feat(printf): added new oprintf() function

Write formatted output directly to given output function

4 files changed, 41 insertions, 4 deletions

diff --git a/README.md b/README.md
index 2c16afd..6583269 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,9 @@ int printf(const char* format, ...);
 int sprintf(char* buffer, const char* format, ...);

 int snprintf(char* buffer, size_t count, const char* format, ...);

 int vsnprintf(char* buffer, size_t count, const char* format, va_list va);

+

+// write to output function (instead of buffer)

+int oprintf(void (*out)(char character), const char* format, ...);

 ```

 

 

diff --git a/printf.c b/printf.c
index f1a51e2..0b94d4a 100644
--- a/printf.c
+++ b/printf.c
@@ -101,6 +101,14 @@ static inline void _out_char(char character, char* buffer, size_t idx, size_t ma
 }

 

 

+// internal output function wrapper

+static inline void _out_fct(char character, char* buffer, size_t idx, size_t maxlen)

+{

+  (void)idx; (void)maxlen;

+  ((void (*)(char character))buffer)(character);  // buffer is the output fct pointer

+}

+

+

 // internal strlen

 // \return The length of the string (excluding the terminating 0)

 static inline unsigned int _strlen(const char* str)

@@ -674,7 +682,17 @@ int snprintf(char* buffer, size_t count, const char* format, ...)
 }

 

 

-inline int vsnprintf(char* buffer, size_t count, const char* format, va_list va)

+int vsnprintf(char* buffer, size_t count, const char* format, va_list va)

 {

   return _vsnprintf(_out_buffer, buffer, count, format, va);

 }

+

+

+int oprintf(void (*out)(char character), const char* format, ...)

+{

+  va_list va;

+  va_start(va, format);

+  const int ret = _vsnprintf(_out_fct, (char*)out, (size_t)-1, format, va);

+  va_end(va);

+  return ret;

+}

diff --git a/printf.h b/printf.h
index 37dbd54..c0ba2ae 100644
--- a/printf.h
+++ b/printf.h
@@ -60,7 +60,7 @@ int printf(const char* format, ...);
 

 /**

  * Tiny sprintf implementation

- * Due to security reasons (buffer overflow) YOU SHOULD CONSIDER USING SNPRINTF INSTEAD!

+ * Due to security reasons (buffer overflow) YOU SHOULD CONSIDER USING (V)SNPRINTF INSTEAD!

  * \param buffer A pointer to the buffer where to store the formatted string. MUST be big enough to store the output!

  * \param format A string that specifies the format of the output

  * \return The number of characters that are WRITTEN into the buffer, not counting the terminating null character

@@ -80,6 +80,16 @@ int  snprintf(char* buffer, size_t count, const char* format, ...);
 int vsnprintf(char* buffer, size_t count, const char* format, va_list va);

 

 

+/**

+ * printf with output function

+ * You may use this as dynamic alternative to printf() with its fixed _putchar() output

+ * \param out An output function which takes one character

+ * \param format A string that specifies the format of the output

+ * \return The number of characters that are sent to the output function, not counting the terminating null character

+ */

+int oprintf(void (*out)(char character), const char* format, ...);

+

+

 #ifdef __cplusplus

 }

 #endif

diff --git a/test/test_suite.cpp b/test/test_suite.cpp
index 9a02b1e..c5614b0 100644
--- a/test/test_suite.cpp
+++ b/test/test_suite.cpp
@@ -50,8 +50,6 @@ void test::_putchar(char character)
 

 

 TEST_CASE("printf", "[]" ) {

-  char buffer[100];

-

   printf_idx = 0U;

   memset(printf_buffer, 0xCC, 100U);

   REQUIRE(test::printf("% d", 4232) == 5);

@@ -59,6 +57,14 @@ TEST_CASE("printf", "[]" ) {
 }

 

 

+TEST_CASE("oprintf", "[]" ) {

+  printf_idx = 0U;

+  memset(printf_buffer, 0xCC, 100U);

+  test::oprintf(&test::_putchar, "This is a test of %X", 0x12EFU);

+  REQUIRE(!strcmp(printf_buffer, "This is a test of 12EF"));

+}

+

+

 TEST_CASE("snprintf", "[]" ) {

   char buffer[100];