exynos4: hal: include: Exif.h: always keep two decimal places in macros

The APEX macros always rounded to int, losing too much precision. Ensure
that we always keep at least two decimal digits.

The more precise F-number comes from the value recorded by the camera
closed source driver.

Added a new macro APEX_SHUTTER_TO_EXPOSURE(x) (credit to tryptophane).

Change-Id: Ief43c15c6517d8dc48d4d4bc9e93df9eb01e6b91

exynos4/hal/include/Exif.h

@@ -20,11 +20,12 @@
 #include <math.h>
 
 #define EXIF_LOG2(x)                    (log((double)(x)) / log(2.0))
-#define APEX_FNUM_TO_APERTURE(x)        ((int)(EXIF_LOG2((double)(x)) * 2 + 0.5))
+#define APEX_FNUM_TO_APERTURE(x)        ((int)(EXIF_LOG2((double)(x)) * 200.0 + 0.5))
 #define APEX_EXPOSURE_TO_SHUTTER(x)     ((x) >= 1 ?                                 \
-                                        (int)(-(EXIF_LOG2((double)(x)) + 0.5)) :    \
-                                        (int)(-(EXIF_LOG2((double)(x)) - 0.5)))
-#define APEX_ISO_TO_FILMSENSITIVITY(x)  ((int)(EXIF_LOG2((x) / 3.125) + 0.5))
+                                        (int)(-(EXIF_LOG2((double)(x)) * 100.0 + 0.5)) :    \
+                                        (int)(-(EXIF_LOG2((double)(x)) * 100.0 - 0.5)))
+#define APEX_ISO_TO_FILMSENSITIVITY(x)  ((int)(EXIF_LOG2((x) / 3.125) * 100.0 + 0.5))
+#define APEX_SHUTTER_TO_EXPOSURE(x)     ((int)((pow(2.0, (double)(x) / 100.0)) + 0.5))
 
 #define NUM_SIZE                    2
 #define IFD_SIZE                    12
@@ -147,15 +148,15 @@ typedef enum {
 #define EXIF_DEF_USERCOMMENTS   "User comments"
 
 #define EXIF_DEF_YCBCR_POSITIONING  1   /* centered */
-#define EXIF_DEF_FNUMBER_NUM        26  /* 2.6 */
-#define EXIF_DEF_FNUMBER_DEN        10
+#define EXIF_DEF_FNUMBER_NUM        265  /* 2.65 */
+#define EXIF_DEF_FNUMBER_DEN        100
 #define EXIF_DEF_EXPOSURE_PROGRAM   3   /* aperture priority */
 #define EXIF_DEF_FOCAL_LEN_NUM      278 /* 2.78mm */
 #define EXIF_DEF_FOCAL_LEN_DEN      100
 #define EXIF_DEF_FLASH              0   /* O: off, 1: on*/
 #define EXIF_DEF_COLOR_SPACE        1
 #define EXIF_DEF_EXPOSURE_MODE      EXIF_EXPOSURE_AUTO
-#define EXIF_DEF_APEX_DEN           10
+#define EXIF_DEF_APEX_DEN           100
 
 #define EXIF_DEF_COMPRESSION        6
 #define EXIF_DEF_RESOLUTION_NUM     72