缓冲区不能正常运行答案

【问题标题】：Buffers do no behave properly缓冲区不能正常运行
【发布时间】：2014-12-02 14:08:21
【问题描述】：

我在汇编编程方面很痛苦，并寻求您的帮助。我不明白的是，即使缓冲区有足够的空间，为什么我会从缓冲区中丢失字符串的字符？

我的 readBuffer 大小是 32，writeBuffer 大小是 64，我的程序所做的是在句号后添加一个空格并将第一个字母大写。

示例：

Good.morning.people hehehe in the jungle the mighty jungle  //this is the data
Good. Morning. People hehehe in the jungle the mighty jungle //this is the output

我的程序做什么：

Good.morning.people hehehe in the jungle the mighty jungle  //this is the data
Good. Morning. People hehehe in e jungle the mighty jungle //this is the output

如你所见，我以 'e' 而不是 'the' 结尾

这是我进行编辑的代码：

Read:

    MOV bx, DataHandle          
    CALL ReadBuffer         
    CMP ax, 0               ;ax = how many symbols did I read
    JE  closeWrite          ;if 0 then close write file

;Editing the string

    MOV  cx, ax               ;CX FOR LOOPING
    MOV  si, offset rBuff     ;read buffer = si
    MOV di, offset wBuff      ;write buffer = di

  Do_It:

    MOV dl, [si]
    CMP dl, '.'                 ;comparing to period
    JNE Keep_Going              ;if not period put it in di (write buffer)
    MOV dh, [si+1]              ;put the char after the period in dh
    CMP dh, ' '                 ;check if space is after it
    JNE If_capital              ;if not I check if it is a capital letter
    MOV dh, [si+2]              ;if there was a space I add the char after the space
    CMP dh, 'a'                 ;checking if it is a capital letter
    JB  Keep_Going  
    CMP dh, 'z'     
    JA  Keep_Going  
    SUB byte ptr [si+2], 32     ;turn it into a  capital letter

  Keep_Going:

    MOV [di], dl                ;put the  char into writebuff
    INC si
    INC di
    LOOP Do_It
    JMP Finishin

  If_capital:

    CMP dh, 'a'     
    JB  Add_Space       
    CMP dh, 'z'     
    JA  Add_Space   
    SUB byte ptr [si+1], 32

  Add_Space:

    MOV [di], '.'       
    INC di
    MOV [di], ' '
    INC di
    INC si
    JMP Do_It

;Write the result

  Finishin:
    MOV cx, ax          
    CALL checkOnScreen       ;print it to command line
    MOV bx, WriteHandle         
    CALL    writeBuffer      ;print it
    CMP ax, rBuffSize        ;compare the size to 32
    JE  Read                 ;if it was 32 then read again

【问题讨论】：

会不会只是你的输出函数搞砸了？据我所知，您正在将原始长度传递给它。
在调试器中逐行通过您的代码

标签： string assembly char output x86-16

【解决方案1】：

您只写了 32 个字节的 wBuff。这是在第一次运行之后：“Good. Morning. People hehehe in”。由于该行较长，其余部分位于 32 字节边界的后面。然后您将指针重置为rBuff 和wBuff 并阅读下一个块：“e 丛林强大的丛林”。该块附加到写入的行。

考虑要写入的块具有可变长度。将JMP Do_It改为LOOP Do_It后，可以通过DI(sub di, OFFSET wBuff)减去wBuff的偏移量来计算长度。

由于我无法解释您代码的相关部分（CMP ax, rBuffSize、JE Read ???），因此我无法展示一个工作示例。

【讨论】：

【解决方案2】：

感谢大家的意见，这次我自己做到了。问题是

Finishin:
    MOV cx, ax          
    CALL checkOnScreen       
    MOV bx, WriteHandle         
    CALL    writeBuffer      
    CMP ax, rBuffSize        
    JE  Read

新代码：

    Finishin:
        MOV cx, strLength2         ;length of writebuffer
        CALL checkOnScreen       
        MOV bx, WriteHandle         
        CALL    writeBuffer      
        CMP ax, rBuffSize        ;ax was messed up so I changed it to strLength1 or readBuffer
        JE  Read

【讨论】：