[BOOT] Print functions for debugging

kernel/boot/debug.c

@@ -0,0 +1,132 @@
+#include <debug.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <string.h>
+#include <vga.h>
+#include <serial.h>
+
+void debug_init()
+{
+  vga_init();
+  serial_init(PORT_COM1);
+}
+
+uint64_t num2str(uint64_t num, uint32_t base, char *buf)
+{
+  // Convert a number to string
+  if(num == 0)
+  {
+    buf[0] = '0';
+    buf[1] = '\0';
+    return 0;
+  }
+  uint32_t i=0, j=0;
+  char chars[] = "0123456789ABCDEF";
+  // Build the string starting with the least significant digit
+  while(num > 0)
+  {
+    buf[i++] = chars[num%base];
+    num /= base;
+  }
+
+  // Invert the string to get digits in right order
+  i--;
+  j=0;
+  while(j<i)
+  {
+    char t = buf[i];
+    buf[i--] = buf[j];
+    buf[j++] = t;
+  }
+
+  // Zero terminate
+  buf[i+j+1] = '\0';
+  return i+j+1;
+}
+
+void debug_putch(char c)
+{
+  vga_printch(c);
+  serial_write(PORT_COM1, c);
+}
+void debug_putsn(char *s, size_t n)
+{
+  while(n--)
+    debug_putch(*s++);
+}
+void debug_puts(char *s)
+{
+  debug_putsn(s, strlen(s));
+}
+
+void debug_vprintf(char *str, va_list args)
+{
+  size_t len = 0;
+  if(!(*str))
+    return;
+  if(*str != '%')
+  {
+    while(str[len] && str[len] != '%')
+      len++;
+    debug_putsn(str, len);
+    return debug_vprintf(&str[len], args);
+  }
+  str++;
+  char *prefix;
+  uint32_t base = 0;
+#define DEBUG_VPRINTF_BASE_CHAR 255
+#define DEBUG_VPRINTF_BASE_STR 1024
+  switch(*str)
+  {
+    case 'b':
+      prefix = "0b";
+      base = 2;
+      break;
+    case 'o':
+      prefix = "0";
+      base = 8;
+      break;
+    case 'd':
+      prefix = "";
+      base = 10;
+      break;
+    case 'x':
+      prefix = "0x";
+      base = 16;
+      break;
+    case 'c':
+      prefix = "";
+      base = DEBUG_VPRINTF_BASE_CHAR;
+      break;
+    case 's':
+      prefix = "";
+      base = DEBUG_VPRINTF_BASE_STR;
+      break;
+    case '%':
+    default:
+      debug_putch('%');
+      break;
+  }
+  if(base == DEBUG_VPRINTF_BASE_STR)
+    debug_puts(va_arg(args, char *));
+  else if(base == DEBUG_VPRINTF_BASE_CHAR)
+    debug_putch((char)va_arg(args, uint64_t));
+  else if(base)
+  {
+    uint64_t num = va_arg(args, uint64_t);
+    char buf[128];
+    num2str(num, base, buf);
+    debug_puts(prefix);
+    debug_puts(buf);
+  }
+  str++;
+  return debug_vprintf(str, args);
+}
+
+void debug_printf(char *str, ...)
+{
+  va_list args;
+  va_start(args, str);
+  debug_vprintf(str, args);
+  va_end(args);
+}