Kernel/drvutil.c

   1 /*
   2  * Acess2 Kernel
   3  * - By John Hodge
   4  *
   5  * drvutil.c
   6  * - Common Driver/Filesystem Helper Functions
   7  */
   8 #define DEBUG   0
   9 #include <acess.h>
  10 #include <api_drv_disk.h>
  11 #include <api_drv_video.h>
  12
  13 // === TYPES ===
  14
  15 // === PROTOTYPES ===
  16 //int   DrvUtil_Video_2DStream(void *Ent, void *Buffer, int Length, tDrvUtil_Video_2DHandlers *Handlers, int SizeofHandlers);
  17 //size_t        DrvUtil_Video_WriteLFB(int Mode, tDrvUtil_Video_BufInfo *FBInfo, size_t Offset, size_t Length, void *Src);
  18 //void  DrvUtil_Video_SetCursor(tDrvUtil_Video_BufInfo *Buf, tVideo_IOCtl_Bitmap *Bitmap);
  19 //void  DrvUtil_Video_DrawCursor(tDrvUtil_Video_BufInfo *Buf, int X, int Y);
  20 void    DrvUtil_Video_RenderCursor(tDrvUtil_Video_BufInfo *Buf);
  21 //void  DrvUtil_Video_RemoveCursor(tDrvUtil_Video_BufInfo *Buf);
  22 void    DrvUtil_Video_2D_Fill(void *Ent, Uint16 X, Uint16 Y, Uint16 W, Uint16 H, Uint32 Colour);
  23 void    DrvUtil_Video_2D_Blit(void *Ent, Uint16 DstX, Uint16 DstY, Uint16 SrcX, Uint16 SrcY, Uint16 W, Uint16 H);
  24
  25 // === GLOBALS ===
  26 tDrvUtil_Video_2DHandlers       gDrvUtil_Stub_2DFunctions = {
  27         NULL,
  28         DrvUtil_Video_2D_Fill,
  29         DrvUtil_Video_2D_Blit
  30 };
  31 tVideo_IOCtl_Bitmap     gDrvUtil_TextModeCursor = {
  32         8, 16,
  33         0, 0,
  34         {
  35                 0, 0, 0         , 0, 0, 0, 0, 0,
  36                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  37                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  38                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  39                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  40                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  41                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  42                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  43                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  44                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  45                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  46                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  47                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  48                 0,-1, 0xFF000000, 0, 0, 0, 0, 0,
  49                 0, 0, 0         , 0, 0, 0, 0, 0,
  50                 0, 0, 0         , 0, 0, 0, 0, 0
  51         }
  52 };
  53
  54 // === CODE ===
  55 // --- Video Driver Helpers ---
  56 int DrvUtil_Video_2DStream(void *Ent, void *Buffer, int Length,
  57         tDrvUtil_Video_2DHandlers *Handlers, int SizeofHandlers)
  58 {
  59         void    *stream = Buffer;
  60          int    rem = Length;
  61          int    op;
  62         while( rem )
  63         {
  64                 rem --;
  65                 op = *(Uint8*)stream;
  66                 stream = (void*)((tVAddr)stream + 1);
  67
  68                 if(op > NUM_VIDEO_2DOPS) {
  69                         Log_Warning("DrvUtil",
  70                                 "DrvUtil_Video_2DStream: Unknown operation %i",
  71                                 op);
  72                         return Length-rem;
  73                 }
  74
  75                 if(op*sizeof(void*) > SizeofHandlers) {
  76                         Log_Warning("DrvUtil",
  77                                 "DrvUtil_Video_2DStream: Driver does not support op %i",
  78                                 op);
  79                         return Length-rem;
  80                 }
  81
  82                 switch(op)
  83                 {
  84                 case VIDEO_2DOP_NOP:    break;
  85
  86                 case VIDEO_2DOP_FILL:
  87                         if(rem < 12)    return Length-rem;
  88
  89                         if(!Handlers->Fill) {
  90                                 Log_Warning("DrvUtil", "DrvUtil_Video_2DStream: Driver"
  91                                         " does not support VIDEO_2DOP_FILL");
  92                                 return Length-rem;
  93                         }
  94
  95                         Handlers->Fill(
  96                                 Ent,
  97                                 ((Uint16*)stream)[0], ((Uint16*)stream)[1],
  98                                 ((Uint16*)stream)[2], ((Uint16*)stream)[3],
  99                                 ((Uint32*)stream)[2]
 100                                 );
 101
 102                         rem -= 12;
 103                         stream = (void*)((tVAddr)stream + 12);
 104                         break;
 105
 106                 case VIDEO_2DOP_BLIT:
 107                         if(rem < 12)    return Length-rem;
 108
 109                         if(!Handlers->Blit) {
 110                                 Log_Warning("DrvUtil", "DrvUtil_Video_2DStream: Driver"
 111                                         " does not support VIDEO_2DOP_BLIT");
 112                                 return Length-rem;
 113                         }
 114
 115                         Handlers->Blit(
 116                                 Ent,
 117                                 ((Uint16*)stream)[0], ((Uint16*)stream)[1],
 118                                 ((Uint16*)stream)[2], ((Uint16*)stream)[3],
 119                                 ((Uint16*)stream)[4], ((Uint16*)stream)[5]
 120                                 );
 121
 122                         rem -= 12;
 123                         stream = (void*)((tVAddr)stream + 12);
 124                         break;
 125
 126                 }
 127         }
 128         return 0;
 129 }
 130
 131 int DrvUtil_Video_WriteLFB(tDrvUtil_Video_BufInfo *FBInfo, size_t Offset, size_t Length, void *Buffer)
 132 {
 133         Uint8   *dest;
 134          int    csr_x, csr_y;
 135         ENTER("pFBInfo xOffset xLength pBuffer",
 136                 Mode, FBInfo, Offset, Length, Buffer);
 137
 138         csr_x = FBInfo->CursorX;
 139         csr_y = FBInfo->CursorY;
 140
 141         DrvUtil_Video_RemoveCursor(FBInfo);
 142
 143         switch( FBInfo->BufferFormat )
 144         {
 145         case VIDEO_BUFFMT_TEXT:
 146                 {
 147                 tVT_Char        *chars = Buffer;
 148                  int    bytes_per_px = (FBInfo->Depth + 7) / 8;
 149                  int    widthInChars = FBInfo->Width/giVT_CharWidth;
 150                  int    heightInChars = FBInfo->Height/giVT_CharHeight;
 151                  int    x, y, i;
 152
 153                 LOG("bytes_per_px = %i", bytes_per_px);
 154                 LOG("widthInChars = %i, heightInChars = %i", widthInChars, heightInChars);
 155
 156                 Length /= sizeof(tVT_Char);     Offset /= sizeof(tVT_Char);
 157
 158                 x = Offset % widthInChars;      y = Offset / widthInChars;
 159                 LOG("x = %i, y = %i", x, y);
 160
 161                 // Sanity Check
 162                 if(Offset > heightInChars * widthInChars)       LEAVE_RET('i', 0);
 163                 if(y >= heightInChars)  LEAVE_RET('i', 0);
 164
 165                 if( Offset + Length > heightInChars*widthInChars )
 166                 {
 167                         Length = heightInChars*widthInChars - Offset;
 168                 }
 169
 170                 dest = FBInfo->Framebuffer;
 171                 LOG("dest = %p", dest);
 172                 dest += y * giVT_CharHeight * FBInfo->Pitch;
 173                 LOG("dest = %p", dest);
 174
 175                 for( i = 0; i < Length; i++ )
 176                 {
 177                         if( y >= heightInChars )
 178                         {
 179                                 Log_Notice("DrvUtil", "Stopped at %i", i);
 180                                 break;
 181                         }
 182
 183                         VT_Font_Render(
 184                                 chars->Ch,
 185                                 dest + x*giVT_CharWidth*bytes_per_px, FBInfo->Depth, FBInfo->Pitch,
 186                                 VT_Colour12toN(chars->BGCol, FBInfo->Depth),
 187                                 VT_Colour12toN(chars->FGCol, FBInfo->Depth)
 188                                 );
 189
 190                         chars ++;
 191                         x ++;
 192                         if( x >= widthInChars )
 193                         {
 194                                 x = 0;
 195                                 y ++;
 196                                 dest += FBInfo->Pitch*giVT_CharHeight;
 197                                 LOG("dest = %p", dest);
 198                         }
 199                 }
 200                 Length = i * sizeof(tVT_Char);
 201                 }
 202                 break;
 203
 204         case VIDEO_BUFFMT_FRAMEBUFFER:
 205                 if(FBInfo->Width*FBInfo->Height*4 < Offset+Length)
 206                 {
 207                         Log_Warning("DrvUtil", "DrvUtil_Video_WriteLFB - Framebuffer Overflow");
 208                         return 0;
 209                 }
 210
 211                 //TODO: Handle non 32-bpp framebuffer modes
 212                 if( FBInfo->Depth != 32 ) {
 213                         Log_Warning("DrvUtil", "DrvUtil_Video_WriteLFB - Don't support non 32-bpp FB mode");
 214                         return 0;
 215                 }
 216
 217
 218                 //TODO: Handle pitch != Width*BytesPerPixel
 219                 // Copy to Frambuffer
 220                 dest = (Uint8 *)FBInfo->Framebuffer + Offset;
 221                 memcpy(dest, Buffer, Length);
 222                 break;
 223
 224         case VIDEO_BUFFMT_2DSTREAM:
 225                 Length = DrvUtil_Video_2DStream(
 226                         FBInfo, Buffer, Length,
 227                         &gDrvUtil_Stub_2DFunctions, sizeof(gDrvUtil_Stub_2DFunctions)
 228                         );
 229                 break;
 230
 231         default:
 232                 LEAVE('i', -1);
 233                 return -1;
 234         }
 235
 236         DrvUtil_Video_DrawCursor(FBInfo, csr_x, csr_y);
 237
 238         LEAVE('x', Length);
 239         return Length;
 240 }
 241
 242 int DrvUtil_Video_SetCursor(tDrvUtil_Video_BufInfo *Buf, tVideo_IOCtl_Bitmap *Bitmap)
 243 {
 244          int    csrX = Buf->CursorX, csrY = Buf->CursorY;
 245         size_t  size;
 246
 247         // Clear old bitmap
 248         if( Buf->CursorBitmap )
 249         {
 250                 DrvUtil_Video_RemoveCursor(Buf);
 251                 if( !Bitmap || Bitmap->W != Buf->CursorBitmap->W || Bitmap->H != Buf->CursorBitmap->H )
 252                 {
 253                         free( Buf->CursorSaveBuf );
 254                         Buf->CursorSaveBuf = NULL;
 255                 }
 256                 if( Buf->CursorBitmap != &gDrvUtil_TextModeCursor)
 257                         free(Buf->CursorBitmap);
 258                 Buf->CursorBitmap = NULL;
 259         }
 260
 261         // If the new bitmap is null, disable drawing
 262         if( !Bitmap )
 263         {
 264                 Buf->CursorX = -1;
 265                 Buf->CursorY = -1;
 266                 return 0;
 267         }
 268
 269         // Sanity check the bitmap
 270         if( !CheckMem(Bitmap, sizeof(*Bitmap)) || !CheckMem(Bitmap->Data, Bitmap->W*Bitmap->H*sizeof(Uint32)) )
 271         {
 272                 Log_Warning("DrvUtil", "DrvUtil_Video_SetCursor: Bitmap (%p) is in invalid memory", Bitmap);
 273                 errno = -EINVAL;
 274                 return -1;
 275         }
 276
 277         // Don't take a copy of the DrvUtil provided cursor
 278         if( Bitmap == &gDrvUtil_TextModeCursor )
 279         {
 280                 Buf->CursorBitmap = Bitmap;
 281         }
 282         else
 283         {
 284                 size = sizeof(tVideo_IOCtl_Bitmap) + Bitmap->W*Bitmap->H*4;
 285
 286                 // Take a copy
 287                 Buf->CursorBitmap = malloc( size );
 288                 memcpy(Buf->CursorBitmap, Bitmap, size);
 289         }
 290
 291         // Restore cursor position
 292         DrvUtil_Video_DrawCursor(Buf, csrX, csrY);
 293         return 0;
 294 }
 295
 296 void DrvUtil_Video_DrawCursor(tDrvUtil_Video_BufInfo *Buf, int X, int Y)
 297 {
 298          int    render_ox=0, render_oy=0, render_w, render_h;
 299
 300         DrvUtil_Video_RemoveCursor(Buf);
 301
 302         // X < 0 disables the cursor
 303         if( X < 0 ) {
 304                 Buf->CursorX = -1;
 305                 return ;
 306         }
 307
 308         // Sanity checking
 309         if( X < 0 || Y < 0 )    return;
 310         if( X >= Buf->Width || Y >= Buf->Height )       return;
 311
 312         // Ensure the cursor is enabled
 313         if( !Buf->CursorBitmap )        return ;
 314
 315         // Save cursor position (for changing the bitmap)
 316         Buf->CursorX = X;       Buf->CursorY = Y;
 317
 318         // Apply cursor's center offset
 319         X -= Buf->CursorBitmap->XOfs;
 320         Y -= Buf->CursorBitmap->YOfs;
 321
 322         // Get the width of the cursor on screen (clipping to right/bottom edges)
 323         render_w = X > Buf->Width  - Buf->CursorBitmap->W ? Buf->Width  - X : Buf->CursorBitmap->W;
 324         render_h = Y > Buf->Height - Buf->CursorBitmap->H ? Buf->Height - Y : Buf->CursorBitmap->H;
 325
 326         // Clipp to left/top edges
 327         if(X < 0) {     render_ox = -X; X = 0;  }
 328         if(Y < 0) {     render_oy = -Y; Y = 0;  }
 329
 330         // Save values
 331         Buf->CursorRenderW = render_w;  Buf->CursorRenderH = render_h;
 332         Buf->CursorDestX   = X;         Buf->CursorDestY = Y;
 333         Buf->CursorReadX   = render_ox; Buf->CursorReadY = render_oy;
 334
 335         // Call render routine
 336         DrvUtil_Video_RenderCursor(Buf);
 337 }
 338
 339 void DrvUtil_Video_RenderCursor(tDrvUtil_Video_BufInfo *Buf)
 340 {
 341          int    src_x = Buf->CursorReadX, src_y = Buf->CursorReadY;
 342          int    render_w = Buf->CursorRenderW, render_h = Buf->CursorRenderH;
 343          int    dest_x = Buf->CursorDestX, dest_y = Buf->CursorDestY;
 344          int    bytes_per_px = (Buf->Depth + 7) / 8;
 345          int    save_pitch = Buf->CursorBitmap->W * bytes_per_px;
 346         void    *dest;
 347         Uint32  *src;
 348          int    x, y;
 349
 350 //      Debug("DrvUtil_Video_RenderCursor: (Buf=%p) dest_x=%i, dest_y=%i", Buf, dest_x, dest_y);
 351
 352         dest = (Uint8*)Buf->Framebuffer + dest_y*Buf->Pitch + dest_x*bytes_per_px;
 353         src = Buf->CursorBitmap->Data + src_y * Buf->CursorBitmap->W + src_x;
 354
 355         // Allocate save buffer if not already
 356         if( !Buf->CursorSaveBuf )
 357                 Buf->CursorSaveBuf = malloc( Buf->CursorBitmap->W*Buf->CursorBitmap->H*bytes_per_px );
 358
 359         // Save behind the cursor
 360         for( y = 0; y < render_h; y ++ )
 361                 memcpy(
 362                         (Uint8*)Buf->CursorSaveBuf + y*save_pitch,
 363                         (Uint8*)dest + y*Buf->Pitch,
 364                         render_w*bytes_per_px
 365                         );
 366         // Draw the cursor
 367         switch(Buf->Depth)
 368         {
 369         case 32:
 370                 for( y = 0; y < render_h; y ++ )
 371                 {
 372                         for(x = 0; x < render_w; x ++ )
 373                         {
 374                                 // TODO: Should I implement alpha blending?
 375                                 if(src[x] & 0xFF000000)
 376                                         ((Uint32*)dest)[x] = src[x];
 377                                 else
 378                                         ;       // NOP, completely transparent
 379                         }
 380                         src += Buf->CursorBitmap->W;
 381                         dest = (Uint8*)dest + Buf->Pitch;
 382                 }
 383                 break;
 384         default:
 385                 Log_Error("DrvUtil", "TODO: Implement non 32-bpp cursor");
 386                 break;
 387         }
 388 }
 389
 390 void DrvUtil_Video_RemoveCursor(tDrvUtil_Video_BufInfo *Buf)
 391 {
 392          int    bytes_per_px = (Buf->Depth + 7) / 8;
 393          int    y, save_pitch;
 394         Uint8   *dest, *src;
 395
 396         // Just a little sanity
 397         if( !Buf->CursorBitmap || Buf->CursorX == -1 )  return ;
 398         if( !Buf->CursorSaveBuf )       return ;
 399
 400 //      Debug("DrvUtil_Video_RemoveCursor: (Buf=%p) dest_x=%i, dest_y=%i", Buf, Buf->CursorDestX, Buf->CursorDestY);
 401
 402         // Set up
 403         save_pitch = Buf->CursorBitmap->W * bytes_per_px;
 404         dest = (Uint8*)Buf->Framebuffer + Buf->CursorDestY * Buf->Pitch + Buf->CursorDestX*bytes_per_px;
 405         src = Buf->CursorSaveBuf;
 406
 407         // Copy each line back
 408         for( y = 0; y < Buf->CursorRenderH; y ++ )
 409         {
 410                 memcpy( dest, src, Buf->CursorRenderW * bytes_per_px );
 411                 src += save_pitch;
 412                 dest += Buf->Pitch;
 413         }
 414
 415         // Set the cursor as removed
 416         Buf->CursorX = -1;
 417 }
 418
 419 void DrvUtil_Video_2D_Fill(void *Ent, Uint16 X, Uint16 Y, Uint16 W, Uint16 H, Uint32 Colour)
 420 {
 421         tDrvUtil_Video_BufInfo  *FBInfo = Ent;
 422
 423         // TODO: Handle non-32bit modes
 424         if( FBInfo->Depth != 32 )       return;
 425
 426         // TODO: Be less hacky
 427          int    pitch = FBInfo->Pitch/4;
 428         Uint32  *buf = (Uint32*)FBInfo->Framebuffer + Y*pitch + X;
 429         while( H -- ) {
 430                 Uint32 *tmp;
 431                  int    i;
 432                 tmp = buf;
 433                 for(i=W;i--;tmp++)      *tmp = Colour;
 434                 buf += pitch;
 435         }
 436 }
 437
 438 void DrvUtil_Video_2D_Blit(void *Ent, Uint16 DstX, Uint16 DstY, Uint16 SrcX, Uint16 SrcY, Uint16 W, Uint16 H)
 439 {
 440         tDrvUtil_Video_BufInfo  *FBInfo = Ent;
 441          int    scrnpitch = FBInfo->Pitch;
 442          int    bytes_per_px = (FBInfo->Depth + 7) / 8;
 443          int    dst = DstY*scrnpitch + DstX;
 444          int    src = SrcY*scrnpitch + SrcX;
 445          int    tmp;
 446
 447         //Log("Vesa_2D_Blit: (Ent=%p, DstX=%i, DstY=%i, SrcX=%i, SrcY=%i, W=%i, H=%i)",
 448         //      Ent, DstX, DstY, SrcX, SrcY, W, H);
 449
 450         if(SrcX + W > FBInfo->Width)    W = FBInfo->Width - SrcX;
 451         if(DstX + W > FBInfo->Width)    W = FBInfo->Width - DstX;
 452         if(SrcY + H > FBInfo->Height)   H = FBInfo->Height - SrcY;
 453         if(DstY + H > FBInfo->Height)   H = FBInfo->Height - DstY;
 454
 455         //Debug("W = %i, H = %i", W, H);
 456
 457         if( dst > src ) {
 458                 // Reverse copy
 459                 dst += H*scrnpitch;
 460                 src += H*scrnpitch;
 461                 while( H -- ) {
 462                         dst -= scrnpitch;
 463                         src -= scrnpitch;
 464                         tmp = W*bytes_per_px;
 465                         for( tmp = W; tmp --; ) {
 466                                 *((Uint8*)FBInfo->Framebuffer + dst + tmp) = *((Uint8*)FBInfo->Framebuffer + src + tmp);
 467                         }
 468                 }
 469         }
 470         else {
 471                 // Normal copy is OK
 472                 while( H -- ) {
 473                         memcpy((Uint8*)FBInfo->Framebuffer + dst, (Uint8*)FBInfo->Framebuffer + src, W*bytes_per_px);
 474                         dst += scrnpitch;
 475                         src += scrnpitch;
 476                 }
 477         }
 478         //Log("Vesa_2D_Blit: RETURN");
 479 }
 480
 481
 482 // --- Disk Driver Helpers ---
 483 Uint64 DrvUtil_ReadBlock(Uint64 Start, Uint64 Length, void *Buffer,
 484         tDrvUtil_Callback ReadBlocks, Uint64 BlockSize, Uint Argument)
 485 {
 486         Uint8   tmp[BlockSize]; // C99
 487         Uint64  block = Start / BlockSize;
 488          int    offset = Start - block * BlockSize;
 489          int    leading = BlockSize - offset;
 490         Uint64  num;
 491          int    tailings;
 492         Uint64  ret;
 493
 494         ENTER("XStart XLength pBuffer pReadBlocks XBlockSize xArgument",
 495                 Start, Length, Buffer, ReadBlocks, BlockSize, Argument);
 496
 497         // Non aligned start, let's fix that!
 498         if(offset != 0)
 499         {
 500                 if(leading > Length)    leading = Length;
 501                 LOG("Reading %i bytes from Block1+%i", leading, offset);
 502                 ret = ReadBlocks(block, 1, tmp, Argument);
 503                 if(ret != 1) {
 504                         LEAVE('i', 0);
 505                         return 0;
 506                 }
 507                 memcpy( Buffer, &tmp[offset], leading );
 508
 509                 if(leading == Length) {
 510                         LEAVE('i', leading);
 511                         return leading;
 512                 }
 513
 514                 Buffer = (Uint8*)Buffer + leading;
 515                 block ++;
 516                 num = ( Length - leading ) / BlockSize;
 517                 tailings = Length - num * BlockSize - leading;
 518         }
 519         else {
 520                 num = Length / BlockSize;
 521                 tailings = Length % BlockSize;
 522         }
 523
 524         // Read central blocks
 525         if(num)
 526         {
 527                 LOG("Reading %i blocks", num);
 528                 ret = ReadBlocks(block, num, Buffer, Argument);
 529                 if(ret != num ) {
 530                         LEAVE('X', leading + ret * BlockSize);
 531                         return leading + ret * BlockSize;
 532                 }
 533         }
 534
 535         // Read last tailing block
 536         if(tailings != 0)
 537         {
 538                 LOG("Reading %i bytes from last block", tailings);
 539                 block += num;
 540                 Buffer = (Uint8*)Buffer + num * BlockSize;
 541                 ret = ReadBlocks(block, 1, tmp, Argument);
 542                 if(ret != 1) {
 543                         LEAVE('X', leading + num * BlockSize);
 544                         return leading + num * BlockSize;
 545                 }
 546                 memcpy( Buffer, tmp, tailings );
 547         }
 548
 549         LEAVE('X', Length);
 550         return Length;
 551 }
 552
 553 Uint64 DrvUtil_WriteBlock(Uint64 Start, Uint64 Length, void *Buffer,
 554         tDrvUtil_Callback ReadBlocks, tDrvUtil_Callback WriteBlocks,
 555         Uint64 BlockSize, Uint Argument)
 556 {
 557         Uint8   tmp[BlockSize]; // C99
 558         Uint64  block = Start / BlockSize;
 559          int    offset = Start - block * BlockSize;
 560          int    leading = BlockSize - offset;
 561         Uint64  num;
 562          int    tailings;
 563         Uint64  ret;
 564
 565         ENTER("XStart XLength pBuffer pReadBlocks pWriteBlocks XBlockSize xArgument",
 566                 Start, Length, Buffer, ReadBlocks, WriteBlocks, BlockSize, Argument);
 567
 568         // Non aligned start, let's fix that!
 569         if(offset != 0)
 570         {
 571                 if(leading > Length)    leading = Length;
 572                 LOG("Writing %i bytes to Block1+%i", leading, offset);
 573                 // Read a copy of the block
 574                 ret = ReadBlocks(block, 1, tmp, Argument);
 575                 if(ret != 1) {
 576                         LEAVE('i', 0);
 577                         return 0;
 578                 }
 579                 // Modify
 580                 memcpy( &tmp[offset], Buffer, leading );
 581                 // Write Back
 582                 ret = WriteBlocks(block, 1, tmp, Argument);
 583                 if(ret != 1) {
 584                         LEAVE('i', 0);
 585                         return 0;
 586                 }
 587
 588                 if(leading == Length) {
 589                         LEAVE('i', leading);
 590                         return leading;
 591                 }
 592
 593                 Buffer = (Uint8*)Buffer + leading;
 594                 block ++;
 595                 num = ( Length - leading ) / BlockSize;
 596                 tailings = Length - num * BlockSize - leading;
 597         }
 598         else {
 599                 num = Length / BlockSize;
 600                 tailings = Length % BlockSize;
 601         }
 602
 603         // Read central blocks
 604         if(num)
 605         {
 606                 LOG("Writing %i blocks", num);
 607                 ret = WriteBlocks(block, num, Buffer, Argument);
 608                 if(ret != num ) {
 609                         LEAVE('X', leading + ret * BlockSize);
 610                         return leading + ret * BlockSize;
 611                 }
 612         }
 613
 614         // Read last tailing block
 615         if(tailings != 0)
 616         {
 617                 LOG("Writing %i bytes to last block", tailings);
 618                 block += num;
 619                 Buffer = (Uint8*)Buffer + num * BlockSize;
 620                 // Read
 621                 ret = ReadBlocks(block, 1, tmp, Argument);
 622                 if(ret != 1) {
 623                         LEAVE('X', leading + num * BlockSize);
 624                         return leading + num * BlockSize;
 625                 }
 626                 // Modify
 627                 memcpy( tmp, Buffer, tailings );
 628                 // Write
 629                 ret = WriteBlocks(block, 1, tmp, Argument);
 630                 if(ret != 1) {
 631                         LEAVE('X', leading + num * BlockSize);
 632                         return leading + num * BlockSize;
 633                 }
 634
 635         }
 636
 637         LEAVE('X', Length);
 638         return Length;
 639 }