Bo, Most of the users on this forum have never interfaced with hardware , as you can see from the responses. Those who have interfaced with hardware have developed circular buffers which they know work , and they reuse them again and again.
I will describe in general terms the structure a circular buffer implemented to receive data , as it is usually more difficult to received the data than to send it due to the asynchronism between the sender and receiver. It has been used for many years , starting in 16bit-DOS , the 32bit-DPMI using interrupt handlers , then Linux using threads. The concept is the same for versions. The following assumes you are receiving data from a sender , and in this case the sender and receiver are connected via 1Gbps Ethernet using Synapse (works really well). A thread receives data into an array of byte. RxBuffer : Array[0..1500] of byte ... and copies the number of bytes received into a circular buffer , which is an array of RxBuffer. In pseudo code it looks like this ... CircularBuffer : Array[0..N] of RxBuffer There is a ReadIndex and a WriteIndex , both longword or longint. The thread moves the data into the circular buffer continuously increase the WriteIndex each write of RxBuffer data. If the WriteIndex > N then WriteIndex := 0 , otherwise it is increased by 1. The main loop (below) moves the byte data using MOVE from CircBuffer to whatever structure it represents , increase the ReadIndex by one and decodes the data as needed. If ReadIndex <> WriteIndex then .. do the work as described above and increment the ReadIndex I use the Free Pascal unit which allows suspending the thread while the ReadIndex is being increased. In the old DOS/DPMI days we would disable interrupts briefly. If you are innterested I can send you code snippets showing exactly how to implement the circular buffer. Regards Brian -- Sent from: http://free-pascal-general.1045716.n5.nabble.com/ _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
