2 files changed, 42 insertions, 9 deletions

diff --git a/README.md b/README.md
index 0988e6e..dbc90c0 100644
--- a/README.md
+++ b/README.md
@@ -76,4 +76,30 @@ make run ROM_SRC=roms/audio.rom CONFIG="-DAUDIO_HIFI"
 make run ROM_SRC=roms/audio.rom CONFIG="-DAUDIO_LOFI"
 ```
 
+### Text layer
+
+When writing text to the screen (for example using the console device) the text
+will be drawn by default on the foreground layer. This can be controlled by
+setting the `TEXT_MODE` option to 0 for foreground mode or 1 for background
+mode.
+
+```
+make run CONFIG="-DTEXT_MODE=1"
+```
+
+### Performance metrics
+
+To enable profiling, the `PROF_ENABLE` macro can be used. This will display the
+cycle count for input handling (INPUT), loop uxn evaluation (EVAL), screen
+buffer flip (FLIP) and audio mixing (MIX). If `PROF_ENABLE` is set to 0, the
+current frame numbers will be displayed, if set to 1, the maximum cycle count
+for each section will be used instead. Enabling profiling can have a small
+performance impact, so these numbers may not be 100% accurate, but should give
+a good indication. Using `PROF_SHOW_X` and `PROF_SHOW_Y` we can control at which
+tile the cycle count text will be located.
+
+```
+make run CONFIG="-DPROF_ENABLE=0 -DPROF_SHOW_Y=8 -DPROF_SHOW_X=8"
+```
+
 [noodle]: https://wiki.xxiivv.com/site/noodle.html
diff --git a/src/main.c b/src/main.c
index 9a22000..4b2b2d6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -25,8 +25,10 @@ WITH REGARD TO THIS SOFTWARE.
 // Config parameters.
 //
 
-#ifndef TEXT_LAYER
+#if !defined(TEXT_MODE) || TEXT_MODE == 0
 #define TEXT_LAYER ppu.fg
+#else
+#define TEXT_LAYER ppu.bg
 #endif
 
 #ifndef CONTROL_METHODS
@@ -39,15 +41,21 @@ WITH REGARD TO THIS SOFTWARE.
 #elif PROF_ENABLE == 1
 #define PROF(F,VAR) (profile_start(),(F),(VAR) = MAX(profile_stop(), (VAR)))
 #endif
-#define PROF_SHOW(X,Y) \
+#ifndef PROF_SHOW_X
+#define PROF_SHOW_X 0
+#endif
+#ifndef PROF_SHOW_Y
+#define PROF_SHOW_Y 0
+#endif
+#define PROF_SHOW() \
     do { \
-        txt_position((X), (Y));\
+        txt_position((PROF_SHOW_X), (PROF_SHOW_Y));\
         txt_printf("INPUT: %lu    ", input_cycles);\
-        txt_position((X), (Y)+1);\
+        txt_position((PROF_SHOW_X), (PROF_SHOW_Y)+1);\
         txt_printf("EVAL:  %lu    ", eval_cycles);\
-        txt_position((X), (Y)+2);\
+        txt_position((PROF_SHOW_X), (PROF_SHOW_Y)+2);\
         txt_printf("FLIP:  %lu    ", flip_cycles);\
-        txt_position((X), (Y)+3);\
+        txt_position((PROF_SHOW_X), (PROF_SHOW_Y)+3);\
         txt_printf("MIX:   %lu    ", mix_cycles);\
     } while (0)
 #define PROF_INIT() \
@@ -57,7 +65,7 @@ WITH REGARD TO THIS SOFTWARE.
     u32 mix_cycles = 0;
 #else
 #define PROF(F,VAR) (F)
-#define PROF_SHOW(X,Y)
+#define PROF_SHOW()
 #define PROF_INIT()
 #endif
 
@@ -405,7 +413,6 @@ int main(void) {
     // Register interrupts.
     irq_init();
     irs_set(IRQ_VBLANK, sound_vsync);
-    // irs_set(IRQ_TIMER_1, irs_stop_sample);
 
     // Initialize VM.
     dma_fill(&u, 0, sizeof(u), 3);
@@ -427,7 +434,7 @@ int main(void) {
         PROF(handle_input(&u), input_cycles);
         PROF(evaluxn(&u, mempeek16(devscreen->dat, 0)), eval_cycles);
         PROF(sound_mix(), mix_cycles);
-        PROF_SHOW(9, 8);
+        PROF_SHOW();
         PROF(flipbuf(&ppu), flip_cycles);
     }