1 files changed, 108 insertions, 0 deletions
diff --git a/console.c b/console.c
new file mode 100644
index 0000000..2035611
--- /dev/null
+++ b/console.c
@@ -0,0 +1,108 @@
+#include <types.h>
+#include <x86.h>
+#include "defs.h"
+
+void
+cons_putc(int c)
+{
+  int crtport = 0x3d4; // io port of CGA
+  unsigned short *crt = (unsigned short *) 0xB8000; // base of CGA memory
+  int ind;
+
+  // cursor position, 16 bits, col + 80*row
+  outb(crtport, 14);
+  ind = inb(crtport + 1) << 8;
+  outb(crtport, 15);
+  ind |= inb(crtport + 1);
+
+  c &= 0xff;
+
+  if(c == '\n'){
+    ind -= (ind % 80);
+    ind += 80;
+  } else {
+    c |= 0x0700; // black on white
+    crt[ind] = c;
+    ind += 1;
+  }
+
+  if((ind / 80) >= 24){
+    // scroll up
+    memcpy(crt, crt + 80, sizeof(crt[0]) * (23 * 80));
+    ind -= 80;
+    memset(crt + ind, 0, sizeof(crt[0]) * ((24 * 80) - ind));
+  }
+
+  outb(crtport, 14);
+  outb(crtport + 1, ind >> 8);
+  outb(crtport, 15);
+  outb(crtport + 1, ind);
+}
+
+void
+printint(int xx, int base, int sgn)
+{
+  char buf[16];
+  char digits[] = "0123456789ABCDEF";
+  int i = 0, neg = 0;
+  unsigned int x;
+  
+  if(sgn && xx < 0){
+    neg = 1;
+    x = 0 - xx;
+  } else {
+    x = xx;
+  }
+
+  do {
+    buf[i++] = digits[x % base];
+  } while((x /= base) != 0);
+  if(neg)
+    buf[i++] = '-';
+
+  while(i > 0){
+    i -= 1;
+    cons_putc(buf[i]);
+  }
+}
+
+/*
+ * print to the console. only understands %d and %x.
+ */
+void
+cprintf(char *fmt, ...)
+{
+  int i, state = 0, c;
+  unsigned int *ap = (unsigned int *) &fmt + 1;
+
+  for(i = 0; fmt[i]; i++){
+    c = fmt[i] & 0xff;
+    if(state == 0){
+      if(c == '%'){
+        state = '%';
+      } else {
+        cons_putc(c);
+      }
+    } else if(state == '%'){
+      if(c == 'd'){
+        printint(*ap, 10, 1);
+        ap++;
+      } else if(c == 'x'){
+        printint(*ap, 16, 0);
+        ap++;
+      } else if(c == '%'){
+        cons_putc(c);
+      }
+      state = 0;
+    }
+  }
+}
+
+void
+panic(char *s)
+{
+  cprintf(s, 0);
+  cprintf("\n", 0);
+  while(1)
+    ;
+}