Function BufferGetBlock 

pub unsafe fn BufferGetBlock(buffer: i32) -> *mut c_void

#define BufferGetBlock(buffer)
(
AssertMacro(BufferIsValid(buffer)),
BufferIsLocal(buffer) ?
LocalBufferBlockPointers[-(buffer) - 1]
:
(Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ)
)