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