Understanding the x86's Decimal Adjust after Addition (DAA) instruction

.hilite {cursor:zoom-in} a:link img.hilite, a:visited img.hilite {color: #fff;} a:hover img.hilite {color: #f66;} 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...