minix/lib/sysutil/kputc.c
Jorrit Herder b69ca94efb Fixed 'bug' in log driver that caused kernel messages not to be displayed.
This was caused by a change in the shared driver code. Not log's fault.

Renamed #definitions of driver process numbers, e.g., TTY now is TTY_PROC_NR.
All known (special) processes now have consistent naming scheme. Kernel tasks
don't follow this scheme.
2005-08-03 08:14:08 +00:00

43 lines
1.5 KiB
C

/* 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 routine can only be used by servers and device drivers. The kernel
* must define its own kputc(). Note that the log driver also defines its own
* kputc() to directly call the TTY instead of going through this library.
*/
#include "sysutil.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 OUTPUT_PROC_NR driver. */
m.DIAG_BUF_COUNT = buf_count;
m.DIAG_PRINT_BUF = print_buf;
m.DIAG_PROC_NR = SELF;
m.m_type = DIAGNOSTICS;
(void) _sendrec(OUTPUT_PROC_NR, &m);
buf_count = 0;
/* If the output fails, e.g., due to an ELOCKED, do not retry output
* at the FS as if this were a normal user-land printf(). This may
* result in even worse problems.
*/
}
if (c != 0) {
/* Append a single character to the output buffer. */
print_buf[buf_count++] = c;
}
}