arduino-nano stdout: add pprint (pgmspace string output)

include/arch/arduino-nano/driver/stdout.h

@@ -6,6 +6,7 @@
 #ifndef STANDARDOUTPUT_H
 #define STANDARDOUTPUT_H
 
+#include <avr/pgmspace.h>
 #include "object/outputstream.h"
 
 class StandardOutput : public OutputStream {
@@ -17,6 +18,7 @@ class StandardOutput : public OutputStream {
 		void setup();
 
 		virtual void put(char c) override;
+		OutputStream & pprint(const char *text);
 };
 
 extern StandardOutput kout;

src/arch/arduino-nano/driver/stdout.cc

@@ -5,7 +5,6 @@
  */
 #include "driver/stdout.h"
 #include <avr/io.h>
-#include <avr/interrupt.h>
 
 #ifndef BAUD
 #define BAUD 9600UL
@@ -28,6 +27,16 @@ void StandardOutput::setup()
 	UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
 }
 
+OutputStream & StandardOutput::pprint(const char *text)
+{
+	PGM_P p = reinterpret_cast<PGM_P>(text);
+	char c;
+	while ((c = pgm_read_byte(p++))) {
+		put(c);
+	}
+	return *this;
+}
+
 void StandardOutput::put(char c)
 {
 	while (!(UCSR0A & _BV(UDRE0)));