minix/lib/syslib/kputc.c

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2005-04-21 16:53:53 +02:00
/* A server must occasionally print some message. It uses a simple version of
* printf() found in the system lib that calls kputc() to output characters.
* Printing is done with a call to the kernel, and not by going through FS.
* This way system messages end up in the kernel messages buffer and can be
* reviewed at a later time.
*
* This routine can only be used by servers and device drivers. The kernel
* must define its own kputc(). Note that the IS also defines its own kputc()
* to directly call the TTY instead of the kernel, because it does not want
* to pollute the kernel message buffer with its debug dumps.
*/
#include "syslib.h"
#include <minix/callnr.h>
#include <minix/minlib.h>
/*===========================================================================*
* kputc *
*===========================================================================*/
void kputc(c)
int c;
{
/* Accumulate another character. If 0 or buffer full, print it. */
static int buf_count; /* # characters in the buffer */
static char print_buf[80]; /* output is buffered here */
message m;
if ((c == 0 && buf_count > 0) || buf_count == sizeof(print_buf)) {
/* Send the buffer to the system task, or, if this process is not a
* server yet, to standard error.
*/
m.DIAG_BUF_COUNT = buf_count;
m.DIAG_PRINT_BUF = print_buf;
m.DIAG_PROC_NR = SELF;
m.m_type = DIAGNOSTICS;
if (_sendrec(TTY, &m) != 0) {
m.m1_i1 = 2;
m.m1_i2 = buf_count;
m.m1_p1 = print_buf;
m.m_type = WRITE;
(void) _sendrec(FS, &m);
}
buf_count = 0;
}
if (c != 0) print_buf[buf_count++] = c;
}