Communication data controller
View Patent ↗A communication data controller is provided which is capable of correctly retransmitting transmission data even if a block of the transmission data exceeding a FIFO (First-In First-Out) memory is written in an overwriting manner to the FIFO memory. The memory stores transmission data to be transmitted to a communication device. Transmission data stored in the memory is written and read to and from the FIFO memory by a CPU (Central Processing Unit). A DMAC (Direct Memory Access Controller) driver, when a request for retransmission of a block is made in the case where the block of transmission data exceeding a capacity of the FIFO memory is written to the FIFO memory, drives the DMAC and transfers the block being stored in the memory to the communication data controller.
1. A communication data controller for controlling communication of communication data comprising:
a First-In First-Out (FIFO) memory to store transmission data, together with retransmission starting point information indicating a starting point at which retransmission of the transmission data is to start;
a read pointer to generate a reading address used to read the transmission data from the FIFO memory;
a reload pointer to output a reading address being stored therein to the read pointer once a request for retransmission of the transmission data is made; and
a pointer controller to store the reading address generated by the read pointer in the reload pointer when the retransmission starting point information is attached to the transmission data read out from the FIFO memory.
2. The communication data controller according to claim 1 , further comprising a separator to separate the retransmission starting point information read out from the FIFO memory.
3. The communication data controller according to claim 2 , wherein the separator outputs the separated retransmission starting point information to the reload pointer and transmits the transmission data to a party with which communication is carried out.
4. A communication data controller for controlling communication of transmission data stored in a memory connected through a bus comprising:
a First-In First-Out (FIFO) memory to store transmission data, together with retransmission starting point information indicating a starting point at which retransmission of the transmission data is to start;
a read pointer to generate a reading address used to read the transmission data from the FIFO memory;
a reload pointer to output the reading address being stored therein to the read pointer once a request for retransmission of the transmission data is made;
a pointer controller to store the reading address generated by the read pointer in the reload pointer when the retransmission starting point information is attached to the transmission data read out from the FIFO memory; and
a Direct Memory Access Controller (DMAC) driver which, once a block of the transmission data exceeding a capacity of the FIFO memory is written to the FIFO memory and once a request for retransmission of the transmission data is made, drives a DMAC being connected to the bus and transfers the block of the transmission data exceeding the capacity of the FIFO memory once written in the FIFO memory, from the memory to the FIFO memory.
5. The communication data controller according to claim 4 , wherein a CPU being connected to the bus sets a head address and size of the block to the DMAC once a head of the block is read out.