git.oblomov.eu Git - wine/blob - msdos/dosmem.c

   1 /*
   2  * DOS memory emulation
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  * Copyright 1996 Marcus Meissner
   6  */
   7
   8 #include <signal.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include "winbase.h"
  12 #include "wine/winbase16.h"
  13 #include "global.h"
  14 #include "ldt.h"
  15 #include "miscemu.h"
  16 #include "vga.h"
  17 #include "dosexe.h"
  18 #include "debugtools.h"
  19
  20 DEFAULT_DEBUG_CHANNEL(dosmem)
  21 DECLARE_DEBUG_CHANNEL(selector)
  22
  23 HANDLE16 DOSMEM_BiosDataSeg;  /* BIOS data segment at 0x40:0 */
  24 HANDLE16 DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
  25
  26 static char     *DOSMEM_dosmem;
  27
  28        DWORD     DOSMEM_CollateTable;
  29
  30        DWORD     DOSMEM_ErrorCall;
  31        DWORD     DOSMEM_ErrorBuffer;
  32
  33 /* use 2 low bits of 'size' for the housekeeping */
  34
  35 #define DM_BLOCK_DEBUG          0xABE00000
  36 #define DM_BLOCK_TERMINAL       0x00000001
  37 #define DM_BLOCK_FREE           0x00000002
  38 #define DM_BLOCK_MASK           0x001FFFFC
  39
  40 /*
  41 #define __DOSMEM_DEBUG__
  42  */
  43
  44 typedef struct {
  45    unsigned     size;
  46 } dosmem_entry;
  47
  48 typedef struct {
  49   unsigned      blocks;
  50   unsigned      free;
  51 } dosmem_info;
  52
  53 #define NEXT_BLOCK(block) \
  54         (dosmem_entry*)(((char*)(block)) + \
  55          sizeof(dosmem_entry) + ((block)->size & DM_BLOCK_MASK))
  56
  57 #define VM_STUB(x) (0x90CF00CD|(x<<8)) /* INT x; IRET; NOP */
  58 #define VM_STUB_SEGMENT 0xf000         /* BIOS segment */
  59
  60 /***********************************************************************
  61  *           DOSMEM_MemoryBase
  62  *
  63  * Gets the DOS memory base.
  64  */
  65 char *DOSMEM_MemoryBase(void)
  66 {
  67     LPDOSTASK lpDosTask = MZ_Current();
  68
  69     if (lpDosTask && lpDosTask->img)
  70         return lpDosTask->img;
  71     else
  72         return DOSMEM_dosmem;
  73 }
  74
  75 /***********************************************************************
  76  *           DOSMEM_MemoryTop
  77  *
  78  * Gets the DOS memory top.
  79  */
  80 static char *DOSMEM_MemoryTop(void)
  81 {
  82     return DOSMEM_MemoryBase()+0x9FFFC; /* 640K */
  83 }
  84
  85 /***********************************************************************
  86  *           DOSMEM_InfoBlock
  87  *
  88  * Gets the DOS memory info block.
  89  */
  90 static dosmem_info *DOSMEM_InfoBlock(void)
  91 {
  92     return (dosmem_info*)(DOSMEM_MemoryBase()+0x10000); /* 64K */
  93 }
  94
  95 /***********************************************************************
  96  *           DOSMEM_RootBlock
  97  *
  98  * Gets the DOS memory root block.
  99  */
 100 static dosmem_entry *DOSMEM_RootBlock(void)
 101 {
 102     /* first block has to be paragraph-aligned */
 103     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock()) +
 104                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 105 }
 106
 107 /***********************************************************************
 108  *           DOSMEM_FillIsrTable
 109  *
 110  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 111  *
 112  * NOTES:
 113  * Linux normally only traps INTs performed from or destined to BIOSSEG
 114  * for us to handle, if the int_revectored table is empty. Filling the
 115  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 116  * to hook interrupts, as well as use their familiar retf tricks to call
 117  * them, AND let Wine handle any unhooked interrupts transparently.
 118  */
 119 static void DOSMEM_FillIsrTable(void)
 120 {
 121     SEGPTR *isr = (SEGPTR*)DOSMEM_MemoryBase();
 122     DWORD *stub = (DWORD*)((char*)isr + (VM_STUB_SEGMENT << 4));
 123     int x;
 124
 125     for (x=0; x<256; x++) isr[x]=PTR_SEG_OFF_TO_SEGPTR(VM_STUB_SEGMENT,x*4);
 126     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 127 }
 128
 129 /***********************************************************************
 130  *           DOSMEM_InitDPMI
 131  *
 132  * Allocate the global DPMI RMCB wrapper.
 133  */
 134 static void DOSMEM_InitDPMI(void)
 135 {
 136     extern UINT16 DPMI_wrap_seg;
 137     static char wrap_code[]={
 138      0xCD,0x31, /* int $0x31 */
 139      0xCB       /* lret */
 140     };
 141     LPSTR wrapper = (LPSTR)DOSMEM_GetBlock(sizeof(wrap_code), &DPMI_wrap_seg);
 142
 143     memcpy(wrapper, wrap_code, sizeof(wrap_code));
 144 }
 145
 146 BIOSDATA * DOSMEM_BiosData()
 147 {
 148     return (BIOSDATA *)(DOSMEM_MemoryBase()+0x400);
 149 }
 150
 151 BYTE * DOSMEM_BiosSys()
 152 {
 153     return DOSMEM_MemoryBase()+0xf0000;
 154 }
 155
 156 struct _DOS_LISTOFLISTS * DOSMEM_LOL()
 157 {
 158     return (struct _DOS_LISTOFLISTS *)DOSMEM_MapRealToLinear
 159       (PTR_SEG_OFF_TO_SEGPTR(HIWORD(DOS_LOLSeg),0));
 160 }
 161
 162 /***********************************************************************
 163  *           DOSMEM_FillBiosSegments
 164  *
 165  * Fill the BIOS data segment with dummy values.
 166  */
 167 static void DOSMEM_FillBiosSegments(void)
 168 {
 169     BYTE *pBiosSys = DOSMEM_BiosSys();
 170     BYTE *pBiosROMTable = pBiosSys+0xe6f5;
 171     BIOSDATA *pBiosData = DOSMEM_BiosData();
 172
 173     /* bogus 0xe0xx addresses !! Adapt int 0x10/0x1b if change needed */
 174     VIDEOFUNCTIONALITY *pVidFunc = (VIDEOFUNCTIONALITY *)(pBiosSys+0xe000);
 175     VIDEOSTATE *pVidState = (VIDEOSTATE *)(pBiosSys+0xe010);
 176     int i;
 177
 178       /* Clear all unused values */
 179     memset( pBiosData, 0, sizeof(*pBiosData) );
 180     memset( pVidFunc,  0, sizeof(*pVidFunc ) );
 181     memset( pVidState, 0, sizeof(*pVidState) );
 182
 183     /* FIXME: should check the number of configured drives and ports */
 184
 185     pBiosData->Com1Addr             = 0x3f8;
 186     pBiosData->Com2Addr             = 0x2f8;
 187     pBiosData->Lpt1Addr             = 0x378;
 188     pBiosData->Lpt2Addr             = 0x278;
 189     pBiosData->InstalledHardware    = 0x5463;
 190     pBiosData->MemSize              = 640;
 191     pBiosData->NextKbdCharPtr       = 0x1e;
 192     pBiosData->FirstKbdCharPtr      = 0x1e;
 193     pBiosData->VideoMode            = 3;
 194     pBiosData->VideoColumns         = 80;
 195     pBiosData->VideoPageSize        = 80 * 25 * 2;
 196     pBiosData->VideoPageStartAddr   = 0xb800;
 197     pBiosData->VideoCtrlAddr        = 0x3d4;
 198     pBiosData->Ticks                = INT1A_GetTicksSinceMidnight();
 199     pBiosData->NbHardDisks          = 2;
 200     pBiosData->KbdBufferStart       = 0x1e;
 201     pBiosData->KbdBufferEnd         = 0x3e;
 202     pBiosData->RowsOnScreenMinus1   = 23;
 203     pBiosData->BytesPerChar         = 0x10;
 204     pBiosData->ModeOptions          = 0x64;
 205     pBiosData->FeatureBitsSwitches  = 0xf9;
 206     pBiosData->VGASettings          = 0x51;
 207     pBiosData->DisplayCombination   = 0x08;
 208     pBiosData->DiskDataRate         = 0;
 209
 210     /* fill ROM configuration table (values from Award) */
 211     *(pBiosROMTable+0x0)        = 0x08; /* number of bytes following LO */
 212     *(pBiosROMTable+0x1)        = 0x00; /* number of bytes following HI */
 213     *(pBiosROMTable+0x2)        = 0xfc; /* model */
 214     *(pBiosROMTable+0x3)        = 0x01; /* submodel */
 215     *(pBiosROMTable+0x4)        = 0x00; /* BIOS revision */
 216     *(pBiosROMTable+0x5)        = 0x74; /* feature byte 1 */
 217     *(pBiosROMTable+0x6)        = 0x00; /* feature byte 2 */
 218     *(pBiosROMTable+0x7)        = 0x00; /* feature byte 3 */
 219     *(pBiosROMTable+0x8)        = 0x00; /* feature byte 4 */
 220     *(pBiosROMTable+0x9)        = 0x00; /* feature byte 5 */
 221
 222
 223     for (i = 0; i < 7; i++)
 224         pVidFunc->ModeSupport[i] = 0xff;
 225
 226     pVidFunc->ScanlineSupport     = 7;
 227     pVidFunc->NumberCharBlocks    = 0;
 228     pVidFunc->ActiveCharBlocks    = 0;
 229     pVidFunc->MiscFlags           = 0x8ff;
 230     pVidFunc->SavePointerFlags    = 0x3f;
 231
 232     pVidState->StaticFuncTable    = 0xf000e000;  /* FIXME: always real mode ? */
 233     pVidState->VideoMode          = pBiosData->VideoMode; /* needs updates! */
 234     pVidState->NumberColumns      = pBiosData->VideoColumns; /* needs updates! */
 235     pVidState->RegenBufLen        = 0;
 236     pVidState->RegenBufAddr       = 0;
 237
 238     for (i = 0; i < 8; i++)
 239         pVidState->CursorPos[i] = 0;
 240
 241     pVidState->CursorType         = 0x0a0b;  /* start/end line */
 242     pVidState->ActivePage         = 0;
 243     pVidState->CRTCPort           = 0x3da;
 244     pVidState->Port3x8            = 0;
 245     pVidState->Port3x9            = 0;
 246     pVidState->NumberRows         = 23;     /* number of rows - 1 */
 247     pVidState->BytesPerChar       = 0x10;
 248     pVidState->DCCActive          = pBiosData->DisplayCombination;
 249     pVidState->DCCAlternate       = 0;
 250     pVidState->NumberColors       = 16;
 251     pVidState->NumberPages        = 1;
 252     pVidState->NumberScanlines    = 3; /* (0,1,2,3) = (200,350,400,480) */
 253     pVidState->CharBlockPrimary   = 0;
 254     pVidState->CharBlockSecondary = 0;
 255     pVidState->MiscFlags =
 256                            (pBiosData->VGASettings & 0x0f)
 257                          | ((pBiosData->ModeOptions & 1) << 4); /* cursor emulation */
 258     pVidState->NonVGASupport      = 0;
 259     pVidState->VideoMem           = (pBiosData->ModeOptions & 0x60 >> 5);
 260     pVidState->SavePointerState   = 0;
 261     pVidState->DisplayStatus      = 4;
 262
 263     /* BIOS date string */
 264     strcpy((char *)pBiosSys+0xfff5, "13/01/99");
 265
 266     /* BIOS ID */
 267     *(pBiosSys+0xfffe) = 0xfc;
 268 }
 269
 270 /***********************************************************************
 271  *           DOSMEM_InitCollateTable
 272  *
 273  * Initialises the collate table (character sorting, language dependent)
 274  */
 275 static void DOSMEM_InitCollateTable()
 276 {
 277         DWORD           x;
 278         unsigned char   *tbl;
 279         int             i;
 280
 281         x = GlobalDOSAlloc16(258);
 282         DOSMEM_CollateTable = MAKELONG(0,(x>>16));
 283         tbl = DOSMEM_MapRealToLinear(DOSMEM_CollateTable);
 284         *(WORD*)tbl     = 0x100;
 285         tbl += 2;
 286         for ( i = 0; i < 0x100; i++) *tbl++ = i;
 287 }
 288
 289 /***********************************************************************
 290  *           DOSMEM_InitErrorTable
 291  *
 292  * Initialises the error tables (DOS 5+)
 293  */
 294 static void DOSMEM_InitErrorTable()
 295 {
 296         DWORD           x;
 297         char            *call;
 298
 299         /* We will use a snippet of real mode code that calls */
 300         /* a WINE-only interrupt to handle moving the requested */
 301         /* message into the buffer... */
 302
 303         /* FIXME - There is still something wrong... */
 304
 305         /* FIXME - Find hex values for opcodes...
 306
 307            (On call, AX contains message number
 308                      DI contains 'offset' (??)
 309             Resturn, ES:DI points to counted string )
 310
 311            PUSH BX
 312            MOV BX, AX
 313            MOV AX, (arbitrary subfunction number)
 314            INT (WINE-only interrupt)
 315            POP BX
 316            RET
 317
 318         */
 319
 320         const int       code = 4;
 321         const int       buffer = 80;
 322         const int       SIZE_TO_ALLOCATE = code + buffer;
 323
 324         /* FIXME - Complete rewrite of the table system to save */
 325         /* precious DOS space. Now, we return the 0001:???? as */
 326         /* DOS 4+ (??, it seems to be the case in MS 7.10) treats that */
 327         /* as a special case and programs will use the alternate */
 328         /* interface (a farcall returned with INT 24 (AX = 0x122e, DL = */
 329         /* 0x08) which lets us have a smaller memory footprint anyway. */
 330
 331         x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);
 332
 333         DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
 334         DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
 335
 336         call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 337
 338         memset(call, 0, SIZE_TO_ALLOCATE);
 339
 340         /* Fixme - Copy assembly into buffer here */
 341 }
 342
 343 /***********************************************************************
 344  *           DOSMEM_InitMemory
 345  *
 346  * Initialises the DOS memory structures.
 347  */
 348 static void DOSMEM_InitMemory(void)
 349 {
 350    /* Low 64Kb are reserved for DOS/BIOS so the useable area starts at
 351     * 1000:0000 and ends at 9FFF:FFEF. */
 352
 353     dosmem_info*        info_block = DOSMEM_InfoBlock();
 354     dosmem_entry*       root_block = DOSMEM_RootBlock();
 355     dosmem_entry*       dm;
 356
 357     root_block->size = DOSMEM_MemoryTop() - (((char*)root_block) + sizeof(dosmem_entry));
 358
 359     info_block->blocks = 0;
 360     info_block->free = root_block->size;
 361
 362     dm = NEXT_BLOCK(root_block);
 363     dm->size = DM_BLOCK_TERMINAL;
 364     root_block->size |= DM_BLOCK_FREE
 365 #ifdef __DOSMEM_DEBUG__
 366                      | DM_BLOCK_DEBUG;
 367 #endif
 368                      ;
 369 }
 370
 371 /***********************************************************************
 372  *           DOSMEM_MovePointers
 373  *
 374  * Relocates any pointers into DOS memory to a new address space.
 375  */
 376 static void DOSMEM_MovePointers(LPVOID dest, LPVOID src, DWORD size)
 377 {
 378   unsigned long delta = (char *) dest - (char *) src;
 379   unsigned cnt;
 380   ldt_entry ent;
 381
 382   /* relocate base addresses of any selectors pointing into memory */
 383   for (cnt=FIRST_LDT_ENTRY_TO_ALLOC; cnt<LDT_SIZE; cnt++) {
 384     LDT_GetEntry(cnt, &ent);
 385     if ((ent.base >= (unsigned long)src) && \
 386         (ent.base < ((unsigned long)src + size))) {
 387       ent.base += delta;
 388       LDT_SetEntry(cnt, &ent);
 389     }
 390   }
 391 }
 392
 393 /***********************************************************************
 394  *           DOSMEM_Init
 395  *
 396  * Create the dos memory segments, and store them into the KERNEL
 397  * exported values.
 398  */
 399 BOOL DOSMEM_Init(BOOL dos_init)
 400 {
 401     LPVOID base = DOSMEM_MemoryBase();
 402     BOOL do_init = dos_init && !DOSMEM_dosmem;
 403
 404     if (!base)
 405     {
 406         /* Allocate 1 MB dosmemory
 407          */
 408         DOSMEM_dosmem = VirtualAlloc( NULL, 0x100000, MEM_COMMIT,
 409                                       PAGE_EXECUTE_READWRITE );
 410         if (!DOSMEM_dosmem)
 411         {
 412             WARN("Could not allocate DOS memory.\n" );
 413             return FALSE;
 414         }
 415         DOSMEM_BiosDataSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0x400,
 416                                      0x100, 0, FALSE, FALSE, FALSE, NULL );
 417         DOSMEM_BiosSysSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0xf0000,
 418                                      0x10000, 0, FALSE, FALSE, FALSE, NULL );
 419         base = DOSMEM_dosmem;
 420         do_init = TRUE;
 421     }
 422
 423     if (do_init) {
 424         DOSMEM_FillIsrTable();
 425         DOSMEM_FillBiosSegments();
 426         DOSMEM_InitMemory();
 427         DOSMEM_InitCollateTable();
 428         DOSMEM_InitErrorTable();
 429         DOSMEM_InitDPMI();
 430         DOSDEV_InstallDOSDevices();
 431     }
 432     else if (dos_init)
 433     {
 434         /* bootstrap the new V86 task with a copy of the "system" memory */
 435         memcpy(base, DOSMEM_dosmem, 0x100000);
 436         /* then move existing selectors to it */
 437         DOSMEM_MovePointers(base, DOSMEM_dosmem, 0x100000);
 438     }
 439     return TRUE;
 440 }
 441
 442
 443 /***********************************************************************
 444  *           DOSMEM_Tick
 445  *
 446  * Increment the BIOS tick counter. Called by timer signal handler.
 447  */
 448 void DOSMEM_Tick( WORD timer )
 449 {
 450     BIOSDATA *pBiosData = DOSMEM_BiosData();
 451     if (pBiosData) pBiosData->Ticks++;
 452 }
 453
 454 /***********************************************************************
 455  *           DOSMEM_GetBlock
 456  *
 457  * Carve a chunk of the DOS memory block (without selector).
 458  */
 459 LPVOID DOSMEM_GetBlock(UINT size, UINT16* pseg)
 460 {
 461    UINT          blocksize;
 462    char         *block = NULL;
 463    dosmem_info  *info_block = DOSMEM_InfoBlock();
 464    dosmem_entry *dm;
 465 #ifdef __DOSMEM_DEBUG_
 466    dosmem_entry *prev = NULL;
 467 #endif
 468
 469    if( size > info_block->free ) return NULL;
 470    dm = DOSMEM_RootBlock();
 471
 472    while (dm && dm->size != DM_BLOCK_TERMINAL)
 473    {
 474 #ifdef __DOSMEM_DEBUG__
 475        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 476        {
 477             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 478             return NULL;
 479        }
 480        prev = dm;
 481 #endif
 482        if( dm->size & DM_BLOCK_FREE )
 483        {
 484            dosmem_entry  *next = NEXT_BLOCK(dm);
 485
 486            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 487            {
 488                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 489                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 490                next = NEXT_BLOCK(dm);
 491            }
 492
 493            blocksize = dm->size & DM_BLOCK_MASK;
 494            if( blocksize >= size )
 495            {
 496                block = ((char*)dm) + sizeof(dosmem_entry);
 497                if( blocksize - size > 0x20 )
 498                {
 499                    /* split dm so that the next one stays
 500                     * paragraph-aligned (and dm loses free bit) */
 501
 502                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 503                                               sizeof(dosmem_entry));
 504                    next = (dosmem_entry*)(((char*)dm) +
 505                            sizeof(dosmem_entry) + dm->size);
 506                    next->size = (blocksize - (dm->size +
 507                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 508 #ifdef __DOSMEM_DEBUG__
 509                                                   | DM_BLOCK_DEBUG
 510 #endif
 511                                                   ;
 512                } else dm->size &= DM_BLOCK_MASK;
 513
 514                info_block->blocks++;
 515                info_block->free -= dm->size;
 516                if( pseg ) *pseg = (block - DOSMEM_MemoryBase()) >> 4;
 517 #ifdef __DOSMEM_DEBUG__
 518                dm->size |= DM_BLOCK_DEBUG;
 519 #endif
 520                break;
 521            }
 522            dm = next;
 523        }
 524        else dm = NEXT_BLOCK(dm);
 525    }
 526    return (LPVOID)block;
 527 }
 528
 529 /***********************************************************************
 530  *           DOSMEM_FreeBlock
 531  */
 532 BOOL DOSMEM_FreeBlock(void* ptr)
 533 {
 534    dosmem_info  *info_block = DOSMEM_InfoBlock();
 535
 536    if( ptr >= (void*)(((char*)DOSMEM_RootBlock()) + sizeof(dosmem_entry)) &&
 537        ptr < (void*)DOSMEM_MemoryTop() && !((((char*)ptr)
 538                   - DOSMEM_MemoryBase()) & 0xf) )
 539    {
 540        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 541
 542        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 543 #ifdef __DOSMEM_DEBUG__
 544          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 545 #endif
 546          )
 547        {
 548              info_block->blocks--;
 549              info_block->free += dm->size;
 550
 551              dm->size |= DM_BLOCK_FREE;
 552              return TRUE;
 553        }
 554    }
 555    return FALSE;
 556 }
 557
 558 /***********************************************************************
 559  *           DOSMEM_ResizeBlock
 560  */
 561 LPVOID DOSMEM_ResizeBlock(void* ptr, UINT size, UINT16* pseg)
 562 {
 563    char         *block = NULL;
 564    dosmem_info  *info_block = DOSMEM_InfoBlock();
 565
 566    if( ptr >= (void*)(((char*)DOSMEM_RootBlock()) + sizeof(dosmem_entry)) &&
 567        ptr < (void*)DOSMEM_MemoryTop() && !((((char*)ptr)
 568                   - DOSMEM_MemoryBase()) & 0xf) )
 569    {
 570        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 571
 572        if( pseg ) *pseg = ((char*)ptr - DOSMEM_MemoryBase()) >> 4;
 573
 574        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 575          )
 576        {
 577              dosmem_entry  *next = NEXT_BLOCK(dm);
 578              UINT blocksize, orgsize = dm->size & DM_BLOCK_MASK;
 579
 580              while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 581              {
 582                  dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 583                  next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 584                  next = NEXT_BLOCK(dm);
 585              }
 586
 587              blocksize = dm->size & DM_BLOCK_MASK;
 588              if (blocksize >= size)
 589              {
 590                  block = ((char*)dm) + sizeof(dosmem_entry);
 591                  if( blocksize - size > 0x20 )
 592                  {
 593                      /* split dm so that the next one stays
 594                       * paragraph-aligned (and next gains free bit) */
 595
 596                      dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 597                                                 sizeof(dosmem_entry));
 598                      next = (dosmem_entry*)(((char*)dm) +
 599                              sizeof(dosmem_entry) + dm->size);
 600                      next->size = (blocksize - (dm->size +
 601                              sizeof(dosmem_entry))) | DM_BLOCK_FREE
 602                                                     ;
 603                  } else dm->size &= DM_BLOCK_MASK;
 604
 605                  info_block->free += orgsize - dm->size;
 606              } else {
 607                  /* the collapse didn't help, try getting a new block */
 608                  block = DOSMEM_GetBlock(size, pseg);
 609                  if (block) {
 610                      /* we got one, copy the old data there (we do need to, right?) */
 611                      memcpy(block, ((char*)dm) + sizeof(dosmem_entry),
 612                                    (size<orgsize) ? size : orgsize);
 613                      /* free old block */
 614                      info_block->blocks--;
 615                      info_block->free += dm->size;
 616
 617                      dm->size |= DM_BLOCK_FREE;
 618                  } else {
 619                      /* and Bill Gates said 640K should be enough for everyone... */
 620
 621                      /* need to split original and collapsed blocks apart again,
 622                       * and free the collapsed blocks again, before exiting */
 623                      if( blocksize - orgsize > 0x20 )
 624                      {
 625                          /* split dm so that the next one stays
 626                           * paragraph-aligned (and next gains free bit) */
 627
 628                          dm->size = (((orgsize + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 629                                                        sizeof(dosmem_entry));
 630                          next = (dosmem_entry*)(((char*)dm) +
 631                                  sizeof(dosmem_entry) + dm->size);
 632                          next->size = (blocksize - (dm->size +
 633                                  sizeof(dosmem_entry))) | DM_BLOCK_FREE
 634                                                         ;
 635                      } else dm->size &= DM_BLOCK_MASK;
 636                  }
 637              }
 638        }
 639    }
 640    return (LPVOID)block;
 641 }
 642
 643
 644 /***********************************************************************
 645  *           DOSMEM_Available
 646  */
 647 UINT DOSMEM_Available(void)
 648 {
 649    UINT          blocksize, available = 0;
 650    dosmem_entry *dm;
 651
 652    dm = DOSMEM_RootBlock();
 653
 654    while (dm && dm->size != DM_BLOCK_TERMINAL)
 655    {
 656 #ifdef __DOSMEM_DEBUG__
 657        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 658        {
 659             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 660             return NULL;
 661        }
 662        prev = dm;
 663 #endif
 664        if( dm->size & DM_BLOCK_FREE )
 665        {
 666            dosmem_entry  *next = NEXT_BLOCK(dm);
 667
 668            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 669            {
 670                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 671                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 672                next = NEXT_BLOCK(dm);
 673            }
 674
 675            blocksize = dm->size & DM_BLOCK_MASK;
 676            if ( blocksize > available ) available = blocksize;
 677            dm = next;
 678        }
 679        else dm = NEXT_BLOCK(dm);
 680    }
 681    return available;
 682 }
 683
 684
 685 /***********************************************************************
 686  *           DOSMEM_MapLinearToDos
 687  *
 688  * Linear address to the DOS address space.
 689  */
 690 UINT DOSMEM_MapLinearToDos(LPVOID ptr)
 691 {
 692     if (((char*)ptr >= DOSMEM_MemoryBase()) &&
 693         ((char*)ptr < DOSMEM_MemoryBase() + 0x100000))
 694           return (UINT)ptr - (UINT)DOSMEM_MemoryBase();
 695     return (UINT)ptr;
 696 }
 697
 698
 699 /***********************************************************************
 700  *           DOSMEM_MapDosToLinear
 701  *
 702  * DOS linear address to the linear address space.
 703  */
 704 LPVOID DOSMEM_MapDosToLinear(UINT ptr)
 705 {
 706     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT)DOSMEM_MemoryBase());
 707     return (LPVOID)ptr;
 708 }
 709
 710
 711 /***********************************************************************
 712  *           DOSMEM_MapRealToLinear
 713  *
 714  * Real mode DOS address into a linear pointer
 715  */
 716 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 717 {
 718    LPVOID       lin;
 719
 720    lin=DOSMEM_MemoryBase()+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 721    TRACE_(selector)("(0x%08lx) returns 0x%p.\n", x, lin );
 722    return lin;
 723 }
 724
 725 /***********************************************************************
 726  *           DOSMEM_AllocSelector
 727  *
 728  * Allocates a protected mode selector for a realmode segment.
 729  */
 730 WORD DOSMEM_AllocSelector(WORD realsel)
 731 {
 732         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 733         WORD    sel;
 734
 735         sel=GLOBAL_CreateBlock(
 736                 GMEM_FIXED,DOSMEM_dosmem+realsel*16,0x10000,
 737                 hModule,FALSE,FALSE,FALSE,NULL
 738         );
 739         TRACE_(selector)("(0x%04x) returns 0x%04x.\n", realsel,sel);
 740         return sel;
 741 }
 742