16进制加法减法溢出问题请问如何判定16进制加法减法有溢出问题,AX=9FD0H+D023H=61F3H,OF=1AX=6FF3H-9FD0H=D023H,OF=1AX=6FF3H-D023H=9FD0H,OF=1AX=147BH+80DCH=9557H,OF=0AX=14C6H+80DCH=95A2H,OF=0,AX=B568H+54B7H=0A1FH,OF=0,AX=42

Question

16进制加法减法溢出问题
请问如何判定16进制加法减法有溢出问题,
AX=9FD0H+ D023H=61F3H,OF=1
AX=6FF3H-9FD0H=D023H,OF=1
AX=6FF3H-D023H=9FD0H,OF=1
AX=147BH+ 80DCH=9557H,OF=0
AX=14C6H+80DCH=95A2H,OF=0 ,
AX=B568H+54B7H=0A1FH,OF=0 ,
AX=42C8H+608DH=A355H,OF=1 ,
AX=D023H+9FD0H=6FF3H,OF=1 ,

Answer 1

溢出,是补码运算的固有缺陷.
补码的符号位也参加了运算.
数值位也可以向符号位进位,就可能导致符号错乱,出现溢出.
只有发生下列四种情况,才会溢出：
正＋正＝负
正－负＝负
负＋负＝正
负－正＝正
那么,题目中的算式,溢出情况如下：
9FD0H + D023H = 61F3H,负＋负＝正,溢出
6FF3H - 9FD0H = D023H,正－负＝负,溢出
6FF3H - D023H = 9FD0H,正－负＝负,溢出
147BH + 80DCH = 9557H,正＋负,
14C6H + 80DCH = 95A2H,正＋负,
B568H + 54B7H = 0A1FH,负＋正,
42C8H + 608DH = A355H,正＋正＝负,溢出
D023H + 9FD0H = 6FF3H,负＋负＝正,溢出