feat(printf): added PRINTF_OVERRIDE_LIBC support

Fixes #16

3 files changed, 46 insertions, 2 deletions

diff --git a/README.md b/README.md
index 95cd069..bc2c62d 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,8 @@ int length = sprintf(NULL, "Hello, world"); // length is set to 12
 

 | Name | Default value | Description |

 |------|---------------|-------------|

+| PRINTF_INCLUDE_CONFIG_H  | undefined | Define this as compiler switch (e.g. `gcc -DPRINTF_INCLUDE_CONFIG_H`) to include a "printf_config.h" definition file |

+| PRINTF_OVERRIDE_LIBC     | undefined | Define this to override the LIBC function declarations by using `printf_()` instead of `printf()` directly |

 | PRINTF_NTOA_BUFFER_SIZE  | 32        | ntoa (integer) conversion buffer size. This must be big enough to hold one converted numeric number _including_ leading zeros, normally 32 is a sufficient value. Created on the stack |

 | PRINTF_FTOA_BUFFER_SIZE  | 32        | ftoa (float) conversion buffer size. This must be big enough to hold one converted float number _including_ leading zeros, normally 32 is a sufficient value. Created on the stack |

 | PRINTF_SUPPORT_FLOAT     | defined   | Define this to enable floating point (%f) support |

diff --git a/printf.c b/printf.c
index ddea9e3..b5a38fc 100644
--- a/printf.c
+++ b/printf.c
@@ -699,8 +699,11 @@ static int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const
 

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

 

-

+#ifndef PRINTF_OVERRIDE_LIBC

 int printf(const char* format, ...)

+#else

+int printf_(const char* format, ...)

+#endif

 {

   va_list va;

   va_start(va, format);

@@ -711,7 +714,11 @@ int printf(const char* format, ...)
 }

 

 

+#ifndef PRINTF_OVERRIDE_LIBC

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

+#else

+int sprintf_(char* buffer, const char* format, ...)

+#endif

 {

   va_list va;

   va_start(va, format);

@@ -721,7 +728,11 @@ int sprintf(char* buffer, const char* format, ...)
 }

 

 

+#ifndef PRINTF_OVERRIDE_LIBC

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

+#else

+int snprintf_(char* buffer, size_t count, const char* format, ...)

+#endif

 {

   va_list va;

   va_start(va, format);

@@ -731,13 +742,21 @@ int snprintf(char* buffer, size_t count, const char* format, ...)
 }

 

 

+#ifndef PRINTF_OVERRIDE_LIBC

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

+#else

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

+#endif

 {

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

 }

 

 

+#ifndef PRINTF_OVERRIDE_LIBC

 int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...)

+#else

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

+#endif

 {

   va_list va;

   va_start(va, format);

diff --git a/printf.h b/printf.h
index b82e70f..69245cb 100644
--- a/printf.h
+++ b/printf.h
@@ -25,7 +25,7 @@
 // \brief Tiny printf, sprintf and snprintf implementation, optimized for speed on

 //        embedded systems with a very limited resources.

 //        Use this instead of bloated standard/newlib printf.

-//        These routines are thread safe and reentrant!

+//        These routines are thread safe and reentrant.

 //

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

 

@@ -56,6 +56,12 @@ extern "C" {
 void _putchar(char character);

 

 

+// if PRINTF_OVERRIDE_LIBC is is defined, the regular printf() API is overridden by macro defines

+// and internal underscore-appended functions like printf_() are used to avoid conflicts with

+// LIBC defined printf() functions.

+// default: undefined

+#ifndef PRINTF_OVERRIDE_LIBC

+

 /**

  * Tiny printf implementation

  * You have to implement _putchar if you use printf()

@@ -97,6 +103,23 @@ int vsnprintf(char* buffer, size_t count, const char* format, va_list va);
  */

 int fctprintf(void (*out)(char character, void* arg), void* arg, const char* format, ...);

 

+#else   // PRINTF_OVERRIDE_LIBC

+

+// override the LIBC defined function names

+#define printf    printf_

+#define sprintf   sprintf_

+#define snprintf  snprintf_

+#define vsnprintf vsnprintf_

+#define fctprintf fctprintf_

+

+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);

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

+

+#endif  // PRINTF_OVERRIDE_LIBC

+

 

 #ifdef __cplusplus

 }