# VHDL - Cheapest-Fastest unsigned to signed binary number converter

We know that to convert unsigned to signed (precisely, I want to convert a pure binary into CA2 number) we must negate the unsigned number adding, then, + 1. In VHDL I can implement an inverter and an adder that manages the carry in. I have two numbers of 32 bits. Is there another way to implement the sum + 1 using anything cheaper? Is there a solution to manage the carry in using only logic gates?

• No, that's for taking the negative of a number. Changing the signedness doesn't involve changing the bit pattern. – Ignacio Vazquez-Abrams Sep 7 '15 at 21:35
• Yeah I know that the pattern is the same, but I need of negative number, I need to see it like a CA2 number – Anth Sep 7 '15 at 21:37
• CA2, CA-2 or CA II may refer to : Carbonic anhydrase II, a human gene California's 2nd congressional district Hummel CA-2, an ultralight aircraft California State Route 2 Ca II, a singly-ionized calcium that produces the H and K lines in the spectrum of many stars – Bruce Abbott Sep 8 '15 at 0:46
• In other words, what (precisely) is a "CA2 number"? It is not a common technical idiom. – Dave Tweed Sep 8 '15 at 0:59
• CA2 : In French it would be "Complément à 2"="Two's complement". – TEMLIB Sep 8 '15 at 1:11

my_signed <= '0' & my_unsigned;