This class represents the global memory (DDR) resource management and data
transfer between AI Engine and global
memory (DDR). The input_gmio object manages data
transfer from global memory (DDR) to AI Engine or
read from global memory (DDR) operation. The output_gmio object manages data transfer from AI Engine to global memory or write to global memory (DDR) operation.
Base Class Member Functions
static void* malloc(size_t size);malloc method allocates
contiguous physical memory space and returns the corresponding virtual address. It
accepts a parameter, size, to specify how many
bytes to be allocated. If successful, the pointer to the allocated memory space is
returned. nullptr is returned in the event of a
failure.static void free(void* address);free method frees memory space
allocated by GMIO::malloc.return_code wait();wait method blocks until all the
previously issued transactions are complete. This method is only applicable for
GMIO objects connected to AI Engine.input_gmio and output_gmio classes are derived from GMIO base
class. Functions malloc(), free(), and wait() are declared in the GMIO base class.input_gmio Member Functions
create(std::string logical_name, size_t burst_length, size_t bandwidth);The above port specification is used to connect DDR memory
to AI Engine kernels. logical_name is the name of the port. The burst_length is the length of DDR memory burst transaction (can be 64,
128 or 256 bytes), and the bandwidth is the
average expected throughput in MB/s.
create(size_t burst_length, size_t bandwidth);burst_length is the length of DDR memory burst
transaction (can be 64, 128 or 256 bytes), and the bandwidth is the average expected throughput in
MB/s.return_code gm2aie_nb(const void* address, size_t transaction_size);gm2aie_nb method initiates a DDR to
AI Engine transfer. The memory
space for the transaction is specified by the address pointer and the
transaction_size parameter (in bytes). The transaction memory space needs to be
within the total memory space allocated by the GMIO::malloc method. It is a non-blocking function in that it does not
wait for the read transaction to
complete.return_code gm2aie(void* address, size_t transaction_size);The gm2aie method is a blocking
version of gm2aie_nb. It blocks until the AI Engine–DDR read transaction completes.
output_gmio Member Functions
create(std::string logical_name, size_t burst_length, size_t bandwidth);logical_name is the name of the port. The burst_length is the length of DDR memory burst transaction (can be 64,
128 or 256 bytes), and the bandwidth is the
average expected throughput in
MB/s.create(size_t burst_length, size_t bandwidth);burst_length is the length of DDR memory burst
transaction (can be 64, 128 or 256 bytes), and the bandwidth is the average expected throughput in
MB/s.return_code aie2gm_nb(void* address, size_t transaction_size);aie2gm_nb method initiates an AI Engine to DDR transfer. The memory space
for the transaction is specified by the address pointer and the transaction_size
parameter (in bytes). The transaction memory space needs to be within the total
memory space allocated by the GMIO::malloc method.
It is a non-blocking function in that it does not wait for the write transaction to
complete.return_code aie2gm(void* address, size_t transaction_size);The aie2gm method is a blocking
version of aie2gm_nb. It blocks until the AI Engine–DDR write transaction completes.
GMIO::malloc() and GMIO::free() to manage DDR memory resources.