Minix1.5/mm/putc.c

/* MM must occasionally print some message.  It uses the standard library
 * routine prink().  (The name "printf" is really a macro defined as "printk").
 * Printing is done by calling the TTY task directly, not going through FS.
 */

#include "mm.h"
#include <minix/com.h>

#define STD_OUTPUT          1	/* file descriptor for standard output */
#define BUF_SIZE          100	/* print buffer size */

PRIVATE int buf_count;		/* # characters in the buffer */
PRIVATE char print_buf[BUF_SIZE];	/* output is buffered here */
PRIVATE message putch_msg;	/* used for message to TTY task */

FORWARD void F_l_u_s_h();

/*===========================================================================*
 *				putc					     *
 *===========================================================================*/
PUBLIC void putc(c)
char c;
{

  /* Accumulate another character.  If '\n' or buffer full, print it. */
  print_buf[buf_count++] = c;
  if (c == '\n' || buf_count == BUF_SIZE) F_l_u_s_h();
}


/*===========================================================================*
 *				F_l_u_s_h				     *
 *===========================================================================*/
PRIVATE void F_l_u_s_h()
{
/* Flush the print buffer by calling TTY task. */

  if (buf_count == 0) return;
  putch_msg.m_type = TTY_WRITE;
  putch_msg.PROC_NR  = 0;
  putch_msg.TTY_LINE = 0;
  putch_msg.ADDRESS  = print_buf;
  putch_msg.COUNT = buf_count;
  sendrec(TTY, &putch_msg);
  buf_count = 0;
}