r;
 947 }
 948
 949 /** Wrapper around printf(), using vsprintf() for the formatting. */
 950 void
 951 _mesa_printf( const char *fmtString, ... )
 952 {
 953    char s[MAXSTRING];
 954    va_list args;
 955    va_start( args, fmtString );
 956    vsnprintf(s, MAXSTRING, fmtString, args);
 957    va_end( args );
 958    fprintf(stderr,"%s", s);
 959 }
 960
 961 /** Wrapper around vsprintf() */
 962 int
 963 _mesa_vsprintf( char *str, const char *fmt, va_list args )
 964 {
 965    return vsprintf( str, fmt, args );
 966 }
 967
 968 /*@}*/
 969
 970
 971 /**********************************************************************/
 972 /** \name Diagnostics */
 973 /*@{*/
 974
 975 /**
 976  * Report a warning (a recoverable error condition) to stderr if
 977  * either DEBUG is defined or the MESA_DEBUG env var is set.
 978  *
 979  * \param ctx GL context.
 980  * \param fmtString printf() alike format string.
 981  */
 982 void
 983 _mesa_warning( GLcontext *ctx, const char *fmtString, ... )
 984 {
 985    GLboolean debug;
 986    char str[MAXSTRING];
 987    va_list args;
 988    (void) ctx;
 989    va_start( args, fmtString );
 990    (void) vsnprintf( str, MAXSTRING, fmtString, args );
 991    va_end( args );
 992 #ifdef DEBUG
 993    debug = GL_TRUE; /* always print warning */
 994 #else
 995    debug = _mesa_getenv("MESA_DEBUG") ? GL_TRUE : GL_FALSE;
 996 #endif
 997    if (debug) {
 998       fprintf(stderr, "Mesa warning: %s\n", str);
 999    }
1000 }
1001
1002 /**
1003  * Report an internla implementation problem.
1004  * Prints the message to stderr via fprintf().
1005  *
1006  * \param ctx GL context.
1007  * \param s problem description string.
1008  */
1009 void
1010 _mesa_problem( const GLcontext *ctx, const char *fmtString, ... )
1011 {
1012    va_list args;
1013    char str[MAXSTRING];
1014    (void) ctx;
1015
1016    va_start( args, fmtString );
1017    vsnprintf( str, MAXSTRING, fmtString, args );
1018    va_end( args );
1019
1020    fprintf(stderr, "Mesa %s implementation error: %s\n", MESA_VERSION_STRING, str);
1021    fprintf(stderr, "Please report at bugzilla.freedesktop.org\n");
1022 }
1023
1024 /**
1025  * Record an OpenGL state error.  These usually occur when the users
1026  * passes invalid parameters to a GL function.
1027  *
1028  * If debugging is enabled (either at compile-time via the DEBUG macro, or
1029  * run-time via the MESA_DEBUG environment variable), report the error with
1030  * _mesa_debug().
1031  *
1032  * \param ctx the GL context.
1033  * \param error the error value.
1034  * \param fmtString printf() style format string, followed by optional args
1035  */
1036 void
1037 _mesa_error( GLcontext *ctx, GLenum error, const char *fmtString, ... )
1038 {
1039    const char *debugEnv;
1040    GLboolean debug;
1041
1042    debugEnv = _mesa_getenv("MESA_DEBUG");
1043
1044 #ifdef DEBUG
1045    if (debugEnv && _mesa_strstr(debugEnv, "silent"))
1046       debug = GL_FALSE;
1047    else
1048       debug = GL_TRUE;
1049 #else
1050    if (debugEnv)
1051       debug = GL_TRUE;
1052    else
1053       debug = GL_FALSE;
1054 #endif
1055
1056    if (debug) {
1057       va_list args;
1058       char where[MAXSTRING];
1059       const char *errstr;
1060
1061       va_start( args, fmtString );
1062       vsnprintf( where, MAXSTRING, fmtString, args );
1063       va_end( args );
1064
1065       switch (error) {
1066          case GL_NO_ERROR:
1067             errstr = "GL_NO_ERROR";
1068             break;
1069          case GL_INVALID_VALUE:
1070             errstr = "GL_INVALID_VALUE";
1071             break;
1072          case GL_INVALID_ENUM:
1073             errstr = "GL_INVALID_ENUM";
1074             break;
1075          case GL_INVALID_OPERATION:
1076             errstr = "GL_INVALID_OPERATION";
1077             break;
1078          case GL_STACK_OVERFLOW:
1079             errstr = "GL_STACK_OVERFLOW";
1080             break;
1081          case GL_STACK_UNDERFLOW:
1082             errstr = "GL_STACK_UNDERFLOW";
1083             break;
1084          case GL_OUT_OF_MEMORY:
1085             errstr = "GL_OUT_OF_MEMORY";
1086             break;
1087          case GL_TABLE_TOO_LARGE:
1088             errstr = "GL_TABLE_TOO_LARGE";
1089             break;
1090          case GL_INVALID_FRAMEBUFFER_OPERATION_EXT:
1091             errstr = "GL_INVALID_FRAMEBUFFER_OPERATION";
1092             break;
1093          default:
1094             errstr = "unknown";
1095             break;
1096       }
1097       _mesa_debug(ctx, "User error: %s in %s\n", errstr, where);
1098    }
1099
1100    _mesa_record_error(ctx, error);
1101 }
1102
1103 /**
1104  * Report debug information.  Print error message to stderr via fprintf().
1105  * No-op if DEBUG mode not enabled.
1106  *
1107  * \param ctx GL context.
1108  * \param fmtString printf()-style format string, followed by optional args.
1109  */
1110 void
1111 _mesa_debug( const GLcontext *ctx, const char *fmtString, ... )
1112 {
1113 #ifdef DEBUG
1114    char s[MAXSTRING];
1115    va_list args;
1116    va_start(args, fmtString);
1117    vsnprintf(s, MAXSTRING, fmtString, args);
1118    va_end(args);
1119    fprintf(stderr, "Mesa: %s", s);
1120 #endif /* DEBUG */
1121    (void) ctx;
1122    (void) fmtString;
1123 }
1124
1125 /*@}*/
1126
1127
1128 /**
1129  * Wrapper for exit().
1130  */
1131 void
1132 _mesa_exit( int status )
1133 {
1134    exit(status);
1135 }