Calculating Cosine and Sine Functions In VHDL - Using Look Up Tables (Need Help)

[jerryt]

I am working on a final project for graduate school. I need to be able to calculate cos (x) and sin (x) in VHDL code. My professor tells me I should use a look up table for cos and sin values. I have never worked with look up tables in VHDL and I am a bit confused on how to do this in VHDL. Any suggestions?

Example:

cos (2) = -0.4161 (I need to find the solution of the cosine function and use it later in my VHDL code)

Thanks for everyone's help in advance! I really appreciate it.

 

[FvM]

There have been various threads about different sine generation methods in FPGAs. Larger look-up tables (LUT) are usually implemented in internal ROM blocks (initialized RAM) as they are provided by most recent FPGA series. The sine function table can be loaded from a file, explicitely coded in a case structure (long winded) or calculated in HDL at compile time. The below thread has examples of the latter method. https://www.edaboard.com/threads/117304/

A sine look-up table is quantized both in angle and magnitude. Thus you need to determine the required resolution respectively address and table value bitwidths.