minix/lib/sysutil/kputc.c
Ben Gras ea75918df1 printf() by kernel and servers now send messages to an array of processes,
OUTPUT_PROCS_ARRAY in <minix/config.h>, in that order, terminated by NONE.
log no longer forwards messages to tty itself. This leads to less funny
loops and more robust debug-message handling. Also the list of
processes receiving messages can easily be changed around or disabled by
editing the array (e.g. disable it by changing the array to { NONE }.).
2005-10-18 10:34:54 +00:00

47 lines
1.6 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)) {
int procs[] = OUTPUT_PROCS_ARRAY;
int p;
for(p = 0; procs[p] != NONE; p++) {
/* Send the buffer to this output driver. */
m.DIAG_BUF_COUNT = buf_count;
m.DIAG_PRINT_BUF = print_buf;
m.DIAG_PROC_NR = SELF;
m.m_type = DIAGNOSTICS;
(void) _sendrec(procs[p], &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;
}
}