- Understanding the x86’s Decimal Adjust after Addition (DAA) instruction (righto.com)
I’ve been looking at the DAA machine instruction on x86 processors, a special instruction for binary-coded decimal arithmetic. Intel’s manuals document each instruction in detail, but the DAA description doesn’t make much sense. I ran an extensive assembly-language test of DAA on a real machine to determine exactly how the instruction behaves. In this blog post, I explain how the instruction works, in case anyone wants a better understanding.