示例#1
0
文件: UsbHcMem.c 项目: MattDevo/edk2
/**
  Free the allocated memory back to the memory pool.

  @param  Pool          The memory pool of the host controller.
  @param  Mem           The memory to free.
  @param  Size          The size of the memory to free.

**/
VOID
UsbHcFreeMem (
  IN USBHC_MEM_POOL     *Pool,
  IN VOID               *Mem,
  IN UINTN              Size
  )
{
  USBHC_MEM_BLOCK       *Head;
  USBHC_MEM_BLOCK       *Block;
  UINT8                 *ToFree;
  UINTN                 AllocSize;
  UINTN                 Byte;
  UINTN                 Bit;
  UINTN                 Count;

  Head      = Pool->Head;
  AllocSize = USBHC_MEM_ROUND (Size);
  ToFree    = (UINT8 *) Mem;

  for (Block = Head; Block != NULL; Block = Block->Next) {
    //
    // scan the memory block list for the memory block that
    // completely contains the memory to free.
    //
    if ((Block->BufHost <= ToFree) && ((ToFree + AllocSize) <= (Block->BufHost + Block->BufLen))) {
      //
      // compute the start byte and bit in the bit array
      //
      Byte  = ((ToFree - Block->BufHost) / USBHC_MEM_UNIT) / 8;
      Bit   = ((ToFree - Block->BufHost) / USBHC_MEM_UNIT) % 8;

      //
      // reset associated bits in bit array
      //
      for (Count = 0; Count < (AllocSize / USBHC_MEM_UNIT); Count++) {
        ASSERT (USB_HC_BIT_IS_SET (Block->Bits[Byte], Bit));

        Block->Bits[Byte] = (UINT8) (Block->Bits[Byte] ^ USB_HC_BIT (Bit));
        NEXT_BIT (Byte, Bit);
      }

      break;
    }
  }

  //
  // If Block == NULL, it means that the current memory isn't
  // in the host controller's pool. This is critical because
  // the caller has passed in a wrong memory pointer
  //
  ASSERT (Block != NULL);

  //
  // Release the current memory block if it is empty and not the head
  //
  if ((Block != Head) && UsbHcIsMemBlockEmpty (Block)) {
    //UsbHcUnlinkMemBlock (Head, Block);
    UsbHcFreeMemBlock (Pool, Block);
  }
}
示例#2
0
/**
  Alloc some memory from the block.

  @param  Block          The memory block to allocate memory from.
  @param  Units          Number of memory units to allocate.

  @return The pointer to the allocated memory. If couldn't allocate the needed memory,
          the return value is NULL.

**/
VOID *
UsbHcAllocMemFromBlock (
  IN  USBHC_MEM_BLOCK     *Block,
  IN  UINTN               Units
  )
{
  UINTN                   Byte;
  UINT8                   Bit;
  UINTN                   StartByte;
  UINT8                   StartBit;
  UINTN                   Available;
  UINTN                   Count;

  ASSERT ((Block != 0) && (Units != 0));

  StartByte  = 0;
  StartBit   = 0;
  Available  = 0;

  for (Byte = 0, Bit = 0; Byte < Block->BitsLen;) {
    //
    // If current bit is zero, the corresponding memory unit is
    // available, otherwise we need to restart our searching.
    // Available counts the consective number of zero bit.
    //
    if (!USB_HC_BIT_IS_SET (Block->Bits[Byte], Bit)) {
      Available++;

      if (Available >= Units) {
        break;
      }

      NEXT_BIT (Byte, Bit);

    } else {
      NEXT_BIT (Byte, Bit);

      Available  = 0;
      StartByte  = Byte;
      StartBit   = Bit;
    }
  }

  if (Available < Units) {
    return NULL;
  }

  //
  // Mark the memory as allocated
  //
  Byte  = StartByte;
  Bit   = StartBit;

  for (Count = 0; Count < Units; Count++) {
    ASSERT (!USB_HC_BIT_IS_SET (Block->Bits[Byte], Bit));

    Block->Bits[Byte] = (UINT8) (Block->Bits[Byte] | USB_HC_BIT (Bit));
    NEXT_BIT (Byte, Bit);
  }

  return Block->BufHost + (StartByte * 8 + StartBit) * USBHC_MEM_UNIT;
}