6 files changed, 185 insertions, 4 deletions

diff --git a/docs/feature_rgblight.md b/docs/feature_rgblight.md
index 8b0a45cb6..4572f45b2 100644
--- a/docs/feature_rgblight.md
+++ b/docs/feature_rgblight.md
@@ -114,7 +114,7 @@ The following options can be used to tweak the various animations:
 |`RGBLIGHT_EFFECT_RGB_TEST`          |*Not defined*|If defined, enable RGB test animation mode.                                          |
 |`RGBLIGHT_EFFECT_ALTERNATING`       |*Not defined*|If defined, enable alternating animation mode.                                       |
 |`RGBLIGHT_ANIMATIONS`               |*Not defined*|If defined, enables all additional animation modes                                   |
-|`RGBLIGHT_EFFECT_BREATHE_CENTER`    |`1.85`       |Used to calculate the curve for the breathing animation. Valid values are 1.0 to 2.7 |
+|`RGBLIGHT_EFFECT_BREATHE_CENTER`    |*Not defined*|If defined, used to calculate the curve for the breathing animation. Valid values are 1.0 to 2.7 |
 |`RGBLIGHT_EFFECT_BREATHE_MAX`       |`255`        |The maximum brightness for the breathing mode. Valid values are 1 to 255             |
 |`RGBLIGHT_EFFECT_SNAKE_LENGTH`      |`4`          |The number of LEDs to light up for the "Snake" animation                             |
 |`RGBLIGHT_EFFECT_KNIGHT_LENGTH`     |`3`          |The number of LEDs to light up for the "Knight" animation                            |
diff --git a/quantum/rgblight.c b/quantum/rgblight.c
index 98755ff08..77772e292 100644
--- a/quantum/rgblight.c
+++ b/quantum/rgblight.c
@@ -879,6 +879,14 @@ void rgblight_task(void) {
 
 // Effects
 #ifdef RGBLIGHT_EFFECT_BREATHING
+
+#ifndef RGBLIGHT_EFFECT_BREATHE_CENTER
+  #ifndef RGBLIGHT_BREATHE_TABLE_SIZE
+    #define RGBLIGHT_BREATHE_TABLE_SIZE 256 // 256 or 128 or 64
+  #endif
+  #include <rgblight_breathe_table.h>
+#endif
+
 __attribute__ ((weak))
 const uint8_t RGBLED_BREATHING_INTERVALS[] PROGMEM = {30, 20, 10, 5};
 
@@ -886,7 +894,11 @@ void rgblight_effect_breathing(animation_status_t *anim) {
   float val;
 
   // http://sean.voisen.org/blog/2011/10/breathing-led-with-arduino/
+#ifdef RGBLIGHT_EFFECT_BREATHE_TABLE
+  val = pgm_read_byte(&rgblight_effect_breathe_table[anim->pos / table_scale]);
+#else
   val = (exp(sin((anim->pos/255.0)*M_PI)) - RGBLIGHT_EFFECT_BREATHE_CENTER/M_E)*(RGBLIGHT_EFFECT_BREATHE_MAX/(M_E-1/M_E));
+#endif
   rgblight_sethsv_noeeprom_old(rgblight_config.hue, rgblight_config.sat, val);
   anim->pos = (anim->pos + 1);
 }
diff --git a/quantum/rgblight.h b/quantum/rgblight.h
index 9ccb3135c..35d7942ca 100644
--- a/quantum/rgblight.h
+++ b/quantum/rgblight.h
@@ -80,9 +80,7 @@ enum RGBLIGHT_EFFECT_MODE {
 
 #define RGBLIGHT_MODES (RGBLIGHT_MODE_last-1)
 
-#ifndef RGBLIGHT_EFFECT_BREATHE_CENTER
-#define RGBLIGHT_EFFECT_BREATHE_CENTER 1.85  // 1-2.7
-#endif
+// sample: #define RGBLIGHT_EFFECT_BREATHE_CENTER   1.85
 
 #ifndef RGBLIGHT_EFFECT_BREATHE_MAX
 #define RGBLIGHT_EFFECT_BREATHE_MAX 255   // 0-255
diff --git a/quantum/rgblight_breathe_table.h b/quantum/rgblight_breathe_table.h
new file mode 100644
index 000000000..7ab8cc947
--- /dev/null
+++ b/quantum/rgblight_breathe_table.h
@@ -0,0 +1,116 @@
+#ifndef RGBLIGHT_EFFECT_BREATHE_TABLE
+#define RGBLIGHT_EFFECT_BREATHE_TABLE
+
+const uint8_t rgblight_effect_breathe_table[] PROGMEM = {
+  /* #define RGBLIGHT_EFFECT_BREATHE_CENTER   1.85 */
+  /* #define RGBLIGHT_EFFECT_BREATHE_MAX      255 */
+
+ #if RGBLIGHT_BREATHE_TABLE_SIZE == 256
+  0x22,  0x23,  0x25,  0x26,  0x28,  0x29,  0x2a,  0x2c,
+  0x2d,  0x2f,  0x30,  0x32,  0x33,  0x35,  0x36,  0x38,
+  0x3a,  0x3b,  0x3d,  0x3e,  0x40,  0x42,  0x43,  0x45,
+  0x47,  0x49,  0x4a,  0x4c,  0x4e,  0x50,  0x51,  0x53,
+  0x55,  0x57,  0x59,  0x5a,  0x5c,  0x5e,  0x60,  0x62,
+  0x64,  0x66,  0x68,  0x69,  0x6b,  0x6d,  0x6f,  0x71,
+  0x73,  0x75,  0x77,  0x79,  0x7b,  0x7d,  0x7f,  0x81,
+  0x83,  0x85,  0x87,  0x89,  0x8a,  0x8c,  0x8e,  0x90,
+  0x92,  0x94,  0x96,  0x98,  0x9a,  0x9c,  0x9e,  0x9f,
+  0xa1,  0xa3,  0xa5,  0xa7,  0xa8,  0xaa,  0xac,  0xae,
+  0xaf,  0xb1,  0xb3,  0xb4,  0xb6,  0xb8,  0xb9,  0xbb,
+  0xbc,  0xbe,  0xbf,  0xc1,  0xc2,  0xc3,  0xc5,  0xc6,
+  0xc7,  0xc9,  0xca,  0xcb,  0xcc,  0xcd,  0xce,  0xd0,
+  0xd1,  0xd2,  0xd2,  0xd3,  0xd4,  0xd5,  0xd6,  0xd7,
+  0xd7,  0xd8,  0xd9,  0xd9,  0xda,  0xda,  0xdb,  0xdb,
+  0xdb,  0xdc,  0xdc,  0xdc,  0xdc,  0xdc,  0xdd,  0xdd,
+  0xdd,  0xdd,  0xdc,  0xdc,  0xdc,  0xdc,  0xdc,  0xdb,
+  0xdb,  0xdb,  0xda,  0xda,  0xd9,  0xd9,  0xd8,  0xd7,
+  0xd7,  0xd6,  0xd5,  0xd4,  0xd3,  0xd2,  0xd2,  0xd1,
+  0xd0,  0xce,  0xcd,  0xcc,  0xcb,  0xca,  0xc9,  0xc7,
+  0xc6,  0xc5,  0xc3,  0xc2,  0xc1,  0xbf,  0xbe,  0xbc,
+  0xbb,  0xb9,  0xb8,  0xb6,  0xb4,  0xb3,  0xb1,  0xaf,
+  0xae,  0xac,  0xaa,  0xa8,  0xa7,  0xa5,  0xa3,  0xa1,
+  0x9f,  0x9e,  0x9c,  0x9a,  0x98,  0x96,  0x94,  0x92,
+  0x90,  0x8e,  0x8c,  0x8a,  0x89,  0x87,  0x85,  0x83,
+  0x81,  0x7f,  0x7d,  0x7b,  0x79,  0x77,  0x75,  0x73,
+  0x71,  0x6f,  0x6d,  0x6b,  0x69,  0x68,  0x66,  0x64,
+  0x62,  0x60,  0x5e,  0x5c,  0x5a,  0x59,  0x57,  0x55,
+  0x53,  0x51,  0x50,  0x4e,  0x4c,  0x4a,  0x49,  0x47,
+  0x45,  0x43,  0x42,  0x40,  0x3e,  0x3d,  0x3b,  0x3a,
+  0x38,  0x36,  0x35,  0x33,  0x32,  0x30,  0x2f,  0x2d,
+  0x2c,  0x2a,  0x29,  0x28,  0x26,  0x25,  0x23,  0x22
+ #endif /* 256 bytes table */
+
+ #if RGBLIGHT_BREATHE_TABLE_SIZE == 128
+  0x22,  0x25,  0x28,  0x2a,
+  0x2d,  0x30,  0x33,  0x36,
+  0x3a,  0x3d,  0x40,  0x43,
+  0x47,  0x4a,  0x4e,  0x51,
+  0x55,  0x59,  0x5c,  0x60,
+  0x64,  0x68,  0x6b,  0x6f,
+  0x73,  0x77,  0x7b,  0x7f,
+  0x83,  0x87,  0x8a,  0x8e,
+  0x92,  0x96,  0x9a,  0x9e,
+  0xa1,  0xa5,  0xa8,  0xac,
+  0xaf,  0xb3,  0xb6,  0xb9,
+  0xbc,  0xbf,  0xc2,  0xc5,
+  0xc7,  0xca,  0xcc,  0xce,
+  0xd1,  0xd2,  0xd4,  0xd6,
+  0xd7,  0xd9,  0xda,  0xdb,
+  0xdb,  0xdc,  0xdc,  0xdd,
+  0xdd,  0xdc,  0xdc,  0xdc,
+  0xdb,  0xda,  0xd9,  0xd8,
+  0xd7,  0xd5,  0xd3,  0xd2,
+  0xd0,  0xcd,  0xcb,  0xc9,
+  0xc6,  0xc3,  0xc1,  0xbe,
+  0xbb,  0xb8,  0xb4,  0xb1,
+  0xae,  0xaa,  0xa7,  0xa3,
+  0x9f,  0x9c,  0x98,  0x94,
+  0x90,  0x8c,  0x89,  0x85,
+  0x81,  0x7d,  0x79,  0x75,
+  0x71,  0x6d,  0x69,  0x66,
+  0x62,  0x5e,  0x5a,  0x57,
+  0x53,  0x50,  0x4c,  0x49,
+  0x45,  0x42,  0x3e,  0x3b,
+  0x38,  0x35,  0x32,  0x2f,
+  0x2c,  0x29,  0x26,  0x23
+ #endif /* 128 bytes table */
+
+ #if RGBLIGHT_BREATHE_TABLE_SIZE == 64
+  0x22,  0x28,
+  0x2d,  0x33,
+  0x3a,  0x40,
+  0x47,  0x4e,
+  0x55,  0x5c,
+  0x64,  0x6b,
+  0x73,  0x7b,
+  0x83,  0x8a,
+  0x92,  0x9a,
+  0xa1,  0xa8,
+  0xaf,  0xb6,
+  0xbc,  0xc2,
+  0xc7,  0xcc,
+  0xd1,  0xd4,
+  0xd7,  0xda,
+  0xdb,  0xdc,
+  0xdd,  0xdc,
+  0xdb,  0xd9,
+  0xd7,  0xd3,
+  0xd0,  0xcb,
+  0xc6,  0xc1,
+  0xbb,  0xb4,
+  0xae,  0xa7,
+  0x9f,  0x98,
+  0x90,  0x89,
+  0x81,  0x79,
+  0x71,  0x69,
+  0x62,  0x5a,
+  0x53,  0x4c,
+  0x45,  0x3e,
+  0x38,  0x32,
+  0x2c,  0x26
+ #endif /* 64 bytes table */
+};
+
+static const int table_scale = 256/sizeof(rgblight_effect_breathe_table);
+
+#endif /* RGBLIGHT_EFFECT_BREATHE_TABLE */
diff --git a/quantum/template/avr/config.h b/quantum/template/avr/config.h
index a9bb75482..48d7afb14 100644
--- a/quantum/template/avr/config.h
+++ b/quantum/template/avr/config.h
@@ -77,6 +77,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //   #define RGBLIGHT_EFFECT_STATIC_GRADIENT
 //   #define RGBLIGHT_EFFECT_RGB_TEST
 //   #define RGBLIGHT_EFFECT_ALTERNATING
+// /*== customize breathing effect ==*/
+//   /*==== (DEFAULT) use fixed table instead of exp() and sin() ====*/
+//   #define RGBLIGHT_BREATHE_TABLE_SIZE 256      // 256(default) or 128 or 64
+//   /*==== use exp() and sin() ====*/
+//   #define RGBLIGHT_EFFECT_BREATHE_CENTER 1.85  // 1 to 2.7
+//   #define RGBLIGHT_EFFECT_BREATHE_MAX    255   // 0 to 255
 // #endif
 
 /* Debounce reduces chatter (unintended double-presses) - set 0 if debouncing is not needed */
diff --git a/util/rgblight_breathing_table_calc.c b/util/rgblight_breathing_table_calc.c
new file mode 100644
index 000000000..fc4d49ea5
--- /dev/null
+++ b/util/rgblight_breathing_table_calc.c
@@ -0,0 +1,49 @@
+//
+// calculate rgblight_effect_breathe_table[] values
+//
+// this is host program for quantum/rgblight.c:void rgblight_effect_breathing();
+//
+// example:
+//  $ edit util/rgblight_breathing_table_calc.c
+//  $ cc -o util/rgblight_breathing_table_calc util/rgblight_breathing_table_calc.c
+//  $ ./util/rgblight_breathing_table_calc > keyboards/KEYBOARD_NAME/keymaps/KEYMAP_NAME/rgblight_breathe_table.h
+//
+#include <stdio.h>
+#include <math.h>
+#include <stdint.h>
+
+/// customize breeathing effect part ///////////////////////////
+#define RGBLIGHT_EFFECT_BREATHE_CENTER 1.85  // 1 to 2.7
+#define RGBLIGHT_EFFECT_BREATHE_MAX    255   // 0 to 255
+////////////////////////////////////////////////////////////////
+
+int main(void) {
+    int pos, step;
+    int table[256];
+    for (pos = 0; pos < 256; pos ++ ) {
+        table[pos] = (uint8_t)(
+              (exp(sin((pos/255.0)*M_PI))- RGBLIGHT_EFFECT_BREATHE_CENTER/M_E)
+              * (RGBLIGHT_EFFECT_BREATHE_MAX/(M_E-1/M_E))
+              );
+    }
+    printf("#ifndef RGBLIGHT_EFFECT_BREATHE_TABLE\n");
+    printf("#define RGBLIGHT_EFFECT_BREATHE_TABLE\n\n");
+    printf("const uint8_t rgblight_effect_breathe_table[] PROGMEM = {\n");
+    printf("  /* #define RGBLIGHT_EFFECT_BREATHE_CENTER   %.2f */\n", RGBLIGHT_EFFECT_BREATHE_CENTER);
+    printf("  /* #define RGBLIGHT_EFFECT_BREATHE_MAX      %d */\n", RGBLIGHT_EFFECT_BREATHE_MAX);
+
+    for (int s = 0, step = (1<<s); s < 3 ; s += 1, step = (1<<s) ) {
+        printf("\n #if RGBLIGHT_BREATHE_TABLE_SIZE == %d\n",
+               s == 0 ? 256:(s== 1 ? 128: 64));
+        for (pos = 0; pos < 256; pos += step ) {
+            printf("  0x%x%s", table[pos], (pos+step)>=256?"":"," );
+            if ((pos+step) % 8 == 0)
+                printf("\n");
+        }
+        printf(" #endif /* %d bytes table */\n", s == 0 ? 256:(s== 1 ? 128: 64));
+    }
+    printf("};\n");
+    printf("\nstatic const int table_scale = 256/sizeof(rgblight_effect_breathe_table);\n");
+    printf("\n#endif /* RGBLIGHT_EFFECT_BREATHE_TABLE */\n");
+    return 0;
+}