msdos/dosmem.c

   1 /*
   2  * DOS memory emulation
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  * Copyright 1996 Marcus Meissner
   6  */
   7
   8 #include "config.h"
   9
  10 #include <signal.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <sys/types.h>
  14 #ifdef HAVE_SYS_MMAN_H
  15 # include <sys/mman.h>
  16 #endif
  17
  18 #include "winbase.h"
  19 #include "wine/winbase16.h"
  20
  21 #include "global.h"
  22 #include "ldt.h"
  23 #include "selectors.h"
  24 #include "miscemu.h"
  25 #include "vga.h"
  26 #include "dosexe.h"
  27 #include "debugtools.h"
  28
  29 DEFAULT_DEBUG_CHANNEL(dosmem);
  30 DECLARE_DEBUG_CHANNEL(selector);
  31
  32 WORD DOSMEM_0000H;        /* segment at 0:0 */
  33 WORD DOSMEM_BiosDataSeg;  /* BIOS data segment at 0x40:0 */
  34 WORD DOSMEM_BiosSysSeg;   /* BIOS ROM segment at 0xf000:0 */
  35
  36 DWORD DOSMEM_CollateTable;
  37
  38 /* use 2 low bits of 'size' for the housekeeping */
  39
  40 #define DM_BLOCK_DEBUG          0xABE00000
  41 #define DM_BLOCK_TERMINAL       0x00000001
  42 #define DM_BLOCK_FREE           0x00000002
  43 #define DM_BLOCK_MASK           0x001FFFFC
  44
  45 /*
  46 #define __DOSMEM_DEBUG__
  47  */
  48
  49 typedef struct {
  50    unsigned     size;
  51 } dosmem_entry;
  52
  53 typedef struct {
  54   unsigned      blocks;
  55   unsigned      free;
  56 } dosmem_info;
  57
  58 #define NEXT_BLOCK(block) \
  59         (dosmem_entry*)(((char*)(block)) + \
  60          sizeof(dosmem_entry) + ((block)->size & DM_BLOCK_MASK))
  61
  62 #define VM_STUB(x) (0x90CF00CD|(x<<8)) /* INT x; IRET; NOP */
  63 #define VM_STUB_SEGMENT 0xf000         /* BIOS segment */
  64
  65 /* DOS memory base */
  66 static char *DOSMEM_dosmem;
  67 /* DOS system base (for interrupt vector table and BIOS data area)
  68  * ...should in theory (i.e. Windows) be equal to DOSMEM_dosmem (NULL),
  69  * but is normally set to 0xf0000 in Wine to allow trapping of NULL pointers,
  70  * and only relocated to NULL when absolutely necessary */
  71 static char *DOSMEM_sysmem;
  72
  73 /* various real-mode code stubs */
  74 WORD DOSMEM_wrap_seg;
  75 WORD DOSMEM_xms_seg;
  76 WORD DOSMEM_dpmi_seg;
  77 WORD DOSMEM_dpmi_sel;
  78
  79 /***********************************************************************
  80  *           DOSMEM_SystemBase
  81  *
  82  * Gets the virtual DOS memory base (interrupt table).
  83  */
  84 char *DOSMEM_SystemBase(void)
  85 {
  86     return DOSMEM_sysmem;
  87 }
  88
  89 /***********************************************************************
  90  *           DOSMEM_MemoryBase
  91  *
  92  * Gets the DOS memory base.
  93  */
  94 char *DOSMEM_MemoryBase(void)
  95 {
  96     return DOSMEM_dosmem;
  97 }
  98
  99 /***********************************************************************
 100  *           DOSMEM_MemoryTop
 101  *
 102  * Gets the DOS memory top.
 103  */
 104 static char *DOSMEM_MemoryTop(void)
 105 {
 106     return DOSMEM_dosmem+0x9FFFC; /* 640K */
 107 }
 108
 109 /***********************************************************************
 110  *           DOSMEM_InfoBlock
 111  *
 112  * Gets the DOS memory info block.
 113  */
 114 static dosmem_info *DOSMEM_InfoBlock(void)
 115 {
 116     return (dosmem_info*)(DOSMEM_dosmem+0x10000); /* 64K */
 117 }
 118
 119 /***********************************************************************
 120  *           DOSMEM_RootBlock
 121  *
 122  * Gets the DOS memory root block.
 123  */
 124 static dosmem_entry *DOSMEM_RootBlock(void)
 125 {
 126     /* first block has to be paragraph-aligned */
 127     return (dosmem_entry*)(((char*)DOSMEM_InfoBlock()) +
 128                            ((((sizeof(dosmem_info) + 0xf) & ~0xf) - sizeof(dosmem_entry))));
 129 }
 130
 131 /***********************************************************************
 132  *           DOSMEM_FillIsrTable
 133  *
 134  * Fill the interrupt table with fake BIOS calls to BIOSSEG (0xf000).
 135  *
 136  * NOTES:
 137  * Linux normally only traps INTs performed from or destined to BIOSSEG
 138  * for us to handle, if the int_revectored table is empty. Filling the
 139  * interrupt table with calls to INT stubs in BIOSSEG allows DOS programs
 140  * to hook interrupts, as well as use their familiar retf tricks to call
 141  * them, AND let Wine handle any unhooked interrupts transparently.
 142  */
 143 static void DOSMEM_FillIsrTable(void)
 144 {
 145     SEGPTR *isr = (SEGPTR*)DOSMEM_sysmem;
 146     int x;
 147
 148     for (x=0; x<256; x++) isr[x]=PTR_SEG_OFF_TO_SEGPTR(VM_STUB_SEGMENT,x*4);
 149 }
 150
 151 static void DOSMEM_MakeIsrStubs(void)
 152 {
 153     DWORD *stub = (DWORD*)(DOSMEM_dosmem + (VM_STUB_SEGMENT << 4));
 154     int x;
 155
 156     for (x=0; x<256; x++) stub[x]=VM_STUB(x);
 157 }
 158
 159 /***********************************************************************
 160  *           DOSMEM_InitDPMI
 161  *
 162  * Allocate the global DPMI RMCB wrapper.
 163  */
 164 static void DOSMEM_InitDPMI(void)
 165 {
 166     LPSTR ptr;
 167
 168     static const char wrap_code[]={
 169      0xCD,0x31, /* int $0x31 */
 170      0xCB       /* lret */
 171     };
 172
 173     static const char enter_xms[]=
 174     {
 175         /* XMS hookable entry point */
 176         0xEB,0x03,           /* jmp entry */
 177         0x90,0x90,0x90,      /* nop;nop;nop */
 178                              /* entry: */
 179         /* real entry point */
 180         /* for simplicity, we'll just use the same hook as DPMI below */
 181         0xCD,0x31,           /* int $0x31 */
 182         0xCB                 /* lret */
 183     };
 184
 185     static const char enter_pm[]=
 186     {
 187         0x50,                /* pushw %ax */
 188         0x52,                /* pushw %dx */
 189         0x55,                /* pushw %bp */
 190         0x89,0xE5,           /* movw %sp,%bp */
 191         /* get return CS */
 192         0x8B,0x56,0x08,      /* movw 8(%bp),%dx */
 193         /* just call int 31 here to get into protected mode... */
 194         /* it'll check whether it was called from dpmi_seg... */
 195         0xCD,0x31,           /* int $0x31 */
 196         /* we are now in the context of a 16-bit relay call */
 197         /* need to fixup our stack;
 198          * 16-bit relay return address will be lost, but we won't worry quite yet */
 199         0x8E,0xD0,           /* movw %ax,%ss */
 200         0x66,0x0F,0xB7,0xE5, /* movzwl %bp,%esp */
 201         /* set return CS */
 202         0x89,0x56,0x08,      /* movw %dx,8(%bp) */
 203         0x5D,                /* popw %bp */
 204         0x5A,                /* popw %dx */
 205         0x58,                /* popw %ax */
 206         0xCB                 /* lret */
 207     };
 208
 209     ptr = DOSMEM_GetBlock( sizeof(wrap_code), &DOSMEM_wrap_seg );
 210     memcpy( ptr, wrap_code, sizeof(wrap_code) );
 211     ptr = DOSMEM_GetBlock( sizeof(enter_xms), &DOSMEM_xms_seg );
 212     memcpy( ptr, enter_xms, sizeof(enter_xms) );
 213     ptr = DOSMEM_GetBlock( sizeof(enter_pm), &DOSMEM_dpmi_seg );
 214     memcpy( ptr, enter_pm, sizeof(enter_pm) );
 215     DOSMEM_dpmi_sel = SELECTOR_AllocBlock( ptr, sizeof(enter_pm), SEGMENT_CODE, FALSE, FALSE );
 216 }
 217
 218 BIOSDATA * DOSMEM_BiosData()
 219 {
 220     return (BIOSDATA *)(DOSMEM_sysmem + 0x400);
 221 }
 222
 223 BYTE * DOSMEM_BiosSys()
 224 {
 225     return DOSMEM_dosmem+0xf0000;
 226 }
 227
 228 struct _DOS_LISTOFLISTS * DOSMEM_LOL()
 229 {
 230     return (struct _DOS_LISTOFLISTS *)DOSMEM_MapRealToLinear
 231       (PTR_SEG_OFF_TO_SEGPTR(HIWORD(DOS_LOLSeg),0));
 232 }
 233
 234 /***********************************************************************
 235  *           DOSMEM_FillBiosSegments
 236  *
 237  * Fill the BIOS data segment with dummy values.
 238  */
 239 static void DOSMEM_FillBiosSegments(void)
 240 {
 241     BYTE *pBiosSys = DOSMEM_BiosSys();
 242     BYTE *pBiosROMTable = pBiosSys+0xe6f5;
 243     BIOSDATA *pBiosData = DOSMEM_BiosData();
 244
 245     /* bogus 0xe0xx addresses !! Adapt int 0x10/0x1b if change needed */
 246     VIDEOFUNCTIONALITY *pVidFunc = (VIDEOFUNCTIONALITY *)(pBiosSys+0xe000);
 247     VIDEOSTATE *pVidState = (VIDEOSTATE *)(pBiosSys+0xe010);
 248     int i;
 249
 250       /* Clear all unused values */
 251     memset( pBiosData, 0, sizeof(*pBiosData) );
 252     memset( pVidFunc,  0, sizeof(*pVidFunc ) );
 253     memset( pVidState, 0, sizeof(*pVidState) );
 254
 255     /* FIXME: should check the number of configured drives and ports */
 256
 257     pBiosData->Com1Addr             = 0x3f8;
 258     pBiosData->Com2Addr             = 0x2f8;
 259     pBiosData->Lpt1Addr             = 0x378;
 260     pBiosData->Lpt2Addr             = 0x278;
 261     pBiosData->InstalledHardware    = 0x5463;
 262     pBiosData->MemSize              = 640;
 263     pBiosData->NextKbdCharPtr       = 0x1e;
 264     pBiosData->FirstKbdCharPtr      = 0x1e;
 265     pBiosData->VideoMode            = 3;
 266     pBiosData->VideoColumns         = 80;
 267     pBiosData->VideoPageSize        = 80 * 25 * 2;
 268     pBiosData->VideoPageStartAddr   = 0xb800;
 269     pBiosData->VideoCtrlAddr        = 0x3d4;
 270     pBiosData->Ticks                = INT1A_GetTicksSinceMidnight();
 271     pBiosData->NbHardDisks          = 2;
 272     pBiosData->KbdBufferStart       = 0x1e;
 273     pBiosData->KbdBufferEnd         = 0x3e;
 274     pBiosData->RowsOnScreenMinus1   = 23;
 275     pBiosData->BytesPerChar         = 0x10;
 276     pBiosData->ModeOptions          = 0x64;
 277     pBiosData->FeatureBitsSwitches  = 0xf9;
 278     pBiosData->VGASettings          = 0x51;
 279     pBiosData->DisplayCombination   = 0x08;
 280     pBiosData->DiskDataRate         = 0;
 281
 282     /* fill ROM configuration table (values from Award) */
 283     *(pBiosROMTable+0x0)        = 0x08; /* number of bytes following LO */
 284     *(pBiosROMTable+0x1)        = 0x00; /* number of bytes following HI */
 285     *(pBiosROMTable+0x2)        = 0xfc; /* model */
 286     *(pBiosROMTable+0x3)        = 0x01; /* submodel */
 287     *(pBiosROMTable+0x4)        = 0x00; /* BIOS revision */
 288     *(pBiosROMTable+0x5)        = 0x74; /* feature byte 1 */
 289     *(pBiosROMTable+0x6)        = 0x00; /* feature byte 2 */
 290     *(pBiosROMTable+0x7)        = 0x00; /* feature byte 3 */
 291     *(pBiosROMTable+0x8)        = 0x00; /* feature byte 4 */
 292     *(pBiosROMTable+0x9)        = 0x00; /* feature byte 5 */
 293
 294
 295     for (i = 0; i < 7; i++)
 296         pVidFunc->ModeSupport[i] = 0xff;
 297
 298     pVidFunc->ScanlineSupport     = 7;
 299     pVidFunc->NumberCharBlocks    = 0;
 300     pVidFunc->ActiveCharBlocks    = 0;
 301     pVidFunc->MiscFlags           = 0x8ff;
 302     pVidFunc->SavePointerFlags    = 0x3f;
 303
 304     pVidState->StaticFuncTable    = 0xf000e000;  /* FIXME: always real mode ? */
 305     pVidState->VideoMode          = pBiosData->VideoMode; /* needs updates! */
 306     pVidState->NumberColumns      = pBiosData->VideoColumns; /* needs updates! */
 307     pVidState->RegenBufLen        = 0;
 308     pVidState->RegenBufAddr       = 0;
 309
 310     for (i = 0; i < 8; i++)
 311         pVidState->CursorPos[i] = 0;
 312
 313     pVidState->CursorType         = 0x0a0b;  /* start/end line */
 314     pVidState->ActivePage         = 0;
 315     pVidState->CRTCPort           = 0x3da;
 316     pVidState->Port3x8            = 0;
 317     pVidState->Port3x9            = 0;
 318     pVidState->NumberRows         = 23;     /* number of rows - 1 */
 319     pVidState->BytesPerChar       = 0x10;
 320     pVidState->DCCActive          = pBiosData->DisplayCombination;
 321     pVidState->DCCAlternate       = 0;
 322     pVidState->NumberColors       = 16;
 323     pVidState->NumberPages        = 1;
 324     pVidState->NumberScanlines    = 3; /* (0,1,2,3) = (200,350,400,480) */
 325     pVidState->CharBlockPrimary   = 0;
 326     pVidState->CharBlockSecondary = 0;
 327     pVidState->MiscFlags =
 328                            (pBiosData->VGASettings & 0x0f)
 329                          | ((pBiosData->ModeOptions & 1) << 4); /* cursor emulation */
 330     pVidState->NonVGASupport      = 0;
 331     pVidState->VideoMem           = (pBiosData->ModeOptions & 0x60 >> 5);
 332     pVidState->SavePointerState   = 0;
 333     pVidState->DisplayStatus      = 4;
 334
 335     /* BIOS date string */
 336     strcpy((char *)pBiosSys+0xfff5, "13/01/99");
 337
 338     /* BIOS ID */
 339     *(pBiosSys+0xfffe) = 0xfc;
 340 }
 341
 342 /***********************************************************************
 343  *           DOSMEM_InitCollateTable
 344  *
 345  * Initialises the collate table (character sorting, language dependent)
 346  */
 347 static void DOSMEM_InitCollateTable()
 348 {
 349         DWORD           x;
 350         unsigned char   *tbl;
 351         int             i;
 352
 353         x = GlobalDOSAlloc16(258);
 354         DOSMEM_CollateTable = MAKELONG(0,(x>>16));
 355         tbl = DOSMEM_MapRealToLinear(DOSMEM_CollateTable);
 356         *(WORD*)tbl     = 0x100;
 357         tbl += 2;
 358         for ( i = 0; i < 0x100; i++) *tbl++ = i;
 359 }
 360
 361 /***********************************************************************
 362  *           DOSMEM_InitErrorTable
 363  *
 364  * Initialises the error tables (DOS 5+)
 365  */
 366 static void DOSMEM_InitErrorTable()
 367 {
 368 #if 0  /* no longer used */
 369         DWORD           x;
 370         char            *call;
 371
 372         /* We will use a snippet of real mode code that calls */
 373         /* a WINE-only interrupt to handle moving the requested */
 374         /* message into the buffer... */
 375
 376         /* FIXME - There is still something wrong... */
 377
 378         /* FIXME - Find hex values for opcodes...
 379
 380            (On call, AX contains message number
 381                      DI contains 'offset' (??)
 382             Resturn, ES:DI points to counted string )
 383
 384            PUSH BX
 385            MOV BX, AX
 386            MOV AX, (arbitrary subfunction number)
 387            INT (WINE-only interrupt)
 388            POP BX
 389            RET
 390
 391         */
 392
 393         const int       code = 4;
 394         const int       buffer = 80;
 395         const int       SIZE_TO_ALLOCATE = code + buffer;
 396
 397         /* FIXME - Complete rewrite of the table system to save */
 398         /* precious DOS space. Now, we return the 0001:???? as */
 399         /* DOS 4+ (??, it seems to be the case in MS 7.10) treats that */
 400         /* as a special case and programs will use the alternate */
 401         /* interface (a farcall returned with INT 24 (AX = 0x122e, DL = */
 402         /* 0x08) which lets us have a smaller memory footprint anyway. */
 403
 404         x = GlobalDOSAlloc16(SIZE_TO_ALLOCATE);
 405
 406         DOSMEM_ErrorCall = MAKELONG(0,(x>>16));
 407         DOSMEM_ErrorBuffer = DOSMEM_ErrorCall + code;
 408
 409         call = DOSMEM_MapRealToLinear(DOSMEM_ErrorCall);
 410
 411         memset(call, 0, SIZE_TO_ALLOCATE);
 412 #endif
 413         /* Fixme - Copy assembly into buffer here */
 414 }
 415
 416 /***********************************************************************
 417  *           DOSMEM_InitMemory
 418  *
 419  * Initialises the DOS memory structures.
 420  */
 421 static void DOSMEM_InitMemory(void)
 422 {
 423    /* Low 64Kb are reserved for DOS/BIOS so the useable area starts at
 424     * 1000:0000 and ends at 9FFF:FFEF. */
 425
 426     dosmem_info*        info_block = DOSMEM_InfoBlock();
 427     dosmem_entry*       root_block = DOSMEM_RootBlock();
 428     dosmem_entry*       dm;
 429
 430     root_block->size = DOSMEM_MemoryTop() - (((char*)root_block) + sizeof(dosmem_entry));
 431
 432     info_block->blocks = 0;
 433     info_block->free = root_block->size;
 434
 435     dm = NEXT_BLOCK(root_block);
 436     dm->size = DM_BLOCK_TERMINAL;
 437     root_block->size |= DM_BLOCK_FREE
 438 #ifdef __DOSMEM_DEBUG__
 439                      | DM_BLOCK_DEBUG;
 440 #endif
 441                      ;
 442 }
 443
 444 /**********************************************************************
 445  *              setup_dos_mem
 446  *
 447  * Setup the first megabyte for DOS memory access
 448  */
 449 static void setup_dos_mem( int dos_init )
 450 {
 451     int sys_offset = 0;
 452     int page_size = VIRTUAL_GetPageSize();
 453     void *addr = VIRTUAL_mmap( -1, (void *)page_size, 0x110000-page_size, 0,
 454                                PROT_READ | PROT_WRITE | PROT_EXEC, 0 );
 455     if (addr == (void *)page_size)  /* we got what we wanted */
 456     {
 457         /* now map from address 0 */
 458         addr = VIRTUAL_mmap( -1, NULL, 0x110000, 0,
 459                              PROT_READ | PROT_WRITE | PROT_EXEC, MAP_FIXED );
 460         if (addr)
 461         {
 462             ERR("MAP_FIXED failed at address 0 for DOS address space\n" );
 463             ExitProcess(1);
 464         }
 465
 466         /* inform the memory manager that there is a mapping here */
 467         VirtualAlloc( addr, 0x110000, MEM_RESERVE | MEM_SYSTEM, PAGE_EXECUTE_READWRITE );
 468
 469         /* protect the first 64K to catch NULL pointers */
 470         if (!dos_init)
 471         {
 472             VirtualProtect( addr, 0x10000, PAGE_NOACCESS, NULL );
 473             /* move the BIOS and ISR area from 0x00000 to 0xf0000 */
 474             sys_offset += 0xf0000;
 475         }
 476     }
 477     else
 478     {
 479         ERR("Cannot use first megabyte for DOS address space, please report\n" );
 480         if (dos_init) ExitProcess(1);
 481         /* allocate the DOS area somewhere else */
 482         addr = VirtualAlloc( NULL, 0x110000, MEM_COMMIT, PAGE_EXECUTE_READWRITE );
 483         if (!addr)
 484         {
 485             ERR( "Cannot allocate DOS memory\n" );
 486             ExitProcess(1);
 487         }
 488     }
 489     DOSMEM_dosmem = addr;
 490     DOSMEM_sysmem = (char*)addr + sys_offset;
 491 }
 492
 493
 494 /***********************************************************************
 495  *           DOSMEM_Init
 496  *
 497  * Create the dos memory segments, and store them into the KERNEL
 498  * exported values.
 499  */
 500 BOOL DOSMEM_Init(BOOL dos_init)
 501 {
 502     static int already_done, already_mapped;
 503
 504     if (!already_done)
 505     {
 506         setup_dos_mem( dos_init );
 507
 508         DOSMEM_0000H = GLOBAL_CreateBlock( GMEM_FIXED, DOSMEM_sysmem,
 509                                            0x10000, 0, FALSE, FALSE, FALSE );
 510         DOSMEM_BiosDataSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_sysmem + 0x400,
 511                                                 0x100, 0, FALSE, FALSE, FALSE );
 512         DOSMEM_BiosSysSeg = GLOBAL_CreateBlock(GMEM_FIXED,DOSMEM_dosmem+0xf0000,
 513                                                0x10000, 0, FALSE, FALSE, FALSE );
 514         DOSMEM_FillBiosSegments();
 515         DOSMEM_FillIsrTable();
 516         DOSMEM_InitMemory();
 517         DOSMEM_InitCollateTable();
 518         DOSMEM_InitErrorTable();
 519         DOSMEM_InitDPMI();
 520         DOSDEV_InstallDOSDevices();
 521         already_done = 1;
 522     }
 523     else if (dos_init && !already_mapped)
 524     {
 525         if (DOSMEM_dosmem)
 526         {
 527             ERR( "Needs access to the first megabyte for DOS mode\n" );
 528             ExitProcess(1);
 529         }
 530         MESSAGE( "Warning: unprotecting the first 64KB of memory to allow real-mode calls.\n"
 531                  "         NULL pointer accesses will no longer be caught.\n" );
 532         VirtualProtect( NULL, 0x10000, PAGE_EXECUTE_READWRITE, NULL );
 533         /* copy the BIOS and ISR area down */
 534         memcpy( DOSMEM_dosmem, DOSMEM_sysmem, 0x400 + 0x100 );
 535         DOSMEM_sysmem = DOSMEM_dosmem;
 536         SetSelectorBase( DOSMEM_0000H, 0 );
 537         SetSelectorBase( DOSMEM_BiosDataSeg, 0x400 );
 538         /* we may now need the actual interrupt stubs, and since we've just moved the
 539          * interrupt vector table away, we can fill the area with stubs instead... */
 540         DOSMEM_MakeIsrStubs();
 541         already_mapped = 1;
 542     }
 543     return TRUE;
 544 }
 545
 546
 547 /***********************************************************************
 548  *           DOSMEM_Tick
 549  *
 550  * Increment the BIOS tick counter. Called by timer signal handler.
 551  */
 552 void DOSMEM_Tick( WORD timer )
 553 {
 554     BIOSDATA *pBiosData = DOSMEM_BiosData();
 555     if (pBiosData) pBiosData->Ticks++;
 556 }
 557
 558 /***********************************************************************
 559  *           DOSMEM_GetBlock
 560  *
 561  * Carve a chunk of the DOS memory block (without selector).
 562  */
 563 LPVOID DOSMEM_GetBlock(UINT size, UINT16* pseg)
 564 {
 565    UINT          blocksize;
 566    char         *block = NULL;
 567    dosmem_info  *info_block = DOSMEM_InfoBlock();
 568    dosmem_entry *dm;
 569 #ifdef __DOSMEM_DEBUG_
 570    dosmem_entry *prev = NULL;
 571 #endif
 572
 573    if( size > info_block->free ) return NULL;
 574    dm = DOSMEM_RootBlock();
 575
 576    while (dm && dm->size != DM_BLOCK_TERMINAL)
 577    {
 578 #ifdef __DOSMEM_DEBUG__
 579        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 580        {
 581             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 582             return NULL;
 583        }
 584        prev = dm;
 585 #endif
 586        if( dm->size & DM_BLOCK_FREE )
 587        {
 588            dosmem_entry  *next = NEXT_BLOCK(dm);
 589
 590            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 591            {
 592                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 593                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 594                next = NEXT_BLOCK(dm);
 595            }
 596
 597            blocksize = dm->size & DM_BLOCK_MASK;
 598            if( blocksize >= size )
 599            {
 600                block = ((char*)dm) + sizeof(dosmem_entry);
 601                if( blocksize - size > 0x20 )
 602                {
 603                    /* split dm so that the next one stays
 604                     * paragraph-aligned (and dm loses free bit) */
 605
 606                    dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 607                                               sizeof(dosmem_entry));
 608                    next = (dosmem_entry*)(((char*)dm) +
 609                            sizeof(dosmem_entry) + dm->size);
 610                    next->size = (blocksize - (dm->size +
 611                            sizeof(dosmem_entry))) | DM_BLOCK_FREE
 612 #ifdef __DOSMEM_DEBUG__
 613                                                   | DM_BLOCK_DEBUG
 614 #endif
 615                                                   ;
 616                } else dm->size &= DM_BLOCK_MASK;
 617
 618                info_block->blocks++;
 619                info_block->free -= dm->size;
 620                if( pseg ) *pseg = (block - DOSMEM_dosmem) >> 4;
 621 #ifdef __DOSMEM_DEBUG__
 622                dm->size |= DM_BLOCK_DEBUG;
 623 #endif
 624                break;
 625            }
 626            dm = next;
 627        }
 628        else dm = NEXT_BLOCK(dm);
 629    }
 630    return (LPVOID)block;
 631 }
 632
 633 /***********************************************************************
 634  *           DOSMEM_FreeBlock
 635  */
 636 BOOL DOSMEM_FreeBlock(void* ptr)
 637 {
 638    dosmem_info  *info_block = DOSMEM_InfoBlock();
 639
 640    if( ptr >= (void*)(((char*)DOSMEM_RootBlock()) + sizeof(dosmem_entry)) &&
 641        ptr < (void*)DOSMEM_MemoryTop() && !((((char*)ptr)
 642                   - DOSMEM_dosmem) & 0xf) )
 643    {
 644        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 645
 646        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 647 #ifdef __DOSMEM_DEBUG__
 648          && ((dm->size & DM_BLOCK_DEBUG) == DM_BLOCK_DEBUG )
 649 #endif
 650          )
 651        {
 652              info_block->blocks--;
 653              info_block->free += dm->size;
 654
 655              dm->size |= DM_BLOCK_FREE;
 656              return TRUE;
 657        }
 658    }
 659    return FALSE;
 660 }
 661
 662 /***********************************************************************
 663  *           DOSMEM_ResizeBlock
 664  */
 665 LPVOID DOSMEM_ResizeBlock(void* ptr, UINT size, UINT16* pseg)
 666 {
 667    char         *block = NULL;
 668    dosmem_info  *info_block = DOSMEM_InfoBlock();
 669
 670    if( ptr >= (void*)(((char*)DOSMEM_RootBlock()) + sizeof(dosmem_entry)) &&
 671        ptr < (void*)DOSMEM_MemoryTop() && !((((char*)ptr)
 672                   - DOSMEM_dosmem) & 0xf) )
 673    {
 674        dosmem_entry  *dm = (dosmem_entry*)(((char*)ptr) - sizeof(dosmem_entry));
 675
 676        if( pseg ) *pseg = ((char*)ptr - DOSMEM_dosmem) >> 4;
 677
 678        if( !(dm->size & (DM_BLOCK_FREE | DM_BLOCK_TERMINAL))
 679          )
 680        {
 681              dosmem_entry  *next = NEXT_BLOCK(dm);
 682              UINT blocksize, orgsize = dm->size & DM_BLOCK_MASK;
 683
 684              while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 685              {
 686                  dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 687                  next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 688                  next = NEXT_BLOCK(dm);
 689              }
 690
 691              blocksize = dm->size & DM_BLOCK_MASK;
 692              if (blocksize >= size)
 693              {
 694                  block = ((char*)dm) + sizeof(dosmem_entry);
 695                  if( blocksize - size > 0x20 )
 696                  {
 697                      /* split dm so that the next one stays
 698                       * paragraph-aligned (and next gains free bit) */
 699
 700                      dm->size = (((size + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 701                                                 sizeof(dosmem_entry));
 702                      next = (dosmem_entry*)(((char*)dm) +
 703                              sizeof(dosmem_entry) + dm->size);
 704                      next->size = (blocksize - (dm->size +
 705                              sizeof(dosmem_entry))) | DM_BLOCK_FREE
 706                                                     ;
 707                  } else dm->size &= DM_BLOCK_MASK;
 708
 709                  info_block->free += orgsize - dm->size;
 710              } else {
 711                  /* the collapse didn't help, try getting a new block */
 712                  block = DOSMEM_GetBlock(size, pseg);
 713                  if (block) {
 714                      /* we got one, copy the old data there (we do need to, right?) */
 715                      memcpy(block, ((char*)dm) + sizeof(dosmem_entry),
 716                                    (size<orgsize) ? size : orgsize);
 717                      /* free old block */
 718                      info_block->blocks--;
 719                      info_block->free += dm->size;
 720
 721                      dm->size |= DM_BLOCK_FREE;
 722                  } else {
 723                      /* and Bill Gates said 640K should be enough for everyone... */
 724
 725                      /* need to split original and collapsed blocks apart again,
 726                       * and free the collapsed blocks again, before exiting */
 727                      if( blocksize - orgsize > 0x20 )
 728                      {
 729                          /* split dm so that the next one stays
 730                           * paragraph-aligned (and next gains free bit) */
 731
 732                          dm->size = (((orgsize + 0xf + sizeof(dosmem_entry)) & ~0xf) -
 733                                                        sizeof(dosmem_entry));
 734                          next = (dosmem_entry*)(((char*)dm) +
 735                                  sizeof(dosmem_entry) + dm->size);
 736                          next->size = (blocksize - (dm->size +
 737                                  sizeof(dosmem_entry))) | DM_BLOCK_FREE
 738                                                         ;
 739                      } else dm->size &= DM_BLOCK_MASK;
 740                  }
 741              }
 742        }
 743    }
 744    return (LPVOID)block;
 745 }
 746
 747
 748 /***********************************************************************
 749  *           DOSMEM_Available
 750  */
 751 UINT DOSMEM_Available(void)
 752 {
 753    UINT          blocksize, available = 0;
 754    dosmem_entry *dm;
 755
 756    dm = DOSMEM_RootBlock();
 757
 758    while (dm && dm->size != DM_BLOCK_TERMINAL)
 759    {
 760 #ifdef __DOSMEM_DEBUG__
 761        if( (dm->size & DM_BLOCK_DEBUG) != DM_BLOCK_DEBUG )
 762        {
 763             WARN("MCB overrun! [prev = 0x%08x]\n", 4 + (UINT)prev);
 764             return NULL;
 765        }
 766        prev = dm;
 767 #endif
 768        if( dm->size & DM_BLOCK_FREE )
 769        {
 770            dosmem_entry  *next = NEXT_BLOCK(dm);
 771
 772            while( next->size & DM_BLOCK_FREE ) /* collapse free blocks */
 773            {
 774                dm->size += sizeof(dosmem_entry) + (next->size & DM_BLOCK_MASK);
 775                next->size = (DM_BLOCK_FREE | DM_BLOCK_TERMINAL);
 776                next = NEXT_BLOCK(dm);
 777            }
 778
 779            blocksize = dm->size & DM_BLOCK_MASK;
 780            if ( blocksize > available ) available = blocksize;
 781            dm = next;
 782        }
 783        else dm = NEXT_BLOCK(dm);
 784    }
 785    return available;
 786 }
 787
 788
 789 /***********************************************************************
 790  *           DOSMEM_MapLinearToDos
 791  *
 792  * Linear address to the DOS address space.
 793  */
 794 UINT DOSMEM_MapLinearToDos(LPVOID ptr)
 795 {
 796     if (((char*)ptr >= DOSMEM_dosmem) &&
 797         ((char*)ptr < DOSMEM_dosmem + 0x100000))
 798           return (UINT)ptr - (UINT)DOSMEM_dosmem;
 799     return (UINT)ptr;
 800 }
 801
 802
 803 /***********************************************************************
 804  *           DOSMEM_MapDosToLinear
 805  *
 806  * DOS linear address to the linear address space.
 807  */
 808 LPVOID DOSMEM_MapDosToLinear(UINT ptr)
 809 {
 810     if (ptr < 0x100000) return (LPVOID)(ptr + (UINT)DOSMEM_dosmem);
 811     return (LPVOID)ptr;
 812 }
 813
 814
 815 /***********************************************************************
 816  *           DOSMEM_MapRealToLinear
 817  *
 818  * Real mode DOS address into a linear pointer
 819  */
 820 LPVOID DOSMEM_MapRealToLinear(DWORD x)
 821 {
 822    LPVOID       lin;
 823
 824    lin=DOSMEM_dosmem+(x&0xffff)+(((x&0xffff0000)>>16)*16);
 825    TRACE_(selector)("(0x%08lx) returns 0x%p.\n", x, lin );
 826    return lin;
 827 }
 828
 829 /***********************************************************************
 830  *           DOSMEM_AllocSelector
 831  *
 832  * Allocates a protected mode selector for a realmode segment.
 833  */
 834 WORD DOSMEM_AllocSelector(WORD realsel)
 835 {
 836         HMODULE16 hModule = GetModuleHandle16("KERNEL");
 837         WORD    sel;
 838
 839         sel=GLOBAL_CreateBlock(
 840                 GMEM_FIXED,DOSMEM_dosmem+realsel*16,0x10000,
 841                 hModule,FALSE,FALSE,FALSE );
 842         TRACE_(selector)("(0x%04x) returns 0x%04x.\n", realsel,sel);
 843         return sel;
 844 }
 845