与-101x86第一个汇编程序及其它

$gcc- Thiswillproduceafile n:theoptimization$gcc–S-

main; .rdata,

o

$0, $0, .def_exit;.scl3;.type32;.def_printf;.scl3;.type32;

_main;%esp,$8,$-16,$0,$15,$15,$4,$4,%eax,--4(%ebp),

gccgcc- alloca main

$LC0, main;

.rdata, o

_main;%esp,$8,$-16,$0,$15,$15,$4,$4,%eax,--4(%ebp),

gccgcc- alloca main

$0,

$LC0,

.def_exit;.scl3;.type32;.def_printf;.scl3;.type32; main;

.rdata, oworld\12\0”.globl

_main;

$16,

%esp,$8, gcc- oworld.c- $-16, alloca 版本３.４.４(32位) main $LC0, $0, "o

_main;

$16,%esp,$8,$-16,$LC0,$0,汇编代码中以“.”开头的行都是汇编代码中以“.”开头的行都是汇编指示（Directives），如“.file”def”text main; #.defdirectivesdefinesadebugging#.scl2meansstorageclass(externalstorageclass)#.type32saysthissymbolisafunction.

地址的符号（Symbol）示例示例指示汇编器符号“_main”是全局的，这样同一程序的其它模块可它则则不是全局可见.p2align#指定下一行代码的对齐方式：第1参数表示按2的多少次幂第216.section.rdata,.ascii o.globl.align1请尝试解释一下intc1局变

oworld.c main; .ascii o.p2align.globl

#1615字节，则不对齐 _main; $16,%esp,$8,$-16,$LC0,$0,_puts; _exit; oworld.c "o.p2align.globl

#1615字节，则不对齐

%esp,$4,

关#分配4字节堆栈关

gcc-O2-mpreferred- main

oworld.c-

$LC0,$0,

oworld.c main;

.ascii o

#1615关oworld.c关oworld.c-gcc-O2-mpreferred-stack-boundary=2-fomit-$4,$LC0,$0,charbig_array[1<<24];/*16MBcharhuge_array[1<<28];/*256MB char*p1,*p2,*p3,intuseless(){return0;int{p1=malloc(1<<28);p2=malloc(1<<8);p3=malloc(1<<28);p4=malloc(1<<8);

/*256MB/*256B/*256MB/*256B/*Someprintstatements...}finalmalloc()

&p2finalmalloc()

addressrange &p2 as-omy-object- //ld–omy-exe-filemy-object-64位环境下添加命令行参数：-moworld

len

o $len,

$msg,$1,$4,$0,$1,

#系统输出（writeint80寄存器eax中存放的是系统调用的功能号，而传给系统调用的数则必须按顺序放到寄存器ebx，ecx，edx，esi，edi中当系统调用完成之后，返回值可以在寄存器eax中获需将系统调用功能号保存在寄存器eax中，全部参数依次放在一ebx中保存指向该内存区域系统调用完成之后，返回值仍将保存在寄存器eax中1(Thiscalldoesnotfork-createchild20intheprocessidofcloneororENOMEMinread-readfromfileor3fileaddressofthebuffertoumnumberofbytesnumberofbytesactually|EAGAIN|EBADF|EFAULTEINTR|EINVAL|EIO|close-closeafileor6filezeroforsuccess|waitpid-waitforaprocessesto7processidoftheprocessto0,oraddressofbuffertoexitoptionflags|0|WNOHANGpidoffinishedprocess||EINVAL|exitstateoffinishedprocess,non-zerovaluewasinputincreate-createa8addressofzero-filepermissionfiledescriptorofopenedfileEACCESS|EEXIST|EFAULTEISDIR|ELOOP|EMFILE,LONG|ENFILEENOENT|ENODEV|ENODIRENOMEM|ENOSPC|ENXIOEROFS|unlink-deleteanameandremovefilewhennotaddressofzero-terminatedpathnameexistingfile0|EACCES|EFAULT|EIO|EISDIR|ELOOP LONG|ENOENT|ENOMEMENOTDIR|EPERM|execve-executeaaddressofzero-terminatedpathnameaddressofzero-terminatedlistofofzero-terminatedargumentaddressofzero-terminatedlistofofzero-terminatedenvironmentIfsuccess,noreturnbecausethenewprograminheritsresourcesandoverwritescaller;otherwise:E2BIG|EACCES|EINVAL|EIO|EISDIR|ELIBBAD|ELOOP|ENFILE|ENOEXEC|ENOENT|ENOMEM|ENOTDIR|EFAULT|ENA LONG|EPERM|chdir-changeworkingaddressofzero-terminatedpathnameexisting0|EACCES|EBADF|EFAULT|EIO|ELOOPLONG|ENOENT|ENOMEM .globl

#

%ecx,%ecx%ecx,%edx,(%ebx),%al,%al$10,-$4,$1,%ebx,

#时，其所需的参数(argcargv)将sys_write)#文件描述符(stdout)指指 入。EAX寄存器用于决定CPUID指令EAX存器的值，CPUID指令在EBX，ECX和EDX寄存（0）值被EAX寄存器并且执行CPUID令时，处理器把厂商ID字符串返回到EBX，EDXECXEBX最低个字EDX中间个字ECX最高个字 "Theprocessvendoridis.sectionm.section

$0,$buffer, %ebx, %edx, %ecx,$as-ocpuid.o

$ld-lc-dynamic-linker/lib/ld-linux.so.2-ocpuid 汇编器使用_start符号表示默认的起始点,此外如果想要汇编 ,需要赋予.globl属性,如:.globl只读数据段一个数据元素时,需要使用Symbol示例如下.ascii o .float 可以在一行中定义多个值如.int20,10,30,

.32.long32位整数和int.octa16.quad8.short16.single单精度浮点数(和float相同和data段不同,无需 特定的数据类型,只需 示例如下.sectionmbuffer,#该语句把1000字节的内存地址赋予buffer外部模块不能相相比较.data段，.bss 的优点是.section.data.long.section.globlmovl$0,movldata_items(,%edi,4),%eaxmovl%eax,%ebxcmpl$0,%eaxjeloop_exitincl%edimovldata_items(,%edi,4),%eaxcmpl%ebx,%eaxjlemovl%eax,%ebxjmpstart_loopmovl$1,int

#1istheexit().section #Thesearethedata.long.section.globlmovl$0,%edi #move0intotheindexregistermovldata_items(,%edi,4),%eax#loadthefirstdatamovl%eax, #sincethisisthefirstitem,%eax#thecmpl$0,%eaxjeloop_exit

#start#checktoseeifwe'vehittheincl%edi #loadnextvaluemovldata_items(,%edi,4),%eaxcmpl%ebx,jlemovl%eax,%ebxjmpstart_loop

#compare#jumptoloopbeginningifthe#oneisn't#movethevalueasthelargest#jumptoloopbeginningmovlmovl$1,#1istheexit()int#%ebxisthestatuscodefortheexitsystem #anditalreadyhasthe um 补充：算术操作指指效描imullR[%edx]:R[%eax]=S*无符号64位mullR[%edx]:R[%eax]=S*有符号64位 R[%edx]:R[%eax]=符号位扩展转换为4字idivlR[%edx]=R[%edx]:R[%eax]%R[%eax]=R[%edx]:R[%eax]/divlR[%edx]=R[%edx]:R[%eax]%R[%eax]=R[%edx]:R[%eax]/64位数通 .section.globlpushlsecondpushlfirstcalltheaddl$8,thestackpointerpushlthefirstpushl$2pushl$5callpoweraddl$8,%esp

#pushsecondargument#pushfirstargument#callthefunction#movethestackpointersecondanswerisin%eax.We%eax,thefirstoutinto%ebxthemtogether;theresultisin%ebxmovl$1,%eax #exit(%ebxisreturned)int$0x80.typepower,@functionpushl%ebpmovl%esp,%ebpsubl$4,%espmovl8(%ebp),%ebxmovl12(%ebp),%ecxmovl%ebx,-

为何还要保存%ebp等操#saveoldbase#makestackpointerthebase#getroomforourlocalstorage#putfirstargumentin%eax#putsecondargumentin%ecx#storecurrentresultcmpl$1,%ecxjeend_power

#ifthepoweris1,wearemovl-4(%ebp),%eax#movethecurrentresultintoimull%ebx, #multiplythecurrentresultbythebasemovl%eax,-4(%ebp)#storethecurrentdecl #decreasethejmppower_loop_start#runforthenextmovl-4(%ebp),%eax#returnvaluegoesinmovl%ebp,popl

#restorethestack#restorethebase.type.typepower, lsthelinkerthatthesymbolpowershouldbetreatedasa阶乘.section.globl #thisisunneededunlesswewanttoshare.globlpushlcall

#Thefactorialtakesoneargument–#thenumberwewantafactorialof.#runthefactorialfunction$4,#restorethe%eax,#factorialreturnstheanswerin%eax,but$1,#wantitin%ebxtosenditasourexit#callthekernel’sexitint#Thisistheactualfunction factorial,pushl

%esp,8(%ebp), #Thismovesthefirstargumenttocmpl$1, #Ifthenumberis1,thatisourbasecase,#wesimplyreturn(1isalreadyin%eaxas#returnjedecl #otherwise,decreasethepushl #pushitforourcalltocall #callmovl8(%ebp), #%eaxhasthereturnvalue,sowereload#parameterintoimull%ebx, #multiplythatbytheresultofthelastcall#factorial(in%eax);theanswerisstoredmovl%ebp,%esppopl%ebpStep1:Step2:Step3:如果输入文件 位置已到文件尾，则转Step7；Step4: Step5:遍历该内容，将其中的小写字母转换成大写；Step6:将转换后的该内容写入输出文件，转Step3；Step7:程序结束。.equ用于把常量值设置为可以在程序中使用的.equfactor,.equLINUX_SYS_CALL,经过设置之后，数据符号值是不能在程序中改动的#######toupper.s#systemcall.equSYS_OPEN,.equSYS_WRITE,.equSYS_READ,.equSYS_CLOSE,.equSYS_EXIT,#optionsforO_RDONLY,O_PERMISSION,#standardfile.equSTDIN,.equSTDOUT,.equSTDERR,#systemcall.equLINUX_SYSCALL,.equEND_OF_FILE,0#Thisisthereturnvalueofreadwhichmeans#hittheendofthe.section.section#Buffer-thisiswherethedataisloadedintofromthe#fileandwrittenfromintotheoutput.equBUFFER_SIZE,mBUFFER_DATA,.section#STACKST_FD_IN,-ST_FD_OUT,-8ST_ARGC,#NumberofST_ARGV_0,#NameofST_ARGV_1,ST_ARGV_2,#Inputfile#Outputfile.globl###INITIALIZEmovl%esp,subl$ST_SIZE_RESERVE,%esp#Allocatespaceforour$SYS_OPEN,#openST_ARGV_1(%ebp),#inputfilenameinto$O_RDONLY,$O_PERMISSION,intmovl%eax, #savethegivenfilemovl$SYS_OPEN,movlST_ARGV_2(%ebp),

#openthemovl$O_CREAT_WRONLY_TRUNC, #flagsforwritingtothe#modefornewmovl$O_PERMISSION,%edxint$LINUX_SYSCALL#storethefiledescriptorheremovl%eax,ST_FD_OUT(%ebp)###BEGINMAINmovl$SYS_READ,movlST_FD_IN(%ebp),%ebx #gettheinputfiledescriptormovl$BUFFER_DATA,%ecx #thelocationtoreadintomovl$BUFFER_SIZE,%edx #thesizeofthebufferint #Sizeofbufferreadisreturned###EXITIFWE’VEREACHEDTHEcmpl$END_OF_FILE,%eaxjleend_loop

#checkforendoffile#iffoundoronerror,gotothe###CONVERTTHEBLOCKTOUPPERpushlpushlcallpopl%eaxaddl$4,%esp

#locationof#sizeofthe#getthesizeback#restore%esp###WRITETHEBLOCKOUTTOTHEOUTPUTmovl%eax,movl$SYS_WRITE,movlST_FD_OUT(%ebp),%ebxmovl$BUFFER_DATA,%ecxint$LINUX_SYSCALL###CONTINUETHEjmp

#sizeofthe#theoutputfile#locationofthe###CLOSETHEmovl$SYS_CLOSE,movlST_FD_OUT(%ebp),intmovl$SYS_CLOSE,%eaxmovlST_FD_IN(%ebp),%ebxint$LINUX_SYSCALLmovl$SYS_EXIT,movl$0,int#convert_to_upper#INPUT:Thefirstparameteristhelocationoftheblockofmemory#Thesecondparameteristhelengthofthat#OUTPUT:Thisfunctionoverwritesthecurrentbufferwiththe.equLOWERCASE_A,.equLOWERCASE_Z,

#Thelowerboundaryofoursearch#Theupperboundaryofour.equUPPER_CONVERSION,’A’-###STACK.equST_BUFFER_LEN,.equST_BUFFER,

#Lengthof#actualpushl%ebpmovl%esp,%ebp#ifabufferwithzerolengthwasgiventous,justcmpl$0,jemovb(%eax,%edi,1),cmpb$LOWERCASE_A,jlcmpb$LOWERCASE_Z,jg

#getthecurrent#gotothenextbyteunlessit###SET###SETUPmovlST_BUFFER(%ebp),movlST_BUFFER_LEN(%ebp),movl$0,#loop#otherwiseconvertthebytetouppercase,andstoreitaddb$UPPER_CONVERSION,movb%cl,inclcmpl%edi,%ebxjneconvert_loopmovl%ebp,%esppopl%ebp

#next#continueunlesswe’vereachedthe#Common#CommonLinux#SystemCall.equSYS_EXIT,.equSYS_READ,.equSYS_WRITE,.equSYS_OPEN,.equSYS_CLOSE,.equSYS_BRK,#SystemCallInterrupt.equLINUX_SYSCALL,#StandardFile.equSTDIN,.equSTDOUT,.equSTDERR,#CommonStatus.equEND_OF_FILE,.equRECORD_FIRSTNAME,.equRECORD_LASTNAME,.equRECORD_ADDRESS,.equRECORD_AGE,.equRECORD_SIZE,使用时.include.include"record-#read-.include"record-.include#INPUT:Thefiledescriptoranda#OUTPUT:Thisfunctionwritesthedatatothebufferandreturns#STACKLOCAL.equST_READ_BUFFER,.equST_FILEDES,

.section.globl.typeread_record,pushlmovl%esp,pushlmovlST_FILEDES(%ebp),%ebxmovlST_READ_BUFFER(%ebp),%ecxmovl$RECORD_SIZE,%edxmovl$SYS_READ,int

#NOTE-%eaxhasthereturnvaluepopl%ebxmovl%ebp,popl#write-.include.include"record-#INPUT:Thefiledescriptoranda#OUTPUT:Thisfunctionproducesastatus#STACKLOCAL.equST_WRITE_BUFFER,.equST_FILEDES,.section.globl.typewrite_record,@functionpushl%ebpmovl%esp,%ebppushl%ebxmovl$SYS_WRITE,movlST_FILEDES(%ebp),%ebxmovlST_WRITE_BUFFER(%ebp),%ecxmovl$RECORD_SIZE,%edxint

#NOTE-%eaxhasthereturnpoplmovl%ebp,popl%ebp#write-.include.include"record-.section.data.ascii.rept31#Paddingto40.byte

OpentheWritethreeClosethe.ascii.rept31#Paddingto40.ascii.rept31#Paddingto40.byte

“.reptN”209#Paddingto2400填充其与“.endr”之间容，重复N…

#skiprecord2~#Thisisthenameof.ascii

filewewillwrite.equST_FILE_DESCRIPTOR,-.globlmovl%esp,subl$4,%esp #Allocatespacetoholdthefiledescriptormovl$SYSOPEN%eaxaswrite-records.s-owrite-record.oaswrite-record.s-owrite-ldwrite-record.owrite-records.o-owrite-movl%eax,ST_FILE_DESCRIPTOR(%ebp)#Storethefilepushlpushl$record1callwrite_recordaddl$8,%esp

#Writethefirst#Writetheremainingrecords;closethefileand…OpentheAttempttoreadaIfweareattheendofthefile,Otherwise,countthecharactersofthefirstWritethefirstnametoWriteanewlinetoGobacktoreadanother#count-#INPUT:Theaddressofthe#OUTPUT:Returnsthecountin.typecount_chars,.globl.equST_STRING_START_ADDRESS,pushl

%esp,$0, #CounterstartsatmovlST_STRING_START_ADDRESS(%ebp), #Startingaddressofmovb(%edx),%alcmpb$0,%aljecount_loop