dlls/kernel/dosmem.c

   1 /*
   2  * DOS memory emulation
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  * Copyright 1996 Marcus Meissner
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include "config.h"
  23 #include "wine/port.h"
  24
  25 #include <signal.h>
  26 #include <stdarg.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sys/types.h>
  30 #ifdef HAVE_SYS_MMAN_H
  31 # include <sys/mman.h>
  32 #endif
  33
  34 #include <time.h>
  35 #ifdef HAVE_SYS_TIME_H
  36 # include <sys/time.h>
  37 #endif
  38
  39 #include "windef.h"
  40 #include "winbase.h"
  41 #include "wine/winbase16.h"
  42
  43 #include "global.h"
  44 #include "selectors.h"
  45 #include "miscemu.h"
  46 #include "wine/debug.h"
  47
  48 WINE_DEFAULT_DEBUG_CHANNEL(dosmem);
  49 WINE_DECLARE_DEBUG_CHANNEL(selector);
  50
  51 WORD DOSMEM_0000H;        /* segment at 0:0 */
  52 WORD DOSMEM_BiosDataSeg;  /* BIOS data segment at 0x40:0 */
  53 WORD DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
  54
  55 /* use 2 low bits of 'size' for the housekeeping */
  56
  57 #define DM_BLOCK_DEBUG          0xABE00000
  58 #define DM_BLOCK_TERMINAL       0x00000001
  59 #define DM_BLOCK_FREE           0x00000002
  60 #define DM_BLOCK_MASK           0x001FFFFC
  61
  62 /*
  63 #define __DOSMEM_DEBUG__
  64  */
  65
  66 typedef struct {
  67    unsigned     size;
  68 } dosmem_entry;
  69
  70 typedef struct {
  71   unsigned      blocks;
  72   unsigned      free;
  73 } dosmem_info;
  74
  75 #define NEXT_BLOCK(block) \
  76         (dosmem_entry*)(((char*)(block)) + \
  77          sizeof(dosmem_entry) + ((block)->size & DM_BLOCK_MASK))
  78
  79 #define VM_STUB(x) (0x90CF00CD|(x<<8)) /* INT x; IRET; NOP */
  80 #define VM_STUB_SEGMENT 0xf000         /* BIOS segment */
  81
  82 /* DOS memory base */
  83 static char *DOSMEM_dosmem;
  84 /* DOS system base (for interrupt vector table and BIOS data area)
  85  * ...should in theory (i.e. Windows) be equal to DOSMEM_dosmem (NULL),
  86  * but is normally set to 0xf0000 in Wine to allow trapping of NULL pointers,
  87  * and only relocated to NULL when absolutely necessary */
  88 static char *DOSMEM_sysmem;
  89
  90 /* Start of DOS conventional memory */
  91 static char *DOSMEM_membase;
  92
  93 static void DOSMEM_InitMemory(void);
  94
  95 /***********************************************************************
  96  *           DOSMEM_MemoryTop
  97  *
  98  * Gets the DOS memory top.
  99  */
 100 static char *DOSMEM_MemoryTop(void)
 101 {
 102     return DOSMEM_dosmem+0x9FFFC; /* 640K */
 103 }
 104
 105 /***********************************************************************
 106  *           DOSMEM_InfoBlock
 107  *
 108  * Gets the DOS memory info block.
 109  */
 110 static dosmem_info *DOSMEM_InfoBlock(void)
 111 {
 112     if (!DOSMEM_membase)
 113     {
 114         DWORD         reserve;
 115
 116         /*
 117          * Reserve either:
 118          * - lowest 64k for NULL pointer catching (Win16)
 119          * - lowest 1k for interrupt handlers and
 120          *   another 0.5k for BIOS, DOS and intra-application
 121          *   areas (DOS)
 122          */
 123         if (DOSMEM_dosmem != DOSMEM_sysmem)
 124             reserve = 0x10000; /* 64k */
 125         else
 126             reserve = 0x600; /* 1.5k */
 127
 128         /*
 129          * Round to paragraph boundary in order to make
 130          * sure the alignment is correct.
 131          */
 132         reserve = ((reserve + 15) >> 4) << 4;
 133
 134         /*
 135          * Set DOS memory base and initialize conventional memory.
 136          */
 137         DOSMEM_membase = DOSMEM_dosmem + reserve;
 138         DOSMEM_InitMemory();
 139     }
 140
 141     return (dosmem_info*)DOSMEM_membase;
 142 }
 143
 144 /***********************************************************************
 145  *           DOSMEM_RootBlock
 146  *
 147  * Gets the DOS memory root block.
 148  */
 149 static dosmem_entry *DOSMEM_RootBlock(void)
 150 {
 151     /* first block has to be paragraph-aligned */
 152     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock()) +
 153                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 154 }
 155
 156 /***********************************************************************
 157  *           DOSMEM_FillIsrTable
 158  *
 159  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 160  *
 161  * NOTES:
 162  * Linux normally only traps INTs performed from or destined to BIOSSEG
 163  * for us to handle, if the int_revectored table is empty. Filling the
 164  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 165  * to hook interrupts, as well as use their familiar retf tricks to call
 166  * them, AND let Wine handle any unhooked interrupts transparently.
 167  */
 168 static void DOSMEM_FillIsrTable(void)
 169 {
 170     SEGPTR *isr = (SEGPTR*)DOSMEM_sysmem;
 171     int x;
 172
 173     for (x=0; x<256; x++) isr[x]=MAKESEGPTR(VM_STUB_SEGMENT,x*4);
 174 }
 175
 176 static void DOSMEM_MakeIsrStubs(void)
 177 {
 178     DWORD *stub = (DWORD*)(DOSMEM_dosmem + (VM_STUB_SEGMENT << 4));
 179     int x;
 180
 181     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 182 }
 183
 184 static BIOSDATA * DOSMEM_BiosData(void)
 185 {
 186     return (BIOSDATA *)(DOSMEM_sysmem + 0x400);
 187 }
 188
 189 /**********************************************************************
 190  *          DOSMEM_GetTicksSinceMidnight
 191  *
 192  * Return number of clock ticks since midnight.
 193  */
 194 static DWORD DOSMEM_GetTicksSinceMidnight(void)
 195 {
 196     struct tm *bdtime;
 197     struct timeval tvs;
 198     time_t seconds;
 199
 200     /* This should give us the (approximately) correct
 201      * 18.206 clock ticks per second since midnight.
 202      */
 203     gettimeofday( &tvs, NULL );
 204     seconds = tvs.tv_sec;
 205     bdtime = localtime( &seconds );
 206     return (((bdtime->tm_hour * 3600 + bdtime->tm_min * 60 +
 207               bdtime->tm_sec) * 18206) / 1000) +
 208                   (tvs.tv_usec / 54927);
 209 }
 210
 211 /***********************************************************************
 212  *           DOSMEM_FillBiosSegments
 213  *
 214  * Fill the BIOS data segment with dummy values.
 215  */
 216 static void DOSMEM_FillBiosSegments(void)
 217 {
 218     BYTE *pBiosSys = DOSMEM_dosmem + 0xf0000;
 219     BYTE *pBiosROMTable = pBiosSys+0xe6f5;
 220     BIOSDATA *pBiosData = DOSMEM_BiosData();
 221
 222       /* Clear all unused values */
 223     memset( pBiosData, 0, sizeof(*pBiosData) );
 224
 225     /* FIXME: should check the number of configured drives and ports */
 226     pBiosData->Com1Addr             = 0x3f8;
 227     pBiosData->Com2Addr             = 0x2f8;
 228     pBiosData->Lpt1Addr             = 0x378;
 229     pBiosData->Lpt2Addr             = 0x278;
 230     pBiosData->InstalledHardware    = 0x5463;
 231     pBiosData->MemSize              = 640;
 232     pBiosData->NextKbdCharPtr       = 0x1e;
 233     pBiosData->FirstKbdCharPtr      = 0x1e;
 234     pBiosData->VideoMode            = 3;
 235     pBiosData->VideoColumns         = 80;
 236     pBiosData->VideoPageSize        = 80 * 25 * 2;
 237     pBiosData->VideoPageStartAddr   = 0xb800;
 238     pBiosData->VideoCtrlAddr        = 0x3d4;
 239     pBiosData->Ticks                = DOSMEM_GetTicksSinceMidnight();
 240     pBiosData->NbHardDisks          = 2;
 241     pBiosData->KbdBufferStart       = 0x1e;
 242     pBiosData->KbdBufferEnd         = 0x3e;
 243     pBiosData->RowsOnScreenMinus1   = 24;
 244     pBiosData->BytesPerChar         = 0x10;
 245     pBiosData->ModeOptions          = 0x64;
 246     pBiosData->FeatureBitsSwitches  = 0xf9;
 247     pBiosData->VGASettings          = 0x51;
 248     pBiosData->DisplayCombination   = 0x08;
 249     pBiosData->DiskDataRate         = 0;
 250
 251     /* fill ROM configuration table (values from Award) */
 252     *(pBiosROMTable+0x0)        = 0x08; /* number of bytes following LO */
 253     *(pBiosROMTable+0x1)        = 0x00; /* number of bytes following HI */
 254     *(pBiosROMTable+0x2)        = 0xfc; /* model */
 255     *(pBiosROMTable+0x3)        = 0x01; /* submodel */
 256     *(pBiosROMTable+0x4)        = 0x00; /* BIOS revision */
 257     *(pBiosROMTable+0x5)        = 0x74; /* feature byte 1 */
 258     *(pBiosROMTable+0x6)        = 0x00; /* feature byte 2 */
 259     *(pBiosROMTable+0x7)        = 0x00; /* feature byte 3 */
 260     *(pBiosROMTable+0x8)        = 0x00; /* feature byte 4 */
 261     *(pBiosROMTable+0x9)        = 0x00; /* feature byte 5 */
 262
 263     /* BIOS date string */
 264     strcpy((char *)pBiosSys+0xfff5, "13/01/99");
 265
 266     /* BIOS ID */
 267     *(pBiosSys+0xfffe) = 0xfc;
 268
 269     /* Reboot vector (f000:fff0 or ffff:0000) */
 270     *(DWORD*)(pBiosSys + 0xfff0) = VM_STUB(0x19);
 271 }
 272
 273 /***********************************************************************
 274  *           DOSMEM_InitMemory
 275  *
 276  * Initialises the DOS memory structures.
 277  */
 278 static void DOSMEM_InitMemory(void)
 279 {
 280     dosmem_info*        info_block = DOSMEM_InfoBlock();
 281     dosmem_entry*       root_block = DOSMEM_RootBlock();
 282     dosmem_entry*       dm;
 283
 284     root_block->size = DOSMEM_MemoryTop() - (((char*)root_block) + sizeof(dosmem_entry));
 285
 286     info_block->blocks = 0;
 287     info_block->free = root_block->size;
 288
 289     dm = NEXT_BLOCK(root_block);
 290     dm->size = DM_BLOCK_TERMINAL;
 291     root_block->size |= DM_BLOCK_FREE
 292 #ifdef __DOSMEM_DEBUG__
 293                      | DM_BLOCK_DEBUG
 294 #endif
 295                      ;
 296
 297     TRACE( "DOS conventional memory initialized, %d bytes free.\n",
 298            DOSMEM_Available() );
 299 }
 300
 301
 302 /**********************************************************************
 303  *              setup_dos_mem
 304  *
 305  * Setup the first megabyte for DOS memory access
 306  */
 307 static void setup_dos_mem( int dos_init )
 308 {
 309     int sys_offset = 0;
 310     int page_size = getpagesize();
 311     void *addr = wine_anon_mmap( (void *)page_size, 0x110000-page_size,
 312                                  PROT_READ | PROT_WRITE | PROT_EXEC, 0 );
 313     if (addr == (void *)page_size)  /* we got what we wanted */
 314     {
 315         /* now map from address 0 */
 316         addr = wine_anon_mmap( NULL, 0x110000, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED );
 317         if (addr)
 318         {
 319             ERR("MAP_FIXED failed at address 0 for DOS address space\n" );
 320             ExitProcess(1);
 321         }
 322
 323         /* inform the memory manager that there is a mapping here */
 324         VirtualAlloc( addr, 0x110000, MEM_RESERVE | MEM_SYSTEM, PAGE_EXECUTE_READWRITE );
 325
 326         /* protect the first 64K to catch NULL pointers */
 327         if (!dos_init)
 328         {
 329             VirtualProtect( addr, 0x10000, PAGE_NOACCESS, NULL );
 330             /* move the BIOS and ISR area from 0x00000 to 0xf0000 */
 331             sys_offset += 0xf0000;
 332         }
 333     }
 334     else
 335     {
 336         ERR("Cannot use first megabyte for DOS address space, please report\n" );
 337         if (dos_init) ExitProcess(1);
 338         /* allocate the DOS area somewhere else */
 339         addr = VirtualAlloc( NULL, 0x110000, MEM_COMMIT, PAGE_EXECUTE_READWRITE );
 340         if (!addr)
 341         {
 342             ERR( "Cannot allocate DOS memory\n" );
 343             ExitProcess(1);
 344         }
 345     }
 346     DOSMEM_dosmem = addr;
 347     DOSMEM_sysmem = (char*)addr + sys_offset;
 348 }
 349
 350
 351 /***********************************************************************
 352  *           DOSMEM_Init
 353  *
 354  * Create the dos memory segments, and store them into the KERNEL
 355  * exported values.
 356  */
 357 BOOL DOSMEM_Init(BOOL dos_init)
 358 {
 359     static int already_done, already_mapped;
 360
 361     if (!already_done)
 362     {
 363         setup_dos_mem( dos_init );
 364
 365         DOSMEM_0000H = GLOBAL_CreateBlock( GMEM_FIXED, DOSMEM_sysmem,
 366                                            0x10000, 0, WINE_LDT_FLAGS_DATA );
 367         DOSMEM_BiosDataSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_sysmem + 0x400,
 368                                                 0x100, 0, WINE_LDT_FLAGS_DATA );
 369         DOSMEM_BiosSysSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0xf0000,
 370                                                0x10000, 0, WINE_LDT_FLAGS_DATA );
 371         DOSMEM_FillBiosSegments();
 372         DOSMEM_FillIsrTable();
 373         already_done = 1;
 374     }
 375     else if (dos_init && !already_mapped)
 376     {
 377         if (DOSMEM_dosmem)
 378         {
 379             ERR( "Needs access to the first megabyte for DOS mode\n" );
 380             ExitProcess(1);
 381         }
 382         MESSAGE( "Warning: unprotecting the first 64KB of memory to allow real-mode calls.\n"
 383                  "         NULL pointer accesses will no longer be caught.\n" );
 384         VirtualProtect( NULL, 0x10000, PAGE_EXECUTE_READWRITE, NULL );
 385         /* copy the BIOS and ISR area down */
 386         memcpy( DOSMEM_dosmem, DOSMEM_sysmem, 0x400 + 0x100 );
 387         DOSMEM_sysmem = DOSMEM_dosmem;
 388         SetSelectorBase( DOSMEM_0000H, 0 );
 389         SetSelectorBase( DOSMEM_BiosDataSeg, 0x400 );
 390         /* we may now need the actual interrupt stubs, and since we've just moved the
 391          * interrupt vector table away, we can fill the area with stubs instead... */
 392         DOSMEM_MakeIsrStubs();
 393         already_mapped = 1;
 394     }
 395     return TRUE;
 396 }
 397
 398
 399 /***********************************************************************
 400  *           DOSMEM_Tick
 401  *
 402  * Increment the BIOS tick counter. Called by timer signal handler.
 403  */
 404 void DOSMEM_Tick( WORD timer )
 405 {
 406     BIOSDATA *pBiosData = DOSMEM_BiosData();
 407     if (pBiosData) pBiosData->Ticks++;
 408 }
 409
 410 /***********************************************************************
 411  *           DOSMEM_GetBlock
 412  *
 413  * Carve a chunk of the DOS memory block (without selector).
 414  */
 415 LPVOID DOSMEM_GetBlock(UINT size, UINT16* pseg)
 416 {
 417    UINT          blocksize;
 418    char         *block = NULL;
 419    dosmem_info  *info_block = DOSMEM_InfoBlock();
 420    dosmem_entry *dm;
 421 #ifdef __DOSMEM_DEBUG_
 422    dosmem_entry *prev = NULL;
 423 #endif
 424
 425    if( size > info_block->free ) return NULL;
 426    dm = DOSMEM_RootBlock();
 427
 428    while (dm && dm->size != DM_BLOCK_TERMINAL)
 429    {
 430 #ifdef __DOSMEM_DEBUG__
 431        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 432        {
 433             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 434             return NULL;
 435        }
 436        prev = dm;
 437 #endif
 438        if( dm->size & DM_BLOCK_FREE )
 439        {
 440            dosmem_entry  *next = NEXT_BLOCK(dm);
 441
 442            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 443            {
 444                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 445                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 446                next = NEXT_BLOCK(dm);
 447            }
 448
 449            blocksize = dm->size & DM_BLOCK_MASK;
 450            if( blocksize >= size )
 451            {
 452                block = ((char*)dm) + sizeof(dosmem_entry);
 453                if( blocksize - size > 0x20 )
 454                {
 455                    /* split dm so that the next one stays
 456                     * paragraph-aligned (and dm loses free bit) */
 457
 458                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 459                                               sizeof(dosmem_entry));
 460                    next = (dosmem_entry*)(((char*)dm) +
 461                            sizeof(dosmem_entry) + dm->size);
 462                    next->size = (blocksize - (dm->size +
 463                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 464 #ifdef __DOSMEM_DEBUG__
 465                                                   | DM_BLOCK_DEBUG
 466 #endif
 467                                                   ;
 468                } else dm->size &= DM_BLOCK_MASK;
 469
 470                info_block->blocks++;
 471                info_block->free -= dm->size;
 472                if( pseg ) *pseg = (block - DOSMEM_dosmem) >> 4;
 473 #ifdef __DOSMEM_DEBUG__
 474                dm->size |= DM_BLOCK_DEBUG;
 475 #endif
 476                break;
 477            }
 478            dm = next;
 479        }
 480        else dm = NEXT_BLOCK(dm);
 481    }
 482    return (LPVOID)block;
 483 }
 484
 485 /***********************************************************************
 486  *           DOSMEM_FreeBlock
 487  */
 488 BOOL DOSMEM_FreeBlock(void* ptr)
 489 {
 490    dosmem_info  *info_block = DOSMEM_InfoBlock();
 491
 492    if( ptr >= (void*)(((char*)DOSMEM_RootBlock()) + sizeof(dosmem_entry)) &&
 493        ptr < (void*)DOSMEM_MemoryTop() && !((((char*)ptr)
 494                   - DOSMEM_dosmem) & 0xf) )
 495    {
 496        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 497
 498        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 499 #ifdef __DOSMEM_DEBUG__
 500          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 501 #endif
 502          )
 503        {
 504              info_block->blocks--;
 505              info_block->free += dm->size;
 506
 507              dm->size |= DM_BLOCK_FREE;
 508              return TRUE;
 509        }
 510    }
 511    return FALSE;
 512 }
 513
 514 /***********************************************************************
 515  *           DOSMEM_ResizeBlock
 516  *
 517  * Resize DOS memory block in place. Returns block size or -1 on error.
 518  *
 519  * If exact is TRUE, returned value is either old or requested block
 520  * size. If exact is FALSE, block is expanded even if there is not
 521  * enough space for full requested block size.
 522  */
 523 UINT DOSMEM_ResizeBlock(void *ptr, UINT size, BOOL exact)
 524 {
 525    char         *block = NULL;
 526    dosmem_info  *info_block = DOSMEM_InfoBlock();
 527    dosmem_entry *dm;
 528    dosmem_entry *next;
 529    UINT blocksize;
 530    UINT orgsize;
 531
 532    if( (ptr < (void*)(sizeof(dosmem_entry) + (char*)DOSMEM_RootBlock())) ||
 533        (ptr >= (void*)DOSMEM_MemoryTop()) ||
 534        (((((char*)ptr) - DOSMEM_dosmem) & 0xf) != 0) )
 535      return (UINT)-1;
 536
 537    dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 538    if( dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL) )
 539        return (UINT)-1;
 540
 541    next = NEXT_BLOCK(dm);
 542    orgsize = dm->size & DM_BLOCK_MASK;
 543
 544    /* collapse free blocks */
 545    while( next->size & DM_BLOCK_FREE )
 546    {
 547        dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 548        next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 549        next = NEXT_BLOCK(dm);
 550    }
 551
 552    blocksize = dm->size & DM_BLOCK_MASK;
 553
 554    /*
 555     * If collapse didn't help we either expand block to maximum
 556     * available size (exact == FALSE) or give collapsed blocks
 557     * back to free storage (exact == TRUE).
 558     */
 559    if (blocksize < size)
 560        size = exact ? orgsize : blocksize;
 561
 562    block = ((char*)dm) + sizeof(dosmem_entry);
 563    if( blocksize - size > 0x20 )
 564    {
 565        /*
 566         * split dm so that the next one stays
 567         * paragraph-aligned (and next gains free bit)
 568         */
 569
 570        dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 571                    sizeof(dosmem_entry));
 572        next = (dosmem_entry*)(((char*)dm) +
 573                               sizeof(dosmem_entry) + dm->size);
 574        next->size = (blocksize - (dm->size +
 575                                   sizeof(dosmem_entry))) | DM_BLOCK_FREE;
 576    }
 577    else
 578    {
 579        dm->size &= DM_BLOCK_MASK;
 580    }
 581
 582    /*
 583     * Adjust available memory if block size changes.
 584     */
 585    info_block->free += orgsize - dm->size;
 586
 587    return size;
 588 }
 589
 590 /***********************************************************************
 591  *           DOSMEM_Available
 592  */
 593 UINT DOSMEM_Available(void)
 594 {
 595    UINT          blocksize, available = 0;
 596    dosmem_entry *dm;
 597
 598    dm = DOSMEM_RootBlock();
 599
 600    while (dm && dm->size != DM_BLOCK_TERMINAL)
 601    {
 602 #ifdef __DOSMEM_DEBUG__
 603        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 604        {
 605             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 606             return NULL;
 607        }
 608        prev = dm;
 609 #endif
 610        if( dm->size & DM_BLOCK_FREE )
 611        {
 612            dosmem_entry  *next = NEXT_BLOCK(dm);
 613
 614            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 615            {
 616                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 617                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 618                next = NEXT_BLOCK(dm);
 619            }
 620
 621            blocksize = dm->size & DM_BLOCK_MASK;
 622            if ( blocksize > available ) available = blocksize;
 623            dm = next;
 624        }
 625        else dm = NEXT_BLOCK(dm);
 626    }
 627    return available;
 628 }
 629
 630
 631 /***********************************************************************
 632  *           DOSMEM_MapLinearToDos
 633  *
 634  * Linear address to the DOS address space.
 635  */
 636 UINT DOSMEM_MapLinearToDos(LPVOID ptr)
 637 {
 638     if (((char*)ptr >= DOSMEM_dosmem) &&
 639         ((char*)ptr < DOSMEM_dosmem + 0x100000))
 640           return (UINT)ptr - (UINT)DOSMEM_dosmem;
 641     return (UINT)ptr;
 642 }
 643
 644
 645 /***********************************************************************
 646  *           DOSMEM_MapDosToLinear
 647  *
 648  * DOS linear address to the linear address space.
 649  */
 650 LPVOID DOSMEM_MapDosToLinear(UINT ptr)
 651 {
 652     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT)DOSMEM_dosmem);
 653     return (LPVOID)ptr;
 654 }
 655
 656
 657 /***********************************************************************
 658  *           DOSMEM_MapRealToLinear
 659  *
 660  * Real mode DOS address into a linear pointer
 661  */
 662 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 663 {
 664    LPVOID       lin;
 665
 666    lin=DOSMEM_dosmem+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 667    TRACE_(selector)("(0x%08lx) returns %p.\n", x, lin );
 668    return lin;
 669 }
 670
 671 /***********************************************************************
 672  *           DOSMEM_AllocSelector
 673  *
 674  * Allocates a protected mode selector for a realmode segment.
 675  */
 676 WORD DOSMEM_AllocSelector(WORD realsel)
 677 {
 678         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 679         WORD    sel;
 680
 681         sel=GLOBAL_CreateBlock( GMEM_FIXED, DOSMEM_dosmem+realsel*16, 0x10000,
 682                                 hModule, WINE_LDT_FLAGS_DATA );
 683         TRACE_(selector)("(0x%04x) returns 0x%04x.\n", realsel,sel);
 684         return sel;
 685 }