How to interpret resource utilisation numbers from Xilinx ISE
I'm new to FPGA programming. I have a design in VHDL, in Xilinx ISE. My synthesis results include: FF, LUT, memory LUT, I/O, BRAM, DSP48, BUFG.
I'd really appreciate pointers to documents and resources that will help me interpret what the numbers next to each utlised resource mean? Specificaly: 1) what do each of them mean?, 2) are they explicitly used in th VHDL code, or has ISE chosen (e.g. the number of DSP48s) the resources to implement my design?, and 3) if my design is above 100% resource utilisation, how can I change my VHDL code to reduce the use of each resource in turn?