putk.c

一个简单的操作系统minix的核心代码

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				src/mm/putk.c	 	 
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19300	/* MM must occasionally print some message.  It uses the standard library
19301	 * routine printk().  (The name "printf" is really a macro defined as 
19302	 * "printk"). Printing is done by calling the TTY task directly, not going 
19303	 * through FS.
19304	 */
19305	
19306	#include "mm.h"
19307	#include <minix/com.h>
19308	
19309	#define BUF_SIZE          100   /* print buffer size */
19310	
19311	PRIVATE int buf_count;          /* # characters in the buffer */
19312	PRIVATE char print_buf[BUF_SIZE];       /* output is buffered here */
19313	PRIVATE message putch_msg;      /* used for message to TTY task */
19314	
19315	_PROTOTYPE( FORWARD void flush, (void) );
19316	
19317	/*===========================================================================*
19318	 *                              putk                                         *
19319	 *===========================================================================*/
19320	PUBLIC void putk(c)
19321	int c;
19322	{
19323	/* Accumulate another character.  If 0 or buffer full, print it. */
19324	
19325	  if (c == 0 || buf_count == BUF_SIZE) flush();
19326	  if (c == '\n') putk('\r');
19327	  if (c != 0) print_buf[buf_count++] = c;
19328	}
	
	
19331	/*===========================================================================*
19332	 *                              flush                                        *
19333	 *===========================================================================*/
19334	PRIVATE void flush()
19335	{
19336	/* Flush the print buffer by calling TTY task. */
19337	
19338	  if (buf_count == 0) return;
19339	  putch_msg.m_type = DEV_WRITE;
19340	  putch_msg.PROC_NR  = 0;
19341	  putch_msg.TTY_LINE = 0;
19342	  putch_msg.ADDRESS  = print_buf;
19343	  putch_msg.COUNT = buf_count;
19344	  sendrec(TTY, &putch_msg);
19345	  buf_count = 0;
19346	}