Abstract: A transmit packet generated by a CPU 1 is held in a buffer 100a (100b). From among packets received from Ethernet 820a (820b), a packet, a destination of which is a communication device 800, is held in the buffer 100a (100b). A packet which should be transmitted is transmitted from a transfer judging circuit 200 to Ethernet 820a or 820b through a MAC unit 300a or 300b. If a transfer judging circuit 200 judges a packet from the Ethernet 820a to be a packet, a destination of which is another communication device, with reference to a destination MAC address, this packet is transferred to the Ethernet 820b through MAC 300b. If a usage rate of a transferring FIFO buffer 130a (130b) exceeds a threshold value in the process of transmitting a packet held in a transmitting FIFO buffer 120a (130b) on a priority basis, the priority order of a transfer packet is made higher than that of a transmit packet so that the transfer packet is transferred to the Ethernet 820a or 820b in preference to the transmit packet.

Abstract: A transmit packet generated by a CPU 1 is held in a buffer 100a (100b). From among packets received from Ethernet 820a (820b), a packet, a destination of which is a communication device 800, is held in the buffer 100a (100b). A packet which should be transmitted is transmitted from a transfer judging circuit 200 to Ethernet 820a or 820b through a MAC unit 300a or 300b. If a transfer judging circuit 200 judges a packet from the Ethernet 820a to be a packet, a destination of which is another communication device, with reference to a destination MAC address, this packet is transferred to the Ethernet 820b through MAC 300b. If a usage rate of a transferring FIFO buffer 130a (130b) exceeds a threshold value in the process of transmitting a packet held in a transmitting FIFO buffer 120a (130b) on a priority basis, the priority order of a transfer packet is made higher than that of a transmit packet so that the transfer packet is transferred to the Ethernet 820a or 820b in preference to the transmit packet.

Abstract: A transmit packet generated by a CPU 1 is held in a buffer 100a (100b). From among packets received from Ethernet 820a (820b), a packet, a destination of which is a communication device 800, is held in the buffer 100a (100b). A packet which should be transmitted is transmitted from a transfer judging circuit 200 to Ethernet 820a or 820b through a MAC unit 300a or 300b. If a transfer judging circuit 200 judges a packet from the Ethernet 820a to be a packet, a destination of which is another communication device, with reference to a destination MAC address, this packet is transferred to the Ethernet 820b through MAC 300b. If a usage rate of a transferring FIFO buffer 130a (130b) exceeds a threshold value in the process of transmitting a packet held in a transmitting FIFO buffer 120a (130b) on a priority basis, the priority order of a transfer packet is made higher than that of a transmit packet so that the transfer packet is transferred to the Ethernet 820a or 820b in preference to the transmit packet.

Abstract: A packet communication apparatus capable of performing packet conversion at high speed for packet transfer or packet transmission/reception has: a packet conversion unit for performing packet conversion for a reception packet received at a plurality of communication units and for a transmission packet to be transmitted from the plurality of communication units; and a transfer control unit for outputting, when the reception packet received by the communication unit is judged as a the transfer packet, the reception packet to a transfer buffer, for outputting the transmission packet to the communication unit corresponding to the communication object at a destination of the transmission packet generated by a packet generating and processing unit, and for outputting the transfer packet to the communication unit corresponding to the communication object at a destination of the transfer packet stored in the transfer buffer.

Abstract: A packet communication apparatus, which includes a CPU, a memory, and a packet communication circuit, acts as an interface between a network-connected controlled object and a network terminal that remotely monitors and controls the controlled object, and transmits and receives a packet between the controlled object and the network terminal, further includes a copy and operation unit that is a hardware unit for executing the checksum calculation to check for a packet error and the copy operation. The copy and operation unit performs the packet data copy operation and the checksum calculation simultaneously between a sending buffer/receiving buffer, formed in the memory and used by the packet communication circuit, and a work area used by a communication processing program, thus reducing the load of the CPU and increasing the communication processing speed.

Abstract: A packet communication apparatus, which includes a CPU, a memory, and a packet communication circuit, acts as an interface between a network-connected controlled object and a network terminal that remotely monitors and controls the controlled object, and transmits and receives a packet between the controlled object and the network terminal, further includes a copy and operation unit that is a hardware unit for executing the checksum calculation to check for a packet error and the copy operation. The copy and operation unit performs the packet data copy operation and the checksum calculation simultaneously between a sending buffer/receiving buffer, formed in the memory and used by the packet communication circuit, and a work area used by a communication processing program, thus reducing the load of the CPU and increasing the communication processing speed.

Abstract: [Problem] To provide a microprocessor in which the bottleneck due to data sharing during memory access when a CPU and a plurality of accelerators are operated in a linked up manner can be minimized, whereby enhanced multimedia processing performance can be achieved. [Means for solving the problem] A multimedia microprocessor 1 includes a CPU 11 and accelerators 12 in which the CPU 11 and the accelerators 12 perform multimedia processing in a linked up manner. In order to prevent the bottleneck caused by data sharing during memory access between the CPU 11 and the accelerators 12 via a memory 2, an I/O dedicated cache 14 is provided in front of the memory 2 to which the CPU 11 and the accelerators 12 can commonly access. Data required for data sharing is stored in the I/O dedicated cache 14, whereby data sharing between the CPU 11 and the accelerators 12 can be performed at higher speed and the speed of multimedia processing can be increased.

Abstract: A packet communication apparatus, which includes a CPU, a memory, and a packet communication circuit, acts as an interface between a network-connected controlled object and a network terminal that remotely monitors and controls the controlled object, and transmits and receives a packet between the controlled object and the network terminal, further includes a copy and operation unit that is a hardware unit for executing the checksum calculation to check for a packet error and the copy operation. The copy and operation unit performs the packet data copy operation and the checksum calculation simultaneously between a sending buffer/receiving buffer, formed in the memory and used by the packet communication circuit, and a work area used by a communication processing program, thus reducing the load of the CPU and increasing the communication processing speed.

Abstract: A packet communication apparatus capable of performing packet conversion at high speed for packet transfer or packet transmission/reception has: a packet conversion unit for performing packet conversion for a reception packet received at a plurality of communication units and for a transmission packet to be transmitted from the plurality of communication units; and a transfer control unit for outputting, when the reception packet received by the communication unit is judged as a the transfer packet, the reception packet to a transfer buffer, for outputting the transmission packet to the communication unit corresponding to the communication object at a destination of the transmission packet generated by a packet generating and processing unit, and for outputting the transfer packet to the communication unit corresponding to the communication object at a destination of the transfer packet stored in the transfer buffer.

Abstract: A transmit packet generated by a CPU 1 is held in a buffer 100a (100b). From among packets received from Ethernet 820a (820b), a packet, a destination of which is a communication device 800, is held in the buffer 100a (100b). A packet which should be transmitted is transmitted from a transfer judging circuit 200 to Ethernet 820a or 820b through a MAC unit 300a or 300b. If a transfer judging circuit 200 judges a packet from the Ethernet 820a to be a packet, a destination of which is another communication device, with reference to a destination MAC address, this packet is transferred to the Ethernet 820b through MAC 300b. If a usage rate of a transferring FIFO buffer 130a (130b) exceeds a threshold value in the process of transmitting a packet held in a transmitting FIFO buffer 120a (130b) on a priority basis, the priority order of a transfer packet is made higher than that of a transmit packet so that the transfer packet is transferred to the Ethernet 820a or 820b in preference to the transmit packet.