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linux 0.11中文版 有注释

<a name='L281'><i><font color='green'>// 如果该字符是键盘中断符(^C)，则向当前进程发送键盘中断信号，并继续处理下一字符。</font></i>
<a name='L282'>          <b>if</b> (c == <a href='../S/38.html#L56' title='Defined at 56 in include/linux/tty.h.'>INTR_CHAR</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>))
<a name='L283'>            <font color='red'>{</font>
<a name='L284'>              <a href='../S/65.html#L135' title='Defined at 135 in kernel/chr_drv/tty_io.c.'>tty_intr</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>, <a href='../S/65.html#L26' title='Defined at 26 in kernel/chr_drv/tty_io.c.'>INTMASK</a>);
<a name='L285'>              <b>continue</b>;
<a name='L286'>            <font color='red'>}</font>
<a name='L287'><i><font color='green'>// 如果该字符是键盘中断符(^\)，则向当前进程发送键盘退出信号，并继续处理下一字符。</font></i>
<a name='L288'>          <b>if</b> (c == <a href='../S/38.html#L57' title='Defined at 57 in include/linux/tty.h.'>QUIT_CHAR</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>))
<a name='L289'>            <font color='red'>{</font>
<a name='L290'>              <a href='../S/65.html#L135' title='Defined at 135 in kernel/chr_drv/tty_io.c.'>tty_intr</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>, <a href='../S/65.html#L27' title='Defined at 27 in kernel/chr_drv/tty_io.c.'>QUITMASK</a>);
<a name='L291'>              <b>continue</b>;
<a name='L292'>            <font color='red'>}</font>
<a name='L293'>        <font color='red'>}</font>
<a name='L294'><i><font color='green'>// 如果该字符是换行符NL(10)，或者是文件结束符EOF(^D)，辅助缓冲队列字符数加1。[??]</font></i>
<a name='L295'>      <b>if</b> (c == 10 || c == <a href='../S/38.html#L60' title='Defined at 60 in include/linux/tty.h.'>EOF_CHAR</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>))
<a name='L296'>        <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary.data++;
<a name='L297'><i><font color='green'>// 如果本地模式标志集中回显标志ECHO 置位，那么，如果字符是换行符NL(10)，则将换行符NL(10)</font></i>
<a name='L298'><i><font color='green'>// 和回车符CR(13)放入tty 写队列缓冲区中；如果字符是控制字符(字符值&lt;32)并且回显控制字符标志</font></i>
<a name='L299'><i><font color='green'>// ECHOCTL 置位，则将字符'^'和字符c+64 放入tty 写队列中(也即会显示^C、^H 等)；否则将该字符</font></i>
<a name='L300'><i><font color='green'>// 直接放入tty 写缓冲队列中。最后调用该tty 的写操作函数。</font></i>
<a name='L301'>      <b>if</b> (<a href='../S/65.html#L43' title='Defined at 43 in kernel/chr_drv/tty_io.c.'>L_ECHO</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>))
<a name='L302'>        <font color='red'>{</font>
<a name='L303'>          <b>if</b> (c == 10)
<a name='L304'>            <font color='red'>{</font>
<a name='L305'>              <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> (10, <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write_q);
<a name='L306'>              <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> (13, <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write_q);
<a name='L307'>            <font color='red'>}</font>
<a name='L308'>          <b>else</b> <b>if</b> (c &lt; 32)
<a name='L309'>            <font color='red'>{</font>
<a name='L310'>              <b>if</b> (<a href='../S/65.html#L46' title='Defined at 46 in kernel/chr_drv/tty_io.c.'>L_ECHOCTL</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>))
<a name='L311'>                <font color='red'>{</font>
<a name='L312'>                  <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> ('^', <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write_q);
<a name='L313'>                  <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> (c + 64, <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write_q);
<a name='L314'>                <font color='red'>}</font>
<a name='L315'>            <font color='red'>}</font>
<a name='L316'>          <b>else</b>
<a name='L317'>            <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> (c, <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write_q);
<a name='L318'>          <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;write (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>);
<a name='L319'>        <font color='red'>}</font>
<a name='L320'><i><font color='green'>// 将该字符放入辅助队列中。</font></i>
<a name='L321'>      <a href='../S/38.html#L52' title='Defined at 52 in include/linux/tty.h.'>PUTCH</a> (c, <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary);
<a name='L322'>    <font color='red'>}</font>
<a name='L323'><i><font color='green'>// 唤醒等待该辅助缓冲队列的进程（如果有的话）。</font></i>
<a name='L324'>  <a href='../S/74.html#L272' title='Defined at 272 in kernel/sched.c.'>wake_up</a> (&amp;<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary.proc_list);
<a name='L325'><font color='red'>}</font>
<a name='L326'>
<a name='L327'><i><font color='green'>//// tty 读函数。</font></i>
<a name='L328'><i><font color='green'>// 参数：channel - 子设备号；buf - 缓冲区指针；nr - 欲读字节数。</font></i>
<a name='L329'><i><font color='green'>// 返回已读字节数。</font></i>
<a name='L330'><b>int</b>
<a name='L331'><a href='../R/714.html' title='Multiple refered from 2 places.'>tty_read</a> (<b>unsigned</b> channel, <b>char</b> *buf, <b>int</b> nr)
<a name='L332'><font color='red'>{</font>
<a name='L333'>  <b>struct</b> tty_struct *<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>;
<a name='L334'>  <b>char</b> c, *b = <a href='../D/716.html' title='Multiple defined in 16 places.'>buf</a>;
<a name='L335'>  <b>int</b> minimum, time, flag = 0;
<a name='L336'>  <b>long</b> oldalarm;
<a name='L337'>
<a name='L338'><i><font color='green'>// 本版本linux 内核的终端只有3 个子设备，分别是控制台(0)、串口终端1(1)和串口终端2(2)。</font></i>
<a name='L339'><i><font color='green'>// 所以任何大于2 的子设备号都是非法的。写的字节数当然也不能小于0 的。</font></i>
<a name='L340'>  <b>if</b> (channel &gt; 2 || nr &lt; 0)
<a name='L341'>    <b>return</b> -1;
<a name='L342'><i><font color='green'>// tty 指针指向子设备号对应ttb_table 表中的tty 结构。</font></i>
<a name='L343'>  <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a> = &amp;tty_table[channel];
<a name='L344'><i><font color='green'>// 下面首先保存进程原定时值，然后根据控制字符VTIME 和VMIN 设置读字符操作的超时定时值。</font></i>
<a name='L345'><i><font color='green'>// 在非规范模式下，这两个值是超时定时值。MIN 表示为了满足读操作，需要读取的最少字符数。</font></i>
<a name='L346'><i><font color='green'>// TIME 是一个十分之一秒计数的计时值。</font></i>
<a name='L347'><i><font color='green'>// 首先取进程中的(报警)定时值(滴答数)。</font></i>
<a name='L348'>  oldalarm = current-&gt;alarm;
<a name='L349'><i><font color='green'>// 并设置读操作超时定时值time 和需要最少读取的字符个数minimum。</font></i>
<a name='L350'>  time = 10L * <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;termios.c_cc[<a href='../S/48.html#L118' title='Defined at 118 in include/termios.h.'>VTIME</a>];
<a name='L351'>  minimum = <a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;termios.c_cc[<a href='../S/48.html#L119' title='Defined at 119 in include/termios.h.'>VMIN</a>];
<a name='L352'><i><font color='green'>// 如果设置了读超时定时值time 但没有设置最少读取个数minimum，那么在读到至少一个字符或者</font></i>
<a name='L353'><i><font color='green'>// 定时超时后读操作将立刻返回。所以这里置minimum=1。</font></i>
<a name='L354'>  <b>if</b> (time &amp;&amp; !minimum)
<a name='L355'>    <font color='red'>{</font>
<a name='L356'>      minimum = 1;
<a name='L357'><i><font color='green'>// 如果进程原定时值是0 或者time+当前系统时间值小于进程原定时值的话，则置重新设置进程定时</font></i>
<a name='L358'><i><font color='green'>// 值为time+当前系统时间，并置flag 标志。</font></i>
<a name='L359'>      <b>if</b> (flag = (!oldalarm || time + jiffies &lt; oldalarm))
<a name='L360'>        current-&gt;alarm = time + jiffies;
<a name='L361'>    <font color='red'>}</font>
<a name='L362'><i><font color='green'>// 如果设置的最少读取字符数&gt;欲读的字符数，则令其等于此次欲读取的字符数。</font></i>
<a name='L363'>  <b>if</b> (minimum &gt; nr)
<a name='L364'>    minimum = nr;
<a name='L365'><i><font color='green'>// 当欲读的字节数&gt;0，则循环执行以下操作。</font></i>
<a name='L366'>  <b>while</b> (nr &gt; 0)
<a name='L367'>    <font color='red'>{</font>
<a name='L368'><i><font color='green'>// 如果flag 不为0(即进程原定时值是0 或者time+当前系统时间值小于进程原定时值)并且进程有定</font></i>
<a name='L369'><i><font color='green'>// 时信号SIGALRM，则复位进程的定时信号并中断循环。</font></i>
<a name='L370'>      <b>if</b> (flag &amp;&amp; (current-&gt;signal &amp; <a href='../S/65.html#L24' title='Defined at 24 in kernel/chr_drv/tty_io.c.'>ALRMMASK</a>))
<a name='L371'>        <font color='red'>{</font>
<a name='L372'>          current-&gt;signal &amp;= ~<a href='../S/65.html#L24' title='Defined at 24 in kernel/chr_drv/tty_io.c.'>ALRMMASK</a>;
<a name='L373'>          <b>break</b>;
<a name='L374'>        <font color='red'>}</font>
<a name='L375'><i><font color='green'>// 如果当前进程有信号要处理，则退出，返回0。</font></i>
<a name='L376'>      <b>if</b> (current-&gt;signal)
<a name='L377'>        <b>break</b>;
<a name='L378'><i><font color='green'>// 如果辅助缓冲队列(规范模式队列)为空，或者设置了规范模式标志并且辅助队列中字符数为0 以及</font></i>
<a name='L379'><i><font color='green'>// 辅助模式缓冲队列空闲空间&gt;20，则进入可中断睡眠状态，返回后继续处理。</font></i>
<a name='L380'>      <b>if</b> (<a href='../S/38.html#L39' title='Defined at 39 in include/linux/tty.h.'>EMPTY</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary) || (<a href='../S/65.html#L41' title='Defined at 41 in kernel/chr_drv/tty_io.c.'>L_CANON</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>) &amp;&amp;
<a name='L381'>                                     !<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary.data
<a name='L382'>                                     &amp;&amp; <a href='../D/215.html' title='Multiple defined in 2 places.'>LEFT</a> (<a href='../S/7.html#L44' title='Defined at 44 in fs/char_dev.c.'>tty</a>-&gt;secondary) &gt; 20))