/**
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);
}
}
/**
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;
}