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 "module.h"
  18 #include "task.h"
  19 #include "debug.h"
  20
  21 HANDLE16 DOSMEM_BiosDataSeg;  /* BIOS data segment at 0x40:0 */
  22 HANDLE16 DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
  23
  24 #pragma pack(4)
  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(HMODULE16 hModule)
  66 {
  67     TDB *pTask = hModule ? NULL : (TDB *)GlobalLock16( GetCurrentTask() );
  68     NE_MODULE *pModule = (hModule || pTask) ? NE_GetPtr( hModule ? hModule : pTask->hModule ) : NULL;
  69
  70     GlobalUnlock16( GetCurrentTask() );
  71     if (pModule && pModule->dos_image)
  72         return pModule->dos_image;
  73     else
  74         return DOSMEM_dosmem;
  75 }
  76
  77 /***********************************************************************
  78  *           DOSMEM_MemoryTop
  79  *
  80  * Gets the DOS memory top.
  81  */
  82 static char *DOSMEM_MemoryTop(HMODULE16 hModule)
  83 {
  84     return DOSMEM_MemoryBase(hModule)+0x9FFFC; /* 640K */
  85 }
  86
  87 /***********************************************************************
  88  *           DOSMEM_InfoBlock
  89  *
  90  * Gets the DOS memory info block.
  91  */
  92 static dosmem_info *DOSMEM_InfoBlock(HMODULE16 hModule)
  93 {
  94     return (dosmem_info*)(DOSMEM_MemoryBase(hModule)+0x10000); /* 64K */
  95 }
  96
  97 /***********************************************************************
  98  *           DOSMEM_RootBlock
  99  *
 100  * Gets the DOS memory root block.
 101  */
 102 static dosmem_entry *DOSMEM_RootBlock(HMODULE16 hModule)
 103 {
 104     /* first block has to be paragraph-aligned */
 105     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock(hModule)) +
 106                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 107 }
 108
 109 /***********************************************************************
 110  *           DOSMEM_FillIsrTable
 111  *
 112  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 113  *
 114  * NOTES:
 115  * Linux normally only traps INTs performed from or destined to BIOSSEG
 116  * for us to handle, if the int_revectored table is empty. Filling the
 117  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 118  * to hook interrupts, as well as use their familiar retf tricks to call
 119  * them, AND let Wine handle any unhooked interrupts transparently.
 120  */
 121 static void DOSMEM_FillIsrTable(HMODULE16 hModule)
 122 {
 123     SEGPTR *isr = (SEGPTR*)DOSMEM_MemoryBase(hModule);
 124     DWORD *stub = (DWORD*)((char*)isr + (VM_STUB_SEGMENT << 4));
 125     int x;
 126
 127     for (x=0; x<256; x++) isr[x]=PTR_SEG_OFF_TO_SEGPTR(VM_STUB_SEGMENT,x*4);
 128     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 129 }
 130
 131 /***********************************************************************
 132  *           DOSMEM_InitDPMI
 133  *
 134  * Allocate the global DPMI RMCB wrapper.
 135  */
 136 static void DOSMEM_InitDPMI(void)
 137 {
 138     extern UINT16 DPMI_wrap_seg;
 139     static char wrap_code[]={
 140      0xCD,0x31, /* int $0x31 */
 141      0xCB       /* lret */
 142     };
 143     LPSTR wrapper = (LPSTR)DOSMEM_GetBlock(0, sizeof(wrap_code), &DPMI_wrap_seg);
 144
 145     memcpy(wrapper, wrap_code, sizeof(wrap_code));
 146 }
 147
 148 BIOSDATA * DOSMEM_BiosData()
 149 {
 150     return (BIOSDATA *)(DOSMEM_MemoryBase(0)+0x400);
 151 }
 152
 153 BYTE * DOSMEM_BiosSys()
 154 {
 155     return DOSMEM_MemoryBase(0)+0xf0000;
 156 }
 157
 158 /***********************************************************************
 159  *           DOSMEM_FillBiosSegments
 160  *
 161  * Fill the BIOS data segment with dummy values.
 162  */
 163 static void DOSMEM_FillBiosSegments(void)
 164 {
 165     BYTE *pBiosSys = (BYTE *)GlobalLock16( DOSMEM_BiosSysSeg );
 166     BYTE *pBiosROMTable = pBiosSys+0xe6f5;
 167     BIOSDATA *pBiosData = (BIOSDATA *)GlobalLock16( DOSMEM_BiosDataSeg );
 168
 169     /* bogus 0xe0xx addresses !! Adapt int 0x10/0x1b if change needed */
 170     BYTE *pVideoStaticFuncTable = pBiosSys+0xe000;
 171     BYTE *pVideoStateInfo = pBiosSys+0xe010;
 172     BYTE *p;
 173     int i;
 174
 175       /* Clear all unused values */
 176     memset( pBiosData, 0, sizeof(*pBiosData) );
 177
 178     /* FIXME: should check the number of configured drives and ports */
 179
 180     pBiosData->Com1Addr             = 0x3f8;
 181     pBiosData->Com2Addr             = 0x2f8;
 182     pBiosData->Lpt1Addr             = 0x378;
 183     pBiosData->Lpt2Addr             = 0x278;
 184     pBiosData->InstalledHardware    = 0x5463;
 185     pBiosData->MemSize              = 640;
 186     pBiosData->NextKbdCharPtr       = 0x1e;
 187     pBiosData->FirstKbdCharPtr      = 0x1e;
 188     pBiosData->VideoMode            = 3;
 189     pBiosData->VideoColumns         = 80;
 190     pBiosData->VideoPageSize        = 80 * 25 * 2;
 191     pBiosData->VideoPageStartAddr   = 0xb800;
 192     pBiosData->VideoCtrlAddr        = 0x3d4;
 193     pBiosData->Ticks                = INT1A_GetTicksSinceMidnight();
 194     pBiosData->NbHardDisks          = 2;
 195     pBiosData->KbdBufferStart       = 0x1e;
 196     pBiosData->KbdBufferEnd         = 0x3e;
 197     pBiosData->RowsOnScreenMinus1   = 23;
 198     pBiosData->BytesPerChar         = 0x10;
 199     pBiosData->ModeOptions          = 0x64;
 200     pBiosData->FeatureBitsSwitches  = 0xf9;
 201     pBiosData->VGASettings          = 0x51;
 202     pBiosData->DisplayCombination   = 0x08;
 203     pBiosData->DiskDataRate         = 0;
 204
 205     /* fill ROM configuration table (values from Award) */
 206     *(WORD *)(pBiosROMTable)= 0x08; /* number of bytes following */
 207     *(pBiosROMTable+0x2)        = 0xfc; /* model */
 208     *(pBiosROMTable+0x3)        = 0x01; /* submodel */
 209     *(pBiosROMTable+0x4)        = 0x00; /* BIOS revision */
 210     *(pBiosROMTable+0x5)        = 0x74; /* feature byte 1 */
 211     *(pBiosROMTable+0x6)        = 0x00; /* feature byte 2 */
 212     *(pBiosROMTable+0x7)        = 0x00; /* feature byte 3 */
 213     *(pBiosROMTable+0x8)        = 0x00; /* feature byte 4 */
 214     *(pBiosROMTable+0x9)        = 0x00; /* feature byte 5 */
 215
 216     p = pVideoStaticFuncTable;
 217     for (i=0; i < 7; i++)
 218       *(p+i)  = 0xff; /* modes supported 1 to 7 */
 219
 220     *(p+0x7)  = 7;                  /* scan lines supported */
 221     *(p+0x8)  = 0;                  /* tot nr of char blocks in text mode */
 222     *(p+0x9)  = 0;                  /* max nr of active char blocks in text */
 223     *(WORD *)(p+0xa) = 0x8ff;       /* misc support flags */
 224     *(WORD *)(p+0xc) = 0;           /* reserved */
 225     *(p+0xe)  = 0x3f;               /* save pointer function flags */
 226     *(p+0xf)  = 0;                  /* reserved */
 227
 228     p = pVideoStateInfo;
 229     *(DWORD *)p = 0xf000e000;       /* address of pVideoStaticFuncTable, FIXME: always real mode ? */
 230     *(p+0x04) =                     /* current video mode, needs updates ! */
 231       pBiosData->VideoMode;
 232     *(WORD *)(p+0x05) =             /* number of columns, needs updates ! */
 233       pBiosData->VideoColumns;
 234     *(WORD *)(p+0x07) = 0;          /* length of regen (???) buffer in bytes */
 235     *(WORD *)(p+0x09) = 0;          /* starting address of regen (?) buffer */
 236     *(WORD *)(p+0x0b) = 0;          /* cursorpos page 0 */
 237     *(WORD *)(p+0x0d) = 0;          /* cursorpos page 1 */
 238     *(WORD *)(p+0x0f) = 0;          /* page 2 */
 239     *(WORD *)(p+0x11) = 0;          /* page 3 */
 240     *(WORD *)(p+0x13) = 0;          /* page 4 */
 241     *(WORD *)(p+0x15) = 0;          /* page 5 */
 242     *(WORD *)(p+0x17) = 0;          /* page 6 */
 243     *(WORD *)(p+0x19) = 0;          /* page 7 */
 244     *(WORD *)(p+0x1b) = 0x0a0b;     /* cursor size (start/end line) */
 245     *(p+0x1d) = 0;                  /* active display page */
 246     *(WORD *)(p+0x1e) = 0x3da;      /* CRTC port address */
 247     *(p+0x20) = 0x0;                /* current setting of port 0x3x8 */
 248     *(p+0x21) = 0x0;                /* current setting of port 0x3x9 */
 249     *(p+0x22) = 23;                 /* number of rows - 1 */
 250     *(WORD *)(p+0x23) = 0x10;       /* bytes/character */
 251     *(p+0x25) =                     /* comb. of active display */
 252       pBiosData->DisplayCombination;
 253     *(p+0x26) = 0;                  /* DCC (???) of alternate display */
 254     *(WORD *)(p+0x27) = 16;         /* number of colors in current mode */
 255     *(p+0x29) = 1;                  /* number of pages in current mode */
 256     *(p+0x2a) = 3;                  /* number of scan lines active */
 257                                     /* (0,1,2,3) =  (200,350,400,480) */
 258     *(p+0x2b) = 0;                  /* primary character block (?) */
 259     *(p+0x2c) = 0;                  /* secondary character block (?) */
 260     *(p+0x2d) =                     /* miscellaneous flags */
 261         (pBiosData->VGASettings & 0x0f)
 262       | ((pBiosData->ModeOptions & 1) << 4); /* cursor emulation */
 263     *(p+0x2e) = 0;                  /* non-VGA mode support */
 264     *(WORD *)(p+0x2f) = 0;          /* reserved */
 265     *(p+0x31) =                     /* video memory available */
 266       (pBiosData->ModeOptions & 0x60 >> 5);
 267     *(p+0x32) = 0;                  /* save pointer state flags */
 268     *(p+0x33) = 4;                  /* display info and status */
 269
 270     /* BIOS date string */
 271     strcpy((char *)pBiosSys+0xfff5, "13/01/99");
 272
 273     /* BIOS ID */
 274     *(pBiosSys+0xfffe) = 0xfc;
 275 }
 276
 277 /***********************************************************************
 278  *           DOSMEM_InitCollateTable
 279  *
 280  * Initialises the collate table (character sorting, language dependent)
 281  */
 282 static void DOSMEM_InitCollateTable()
 283 {
 284         DWORD           x;
 285         unsigned char   *tbl;
 286         int             i;
 287
 288         x = GlobalDOSAlloc16(258);
 289         DOSMEM_CollateTable = MAKELONG(0,(x>>16));
 290         tbl = DOSMEM_MapRealToLinear(DOSMEM_CollateTable);
 291         *(WORD*)tbl     = 0x100;
 292         tbl += 2;
 293         for ( i = 0; i < 0x100; i++) *tbl++ = i;
 294 }
 295
 296 /***********************************************************************
 297  *           DOSMEM_InitErrorTable
 298  *
 299  * Initialises the error tables (DOS 5+)
 300  */
 301 static void DOSMEM_InitErrorTable()
 302 {
 303         DWORD           x;
 304         char            *call;
 305
 306         /* We will use a snippet of real mode code that calls */
 307         /* a WINE-only interrupt to handle moving the requested */
 308         /* message into the buffer... */
 309
 310         /* FIXME - There is still something wrong... */
 311
 312         /* FIXME - Find hex values for opcodes...
 313
 314            (On call, AX contains message number
 315                      DI contains 'offset' (??)
 316             Resturn, ES:DI points to counted string )
 317
 318            PUSH BX
 319            MOV BX, AX
 320            MOV AX, (arbitrary subfunction number)
 321            INT (WINE-only interrupt)
 322            POP BX
 323            RET
 324
 325         */
 326
 327         const int       code = 4;
 328         const int       buffer = 80;
 329         const int       SIZE_TO_ALLOCATE = code + buffer;
 330
 331         /* FIXME - Complete rewrite of the table system to save */
 332         /* precious DOS space. Now, we return the 0001:???? as */
 333         /* DOS 4+ (??, it seems to be the case in MS 7.10) treats that */
 334         /* as a special case and programs will use the alternate */
 335         /* interface (a farcall returned with INT 24 (AX = 0x122e, DL = */
 336         /* 0x08) which lets us have a smaller memory footprint anyway. */
 337
 338         x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);
 339
 340         DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
 341         DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
 342
 343         call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 344
 345         memset(call, 0, SIZE_TO_ALLOCATE);
 346
 347         /* Fixme - Copy assembly into buffer here */
 348 }
 349
 350 /***********************************************************************
 351  *           DOSMEM_InitMemory
 352  *
 353  * Initialises the DOS memory structures.
 354  */
 355 static void DOSMEM_InitMemory(HMODULE16 hModule)
 356 {
 357    /* Low 64Kb are reserved for DOS/BIOS so the useable area starts at
 358     * 1000:0000 and ends at 9FFF:FFEF. */
 359
 360     dosmem_info*        info_block = DOSMEM_InfoBlock(hModule);
 361     dosmem_entry*       root_block = DOSMEM_RootBlock(hModule);
 362     dosmem_entry*       dm;
 363
 364     root_block->size = DOSMEM_MemoryTop(hModule) - (((char*)root_block) + sizeof(dosmem_entry));
 365
 366     info_block->blocks = 0;
 367     info_block->free = root_block->size;
 368
 369     dm = NEXT_BLOCK(root_block);
 370     dm->size = DM_BLOCK_TERMINAL;
 371     root_block->size |= DM_BLOCK_FREE
 372 #ifdef __DOSMEM_DEBUG__
 373                      | DM_BLOCK_DEBUG;
 374 #endif
 375                      ;
 376 }
 377
 378 /***********************************************************************
 379  *           DOSMEM_Init
 380  *
 381  * Create the dos memory segments, and store them into the KERNEL
 382  * exported values.
 383  */
 384 BOOL DOSMEM_Init(HMODULE16 hModule)
 385 {
 386     if (!hModule)
 387     {
 388         /* Allocate 1 MB dosmemory
 389          * - it is mostly wasted but we can use some of it to
 390          *   store internal translation tables, etc...
 391          */
 392         DOSMEM_dosmem = VirtualAlloc( NULL, 0x100000, MEM_COMMIT,
 393                                       PAGE_EXECUTE_READWRITE );
 394         if (!DOSMEM_dosmem)
 395         {
 396             WARN(dosmem, "Could not allocate DOS memory.\n" );
 397             return FALSE;
 398         }
 399         DOSMEM_BiosDataSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0x400,
 400                                      0x100, 0, FALSE, FALSE, FALSE, NULL );
 401         DOSMEM_BiosSysSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0xf0000,
 402                                      0x10000, 0, FALSE, FALSE, FALSE, NULL );
 403         DOSMEM_FillIsrTable(0);
 404         DOSMEM_FillBiosSegments();
 405         DOSMEM_InitMemory(0);
 406         DOSMEM_InitCollateTable();
 407         DOSMEM_InitErrorTable();
 408         DOSMEM_InitDPMI();
 409     }
 410     else
 411     {
 412 #if 0
 413         DOSMEM_FillIsrTable(hModule);
 414         DOSMEM_InitMemory(hModule);
 415 #else
 416         /* bootstrap the new V86 task with a copy of the "system" memory */
 417         memcpy(DOSMEM_MemoryBase(hModule), DOSMEM_dosmem, 0x100000);
 418 #endif
 419     }
 420     return TRUE;
 421 }
 422
 423
 424 /***********************************************************************
 425  *           DOSMEM_Tick
 426  *
 427  * Increment the BIOS tick counter. Called by timer signal handler.
 428  */
 429 void DOSMEM_Tick( WORD timer )
 430 {
 431     BIOSDATA *pBiosData = DOSMEM_BiosData();
 432     if (pBiosData) pBiosData->Ticks++;
 433 }
 434
 435 /***********************************************************************
 436  *           DOSMEM_GetBlock
 437  *
 438  * Carve a chunk of the DOS memory block (without selector).
 439  */
 440 LPVOID DOSMEM_GetBlock(HMODULE16 hModule, UINT size, UINT16* pseg)
 441 {
 442    UINT          blocksize;
 443    char         *block = NULL;
 444    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 445    dosmem_entry *dm;
 446 #ifdef __DOSMEM_DEBUG_
 447    dosmem_entry *prev = NULL;
 448 #endif
 449
 450    if( size > info_block->free ) return NULL;
 451    dm = DOSMEM_RootBlock(hModule);
 452
 453    while (dm && dm->size != DM_BLOCK_TERMINAL)
 454    {
 455 #ifdef __DOSMEM_DEBUG__
 456        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 457        {
 458             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 459             return NULL;
 460        }
 461        prev = dm;
 462 #endif
 463        if( dm->size & DM_BLOCK_FREE )
 464        {
 465            dosmem_entry  *next = NEXT_BLOCK(dm);
 466
 467            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 468            {
 469                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 470                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 471                next = NEXT_BLOCK(dm);
 472            }
 473
 474            blocksize = dm->size & DM_BLOCK_MASK;
 475            if( blocksize >= size )
 476            {
 477                block = ((char*)dm) + sizeof(dosmem_entry);
 478                if( blocksize - size > 0x20 )
 479                {
 480                    /* split dm so that the next one stays
 481                     * paragraph-aligned (and dm loses free bit) */
 482
 483                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 484                                               sizeof(dosmem_entry));
 485                    next = (dosmem_entry*)(((char*)dm) +
 486                            sizeof(dosmem_entry) + dm->size);
 487                    next->size = (blocksize - (dm->size +
 488                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 489 #ifdef __DOSMEM_DEBUG__
 490                                                   | DM_BLOCK_DEBUG
 491 #endif
 492                                                   ;
 493                } else dm->size &= DM_BLOCK_MASK;
 494
 495                info_block->blocks++;
 496                info_block->free -= dm->size;
 497                if( pseg ) *pseg = (block - DOSMEM_MemoryBase(hModule)) >> 4;
 498 #ifdef __DOSMEM_DEBUG__
 499                dm->size |= DM_BLOCK_DEBUG;
 500 #endif
 501                break;
 502            }
 503            dm = next;
 504        }
 505        else dm = NEXT_BLOCK(dm);
 506    }
 507    return (LPVOID)block;
 508 }
 509
 510 /***********************************************************************
 511  *           DOSMEM_FreeBlock
 512  */
 513 BOOL DOSMEM_FreeBlock(HMODULE16 hModule, void* ptr)
 514 {
 515    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 516
 517    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 518        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 519                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 520    {
 521        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 522
 523        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 524 #ifdef __DOSMEM_DEBUG__
 525          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 526 #endif
 527          )
 528        {
 529              info_block->blocks--;
 530              info_block->free += dm->size;
 531
 532              dm->size |= DM_BLOCK_FREE;
 533              return TRUE;
 534        }
 535    }
 536    return FALSE;
 537 }
 538
 539 /***********************************************************************
 540  *           DOSMEM_ResizeBlock
 541  */
 542 LPVOID DOSMEM_ResizeBlock(HMODULE16 hModule, void* ptr, UINT size, UINT16* pseg)
 543 {
 544    char         *block = NULL;
 545    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 546
 547    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 548        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 549                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 550    {
 551        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 552
 553        if( pseg ) *pseg = ((char*)ptr - DOSMEM_MemoryBase(hModule)) >> 4;
 554
 555        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 556          )
 557        {
 558              dosmem_entry  *next = NEXT_BLOCK(dm);
 559              UINT blocksize, orgsize = dm->size & DM_BLOCK_MASK;
 560
 561              while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 562              {
 563                  dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 564                  next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 565                  next = NEXT_BLOCK(dm);
 566              }
 567
 568              blocksize = dm->size & DM_BLOCK_MASK;
 569              if (blocksize >= size)
 570              {
 571                  block = ((char*)dm) + sizeof(dosmem_entry);
 572                  if( blocksize - size > 0x20 )
 573                  {
 574                      /* split dm so that the next one stays
 575                       * paragraph-aligned (and next gains free bit) */
 576
 577                      dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 578                                                 sizeof(dosmem_entry));
 579                      next = (dosmem_entry*)(((char*)dm) +
 580                              sizeof(dosmem_entry) + dm->size);
 581                      next->size = (blocksize - (dm->size +
 582                              sizeof(dosmem_entry))) | DM_BLOCK_FREE
 583                                                     ;
 584                  } else dm->size &= DM_BLOCK_MASK;
 585
 586                  info_block->free += orgsize - dm->size;
 587              } else {
 588                  /* the collapse didn't help, try getting a new block */
 589                  block = DOSMEM_GetBlock(hModule, size, pseg);
 590                  if (block) {
 591                      /* we got one, copy the old data there (we do need to, right?) */
 592                      memcpy(block, ((char*)dm) + sizeof(dosmem_entry),
 593                                    (size<orgsize) ? size : orgsize);
 594                      /* free old block */
 595                      info_block->blocks--;
 596                      info_block->free += dm->size;
 597
 598                      dm->size |= DM_BLOCK_FREE;
 599                  } else {
 600                      /* and Bill Gates said 640K should be enough for everyone... */
 601
 602                      /* need to split original and collapsed blocks apart again,
 603                       * and free the collapsed blocks again, before exiting */
 604                      if( blocksize - orgsize > 0x20 )
 605                      {
 606                          /* split dm so that the next one stays
 607                           * paragraph-aligned (and next gains free bit) */
 608
 609                          dm->size = (((orgsize + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 610                                                        sizeof(dosmem_entry));
 611                          next = (dosmem_entry*)(((char*)dm) +
 612                                  sizeof(dosmem_entry) + dm->size);
 613                          next->size = (blocksize - (dm->size +
 614                                  sizeof(dosmem_entry))) | DM_BLOCK_FREE
 615                                                         ;
 616                      } else dm->size &= DM_BLOCK_MASK;
 617                  }
 618              }
 619        }
 620    }
 621    return (LPVOID)block;
 622 }
 623
 624
 625 /***********************************************************************
 626  *           DOSMEM_Available
 627  */
 628 UINT DOSMEM_Available(HMODULE16 hModule)
 629 {
 630    UINT          blocksize, available = 0;
 631    dosmem_entry *dm;
 632
 633    dm = DOSMEM_RootBlock(hModule);
 634
 635    while (dm && dm->size != DM_BLOCK_TERMINAL)
 636    {
 637 #ifdef __DOSMEM_DEBUG__
 638        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 639        {
 640             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 641             return NULL;
 642        }
 643        prev = dm;
 644 #endif
 645        if( dm->size & DM_BLOCK_FREE )
 646        {
 647            dosmem_entry  *next = NEXT_BLOCK(dm);
 648
 649            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 650            {
 651                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 652                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 653                next = NEXT_BLOCK(dm);
 654            }
 655
 656            blocksize = dm->size & DM_BLOCK_MASK;
 657            if ( blocksize > available ) available = blocksize;
 658            dm = next;
 659        }
 660        else dm = NEXT_BLOCK(dm);
 661    }
 662    return available;
 663 }
 664
 665
 666 /***********************************************************************
 667  *           DOSMEM_MapLinearToDos
 668  *
 669  * Linear address to the DOS address space.
 670  */
 671 UINT DOSMEM_MapLinearToDos(LPVOID ptr)
 672 {
 673     if (((char*)ptr >= DOSMEM_MemoryBase(0)) &&
 674         ((char*)ptr < DOSMEM_MemoryBase(0) + 0x100000))
 675           return (UINT)ptr - (UINT)DOSMEM_MemoryBase(0);
 676     return (UINT)ptr;
 677 }
 678
 679
 680 /***********************************************************************
 681  *           DOSMEM_MapDosToLinear
 682  *
 683  * DOS linear address to the linear address space.
 684  */
 685 LPVOID DOSMEM_MapDosToLinear(UINT ptr)
 686 {
 687     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT)DOSMEM_MemoryBase(0));
 688     return (LPVOID)ptr;
 689 }
 690
 691
 692 /***********************************************************************
 693  *           DOSMEM_MapRealToLinear
 694  *
 695  * Real mode DOS address into a linear pointer
 696  */
 697 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 698 {
 699    LPVOID       lin;
 700
 701    lin=DOSMEM_MemoryBase(0)+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 702    TRACE(selector,"(0x%08lx) returns 0x%p.\n",
 703                     x,lin );
 704    return lin;
 705 }
 706
 707 /***********************************************************************
 708  *           DOSMEM_AllocSelector
 709  *
 710  * Allocates a protected mode selector for a realmode segment.
 711  */
 712 WORD DOSMEM_AllocSelector(WORD realsel)
 713 {
 714         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 715         WORD    sel;
 716
 717         sel=GLOBAL_CreateBlock(
 718                 GMEM_FIXED,DOSMEM_dosmem+realsel*16,0x10000,
 719                 hModule,FALSE,FALSE,FALSE,NULL
 720         );
 721         TRACE(selector,"(0x%04x) returns 0x%04x.\n",
 722                 realsel,sel
 723         );
 724         return sel;
 725 }
 726