From 042f61bdb3d3d8d30fd1a1d4bb37e498b2fc67a1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Wed, 6 Dec 2017 19:43:59 +0100
Subject: [PATCH] Add padding to field width (right adjust)

---
 src/kernel/boot/debug.c  | 16 ++++++++++++++++
 src/kernel/boot/debug.tt | 15 +++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/kernel/boot/debug.c b/src/kernel/boot/debug.c
index 8369926..ad16ddc 100644
--- a/src/kernel/boot/debug.c
+++ b/src/kernel/boot/debug.c
@@ -3,6 +3,7 @@
 #include <stdint.h>
 #include <serial.h>
 #include <vga.h>
+#include <memory.h>
 
 // TODO: Temporary declarations
 void vga_write(char c);
@@ -69,6 +70,18 @@ void debug_vprintf(char *fmt, va_list args)
   }
 
   fmt++;
+  size_t padwidth = 0;
+  char padchar = ' ';
+  if(*fmt == '0')
+  {
+    padchar = '0';
+    fmt++;
+  }
+  while(*fmt >= '0' && *fmt <= '9')
+  {
+    padwidth *= 10;
+    padwidth += (int)(*fmt++ - '0');
+  }
   uint64_t base = 0;
   switch(*fmt)
   {
@@ -100,6 +113,9 @@ void debug_vprintf(char *fmt, va_list args)
     uintmax_t number = va_arg(args, uintmax_t);
     char buf[128];
     num2str(buf, number, base);
+    if(padwidth > strlen(buf))
+      for(size_t i = 0; i < (padwidth - strlen(buf)); i++)
+        debug_putch(padchar);
     debug_puts(buf);
   }
 
diff --git a/src/kernel/boot/debug.tt b/src/kernel/boot/debug.tt
index 47bec7f..a10fc1d 100644
--- a/src/kernel/boot/debug.tt
+++ b/src/kernel/boot/debug.tt
@@ -115,3 +115,18 @@ TEST(printf_keeps_going_for_unknown_format_specifier)
   debug_printf("%y");
   ASSERT_EQ_STR(vga_recv, "%y", BUFFER_SIZE);
 }
+TEST(printf_pads_value)
+{
+  debug_printf("%5d", 123);
+  ASSERT_EQ_STR(vga_recv, "  123", BUFFER_SIZE);
+}
+TEST(printf_pads_more_than_9)
+{
+  debug_printf("%16d", 1);
+  ASSERT_EQ_STR(vga_recv, "               1", BUFFER_SIZE);
+}
+TEST(printf_zero_pads)
+{
+  debug_printf("%05d", 123);
+  ASSERT_EQ_STR(vga_recv, "00123", BUFFER_SIZE);
+}