feat(printf): added vprintf() support

Closes #43

printf.c

@@ -884,6 +884,13 @@ int snprintf_(char* buffer, size_t count, const char* format, ...)
 }
 
 
+int vprintf_(const char* format, va_list va)
+{
+  char buffer[1];
+  return _vsnprintf(_out_char, buffer, (size_t)-1, format, va);
+}
+
+
 int vsnprintf_(char* buffer, size_t count, const char* format, va_list va)
 {
   return _vsnprintf(_out_buffer, buffer, count, format, va);

printf.h

@@ -1,6 +1,6 @@
 ///////////////////////////////////////////////////////////////////////////////
 // \author (c) Marco Paland (info@paland.com)
-//             2014-2018, PALANDesign Hannover, Germany
+//             2014-2019, PALANDesign Hannover, Germany
 //
 // \license The MIT License (MIT)
 //
@@ -77,6 +77,7 @@ int sprintf_(char* buffer, const char* format, ...);
  * \param buffer A pointer to the buffer where to store the formatted string
  * \param count The maximum number of characters to store in the buffer, including a terminating null character
  * \param format A string that specifies the format of the output
+ * \param va A value identifying a variable arguments list
  * \return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
  *         If the formatted string is truncated the buffer size (count) is returned
  */
@@ -86,6 +87,16 @@ int  snprintf_(char* buffer, size_t count, const char* format, ...);
 int vsnprintf_(char* buffer, size_t count, const char* format, va_list va);
 
 
+/**
+ * Tiny vprintf implementation
+ * \param format A string that specifies the format of the output
+ * \param va A value identifying a variable arguments list
+ * \return The number of characters that are WRITTEN into the buffer, not counting the terminating null character
+ */
+#define vprintf vprintf_
+int vprintf_(const char* format, va_list va);
+
+
 /**
  * printf with output function
  * You may use this as dynamic alternative to printf() with its fixed _putchar() output

test/test_suite.cpp

@@ -85,6 +85,13 @@ TEST_CASE("snprintf", "[]" ) {
   REQUIRE(!strcmp(buffer, "-1"));
 }
 
+static void vprintf_builder_1(char* buffer, ...)
+{
+  va_list args;
+  va_start(args, buffer);
+  test::vprintf("%d", args);
+  va_end(args);
+}
 
 static void vsnprintf_builder_1(char* buffer, ...)
 {
@@ -103,6 +110,17 @@ static void vsnprintf_builder_3(char* buffer, ...)
 }
 
 
+TEST_CASE("vprintf", "[]" ) {
+  char buffer[100];
+  printf_idx = 0U;
+  memset(printf_buffer, 0xCC, 100U);
+  vprintf_builder_1(buffer, 2345);
+  REQUIRE(printf_buffer[4] == (char)0xCC);
+  printf_buffer[4] = 0;
+  REQUIRE(!strcmp(printf_buffer, "2345"));
+}
+
+
 TEST_CASE("vsnprintf", "[]" ) {
   char buffer[100];