教程讲稿与汇编

预备知识1K

=1M=1024K=1G=1024M=1T=1024G=1P=1024T=

1个二进制位 （比特8个二进制位：Byte（字节）1Byte=8bit Word（字）1Word=2Byte=数制基数 二进20,八进80,1,2,3,4,5,6,十进0,1,2,3,4,5,6,7,8,十六进0,1,2,3,4,5,6,7,8,A,B,C,D,E, 降幂法 05C3

3D25＋3＋31D2EHH—4205C376HH“与”运算 “或”运算 AB AB000000010011100101111111 AAAB0100010011101110例：X= Y=5555H，Z=XY=X=0000000011111111Y=0101010101010101Z=0101010110101010Z=机器字(machineword)地址的表示空间是对很多地址的表示空间是对很多内存需求量大的应用而言，非常有64位字地址的表示空间约是1.8X1019目前的x86-64机型实际支持48位宽的地址:256==地====

=

=== BigEndian:Sun,PPCMac,低位字节(Leastsignificantbyte,LSB)占据高地LittleEndian:与LSB相Big

数值是 Little

001110110011101101103B6DintB=-longintC=IA32,x86-

x86-

IA32,x86- CDataTypicalCDataTypical32-x86-x86-111222444448long888444888long8char448Oranyother 判断以下的推断或者等式是否成立(不成立则给出范例x,y为32位带符号整初始

x< ((x*2)<ux>=x&7== (x<<30)<ux>-intx=inty=bar();unsignedux=unsignedintx=inty=bar();unsignedux=unsigneduy=x*x>=x>0&&y> x+y>x>= -x<=x<= -x>=(x|-x)>>31==-ux>>3==xx>>3==x&(x-1)!= 无符号 带符号数（补码，Two’sB2U(X xi2

B2T(X xw12w1xishortshortintx=15213;shortinty=-x3By-C4符号位（sign对于补码表示,MSB表示整数的符1for01for无符号

带符号数（补码

2w–

2w–1–负1=假设字长为FF7F-80-FF0000XX001122334455667789

xwx x常数如果有“U”作为后缀则是无符号数，如 如果无符号数与带符号数混合使用，则带符号数默认转换为无符号UU实例UU00-U-(unsigned)-UMax–1

TMax+

模运按位运建议：不能仅仅因为取值范围是非负而使forfor(i=cnt-2;i>=0;i--a[i]+=#defineDELTAsizeof(int)inti;for(i=CNT;i-DELTA>=0;i-=..TrueSum:w+1

•••••••••u+••DiscardCarry:w UAddw(u•• UAddw(u, （u+v）mod uwuvuv2uv2TrueSum:w+1

•••••••••u+••DiscardCarry:w TAddw(u••与无符号数的一Signedvs.unsignedadditioninints,t,u,s=(int)((unsigned)u+(unsigned)t=u+s==0

True0

2w

TAdd0

11

–2w

v2w

uvTMinwuvTMaxwuu>>kgivesu/2k采用逻辑右00uBinary00uBinary/u/.u/2k000100xBx>>1Dx>>03x>>00Cunsignedunsignedudiv8(unsigned{return}CompiledArithmetic $3, $3,#Logicalshiftreturnx>>x>>kgivesx/2k采用算术右但是x<0时，舍入错000

Binary110000/x00/x/.

RoundDown(x/y--C4y>>--E2y>>--FCy>>--FFWantx2k (需要向0舍入，而不是向下舍入Computeas(x+2k-1)/2kInC:(x+(1<<k)-1)>>BiasesdividendtowardCase1:No

110001010001110111Binary/u/2k001000111.11BiasingBiasinghasnoCase2:

k110110011001100

Incrementedby

Binary100/x/2k100/x/2k11.100

IncrementedbyCintintidiv8(int{return}CompiledArithmetic testltestl%eax,$3,$7,%eaxifx<0x+=#Arithmeticreturnx>> 判断以下的推断或者等式是否成立(不成立则给出示例x,y为32位带符号整初始

x< ((x*2)<ux>=x&7== (x<<30)<ux>-intx=inty=bar();unsignedux=unsignedintx=inty=bar();unsi