求问怎样用汇编编写简易计算器程序,该怎么处理

;要求：;输入一个表达式，输出十进制结果，例如:;输入1234+5678-1111*9876/4321;输出13258;注意:表达式中只允许出现+-*/，没有其它运算符，表达式总长度不超过80字符;;运算过程不考虑优先级，一律从左到右;;计算除法时只要商，不要余数;;计算过程中算得的中间值以及最终结果都假定不会超过32位;;程序中可以使用32位寄存器及386指令。 ; 如何编译链接该程序; 本程序需使用masm32来编译，若你的masm32安装在c盘，请设置如下环境变量; set include=c:\masm32\include; set lib=c:\masm32\lib; set PATH=c:\masm32\bin;%PATH%; 若本程序名为test.asm,则运行如下命令编译和链接和运行;ml /c /coff test.asm; link /subsystem:console test.obj; test.exe.386.model flat,stdcall ; 32 bit memory modeloption casemap :none  ; case sensitiveinclude windows.incinclude user32.incincludelib user32.libinclude kernel32.incincludelib kernel32.lib.data        inBuffer      db    256 dup(?)  ;输入缓冲区        outBuffer     db    256 dup(?)  ;输出缓冲区        hOutput       dd    ?        hInput        dd    ?        num1          dd    ?            ;被分解的数        num2          dd    ?            ;被分解的数的平方        result        dd    ?        count         dd    ?        pre_status    dd    ?        curr_status   dd    ?        curr_num      dd    ?        st_comb       dd    ?        dwLen         dd    ?        tLen          dd    ?          curr_sign     db    ?        pre_sign      db    ?        .const       szFmtout1        db    '%d',0       szOutString      db    'Please input a expression',13,10       .codeST_NIL  equ     0  ;初始状态ST_NUM  equ     1  ;操作数状态ST_OP   equ     2  ;操作符状态ST_END  equ     3  ;结束状态;var_N1: input parameter, the first number;var_N2: input paramenter, the second number;var_sign: op signcalc  proc far C uses ebx ecx, var_N1,var_N2, var_sign    mov eax,var_N1    mov edx,var_N2    mov ecx,var_sign        mov  ebx,edxcheck_01:    cmp  cl, '+'    jnz  check_02do_add:    add  eax,ebx    jmp  this_exitcheck_02:    cmp cl, '-'    jnz check_03do_sub:    sub eax,ebx    jmp this_exitcheck_03:    cmp cl, '*'    jnz check_04do_mul:    imul  ebx    jmp  this_exitcheck_04:    cmp cl, '/'    jnz errdo_div:     xor edx,edx    idiv ebx    jmp this_exiterr:    xor eax,eax this_exit:    retcalc endp   ;var_string: input parameter,the expression address;eax: out parameter,  the resultcalc_exp  proc far C USES esi edi ebx ecx ,var_string    mov esi,var_string    xor eax,eax    xor ecx,ecx    mov count,eax    mov pre_status,ST_NIL  loop_start:    mov cl,[esi]    inc esicmp_01:    cmp cl,'0'    jl  cmp_11 cmp_02:    cmp cl,'9'    jg  cmp_11case_01:     mov curr_status,ST_NUM    jmp next_02    cmp_11:       cmp cl,'+'    jz  case_02cmp_12:    cmp cl,'-'    jz  case_02cmp_13:      cmp cl,'*'    jz  case_02cmp_14:     cmp cl,'/'    jz  case_02    jmp case_03case_02:    mov curr_status,ST_OP    jmp next_02case_03:    mov  curr_status,ST_END    jmp  next_02    next_02:    mov eax,pre_status    shl eax,2    add eax,curr_status    mov st_comb,eaxcheck_01:       cmp st_comb,ST_NIL*4+ST_NUM     ;  上次状态是ST_NIL，当前状态是ST_NUM    jnz check_02case1_01:    sub  cl,'0'    mov  curr_num, ecx    jmp  next_loopcheck_02:    cmp st_comb,ST_OP*4+ST_NUM      ;  上次状态是ST_OP，当前状态是ST_NUM    jnz check_03case1_02:    sub  cl,'0'    mov  curr_num, ecx    jmp  next_loopcheck_03:    cmp st_comb,ST_NUM*4+ST_OP     ;  上次状态是ST_NUM，当前状态是ST_OP    jnz check_04case1_03:    mov curr_sign,cl    cmp count,0    jnz case1_03_02case1_03_01:    mov eax,curr_num    mov num1,eax    jmp case1_03_nextcase1_03_02:            mov edx,curr_num    mov num2,edx    mov eax,num1    mov cl,pre_sign    invoke calc,eax,edx,ecx    mov num1,eaxcase1_03_next:    inc count    mov cl,curr_sign    mov pre_sign,cl    jmp next_loop    check_04:    cmp st_comb,ST_NUM*4+ST_END     ;  上次状态是ST_NUM，当前状态是ST_END     jnz check_05        cmp count,0    jnz case1_04_02case1_04_01:    mov eax,curr_num    mov num1,eax    jmp case1_04_nextcase1_04_02:            mov edx,curr_num    mov num2,edx    mov eax,num1    mov cl,pre_sign    invoke calc,eax,edx,ecx    mov num1,eaxcase1_04_next:    inc count    jmp this_exitcheck_05:    cmp st_comb,ST_NUM*4+ST_NUM     ;  上次状态是ST_NUM，当前状态是ST_NUM    jnz check_06case1_05:    mov edx,curr_num    shl edx,1    lea eax,[edx+edx*4]     sub cl,'0'    movzx edx,cl    add eax,edx    mov curr_num,eax    jmp next_loopcheck_06:                       ;  无效的状态，直接退出    jmp  this_exit              next_loop:    mov edx,curr_status    mov pre_status,edx    jmp loop_startthis_exit:    mov eax,num1    retcalc_exp endp   main proc farstart:    invoke GetStdHandle,STD_OUTPUT_HANDLE   ; 获取控制台输出设备的句柄    mov    hOutput,eax    invoke WriteConsole,hOutput,addr szOutString,sizeof szOutString,addr tLen,0        invoke GetStdHandle,STD_INPUT_HANDLE      ; 获取控制台输入设备的句柄    mov hInput, eax    invoke ReadFile,hInput,addr inBuffer,sizeof inBuffer,ADDR tLen,NULL    lea    esi, inBuffer            invoke calc_exp,esi      ;转化字符串为一个数    mov    result, eax      ;将这个数存入number        invoke wsprintf, addr outBuffer , addr szFmtout1,result    mov    dwLen, eax    invoke WriteConsole,hOutput,addr outBuffer,dwLen,addr tLen,0        xor eax, eax    invoke ExitProcess,eax  ;退出进程    ret main endpend main