putk.c

一个简单的操作系统minix的核心代码

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				src/fs/putk.c	 	 
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27600	/* FS must occasionally print some message.  It uses the standard library
27601	 * routine prink().  (The name "printf" is really a macro defined as "printk").
27602	 * Printing is done by calling the TTY task directly, not going through FS.
27603	 */
27604	
27605	#include "fs.h"
27606	#include <minix/com.h>
27607	
27608	#define BUF_SIZE          100   /* print buffer size */
27609	
27610	PRIVATE int buf_count;          /* # characters in the buffer */
27611	PRIVATE char print_buf[BUF_SIZE];       /* output is buffered here */
27612	PRIVATE message putch_msg;      /* used for message to TTY task */
27613	
27614	FORWARD _PROTOTYPE( void flush, (void)                                  );
27615	
27616	/*===========================================================================*
27617	 *                              putk                                         *
27618	 *===========================================================================*/
27619	PUBLIC void putk(c)
27620	int c;
27621	{
27622	/* Accumulate another character.  If 0 or buffer full, print it. */
27623	
27624	  if (c == 0 || buf_count == BUF_SIZE) flush();
27625	  if (c == '\n') putk('\r');
27626	  if (c != 0) print_buf[buf_count++] = c;
27627	}
	
	
27630	/*===========================================================================*
27631	 *                              flush                                        *
27632	 *===========================================================================*/
27633	PRIVATE void flush()
27634	{
27635	/* Flush the print buffer by calling TTY task. */
27636	
27637	
27638	  if (buf_count == 0) return;
27639	  putch_msg.m_type = DEV_WRITE;
27640	  putch_msg.PROC_NR  = 1;
27641	  putch_msg.TTY_LINE = 0;
27642	  putch_msg.ADDRESS  = print_buf;
27643	  putch_msg.COUNT = buf_count;
27644	  call_task(TTY, &putch_msg);
27645	  buf_count = 0;
27646	}