define debug_printf variant as well

src/keyboard/controller.c

@@ -1226,7 +1226,7 @@ int8_t usb_extra_consumer_send() {
 
 #ifdef KBD_DEBUG
 // transmit a character.  0 returned on success, -1 on error
-int8_t usb_debug_putchar(uint8_t c) {
+int8_t usb_debug_putchar(char c) {
   static uint8_t previous_timeout = 0;
   uint8_t timeout, intr_state;
 
@@ -1297,13 +1297,25 @@ void usb_debug_flush_output(void) {
   SREG = intr_state;
 }
 
-void debug_print_ptr(const char *s) {
+void usb_debug_print(const char *s) {
   char c;
+  while ((c = pgm_read_byte(c))) {
+    usb_debug_putchar(c);
+  }
+  usb_debug_flush_output();
+}
 
-  while (1) {
-    c = pgm_read_byte(s++);
-    if (!c) { break; }
-    if (c == '\n') { usb_debug_putchar('\r'); }
+void usb_debug_printf(const char *fmt, ...) {
+  char buf[128];
+
+  va_list args;
+  va_start(args, fmt);
+  vsnprintf(buf, sizeof(buf), fmt, args);
+  va_end(args);
+
+  for (int i = 0; i < sizeof(buf); i++) {
+    char c = buf[i];
+    if (!c) break;
     usb_debug_putchar(c);
   }
   usb_debug_flush_output();
@@ -1311,7 +1323,9 @@ void debug_print_ptr(const char *s) {
 #endif
 
 #ifdef KBD_DEBUG
-#define debug_print(s) debug_print_ptr(PSTR(s))
+#define debug_print(s)       	usb_debug_print(PSTR(s))
+#define debug_printf(args...)	usb_debug_printf(args)
 #else
 #define debug_print(s)
+#define debug_printf(...)
 #endif

src/keyboard/controller.h

@@ -10,8 +10,10 @@
 
 #define USB_DEBUG_HID
 
+#include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/pgmspace.h>
@@ -205,9 +207,8 @@ extern uint16_t consumer_key;
 
 extern volatile uint8_t debug_flush_timer;
 
-// this macro allows you to write print("some text") and
-// the string is automatically placed into flash memory :)
-void debug_print_ptr(const char *s);
+void usb_debug_print(const char *s);
+void usb_debug_printf(const char *fmt, ...);
 
-int8_t usb_debug_putchar(uint8_t c);	// transmit a character
+int8_t usb_debug_putchar(char c);	// transmit a character
 void usb_debug_flush_output(void);  	// immediately transmit any buffered output

src/main.c

@@ -197,7 +197,7 @@ void layer_disable(uint8_t layer) {
   layers_active[layer] = false;
 
   if (layers_sticky[layer] != StickyNone) {
-    debug_print("sticky up!\n");
+    debug_printf("sticky %d up!\n", layer);
   }
   layers_sticky[layer] = StickyNone;
 
@@ -486,7 +486,7 @@ void kbfun_layer_sticky() {
         layer_disable_top();
       }
       layer_enable(layer, StickyOnceDown);
-      debug_print("sticky down!\n");
+      debug_printf("sticky %d down!\n", layer);
 
       // this should be the only place we care about this flag being cleared
       non_trans_key_pressed = false;
@@ -501,7 +501,7 @@ void kbfun_layer_sticky() {
         //  was pressed, push the layer again, but in the
         //  StickyOnceUp state
         layer_enable(layer, StickyOnceUp);
-        debug_print("sticky still down!\n");
+        debug_printf("sticky %d still down!\n", layer);
       }
     }
   }