Provide self-documenting API for disabling trailing-0xff removal

src/arduino.c

@@ -131,6 +131,5 @@ void arduino_initpgm(PROGRAMMER * pgm)
   pgm->open = arduino_open;
   pgm->close = arduino_close;
 
-  /* disable trailing-0xff removal when reading input files and avr flash */
+  disable_trailing_ff_removal(); /* so that arduino bootloader can ignore chip erase */
-  avr_mem_hiaddr(NULL);
 }

src/libavrdude.h

@@ -787,6 +787,7 @@ int avr_get_cycle_count(PROGRAMMER * pgm, AVRPART * p, int * cycles);
 
 int avr_put_cycle_count(PROGRAMMER * pgm, AVRPART * p, int cycles);
 
+#define disable_trailing_ff_removal() avr_mem_hiaddr(NULL)
 int avr_mem_hiaddr(AVRMEM * mem);
 
 int avr_chip_erase(PROGRAMMER * pgm, AVRPART * p);

src/main.c

@@ -528,7 +528,7 @@ int main(int argc, char * argv [])
 
       case 'D': /* disable auto erase */
         uflags &= ~UF_AUTO_ERASE;
-        avr_mem_hiaddr(NULL); /* disable trailing 0xff optimisation */
+        disable_trailing_ff_removal();
         break;
 
       case 'e': /* perform a chip erase */