feat(printf): add vsnprintf function

fixes #5

2 files changed, 30 insertions, 19 deletions

diff --git a/printf.c b/printf.c
index 21d5620..ed6e745 100644
--- a/printf.c
+++ b/printf.c
@@ -30,19 +30,21 @@
 //

 ///////////////////////////////////////////////////////////////////////////////

 

-#include <stdarg.h>

 #include <stdbool.h>

+#include <stddef.h>

 #include <stdint.h>

 #include "printf.h"

 

 

-// buffer size used for printf (created on stack)

+// buffer size used omly for printf (created on stack)

 #define PRINTF_BUFFER_SIZE        128U

 

-// ntoa conversion buffer size, this must be big enough to hold one converted numeric number (created on stack)

+// ntoa conversion buffer size, this must be big enough to hold

+// one converted numeric number including padded zeros (created on stack)

 #define PRINTF_NTOA_BUFFER_SIZE    32U

 

-// ftoa conversion buffer size, this must be big enough to hold one converted float number (created on stack)

+// ftoa conversion buffer size, this must be big enough to hold

+// one converted float number including padded zeros (created on stack)

 #define PRINTF_FTOA_BUFFER_SIZE    32U

 

 // define this to support floating point (%f)

@@ -349,14 +351,14 @@ static size_t _ftoa(double value, char* buffer, size_t maxlen, unsigned int prec
 

 

 // internal vsnprintf

-static size_t _vsnprintf(char* buffer, size_t buffer_len, const char* format, va_list va)

+static int _vsnprintf(char* buffer, size_t buffer_len, const char* format, va_list va)

 {

   unsigned int flags, width, precision, n;

   size_t idx = 0U;

 

   // check if buffer is valid

   if (!buffer) {

-    return 0U;

+    return -1;

   }

 

   while ((idx < buffer_len) && *format)

@@ -587,7 +589,7 @@ static size_t _vsnprintf(char* buffer, size_t buffer_len, const char* format, va
   }

 

   // return written chars without terminating \0

-  return idx;

+  return (int)idx;

 }

 

 

@@ -598,12 +600,12 @@ int printf(const char* format, ...)
   va_list va;

   va_start(va, format);

   char buffer[PRINTF_BUFFER_SIZE];

-  size_t ret = _vsnprintf(buffer, PRINTF_BUFFER_SIZE, format, va);

+  int ret = _vsnprintf(buffer, PRINTF_BUFFER_SIZE, format, va);

   va_end(va);

   for (size_t i = 0U; i < ret; ++i) {

     _putchar(buffer[i]);

   }

-  return (int)ret;

+  return ret;

 }

 

 

@@ -611,9 +613,9 @@ int sprintf(char* buffer, const char* format, ...)
 {

   va_list va;

   va_start(va, format);

-  size_t ret = _vsnprintf(buffer, (size_t)-1, format, va);

+  int ret = _vsnprintf(buffer, (size_t)-1, format, va);

   va_end(va);

-  return (int)ret;

+  return ret;

 }

 

 

@@ -621,7 +623,14 @@ int snprintf(char* buffer, size_t count, const char* format, ...)
 {

   va_list va;

   va_start(va, format);

-  size_t ret = _vsnprintf(buffer, count, format, va);

+  int ret = _vsnprintf(buffer, count, format, va);

   va_end(va);

-  return (int)ret;

+  return ret;

 }

+

+

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

+{

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

+}

+

diff --git a/printf.h b/printf.h
index d90ff45..e39bbb2 100644
--- a/printf.h
+++ b/printf.h
@@ -32,7 +32,7 @@
 #ifndef _PRINTF_H_

 #define _PRINTF_H_

 

-#include <stddef.h>

+#include <stdarg.h>

 

 

 #ifdef __cplusplus

@@ -62,19 +62,21 @@ int printf(const char* format, ...);
  * Due to security reasons (buffer overflow) YOU SHOULD CONSIDER USING 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 array, not counting the terminating null character

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

  */

 int sprintf(char* buffer, const char* format, ...);

 

 

 /**

- * Tiny snprintf implementation

+ * Tiny snprintf/vsnprintf implementation

  * \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 the terminating null character

+ * \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

- * \return The number of characters that are written into the array, not counting the terminating null character

+ * \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

  */

-int snprintf(char* buffer, size_t count, 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);

 

 

 #ifdef __cplusplus