fixup! WIP - use gamma_correction instead of brightness

core/embed/unix/common.c

@@ -18,6 +18,7 @@
  */
 
 #include <SDL.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/time.h>
@@ -31,7 +32,7 @@
 #include "memzero.h"
 
 extern void main_clean_exit();
-extern int GAMMA_CORRECTION_PERCENTAGE;
+extern float DISPLAY_GAMMA;
 
 void __attribute__((noreturn)) __shutdown(void) {
   printf("SHUTDOWN\n");
@@ -148,14 +149,12 @@ static int SDLCALL emulator_event_filter(void *userdata, SDL_Event *event) {
           display_save("emu");
           return 0;
         case SDLK_LEFT:
-          GAMMA_CORRECTION_PERCENTAGE -= 1;
-          printf("GAMMA_CORRECTION_PERCENTAGE: %d\n",
-                 GAMMA_CORRECTION_PERCENTAGE);
+          DISPLAY_GAMMA = fmaxf(0.0f, DISPLAY_GAMMA - 0.05f);
+          printf("DISPLAY_GAMMA: %0.2f\n", DISPLAY_GAMMA);
           return 0;
         case SDLK_RIGHT:
-          GAMMA_CORRECTION_PERCENTAGE += 1;
-          printf("GAMMA_CORRECTION_PERCENTAGE: %d\n",
-                 GAMMA_CORRECTION_PERCENTAGE);
+          DISPLAY_GAMMA = fminf(8.0f, DISPLAY_GAMMA + 0.05f);
+          printf("DISPLAY_GAMMA: %0.2f\n", DISPLAY_GAMMA);
           return 0;
       }
       break;

core/embed/unix/display-unix.c

@@ -70,7 +70,7 @@ static SDL_Surface *PREV_SAVED;
 
 static int DISPLAY_BACKLIGHT = -1;
 static int DISPLAY_ORIENTATION = -1;
-int GAMMA_CORRECTION_PERCENTAGE = 55;
+float DISPLAY_GAMMA = 0.55f;
 int sdl_display_res_x = DISPLAY_RESX, sdl_display_res_y = DISPLAY_RESY;
 int sdl_touch_offset_x, sdl_touch_offset_y;
 
@@ -98,11 +98,9 @@ uint16_t gamma_correct(uint16_t c) {
   float fg = g / 63.0;
   float fb = b / 31.0;
 
-  float gamma = GAMMA_CORRECTION_PERCENTAGE / 100.0;
-
-  fr = pow(fr, gamma);
-  fg = pow(fg, gamma);
-  fb = pow(fb, gamma);
+  fr = pow(fr, DISPLAY_GAMMA);
+  fg = pow(fg, DISPLAY_GAMMA);
+  fb = pow(fb, DISPLAY_GAMMA);
 
   r = (int)round(fr * 31.0);
   g = (int)round(fg * 63.0);