root/kernel/printk.c

DEFINITIONS

1. printint
2. printptr
3. printk
4. panic
5. printkinit

   1 //
   2 // formatted console output -- printk, panic.
   3 //
   4 
   5 #include <stdarg.h>
   6 
   7 #include "types.h"
   8 #include "param.h"
   9 #include "spinlock.h"
  10 #include "sleeplock.h"
  11 #include "fs.h"
  12 #include "file.h"
  13 #include "memlayout.h"
  14 #include "riscv.h"
  15 #include "defs.h"
  16 #include "proc.h"
  17 
  18 volatile int panicking = 0; // printing a panic message
  19 volatile int panicked = 0;  // spinning forever at end of a panic
  20 
  21 // lock to avoid interleaving concurrent printk's.
  22 static struct {
  23   struct spinlock lock;
  24 } pr;
  25 
  26 static char digits[] = "0123456789abcdef";
  27 
  28 static void
  29 printint(long long xx, int base, int sign)
  30 {
  31   char buf[20];
  32   int i;
  33   unsigned long long x;
  34 
  35   if (sign && (sign = (xx < 0)))
  36     x = -xx;
  37   else
  38     x = xx;
  39 
  40   i = 0;
  41   do {
  42     buf[i++] = digits[x % base];
  43   } while ((x /= base) != 0);
  44 
  45   if (sign)
  46     buf[i++] = '-';
  47 
  48   while (--i >= 0)
  49     consputc(buf[i]);
  50 }
  51 
  52 static void
  53 printptr(uint64 x)
  54 {
  55   int i;
  56   consputc('0');
  57   consputc('x');
  58   for (i = 0; i < (sizeof(uint64) * 2); i++, x <<= 4)
  59     consputc(digits[x >> (sizeof(uint64) * 8 - 4)]);
  60 }
  61 
  62 // Print to the console.
  63 int
  64 printk(char *fmt, ...)
  65 {
  66   va_list ap;
  67   int i, cx, c0, c1, c2;
  68   char *s;
  69 
  70   if (panicking == 0)
  71     acquire(&pr.lock);
  72 
  73   va_start(ap, fmt);
  74   for (i = 0; (cx = fmt[i] & 0xff) != 0; i++) {
  75     if (cx != '%') {
  76       consputc(cx);
  77       continue;
  78     }
  79     i++;
  80     c0 = fmt[i + 0] & 0xff;
  81     c1 = c2 = 0;
  82     if (c0)
  83       c1 = fmt[i + 1] & 0xff;
  84     if (c1)
  85       c2 = fmt[i + 2] & 0xff;
  86     if (c0 == 'd') {
  87       printint(va_arg(ap, int), 10, 1);
  88     } else if (c0 == 'l' && c1 == 'd') {
  89       printint(va_arg(ap, uint64), 10, 1);
  90       i += 1;
  91     } else if (c0 == 'l' && c1 == 'l' && c2 == 'd') {
  92       printint(va_arg(ap, uint64), 10, 1);
  93       i += 2;
  94     } else if (c0 == 'u') {
  95       printint(va_arg(ap, uint32), 10, 0);
  96     } else if (c0 == 'l' && c1 == 'u') {
  97       printint(va_arg(ap, uint64), 10, 0);
  98       i += 1;
  99     } else if (c0 == 'l' && c1 == 'l' && c2 == 'u') {
 100       printint(va_arg(ap, uint64), 10, 0);
 101       i += 2;
 102     } else if (c0 == 'x') {
 103       printint(va_arg(ap, uint32), 16, 0);
 104     } else if (c0 == 'l' && c1 == 'x') {
 105       printint(va_arg(ap, uint64), 16, 0);
 106       i += 1;
 107     } else if (c0 == 'l' && c1 == 'l' && c2 == 'x') {
 108       printint(va_arg(ap, uint64), 16, 0);
 109       i += 2;
 110     } else if (c0 == 'p') {
 111       printptr(va_arg(ap, uint64));
 112     } else if (c0 == 'c') {
 113       consputc(va_arg(ap, uint));
 114     } else if (c0 == 's') {
 115       if ((s = va_arg(ap, char *)) == 0)
 116         s = "(null)";
 117       for (; *s; s++)
 118         consputc(*s);
 119     } else if (c0 == '%') {
 120       consputc('%');
 121     } else if (c0 == 0) {
 122       break;
 123     } else {
 124       // Print unknown % sequence to draw attention.
 125       consputc('%');
 126       consputc(c0);
 127     }
 128   }
 129   va_end(ap);
 130 
 131   if (panicking == 0)
 132     release(&pr.lock);
 133 
 134   return 0;
 135 }
 136 
 137 void
 138 panic(char *s)
 139 {
 140   panicking = 1;
 141   printk("panic: ");
 142   printk("%s\n", s);
 143   panicked = 1; // freeze uart output from other CPUs
 144   for (;;)
 145     ;
 146 }
 147 
 148 void
 149 printkinit(void)
 150 {
 151   initlock(&pr.lock, "pr");
 152 }