Modify implementation to work with new library

- Add a new definition that is necessary for providing the expected functions
- Rename _putchar to putchar_()

Author: phillipjohnston

README.md

@@ -1,6 +1,6 @@
 # Arduino Printf
 
-This library adds support for the `printf()` function to Arduino projects. This code leverages the wonderful [mpaland/printf](https://github.com/mpaland/printf) library, which is designed for use in embedded systems. For more information about what is available, please refer to the [parent library documentation](https://github.com/mpaland/printf/blob/master/README.md).
+This library adds support for the `printf()` function to Arduino projects. This code leverages the wonderful [eyalroz/printf](https://github.com/mpaland/printf) library, which is designed for use in embedded systems. For more information about what is available, please refer to the [parent library documentation](https://github.com/mpaland/printf/blob/master/README.md).
 
 ## What This Library Provides
 
@@ -96,5 +96,5 @@ Multiple examples are provided with this library in the [examples/](examples/) f
     - Any class derived from the `Print` base class can be used with the **Arduino Printf** library
     - This example initializes `printf` with `Serial1` instead of `Serial`
 * [Override Putchar](examples/override_putchar/override_putchar.ino)
-    - This example overrides `_putchar()` and adds a space in between every letter
-    - You can implement any kind of logic within `_putchar()` that you like, such as outputting information to multiple ports
+    - This example overrides `putchar_()` and adds a space in between every letter
+    - You can implement any kind of logic within `putchar_()` that you like, such as outputting information to multiple ports

advanced_usage.md

@@ -1,6 +1,6 @@
 ## Advanced Usage
 
-You can include `printf.h` directly and supply your own implementation of `_putchar()`. This approach is useful if you want to use the library in a test suite (skipping Arduino SDK headers).
+You can include `printf.h` directly and supply your own implementation of `putchar_()`. This approach is useful if you want to use the library in a test suite (skipping Arduino SDK headers).
 
 ### Changing Default Output Target
 
@@ -13,4 +13,4 @@ Serial1.begin(115200);
 
 ### More Complicated Output Scenarios
 
-More complicated logic is possible, such as sending `printf()` output to multiple locations. The `mpaland/printf` library requires that the end-user defines a `_putchar()` function, which is used by all other library functions. There is an example script that explains this.
+More complicated logic is possible, such as sending `printf()` output to multiple locations. The `mpaland/printf` library requires that the end-user defines a `putchar_()` function, which is used by all other library functions. There is an example script that explains this.

examples/override_putchar/override_putchar.ino

@@ -1,7 +1,7 @@
 /**
 * This sketch demonstrates the ability to override the ArduinoPrintf library's
-* default implementation of _putchar() with a custom user implementation.
-* You can do anything you want in your _putchar() function: output to multiple ports,
+* default implementation of putchar_() with a custom user implementation.
+* You can do anything you want in your putchar_() function: output to multiple ports,
 * filter data, add extra characters, etc.
 */
 
@@ -12,7 +12,7 @@ void setup() {
   Serial.begin(115200);
 }
 
-void _putchar(char character)
+void putchar_(char character)
 {
   Serial.print(character);
   Serial.print(' ');

extras/printf/printf.c

@@ -49,7 +49,7 @@
 #include "printf_config.h"
 #endif
 
-#include <printf/printf.h>
+#include "printf.h"
 
 #if PRINTF_ALIAS_STANDARD_FUNCTION_NAMES
 # define printf_    printf

src/LibPrintf.cpp

@@ -21,7 +21,7 @@ void printf_init(Print& PrintClass)
 
 // If you use the default printf() implementation, this function will route the output
 // to the Serial class
-extern "C" __attribute__((weak)) void _putchar(char character)
+extern "C" __attribute__((weak)) void putchar_(char character)
 {
 	print_instance->print(character);
 }

src/LibPrintf.h

@@ -2,8 +2,12 @@
 #define ARDUINO_PRINTF_H_
 
 #include "Print.h"
+#define PRINTF_ALIAS_STANDARD_FUNCTION_NAMES 1
 #include "../extras/printf/printf.h"
 
+// Adds a compatibility definition for those who were using the old library
+#define _putchar(c) putchar_(c)
+
 // In Setup(), you must initialize printf with a Print class if you don't want
 // to use the default Serial object. If you want the default behavior, calling this
 // function is not necessary.