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 DECLARE_DEBUG_CHANNEL(dosmem)
  22 DECLARE_DEBUG_CHANNEL(selector)
  23
  24 HANDLE16 DOSMEM_BiosDataSeg;  /* BIOS data segment at 0x40:0 */
  25 HANDLE16 DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
  26
  27 #pragma pack(4)
  28
  29 static char     *DOSMEM_dosmem;
  30
  31        DWORD     DOSMEM_CollateTable;
  32
  33        DWORD     DOSMEM_ErrorCall;
  34        DWORD     DOSMEM_ErrorBuffer;
  35
  36 /* use 2 low bits of 'size' for the housekeeping */
  37
  38 #define DM_BLOCK_DEBUG          0xABE00000
  39 #define DM_BLOCK_TERMINAL       0x00000001
  40 #define DM_BLOCK_FREE           0x00000002
  41 #define DM_BLOCK_MASK           0x001FFFFC
  42
  43 /*
  44 #define __DOSMEM_DEBUG__
  45  */
  46
  47 typedef struct {
  48    unsigned     size;
  49 } dosmem_entry;
  50
  51 typedef struct {
  52   unsigned      blocks;
  53   unsigned      free;
  54 } dosmem_info;
  55
  56 #define NEXT_BLOCK(block) \
  57         (dosmem_entry*)(((char*)(block)) + \
  58          sizeof(dosmem_entry) + ((block)->size & DM_BLOCK_MASK))
  59
  60 #define VM_STUB(x) (0x90CF00CD|(x<<8)) /* INT x; IRET; NOP */
  61 #define VM_STUB_SEGMENT 0xf000         /* BIOS segment */
  62
  63 /***********************************************************************
  64  *           DOSMEM_MemoryBase
  65  *
  66  * Gets the DOS memory base.
  67  */
  68 char *DOSMEM_MemoryBase(HMODULE16 hModule)
  69 {
  70     TDB *pTask = hModule ? NULL : (TDB *)GlobalLock16( GetCurrentTask() );
  71     NE_MODULE *pModule = (hModule || pTask) ? NE_GetPtr( hModule ? hModule : pTask->hModule ) : NULL;
  72
  73     GlobalUnlock16( GetCurrentTask() );
  74     if (pModule && pModule->dos_image)
  75         return pModule->dos_image;
  76     else
  77         return DOSMEM_dosmem;
  78 }
  79
  80 /***********************************************************************
  81  *           DOSMEM_MemoryTop
  82  *
  83  * Gets the DOS memory top.
  84  */
  85 static char *DOSMEM_MemoryTop(HMODULE16 hModule)
  86 {
  87     return DOSMEM_MemoryBase(hModule)+0x9FFFC; /* 640K */
  88 }
  89
  90 /***********************************************************************
  91  *           DOSMEM_InfoBlock
  92  *
  93  * Gets the DOS memory info block.
  94  */
  95 static dosmem_info *DOSMEM_InfoBlock(HMODULE16 hModule)
  96 {
  97     return (dosmem_info*)(DOSMEM_MemoryBase(hModule)+0x10000); /* 64K */
  98 }
  99
 100 /***********************************************************************
 101  *           DOSMEM_RootBlock
 102  *
 103  * Gets the DOS memory root block.
 104  */
 105 static dosmem_entry *DOSMEM_RootBlock(HMODULE16 hModule)
 106 {
 107     /* first block has to be paragraph-aligned */
 108     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock(hModule)) +
 109                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 110 }
 111
 112 /***********************************************************************
 113  *           DOSMEM_FillIsrTable
 114  *
 115  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 116  *
 117  * NOTES:
 118  * Linux normally only traps INTs performed from or destined to BIOSSEG
 119  * for us to handle, if the int_revectored table is empty. Filling the
 120  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 121  * to hook interrupts, as well as use their familiar retf tricks to call
 122  * them, AND let Wine handle any unhooked interrupts transparently.
 123  */
 124 static void DOSMEM_FillIsrTable(HMODULE16 hModule)
 125 {
 126     SEGPTR *isr = (SEGPTR*)DOSMEM_MemoryBase(hModule);
 127     DWORD *stub = (DWORD*)((char*)isr + (VM_STUB_SEGMENT << 4));
 128     int x;
 129
 130     for (x=0; x<256; x++) isr[x]=PTR_SEG_OFF_TO_SEGPTR(VM_STUB_SEGMENT,x*4);
 131     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 132 }
 133
 134 /***********************************************************************
 135  *           DOSMEM_InitDPMI
 136  *
 137  * Allocate the global DPMI RMCB wrapper.
 138  */
 139 static void DOSMEM_InitDPMI(void)
 140 {
 141     extern UINT16 DPMI_wrap_seg;
 142     static char wrap_code[]={
 143      0xCD,0x31, /* int $0x31 */
 144      0xCB       /* lret */
 145     };
 146     LPSTR wrapper = (LPSTR)DOSMEM_GetBlock(0, sizeof(wrap_code), &DPMI_wrap_seg);
 147
 148     memcpy(wrapper, wrap_code, sizeof(wrap_code));
 149 }
 150
 151 BIOSDATA * DOSMEM_BiosData()
 152 {
 153     return (BIOSDATA *)(DOSMEM_MemoryBase(0)+0x400);
 154 }
 155
 156 BYTE * DOSMEM_BiosSys()
 157 {
 158     return DOSMEM_MemoryBase(0)+0xf0000;
 159 }
 160
 161 /***********************************************************************
 162  *           DOSMEM_FillBiosSegments
 163  *
 164  * Fill the BIOS data segment with dummy values.
 165  */
 166 static void DOSMEM_FillBiosSegments(void)
 167 {
 168     BYTE *pBiosSys = (BYTE *)GlobalLock16( DOSMEM_BiosSysSeg );
 169     BYTE *pBiosROMTable = pBiosSys+0xe6f5;
 170     BIOSDATA *pBiosData = (BIOSDATA *)GlobalLock16( DOSMEM_BiosDataSeg );
 171
 172     /* bogus 0xe0xx addresses !! Adapt int 0x10/0x1b if change needed */
 173     BYTE *pVideoStaticFuncTable = pBiosSys+0xe000;
 174     BYTE *pVideoStateInfo = pBiosSys+0xe010;
 175     BYTE *p;
 176     int i;
 177
 178       /* Clear all unused values */
 179     memset( pBiosData, 0, sizeof(*pBiosData) );
 180
 181     /* FIXME: should check the number of configured drives and ports */
 182
 183     pBiosData->Com1Addr             = 0x3f8;
 184     pBiosData->Com2Addr             = 0x2f8;
 185     pBiosData->Lpt1Addr             = 0x378;
 186     pBiosData->Lpt2Addr             = 0x278;
 187     pBiosData->InstalledHardware    = 0x5463;
 188     pBiosData->MemSize              = 640;
 189     pBiosData->NextKbdCharPtr       = 0x1e;
 190     pBiosData->FirstKbdCharPtr      = 0x1e;
 191     pBiosData->VideoMode            = 3;
 192     pBiosData->VideoColumns         = 80;
 193     pBiosData->VideoPageSize        = 80 * 25 * 2;
 194     pBiosData->VideoPageStartAddr   = 0xb800;
 195     pBiosData->VideoCtrlAddr        = 0x3d4;
 196     pBiosData->Ticks                = INT1A_GetTicksSinceMidnight();
 197     pBiosData->NbHardDisks          = 2;
 198     pBiosData->KbdBufferStart       = 0x1e;
 199     pBiosData->KbdBufferEnd         = 0x3e;
 200     pBiosData->RowsOnScreenMinus1   = 23;
 201     pBiosData->BytesPerChar         = 0x10;
 202     pBiosData->ModeOptions          = 0x64;
 203     pBiosData->FeatureBitsSwitches  = 0xf9;
 204     pBiosData->VGASettings          = 0x51;
 205     pBiosData->DisplayCombination   = 0x08;
 206     pBiosData->DiskDataRate         = 0;
 207
 208     /* fill ROM configuration table (values from Award) */
 209     *(WORD *)(pBiosROMTable)= 0x08; /* number of bytes following */
 210     *(pBiosROMTable+0x2)        = 0xfc; /* model */
 211     *(pBiosROMTable+0x3)        = 0x01; /* submodel */
 212     *(pBiosROMTable+0x4)        = 0x00; /* BIOS revision */
 213     *(pBiosROMTable+0x5)        = 0x74; /* feature byte 1 */
 214     *(pBiosROMTable+0x6)        = 0x00; /* feature byte 2 */
 215     *(pBiosROMTable+0x7)        = 0x00; /* feature byte 3 */
 216     *(pBiosROMTable+0x8)        = 0x00; /* feature byte 4 */
 217     *(pBiosROMTable+0x9)        = 0x00; /* feature byte 5 */
 218
 219     p = pVideoStaticFuncTable;
 220     for (i=0; i < 7; i++)
 221       *(p+i)  = 0xff; /* modes supported 1 to 7 */
 222
 223     *(p+0x7)  = 7;                  /* scan lines supported */
 224     *(p+0x8)  = 0;                  /* tot nr of char blocks in text mode */
 225     *(p+0x9)  = 0;                  /* max nr of active char blocks in text */
 226     *(WORD *)(p+0xa) = 0x8ff;       /* misc support flags */
 227     *(WORD *)(p+0xc) = 0;           /* reserved */
 228     *(p+0xe)  = 0x3f;               /* save pointer function flags */
 229     *(p+0xf)  = 0;                  /* reserved */
 230
 231     p = pVideoStateInfo;
 232     *(DWORD *)p = 0xf000e000;       /* address of pVideoStaticFuncTable, FIXME: always real mode ? */
 233     *(p+0x04) =                     /* current video mode, needs updates ! */
 234       pBiosData->VideoMode;
 235     *(WORD *)(p+0x05) =             /* number of columns, needs updates ! */
 236       pBiosData->VideoColumns;
 237     *(WORD *)(p+0x07) = 0;          /* length of regen (???) buffer in bytes */
 238     *(WORD *)(p+0x09) = 0;          /* starting address of regen (?) buffer */
 239     *(WORD *)(p+0x0b) = 0;          /* cursorpos page 0 */
 240     *(WORD *)(p+0x0d) = 0;          /* cursorpos page 1 */
 241     *(WORD *)(p+0x0f) = 0;          /* page 2 */
 242     *(WORD *)(p+0x11) = 0;          /* page 3 */
 243     *(WORD *)(p+0x13) = 0;          /* page 4 */
 244     *(WORD *)(p+0x15) = 0;          /* page 5 */
 245     *(WORD *)(p+0x17) = 0;          /* page 6 */
 246     *(WORD *)(p+0x19) = 0;          /* page 7 */
 247     *(WORD *)(p+0x1b) = 0x0a0b;     /* cursor size (start/end line) */
 248     *(p+0x1d) = 0;                  /* active display page */
 249     *(WORD *)(p+0x1e) = 0x3da;      /* CRTC port address */
 250     *(p+0x20) = 0x0;                /* current setting of port 0x3x8 */
 251     *(p+0x21) = 0x0;                /* current setting of port 0x3x9 */
 252     *(p+0x22) = 23;                 /* number of rows - 1 */
 253     *(WORD *)(p+0x23) = 0x10;       /* bytes/character */
 254     *(p+0x25) =                     /* comb. of active display */
 255       pBiosData->DisplayCombination;
 256     *(p+0x26) = 0;                  /* DCC (???) of alternate display */
 257     *(WORD *)(p+0x27) = 16;         /* number of colors in current mode */
 258     *(p+0x29) = 1;                  /* number of pages in current mode */
 259     *(p+0x2a) = 3;                  /* number of scan lines active */
 260                                     /* (0,1,2,3) =  (200,350,400,480) */
 261     *(p+0x2b) = 0;                  /* primary character block (?) */
 262     *(p+0x2c) = 0;                  /* secondary character block (?) */
 263     *(p+0x2d) =                     /* miscellaneous flags */
 264         (pBiosData->VGASettings & 0x0f)
 265       | ((pBiosData->ModeOptions & 1) << 4); /* cursor emulation */
 266     *(p+0x2e) = 0;                  /* non-VGA mode support */
 267     *(WORD *)(p+0x2f) = 0;          /* reserved */
 268     *(p+0x31) =                     /* video memory available */
 269       (pBiosData->ModeOptions & 0x60 >> 5);
 270     *(p+0x32) = 0;                  /* save pointer state flags */
 271     *(p+0x33) = 4;                  /* display info and status */
 272
 273     /* BIOS date string */
 274     strcpy((char *)pBiosSys+0xfff5, "13/01/99");
 275
 276     /* BIOS ID */
 277     *(pBiosSys+0xfffe) = 0xfc;
 278 }
 279
 280 /***********************************************************************
 281  *           DOSMEM_InitCollateTable
 282  *
 283  * Initialises the collate table (character sorting, language dependent)
 284  */
 285 static void DOSMEM_InitCollateTable()
 286 {
 287         DWORD           x;
 288         unsigned char   *tbl;
 289         int             i;
 290
 291         x = GlobalDOSAlloc16(258);
 292         DOSMEM_CollateTable = MAKELONG(0,(x>>16));
 293         tbl = DOSMEM_MapRealToLinear(DOSMEM_CollateTable);
 294         *(WORD*)tbl     = 0x100;
 295         tbl += 2;
 296         for ( i = 0; i < 0x100; i++) *tbl++ = i;
 297 }
 298
 299 /***********************************************************************
 300  *           DOSMEM_InitErrorTable
 301  *
 302  * Initialises the error tables (DOS 5+)
 303  */
 304 static void DOSMEM_InitErrorTable()
 305 {
 306         DWORD           x;
 307         char            *call;
 308
 309         /* We will use a snippet of real mode code that calls */
 310         /* a WINE-only interrupt to handle moving the requested */
 311         /* message into the buffer... */
 312
 313         /* FIXME - There is still something wrong... */
 314
 315         /* FIXME - Find hex values for opcodes...
 316
 317            (On call, AX contains message number
 318                      DI contains 'offset' (??)
 319             Resturn, ES:DI points to counted string )
 320
 321            PUSH BX
 322            MOV BX, AX
 323            MOV AX, (arbitrary subfunction number)
 324            INT (WINE-only interrupt)
 325            POP BX
 326            RET
 327
 328         */
 329
 330         const int       code = 4;
 331         const int       buffer = 80;
 332         const int       SIZE_TO_ALLOCATE = code + buffer;
 333
 334         /* FIXME - Complete rewrite of the table system to save */
 335         /* precious DOS space. Now, we return the 0001:???? as */
 336         /* DOS 4+ (??, it seems to be the case in MS 7.10) treats that */
 337         /* as a special case and programs will use the alternate */
 338         /* interface (a farcall returned with INT 24 (AX = 0x122e, DL = */
 339         /* 0x08) which lets us have a smaller memory footprint anyway. */
 340
 341         x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);
 342
 343         DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
 344         DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
 345
 346         call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 347
 348         memset(call, 0, SIZE_TO_ALLOCATE);
 349
 350         /* Fixme - Copy assembly into buffer here */
 351 }
 352
 353 /***********************************************************************
 354  *           DOSMEM_InitMemory
 355  *
 356  * Initialises the DOS memory structures.
 357  */
 358 static void DOSMEM_InitMemory(HMODULE16 hModule)
 359 {
 360    /* Low 64Kb are reserved for DOS/BIOS so the useable area starts at
 361     * 1000:0000 and ends at 9FFF:FFEF. */
 362
 363     dosmem_info*        info_block = DOSMEM_InfoBlock(hModule);
 364     dosmem_entry*       root_block = DOSMEM_RootBlock(hModule);
 365     dosmem_entry*       dm;
 366
 367     root_block->size = DOSMEM_MemoryTop(hModule) - (((char*)root_block) + sizeof(dosmem_entry));
 368
 369     info_block->blocks = 0;
 370     info_block->free = root_block->size;
 371
 372     dm = NEXT_BLOCK(root_block);
 373     dm->size = DM_BLOCK_TERMINAL;
 374     root_block->size |= DM_BLOCK_FREE
 375 #ifdef __DOSMEM_DEBUG__
 376                      | DM_BLOCK_DEBUG;
 377 #endif
 378                      ;
 379 }
 380
 381 /***********************************************************************
 382  *           DOSMEM_Init
 383  *
 384  * Create the dos memory segments, and store them into the KERNEL
 385  * exported values.
 386  */
 387 BOOL DOSMEM_Init(HMODULE16 hModule)
 388 {
 389     if (!hModule)
 390     {
 391         /* Allocate 1 MB dosmemory
 392          * - it is mostly wasted but we can use some of it to
 393          *   store internal translation tables, etc...
 394          */
 395         DOSMEM_dosmem = VirtualAlloc( NULL, 0x100000, MEM_COMMIT,
 396                                       PAGE_EXECUTE_READWRITE );
 397         if (!DOSMEM_dosmem)
 398         {
 399             WARN(dosmem, "Could not allocate DOS memory.\n" );
 400             return FALSE;
 401         }
 402         DOSMEM_BiosDataSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0x400,
 403                                      0x100, 0, FALSE, FALSE, FALSE, NULL );
 404         DOSMEM_BiosSysSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0xf0000,
 405                                      0x10000, 0, FALSE, FALSE, FALSE, NULL );
 406         DOSMEM_FillIsrTable(0);
 407         DOSMEM_FillBiosSegments();
 408         DOSMEM_InitMemory(0);
 409         DOSMEM_InitCollateTable();
 410         DOSMEM_InitErrorTable();
 411         DOSMEM_InitDPMI();
 412     }
 413     else
 414     {
 415 #if 0
 416         DOSMEM_FillIsrTable(hModule);
 417         DOSMEM_InitMemory(hModule);
 418 #else
 419         /* bootstrap the new V86 task with a copy of the "system" memory */
 420         memcpy(DOSMEM_MemoryBase(hModule), DOSMEM_dosmem, 0x100000);
 421 #endif
 422     }
 423     return TRUE;
 424 }
 425
 426
 427 /***********************************************************************
 428  *           DOSMEM_Tick
 429  *
 430  * Increment the BIOS tick counter. Called by timer signal handler.
 431  */
 432 void DOSMEM_Tick( WORD timer )
 433 {
 434     BIOSDATA *pBiosData = DOSMEM_BiosData();
 435     if (pBiosData) pBiosData->Ticks++;
 436 }
 437
 438 /***********************************************************************
 439  *           DOSMEM_GetBlock
 440  *
 441  * Carve a chunk of the DOS memory block (without selector).
 442  */
 443 LPVOID DOSMEM_GetBlock(HMODULE16 hModule, UINT size, UINT16* pseg)
 444 {
 445    UINT          blocksize;
 446    char         *block = NULL;
 447    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 448    dosmem_entry *dm;
 449 #ifdef __DOSMEM_DEBUG_
 450    dosmem_entry *prev = NULL;
 451 #endif
 452
 453    if( size > info_block->free ) return NULL;
 454    dm = DOSMEM_RootBlock(hModule);
 455
 456    while (dm && dm->size != DM_BLOCK_TERMINAL)
 457    {
 458 #ifdef __DOSMEM_DEBUG__
 459        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 460        {
 461             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 462             return NULL;
 463        }
 464        prev = dm;
 465 #endif
 466        if( dm->size & DM_BLOCK_FREE )
 467        {
 468            dosmem_entry  *next = NEXT_BLOCK(dm);
 469
 470            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 471            {
 472                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 473                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 474                next = NEXT_BLOCK(dm);
 475            }
 476
 477            blocksize = dm->size & DM_BLOCK_MASK;
 478            if( blocksize >= size )
 479            {
 480                block = ((char*)dm) + sizeof(dosmem_entry);
 481                if( blocksize - size > 0x20 )
 482                {
 483                    /* split dm so that the next one stays
 484                     * paragraph-aligned (and dm loses free bit) */
 485
 486                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 487                                               sizeof(dosmem_entry));
 488                    next = (dosmem_entry*)(((char*)dm) +
 489                            sizeof(dosmem_entry) + dm->size);
 490                    next->size = (blocksize - (dm->size +
 491                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 492 #ifdef __DOSMEM_DEBUG__
 493                                                   | DM_BLOCK_DEBUG
 494 #endif
 495                                                   ;
 496                } else dm->size &= DM_BLOCK_MASK;
 497
 498                info_block->blocks++;
 499                info_block->free -= dm->size;
 500                if( pseg ) *pseg = (block - DOSMEM_MemoryBase(hModule)) >> 4;
 501 #ifdef __DOSMEM_DEBUG__
 502                dm->size |= DM_BLOCK_DEBUG;
 503 #endif
 504                break;
 505            }
 506            dm = next;
 507        }
 508        else dm = NEXT_BLOCK(dm);
 509    }
 510    return (LPVOID)block;
 511 }
 512
 513 /***********************************************************************
 514  *           DOSMEM_FreeBlock
 515  */
 516 BOOL DOSMEM_FreeBlock(HMODULE16 hModule, void* ptr)
 517 {
 518    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 519
 520    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 521        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 522                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 523    {
 524        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 525
 526        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 527 #ifdef __DOSMEM_DEBUG__
 528          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 529 #endif
 530          )
 531        {
 532              info_block->blocks--;
 533              info_block->free += dm->size;
 534
 535              dm->size |= DM_BLOCK_FREE;
 536              return TRUE;
 537        }
 538    }
 539    return FALSE;
 540 }
 541
 542 /***********************************************************************
 543  *           DOSMEM_ResizeBlock
 544  */
 545 LPVOID DOSMEM_ResizeBlock(HMODULE16 hModule, void* ptr, UINT size, UINT16* pseg)
 546 {
 547    char         *block = NULL;
 548    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 549
 550    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 551        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 552                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 553    {
 554        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 555
 556        if( pseg ) *pseg = ((char*)ptr - DOSMEM_MemoryBase(hModule)) >> 4;
 557
 558        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 559          )
 560        {
 561              dosmem_entry  *next = NEXT_BLOCK(dm);
 562              UINT blocksize, orgsize = dm->size & DM_BLOCK_MASK;
 563
 564              while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 565              {
 566                  dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 567                  next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 568                  next = NEXT_BLOCK(dm);
 569              }
 570
 571              blocksize = dm->size & DM_BLOCK_MASK;
 572              if (blocksize >= size)
 573              {
 574                  block = ((char*)dm) + sizeof(dosmem_entry);
 575                  if( blocksize - size > 0x20 )
 576                  {
 577                      /* split dm so that the next one stays
 578                       * paragraph-aligned (and next gains free bit) */
 579
 580                      dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 581                                                 sizeof(dosmem_entry));
 582                      next = (dosmem_entry*)(((char*)dm) +
 583                              sizeof(dosmem_entry) + dm->size);
 584                      next->size = (blocksize - (dm->size +
 585                              sizeof(dosmem_entry))) | DM_BLOCK_FREE
 586                                                     ;
 587                  } else dm->size &= DM_BLOCK_MASK;
 588
 589                  info_block->free += orgsize - dm->size;
 590              } else {
 591                  /* the collapse didn't help, try getting a new block */
 592                  block = DOSMEM_GetBlock(hModule, size, pseg);
 593                  if (block) {
 594                      /* we got one, copy the old data there (we do need to, right?) */
 595                      memcpy(block, ((char*)dm) + sizeof(dosmem_entry),
 596                                    (size<orgsize) ? size : orgsize);
 597                      /* free old block */
 598                      info_block->blocks--;
 599                      info_block->free += dm->size;
 600
 601                      dm->size |= DM_BLOCK_FREE;
 602                  } else {
 603                      /* and Bill Gates said 640K should be enough for everyone... */
 604
 605                      /* need to split original and collapsed blocks apart again,
 606                       * and free the collapsed blocks again, before exiting */
 607                      if( blocksize - orgsize > 0x20 )
 608                      {
 609                          /* split dm so that the next one stays
 610                           * paragraph-aligned (and next gains free bit) */
 611
 612                          dm->size = (((orgsize + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 613                                                        sizeof(dosmem_entry));
 614                          next = (dosmem_entry*)(((char*)dm) +
 615                                  sizeof(dosmem_entry) + dm->size);
 616                          next->size = (blocksize - (dm->size +
 617                                  sizeof(dosmem_entry))) | DM_BLOCK_FREE
 618                                                         ;
 619                      } else dm->size &= DM_BLOCK_MASK;
 620                  }
 621              }
 622        }
 623    }
 624    return (LPVOID)block;
 625 }
 626
 627
 628 /***********************************************************************
 629  *           DOSMEM_Available
 630  */
 631 UINT DOSMEM_Available(HMODULE16 hModule)
 632 {
 633    UINT          blocksize, available = 0;
 634    dosmem_entry *dm;
 635
 636    dm = DOSMEM_RootBlock(hModule);
 637
 638    while (dm && dm->size != DM_BLOCK_TERMINAL)
 639    {
 640 #ifdef __DOSMEM_DEBUG__
 641        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 642        {
 643             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 644             return NULL;
 645        }
 646        prev = dm;
 647 #endif
 648        if( dm->size & DM_BLOCK_FREE )
 649        {
 650            dosmem_entry  *next = NEXT_BLOCK(dm);
 651
 652            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 653            {
 654                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 655                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 656                next = NEXT_BLOCK(dm);
 657            }
 658
 659            blocksize = dm->size & DM_BLOCK_MASK;
 660            if ( blocksize > available ) available = blocksize;
 661            dm = next;
 662        }
 663        else dm = NEXT_BLOCK(dm);
 664    }
 665    return available;
 666 }
 667
 668
 669 /***********************************************************************
 670  *           DOSMEM_MapLinearToDos
 671  *
 672  * Linear address to the DOS address space.
 673  */
 674 UINT DOSMEM_MapLinearToDos(LPVOID ptr)
 675 {
 676     if (((char*)ptr >= DOSMEM_MemoryBase(0)) &&
 677         ((char*)ptr < DOSMEM_MemoryBase(0) + 0x100000))
 678           return (UINT)ptr - (UINT)DOSMEM_MemoryBase(0);
 679     return (UINT)ptr;
 680 }
 681
 682
 683 /***********************************************************************
 684  *           DOSMEM_MapDosToLinear
 685  *
 686  * DOS linear address to the linear address space.
 687  */
 688 LPVOID DOSMEM_MapDosToLinear(UINT ptr)
 689 {
 690     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT)DOSMEM_MemoryBase(0));
 691     return (LPVOID)ptr;
 692 }
 693
 694
 695 /***********************************************************************
 696  *           DOSMEM_MapRealToLinear
 697  *
 698  * Real mode DOS address into a linear pointer
 699  */
 700 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 701 {
 702    LPVOID       lin;
 703
 704    lin=DOSMEM_MemoryBase(0)+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 705    TRACE(selector,"(0x%08lx) returns 0x%p.\n",
 706                     x,lin );
 707    return lin;
 708 }
 709
 710 /***********************************************************************
 711  *           DOSMEM_AllocSelector
 712  *
 713  * Allocates a protected mode selector for a realmode segment.
 714  */
 715 WORD DOSMEM_AllocSelector(WORD realsel)
 716 {
 717         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 718         WORD    sel;
 719
 720         sel=GLOBAL_CreateBlock(
 721                 GMEM_FIXED,DOSMEM_dosmem+realsel*16,0x10000,
 722                 hModule,FALSE,FALSE,FALSE,NULL
 723         );
 724         TRACE(selector,"(0x%04x) returns 0x%04x.\n",
 725                 realsel,sel
 726         );
 727         return sel;
 728 }
 729