Double precision maths library

The problem here is not just C.

The float implementation of C51 uses registers for float operations. It can do this because there are eight 1-byte registers and each float only uses 4 bytes. So, C51's implementation is actually pretty fast.

When you start to implement double operations, you need 8 bytes for each operand and 16 bytes for both. So, you can't do everything in registers. Assuming that you could do everything in registers, I'd expect most operations to be at least 4 times slower. Since you'll have to swap registers out to memory, a factor of 10x is probably not too bad.

Jon

The problem here is not just C.

The float implementation of C51 uses registers for float operations. It can do this because there are eight 1-byte registers and each float only uses 4 bytes. So, C51's implementation is actually pretty fast.

When you start to implement double operations, you need 8 bytes for each operand and 16 bytes for both. So, you can't do everything in registers. Assuming that you could do everything in registers, I'd expect most operations to be at least 4 times slower. Since you'll have to swap registers out to memory, a factor of 10x is probably not too bad.

Jon

Hello Jon

Thanks for the explanation - that makes perfect sense.

Coding now complete... into testing.

best regards - Paul