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 "windows.h"
  12 #include "winbase.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_BiosSeg;  /* BIOS data segment at 0x40:0 */
  22
  23 #pragma pack(1)
  24
  25 typedef struct
  26 {
  27     WORD  Com1Addr;                  /* 00: COM1 I/O address */
  28     WORD  Com2Addr;                  /* 02: COM2 I/O address */
  29     WORD  Com3Addr;                  /* 04: COM3 I/O address */
  30     WORD  Com4Addr;                  /* 06: COM4 I/O address */
  31     WORD  Lpt1Addr;                  /* 08: LPT1 I/O address */
  32     WORD  Lpt2Addr;                  /* 0a: LPT2 I/O address */
  33     WORD  Lpt3Addr;                  /* 0c: LPT3 I/O address */
  34     WORD  Lpt4Addr;                  /* 0e: LPT4 I/O address */
  35     WORD  InstalledHardware;         /* 10: Installed hardware flags */
  36     BYTE  POSTstatus;                /* 12: Power-On Self Test status */
  37     WORD  MemSize WINE_PACKED;       /* 13: Base memory size in Kb */
  38     WORD  unused1 WINE_PACKED;       /* 15: Manufacturing test scratch pad */
  39     BYTE  KbdFlags1;                 /* 17: Keyboard flags 1 */
  40     BYTE  KbdFlags2;                 /* 18: Keyboard flags 2 */
  41     BYTE  unused2;                   /* 19: Keyboard driver workspace */
  42     WORD  NextKbdCharPtr;            /* 1a: Next character in kbd buffer */
  43     WORD  FirstKbdCharPtr;           /* 1c: First character in kbd buffer */
  44     WORD  KbdBuffer[16];             /* 1e: Keyboard buffer */
  45     BYTE  DisketteStatus1;           /* 3e: Diskette recalibrate status */
  46     BYTE  DisketteStatus2;           /* 3f: Diskette motor status */
  47     BYTE  DisketteStatus3;           /* 40: Diskette motor timeout */
  48     BYTE  DisketteStatus4;           /* 41: Diskette last operation status */
  49     BYTE  DiskStatus[7];             /* 42: Disk status/command bytes */
  50     BYTE  VideoMode;                 /* 49: Video mode */
  51     WORD  VideoColumns;              /* 4a: Number of columns */
  52     WORD  VideoPageSize;             /* 4c: Video page size in bytes */
  53     WORD  VideoPageStartAddr;        /* 4e: Video page start address */
  54     BYTE  VideoCursorPos[16];        /* 50: Cursor position for 8 pages */
  55     WORD  VideoCursorType;           /* 60: Video cursor type */
  56     BYTE  VideoCurPage;              /* 62: Video current page */
  57     WORD  VideoCtrlAddr WINE_PACKED; /* 63: Video controller address */
  58     BYTE  VideoReg1;                 /* 65: Video mode select register */
  59     BYTE  VideoReg2;                 /* 66: Video CGA palette register */
  60     DWORD ResetEntry WINE_PACKED;    /* 67: Warm reset entry point */
  61     BYTE  LastIRQ;                   /* 6b: Last unexpected interrupt */
  62     DWORD Ticks;                     /* 6c: Ticks since midnight */
  63     BYTE  TicksOverflow;             /* 70: Timer overflow if past midnight */
  64     BYTE  CtrlBreakFlag;             /* 71: Ctrl-Break flag */
  65     WORD  ResetFlag;                 /* 72: POST Reset flag */
  66     BYTE  DiskOpStatus;              /* 74: Last hard-disk operation status */
  67     BYTE  NbHardDisks;               /* 75: Number of hard disks */
  68     BYTE  DiskCtrlByte;              /* 76: Disk control byte */
  69     BYTE  DiskIOPort;                /* 77: Disk I/O port offset */
  70     BYTE  LptTimeout[4];             /* 78: Timeouts for parallel ports */
  71     BYTE  ComTimeout[4];             /* 7c: Timeouts for serial ports */
  72     WORD  KbdBufferStart;            /* 80: Keyboard buffer start */
  73     WORD  KbdBufferEnd;              /* 82: Keyboard buffer end */
  74 } BIOSDATA;
  75
  76 #pragma pack(4)
  77
  78 static BIOSDATA *pBiosData = NULL;
  79 static char     *DOSMEM_dosmem;
  80
  81        DWORD     DOSMEM_CollateTable;
  82
  83        DWORD     DOSMEM_ErrorCall;
  84        DWORD     DOSMEM_ErrorBuffer;
  85
  86 /* use 2 low bits of 'size' for the housekeeping */
  87
  88 #define DM_BLOCK_DEBUG          0xABE00000
  89 #define DM_BLOCK_TERMINAL       0x00000001
  90 #define DM_BLOCK_FREE           0x00000002
  91 #define DM_BLOCK_MASK           0x001FFFFC
  92
  93 /*
  94 #define __DOSMEM_DEBUG__
  95  */
  96
  97 typedef struct {
  98    unsigned     size;
  99 } dosmem_entry;
 100
 101 typedef struct {
 102   unsigned      blocks;
 103   unsigned      free;
 104 } dosmem_info;
 105
 106 #define NEXT_BLOCK(block) \
 107         (dosmem_entry*)(((char*)(block)) + \
 108          sizeof(dosmem_entry) + ((block)->size & DM_BLOCK_MASK))
 109
 110 #define VM_STUB(x) (0x90CF00CD|(x<<8)) /* INT x; IRET; NOP */
 111 #define VM_STUB_SEGMENT 0xf000         /* BIOS segment */
 112
 113 /***********************************************************************
 114  *           DOSMEM_MemoryBase
 115  *
 116  * Gets the DOS memory base.
 117  */
 118 char *DOSMEM_MemoryBase(HMODULE16 hModule)
 119 {
 120     TDB *pTask = hModule ? NULL : (TDB *)GlobalLock16( GetCurrentTask() );
 121     NE_MODULE *pModule = (hModule || pTask) ? NE_GetPtr( hModule ? hModule : pTask->hModule ) : NULL;
 122
 123     GlobalUnlock16( GetCurrentTask() );
 124     if (pModule && pModule->dos_image)
 125         return pModule->dos_image;
 126     else
 127         return DOSMEM_dosmem;
 128 }
 129
 130 /***********************************************************************
 131  *           DOSMEM_MemoryTop
 132  *
 133  * Gets the DOS memory top.
 134  */
 135 static char *DOSMEM_MemoryTop(HMODULE16 hModule)
 136 {
 137     return DOSMEM_MemoryBase(hModule)+0x9FFFC; /* 640K */
 138 }
 139
 140 /***********************************************************************
 141  *           DOSMEM_InfoBlock
 142  *
 143  * Gets the DOS memory info block.
 144  */
 145 static dosmem_info *DOSMEM_InfoBlock(HMODULE16 hModule)
 146 {
 147     return (dosmem_info*)(DOSMEM_MemoryBase(hModule)+0x10000); /* 64K */
 148 }
 149
 150 /***********************************************************************
 151  *           DOSMEM_RootBlock
 152  *
 153  * Gets the DOS memory root block.
 154  */
 155 static dosmem_entry *DOSMEM_RootBlock(HMODULE16 hModule)
 156 {
 157     /* first block has to be paragraph-aligned */
 158     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock(hModule)) +
 159                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 160 }
 161
 162 /***********************************************************************
 163  *           DOSMEM_FillIsrTable
 164  *
 165  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 166  *
 167  * NOTES:
 168  * Linux normally only traps INTs performed from or destined to BIOSSEG
 169  * for us to handle, if the int_revectored table is empty. Filling the
 170  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 171  * to hook interrupts, as well as use their familiar retf tricks to call
 172  * them, AND let Wine handle any unhooked interrupts transparently.
 173  */
 174 static void DOSMEM_FillIsrTable(HMODULE16 hModule)
 175 {
 176     SEGPTR *isr = (SEGPTR*)DOSMEM_MemoryBase(hModule);
 177     DWORD *stub = (DWORD*)((char*)isr + (VM_STUB_SEGMENT << 4));
 178     int x;
 179
 180     for (x=0; x<256; x++) isr[x]=PTR_SEG_OFF_TO_SEGPTR(VM_STUB_SEGMENT,x*4);
 181     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 182 }
 183
 184 /***********************************************************************
 185  *           DOSMEM_FillBiosSegment
 186  *
 187  * Fill the BIOS data segment with dummy values.
 188  */
 189 static void DOSMEM_FillBiosSegment(void)
 190 {
 191     pBiosData = (BIOSDATA *)GlobalLock16( DOSMEM_BiosSeg );
 192
 193       /* Clear all unused values */
 194     memset( pBiosData, 0, sizeof(*pBiosData) );
 195
 196     /* FIXME: should check the number of configured drives and ports */
 197
 198     pBiosData->Com1Addr             = 0x3e8;
 199     pBiosData->Com2Addr             = 0x2e8;
 200     pBiosData->Lpt1Addr             = 0x378;
 201     pBiosData->Lpt2Addr             = 0x278;
 202     pBiosData->InstalledHardware    = 0x8443;
 203     pBiosData->MemSize              = 640;
 204     pBiosData->NextKbdCharPtr       = 0x1e;
 205     pBiosData->FirstKbdCharPtr      = 0x1e;
 206     pBiosData->VideoMode            = 3;
 207     pBiosData->VideoColumns         = 80;
 208     pBiosData->VideoPageSize        = 80 * 25 * 2;
 209     pBiosData->VideoPageStartAddr   = 0xb800;
 210     pBiosData->VideoCtrlAddr        = 0x3d4;
 211     pBiosData->Ticks                = INT1A_GetTicksSinceMidnight();
 212     pBiosData->NbHardDisks          = 2;
 213     pBiosData->KbdBufferStart       = 0x1e;
 214     pBiosData->KbdBufferEnd         = 0x3e;
 215 }
 216
 217 /***********************************************************************
 218  *           DOSMEM_InitCollateTable
 219  *
 220  * Initialises the collate table (character sorting, language dependent)
 221  */
 222 static void DOSMEM_InitCollateTable()
 223 {
 224         DWORD           x;
 225         unsigned char   *tbl;
 226         int             i;
 227
 228         x = GlobalDOSAlloc(258);
 229         DOSMEM_CollateTable = MAKELONG(0,(x>>16));
 230         tbl = DOSMEM_MapRealToLinear(DOSMEM_CollateTable);
 231         *(WORD*)tbl     = 0x100;
 232         tbl += 2;
 233         for ( i = 0; i < 0x100; i++) *tbl++ = i;
 234 }
 235
 236 /***********************************************************************
 237  *           DOSMEM_InitErrorTable
 238  *
 239  * Initialises the error tables (DOS 5+)
 240  */
 241 static void DOSMEM_InitErrorTable()
 242 {
 243         DWORD           x;
 244         char            *call;
 245
 246         /* We will use a snippet of real mode code that calls */
 247         /* a WINE-only interrupt to handle moving the requested */
 248         /* message into the buffer... */
 249
 250         /* FIXME - There is still something wrong... */
 251
 252         /* FIXME - Find hex values for opcodes...
 253
 254            (On call, AX contains message number
 255                      DI contains 'offset' (??)
 256             Resturn, ES:DI points to counted string )
 257
 258            PUSH BX
 259            MOV BX, AX
 260            MOV AX, (arbitrary subfunction number)
 261            INT (WINE-only interrupt)
 262            POP BX
 263            RET
 264
 265         */
 266
 267         const int       code = 4;
 268         const int       buffer = 80;
 269         const int       SIZE_TO_ALLOCATE = code + buffer;
 270
 271         /* FIXME - Complete rewrite of the table system to save */
 272         /* precious DOS space. Now, we return the 0001:???? as */
 273         /* DOS 4+ (??, it seems to be the case in MS 7.10) treats that */
 274         /* as a special case and programs will use the alternate */
 275         /* interface (a farcall returned with INT 24 (AX = 0x122e, DL = */
 276         /* 0x08) which lets us have a smaller memory footprint anyway. */
 277
 278         x = GlobalDOSAlloc(SIZE_TO_ALLOCATE);
 279
 280         DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
 281         DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
 282
 283         call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 284
 285         memset(call, 0, SIZE_TO_ALLOCATE);
 286
 287         /* Fixme - Copy assembly into buffer here */
 288 }
 289
 290 /***********************************************************************
 291  *           DOSMEM_InitMemory
 292  *
 293  * Initialises the DOS memory structures.
 294  */
 295 static void DOSMEM_InitMemory(HMODULE16 hModule)
 296 {
 297    /* Low 64Kb are reserved for DOS/BIOS so the useable area starts at
 298     * 1000:0000 and ends at 9FFF:FFEF. */
 299
 300     dosmem_info*        info_block = DOSMEM_InfoBlock(hModule);
 301     dosmem_entry*       root_block = DOSMEM_RootBlock(hModule);
 302     dosmem_entry*       dm;
 303
 304     root_block->size = DOSMEM_MemoryTop(hModule) - (((char*)root_block) + sizeof(dosmem_entry));
 305
 306     info_block->blocks = 0;
 307     info_block->free = root_block->size;
 308
 309     dm = NEXT_BLOCK(root_block);
 310     dm->size = DM_BLOCK_TERMINAL;
 311     root_block->size |= DM_BLOCK_FREE
 312 #ifdef __DOSMEM_DEBUG__
 313                      | DM_BLOCK_DEBUG;
 314 #endif
 315                      ;
 316 }
 317
 318 /***********************************************************************
 319  *           DOSMEM_Init
 320  *
 321  * Create the dos memory segments, and store them into the KERNEL
 322  * exported values.
 323  */
 324 BOOL32 DOSMEM_Init(HMODULE16 hModule)
 325 {
 326     if (!hModule)
 327     {
 328         /* Allocate 1 MB dosmemory
 329          * - it is mostly wasted but we use can some of it to
 330          *   store internal translation tables, etc...
 331          */
 332         DOSMEM_dosmem = VirtualAlloc( NULL, 0x100000, MEM_COMMIT,
 333                                       PAGE_EXECUTE_READWRITE );
 334         if (!DOSMEM_dosmem)
 335         {
 336             WARN(dosmem, "Could not allocate DOS memory.\n" );
 337             return FALSE;
 338         }
 339         DOSMEM_BiosSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0x400,0x100,
 340                                         0, FALSE, FALSE, FALSE, NULL );
 341         DOSMEM_FillIsrTable(0);
 342         DOSMEM_FillBiosSegment();
 343         DOSMEM_InitMemory(0);
 344         DOSMEM_InitCollateTable();
 345         DOSMEM_InitErrorTable();
 346     }
 347     else
 348     {
 349 #if 0
 350         DOSMEM_FillIsrTable(hModule);
 351         DOSMEM_InitMemory(hModule);
 352 #else
 353         /* bootstrap the new V86 task with a copy of the "system" memory */
 354         memcpy(DOSMEM_MemoryBase(hModule), DOSMEM_dosmem, 0x100000);
 355 #endif
 356     }
 357     return TRUE;
 358 }
 359
 360
 361 /***********************************************************************
 362  *           DOSMEM_Tick
 363  *
 364  * Increment the BIOS tick counter. Called by timer signal handler.
 365  */
 366 void DOSMEM_Tick(void)
 367 {
 368     if (pBiosData) pBiosData->Ticks++;
 369 }
 370
 371 /***********************************************************************
 372  *           DOSMEM_GetBlock
 373  *
 374  * Carve a chunk of the DOS memory block (without selector).
 375  */
 376 LPVOID DOSMEM_GetBlock(HMODULE16 hModule, UINT32 size, UINT16* pseg)
 377 {
 378    UINT32        blocksize;
 379    char         *block = NULL;
 380    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 381    dosmem_entry *dm;
 382 #ifdef __DOSMEM_DEBUG_
 383    dosmem_entry *prev = NULL;
 384 #endif
 385
 386    if( size > info_block->free ) return NULL;
 387    dm = DOSMEM_RootBlock(hModule);
 388
 389    while (dm && dm->size != DM_BLOCK_TERMINAL)
 390    {
 391 #ifdef __DOSMEM_DEBUG__
 392        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 393        {
 394             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT32)prev);
 395             return NULL;
 396        }
 397        prev = dm;
 398 #endif
 399        if( dm->size & DM_BLOCK_FREE )
 400        {
 401            dosmem_entry  *next = NEXT_BLOCK(dm);
 402
 403            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 404            {
 405                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 406                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 407                next = NEXT_BLOCK(dm);
 408            }
 409
 410            blocksize = dm->size & DM_BLOCK_MASK;
 411            if( blocksize >= size )
 412            {
 413                block = ((char*)dm) + sizeof(dosmem_entry);
 414                if( blocksize - size > 0x20 )
 415                {
 416                    /* split dm so that the next one stays
 417                     * paragraph-aligned (and dm loses free bit) */
 418
 419                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 420                                               sizeof(dosmem_entry));
 421                    next = (dosmem_entry*)(((char*)dm) +
 422                            sizeof(dosmem_entry) + dm->size);
 423                    next->size = (blocksize - (dm->size +
 424                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 425 #ifdef __DOSMEM_DEBUG__
 426                                                   | DM_BLOCK_DEBUG
 427 #endif
 428                                                   ;
 429                } else dm->size &= DM_BLOCK_MASK;
 430
 431                info_block->blocks++;
 432                info_block->free -= dm->size;
 433                if( pseg ) *pseg = (block - DOSMEM_MemoryBase(hModule)) >> 4;
 434 #ifdef __DOSMEM_DEBUG__
 435                dm->size |= DM_BLOCK_DEBUG;
 436 #endif
 437                break;
 438            }
 439            dm = next;
 440        }
 441        else dm = NEXT_BLOCK(dm);
 442    }
 443    return (LPVOID)block;
 444 }
 445
 446 /***********************************************************************
 447  *           DOSMEM_FreeBlock
 448  */
 449 BOOL32 DOSMEM_FreeBlock(HMODULE16 hModule, void* ptr)
 450 {
 451    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 452
 453    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 454        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 455                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 456    {
 457        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 458
 459        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 460 #ifdef __DOSMEM_DEBUG__
 461          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 462 #endif
 463          )
 464        {
 465              info_block->blocks--;
 466              info_block->free += dm->size;
 467
 468              dm->size |= DM_BLOCK_FREE;
 469              return TRUE;
 470        }
 471    }
 472    return FALSE;
 473 }
 474
 475 /***********************************************************************
 476  *           DOSMEM_ResizeBlock
 477  */
 478 LPVOID DOSMEM_ResizeBlock(HMODULE16 hModule, void* ptr, UINT32 size, UINT16* pseg)
 479 {
 480    char         *block = NULL;
 481    dosmem_info  *info_block = DOSMEM_InfoBlock(hModule);
 482
 483    if( ptr >= (void*)(((char*)DOSMEM_RootBlock(hModule)) + sizeof(dosmem_entry)) &&
 484        ptr < (void*)DOSMEM_MemoryTop(hModule) && !((((char*)ptr)
 485                   - DOSMEM_MemoryBase(hModule)) & 0xf) )
 486    {
 487        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 488
 489        if( pseg ) *pseg = ((char*)ptr - DOSMEM_MemoryBase(hModule)) >> 4;
 490
 491        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 492          )
 493        {
 494              dosmem_entry  *next = NEXT_BLOCK(dm);
 495              UINT32 blocksize, orgsize = dm->size & DM_BLOCK_MASK;
 496
 497              while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 498              {
 499                  dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 500                  next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 501                  next = NEXT_BLOCK(dm);
 502              }
 503
 504              blocksize = dm->size & DM_BLOCK_MASK;
 505              if (blocksize >= size)
 506              {
 507                  block = ((char*)dm) + sizeof(dosmem_entry);
 508                  if( blocksize - size > 0x20 )
 509                  {
 510                      /* split dm so that the next one stays
 511                       * paragraph-aligned (and next gains free bit) */
 512
 513                      dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 514                                                 sizeof(dosmem_entry));
 515                      next = (dosmem_entry*)(((char*)dm) +
 516                              sizeof(dosmem_entry) + dm->size);
 517                      next->size = (blocksize - (dm->size +
 518                              sizeof(dosmem_entry))) | DM_BLOCK_FREE
 519                                                     ;
 520                  } else dm->size &= DM_BLOCK_MASK;
 521
 522                  info_block->free += orgsize - dm->size;
 523              } else {
 524                  block = DOSMEM_GetBlock(hModule, size, pseg);
 525                  if (block) {
 526                      info_block->blocks--;
 527                      info_block->free += dm->size;
 528
 529                      dm->size |= DM_BLOCK_FREE;
 530                  }
 531              }
 532        }
 533    }
 534    return (LPVOID)block;
 535 }
 536
 537
 538 /***********************************************************************
 539  *           DOSMEM_Available
 540  */
 541 UINT32 DOSMEM_Available(HMODULE16 hModule)
 542 {
 543    UINT32        blocksize, available = 0;
 544    dosmem_entry *dm;
 545
 546    dm = DOSMEM_RootBlock(hModule);
 547
 548    while (dm && dm->size != DM_BLOCK_TERMINAL)
 549    {
 550 #ifdef __DOSMEM_DEBUG__
 551        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 552        {
 553             WARN(dosmem,"MCB overrun! [prev = 0x%08x]\n", 4 + (UINT32)prev);
 554             return NULL;
 555        }
 556        prev = dm;
 557 #endif
 558        if( dm->size & DM_BLOCK_FREE )
 559        {
 560            dosmem_entry  *next = NEXT_BLOCK(dm);
 561
 562            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 563            {
 564                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 565                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 566                next = NEXT_BLOCK(dm);
 567            }
 568
 569            blocksize = dm->size & DM_BLOCK_MASK;
 570            if ( blocksize > available ) available = blocksize;
 571            dm = next;
 572        }
 573        else dm = NEXT_BLOCK(dm);
 574    }
 575    return available;
 576 }
 577
 578
 579 /***********************************************************************
 580  *           DOSMEM_MapLinearToDos
 581  *
 582  * Linear address to the DOS address space.
 583  */
 584 UINT32 DOSMEM_MapLinearToDos(LPVOID ptr)
 585 {
 586     if (((char*)ptr >= DOSMEM_MemoryBase(0)) &&
 587         ((char*)ptr < DOSMEM_MemoryBase(0) + 0x100000))
 588           return (UINT32)ptr - (UINT32)DOSMEM_MemoryBase(0);
 589     return (UINT32)ptr;
 590 }
 591
 592
 593 /***********************************************************************
 594  *           DOSMEM_MapDosToLinear
 595  *
 596  * DOS linear address to the linear address space.
 597  */
 598 LPVOID DOSMEM_MapDosToLinear(UINT32 ptr)
 599 {
 600     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT32)DOSMEM_MemoryBase(0));
 601     return (LPVOID)ptr;
 602 }
 603
 604
 605 /***********************************************************************
 606  *           DOSMEM_MapRealToLinear
 607  *
 608  * Real mode DOS address into a linear pointer
 609  */
 610 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 611 {
 612    LPVOID       lin;
 613
 614    lin=DOSMEM_MemoryBase(0)+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 615    TRACE(selector,"(0x%08lx) returns 0x%p.\n",
 616                     x,lin );
 617    return lin;
 618 }
 619
 620 /***********************************************************************
 621  *           DOSMEM_AllocSelector
 622  *
 623  * Allocates a protected mode selector for a realmode segment.
 624  */
 625 WORD DOSMEM_AllocSelector(WORD realsel)
 626 {
 627         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 628         WORD    sel;
 629
 630         sel=GLOBAL_CreateBlock(
 631                 GMEM_FIXED,DOSMEM_dosmem+realsel*16,0x10000,
 632                 hModule,FALSE,FALSE,FALSE,NULL
 633         );
 634         TRACE(selector,"(0x%04x) returns 0x%04x.\n",
 635                 realsel,sel
 636         );
 637         return sel;
 638 }
 639