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