add attiny2313 hello world

attiny2313/Makefile

@@ -0,0 +1,9 @@
+#/bin/bash
+
+#avr-gcc    -std=c99 -Os -Wall -mmcu=attiny2313 -S -o hello.s hello.c
+#avr-gcc    -Os -Wall -mmcu=attiny2313 -c -o hello.o hello.s
+#avr-gcc    -Os -Wall -mmcu=attiny2313 -o hello.out hello.o
+#avr-strip  hello.out
+
+avr-gcc    -Os -std=c99 -Wall -mmcu=attiny2313 -o hello.out hello.c
+avr-strip  hello.out

attiny2313/hello.c

@@ -0,0 +1,16 @@
+#define F_CPU 1000000UL
+
+#include <avr/io.h>
+#include <util/delay.h>
+
+int main() {
+  uint8_t x = 0b00000001;
+  DDRB = 0b00000001;
+  PORTB = 0b00000000;
+  while (1) {
+    x = (!DDRB && (x)) || (DDRB && (!x));
+    PORTB = x;
+    _delay_ms(1000);
+  }
+  return(0);
+}