From d05ddfeab4d1c3ccbac334e54f44a34096f64cc9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Fri, 1 Dec 2017 22:16:26 +0100
Subject: [PATCH] Debug printing functions

---
 src/kernel/boot/debug.c    | 116 ++++++++++++++++++++++++++++++++++++
 src/kernel/boot/debug.tt   | 117 +++++++++++++++++++++++++++++++++++++
 src/kernel/include/debug.h |   9 +++
 3 files changed, 242 insertions(+)
 create mode 100644 src/kernel/boot/debug.c
 create mode 100644 src/kernel/boot/debug.tt
 create mode 100644 src/kernel/include/debug.h

diff --git a/src/kernel/boot/debug.c b/src/kernel/boot/debug.c
new file mode 100644
index 0000000..3144eb4
--- /dev/null
+++ b/src/kernel/boot/debug.c
@@ -0,0 +1,116 @@
+#include <stddef.h>
+#include <stdarg.h>
+#include <stdint.h>
+
+// TODO: Temporary declarations
+void vga_write(char c);
+void serial_write(int port, char c);
+#define PORT_COM1 0
+
+
+void num2str(char *buf, uint64_t num, uint64_t base)
+{
+  if(num == 0)
+  {
+    buf[0] = '0';
+    buf[1] = '\0';
+    return;
+  }
+  uint64_t i=0, j=0;
+  char chars[] = "0123456789ABCDEF";
+  while(num > 0)
+  {
+    buf[i++] = chars[num%base];
+    num /= base;
+  }
+  i--;
+  while(j<i)
+  {
+    char t = buf[i];
+    buf[i--] = buf[j];
+    buf[j++] = t;
+  }
+  buf[i+j+1] = '\0';
+}
+
+
+void debug_putch(char c)
+{
+  vga_write(c);
+  serial_write(PORT_COM1, c);
+}
+
+void debug_putsn(char *s, size_t n)
+{
+  while(n--)
+    debug_putch(*s++);
+}
+
+void debug_puts(char *s)
+{
+  size_t len = 0;
+  while(s[len]) len++;
+  debug_putsn(s, len);
+}
+
+void debug_vprintf(char *fmt, va_list args)
+{
+  if(!(*fmt))
+    return;
+
+  if(*fmt != '%')
+  {
+    size_t len = 0;
+    while(fmt[len] && fmt[len] != '%')
+      len++;
+    debug_putsn(fmt, len);
+    debug_vprintf(&fmt[len], args);
+    return;
+  }
+
+  fmt++;
+  uint64_t base = 0;
+  switch(*fmt)
+  {
+    case 'b':
+      base = 2;
+      break;
+    case 'o':
+      base = 8;
+      break;
+    case 'd':
+      base = 10;
+      break;
+    case 'x':
+      base = 16;
+      break;
+    case 'c':
+      debug_putch((char)va_arg(args, uint64_t));
+      break;
+    case 's':
+      debug_puts(va_arg(args, char*));
+      break;
+    default:
+      debug_putch('%');
+      fmt--;
+  }
+
+  if(base)
+  {
+    uintmax_t number = va_arg(args, uintmax_t);
+    char buf[128];
+    num2str(buf, number, base);
+    debug_puts(buf);
+  }
+
+  fmt++;
+  debug_vprintf(fmt, args);
+}
+
+void debug_printf(char *fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  debug_vprintf(fmt, args);
+  va_end(args);
+}
diff --git a/src/kernel/boot/debug.tt b/src/kernel/boot/debug.tt
new file mode 100644
index 0000000..bb1d00b
--- /dev/null
+++ b/src/kernel/boot/debug.tt
@@ -0,0 +1,117 @@
+// vim: ft=c
+#include <ttest.h>
+#include "debug.c"
+
+#define BUFFER_SIZE 16
+char vga_recv[BUFFER_SIZE];
+char serial_recv[BUFFER_SIZE];
+
+BEFORE()
+{
+  for(int i = 0; i < BUFFER_SIZE; i++)
+  {
+    vga_recv[i] = '\0';
+    serial_recv[i] = '\0';
+  }
+}
+
+void vga_write(char c)
+{
+  static int i = 0;
+  vga_recv[i++] = c;
+}
+void serial_write(int port, char c)
+{
+  (void)port;
+  static int i = 0;
+  serial_recv[i++] = c;
+}
+
+TEST(putch_sends_character_to_vga)
+{
+  char input = 'a';
+  debug_putch(input);
+  ASSERT_EQ_CHR(vga_recv[0], input);
+}
+TEST(putch_sends_character_to_serial)
+{
+  char input = 'a';
+  debug_putch(input);
+  ASSERT_EQ_CHR(serial_recv[0], input);
+}
+
+TEST(putsn_writes_string)
+{
+  char *str = "hello";
+  debug_putsn(str, 5);
+  ASSERT_EQ_STR(vga_recv, str, BUFFER_SIZE);
+}
+TEST(putsn_writes_correct_number_of_characters)
+{
+  char *str = "1234567890";
+  debug_putsn(str, 5);
+  ASSERT_EQ_STR(vga_recv, "12345", BUFFER_SIZE);
+}
+TEST(puts_writes_string)
+{
+  char *str = "world";
+  debug_puts(str);
+  ASSERT_EQ_STR(vga_recv, str, BUFFER_SIZE);
+}
+
+TEST(printf_prints_string)
+{
+  char *str = "Hello, world!";
+  debug_printf(str);
+  ASSERT_EQ_STR(vga_recv, str, BUFFER_SIZE);
+}
+TEST(printf_does_not_print_percent)
+{
+  debug_printf("123%d", 45);
+  ASSERT_NEQ_CHR(vga_recv[3], '%');
+}
+TEST(printf_prints_binary_number)
+{
+  debug_printf("%b", 0x55aa);
+  ASSERT_EQ_STR(vga_recv, "101010110101010", BUFFER_SIZE);
+}
+TEST(printf_prints_ocal_number)
+{
+  debug_printf("%o", 8);
+  ASSERT_EQ_STR(vga_recv, "10", BUFFER_SIZE);
+}
+TEST(printf_prints_decimal_number)
+{
+  debug_printf("%d", 123);
+  ASSERT_EQ_STR(vga_recv, "123", BUFFER_SIZE);
+}
+TEST(printf_prints_hexadecimal_number)
+{
+  debug_printf("%x", 42);
+  ASSERT_EQ_STR(vga_recv, "2A", BUFFER_SIZE);
+}
+TEST(printf_prints_char)
+{
+  debug_printf("%c", 'X');
+  ASSERT_EQ_STR(vga_recv, "X", BUFFER_SIZE);
+}
+TEST(printf_prints_passed_string)
+{
+  debug_printf("%s", "asdf");
+  ASSERT_EQ_STR(vga_recv, "asdf", BUFFER_SIZE);
+}
+TEST(printf_keeps_printing_after_number)
+{
+  debug_printf("%x123", 0);
+  ASSERT_EQ_STR(vga_recv, "0123", BUFFER_SIZE);
+}
+TEST(printf_prints_text_around_number)
+{
+  debug_printf("ABC%dDEF", 0);
+  ASSERT_EQ_STR(vga_recv, "ABC0DEF", BUFFER_SIZE);
+}
+TEST(printf_keeps_going_for_unknown_format_specifier)
+{
+  debug_printf("%y");
+  ASSERT_EQ_STR(vga_recv, "%y", BUFFER_SIZE);
+}
diff --git a/src/kernel/include/debug.h b/src/kernel/include/debug.h
new file mode 100644
index 0000000..c4950b8
--- /dev/null
+++ b/src/kernel/include/debug.h
@@ -0,0 +1,9 @@
+#pragma once
+#include <stddef.h>
+#include <stdarg.h>
+
+void debug_putch(char c);
+void debug_putsn(char *s, size_t n);
+void debug_puts(char *s);
+void debug_vprintf(char *fmt, va_list args);
+void debug_printf(char *fmt, ...);