Extract sendstring into its own compilation unit (#12060)

* Extract sendstring into its own compilation unit

* License headers?

* Put this include in the header

4 files changed, 300 insertions, 258 deletions

diff --git a/quantum/quantum.c b/quantum/quantum.c
index db99e80fa0..80c4e8f00c 100644
--- a/quantum/quantum.c
+++ b/quantum/quantum.c
@@ -14,7 +14,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <ctype.h>
 #include "quantum.h"
 
 #ifdef BLUETOOTH_ENABLE
@@ -325,237 +324,6 @@ bool process_record_quantum(keyrecord_t *record) {
     return process_action_kb(record);
 }
 
-// clang-format off
-
-/* Bit-Packed look-up table to convert an ASCII character to whether
- * [Shift] needs to be sent with the keycode.
- */
-__attribute__((weak)) const uint8_t ascii_to_shift_lut[16] PROGMEM = {
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-
-    KCLUT_ENTRY(0, 1, 1, 1, 1, 1, 1, 0),
-    KCLUT_ENTRY(1, 1, 1, 1, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 1, 0, 1, 0, 1, 1),
-    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
-    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
-    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
-    KCLUT_ENTRY(1, 1, 1, 0, 0, 0, 1, 1),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 1, 1, 1, 1, 0),
-};
-
-/* Bit-Packed look-up table to convert an ASCII character to whether
- * [AltGr] needs to be sent with the keycode.
- */
-__attribute__((weak)) const uint8_t ascii_to_altgr_lut[16] PROGMEM = {
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-};
-
-/* Bit-Packed look-up table to convert an ASCII character to whether
- * [Space] needs to be sent after the keycode
- */
-__attribute__((weak)) const uint8_t ascii_to_dead_lut[16] PROGMEM = {
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
-};
-
-/* Look-up table to convert an ASCII character to a keycode.
- */
-__attribute__((weak)) const uint8_t ascii_to_keycode_lut[128] PROGMEM = {
-    // NUL   SOH      STX      ETX      EOT      ENQ      ACK      BEL
-    XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
-    // BS    TAB      LF       VT       FF       CR       SO       SI
-    KC_BSPC, KC_TAB,  KC_ENT,  XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
-    // DLE   DC1      DC2      DC3      DC4      NAK      SYN      ETB
-    XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
-    // CAN   EM       SUB      ESC      FS       GS       RS       US
-    XXXXXXX, XXXXXXX, XXXXXXX, KC_ESC,  XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
-
-    //       !        "        #        $        %        &        '
-    KC_SPC,  KC_1,    KC_QUOT, KC_3,    KC_4,    KC_5,    KC_7,    KC_QUOT,
-    // (     )        *        +        ,        -        .        /
-    KC_9,    KC_0,    KC_8,    KC_EQL,  KC_COMM, KC_MINS, KC_DOT,  KC_SLSH,
-    // 0     1        2        3        4        5        6        7
-    KC_0,    KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,
-    // 8     9        :        ;        <        =        >        ?
-    KC_8,    KC_9,    KC_SCLN, KC_SCLN, KC_COMM, KC_EQL,  KC_DOT,  KC_SLSH,
-    // @     A        B        C        D        E        F        G
-    KC_2,    KC_A,    KC_B,    KC_C,    KC_D,    KC_E,    KC_F,    KC_G,
-    // H     I        J        K        L        M        N        O
-    KC_H,    KC_I,    KC_J,    KC_K,    KC_L,    KC_M,    KC_N,    KC_O,
-    // P     Q        R        S        T        U        V        W
-    KC_P,    KC_Q,    KC_R,    KC_S,    KC_T,    KC_U,    KC_V,    KC_W,
-    // X     Y        Z        [        \        ]        ^        _
-    KC_X,    KC_Y,    KC_Z,    KC_LBRC, KC_BSLS, KC_RBRC, KC_6,    KC_MINS,
-    // `     a        b        c        d        e        f        g
-    KC_GRV,  KC_A,    KC_B,    KC_C,    KC_D,    KC_E,    KC_F,    KC_G,
-    // h     i        j        k        l        m        n        o
-    KC_H,    KC_I,    KC_J,    KC_K,    KC_L,    KC_M,    KC_N,    KC_O,
-    // p     q        r        s        t        u        v        w
-    KC_P,    KC_Q,    KC_R,    KC_S,    KC_T,    KC_U,    KC_V,    KC_W,
-    // x     y        z        {        |        }        ~        DEL
-    KC_X,    KC_Y,    KC_Z,    KC_LBRC, KC_BSLS, KC_RBRC, KC_GRV,  KC_DEL
-};
-
-// clang-format on
-
-// Note: we bit-pack in "reverse" order to optimize loading
-#define PGM_LOADBIT(mem, pos) ((pgm_read_byte(&((mem)[(pos) / 8])) >> ((pos) % 8)) & 0x01)
-
-void send_string(const char *str) { send_string_with_delay(str, 0); }
-
-void send_string_P(const char *str) { send_string_with_delay_P(str, 0); }
-
-void send_string_with_delay(const char *str, uint8_t interval) {
-    while (1) {
-        char ascii_code = *str;
-        if (!ascii_code) break;
-        if (ascii_code == SS_QMK_PREFIX) {
-            ascii_code = *(++str);
-            if (ascii_code == SS_TAP_CODE) {
-                // tap
-                uint8_t keycode = *(++str);
-                tap_code(keycode);
-            } else if (ascii_code == SS_DOWN_CODE) {
-                // down
-                uint8_t keycode = *(++str);
-                register_code(keycode);
-            } else if (ascii_code == SS_UP_CODE) {
-                // up
-                uint8_t keycode = *(++str);
-                unregister_code(keycode);
-            } else if (ascii_code == SS_DELAY_CODE) {
-                // delay
-                int     ms      = 0;
-                uint8_t keycode = *(++str);
-                while (isdigit(keycode)) {
-                    ms *= 10;
-                    ms += keycode - '0';
-                    keycode = *(++str);
-                }
-                while (ms--) wait_ms(1);
-            }
-        } else {
-            send_char(ascii_code);
-        }
-        ++str;
-        // interval
-        {
-            uint8_t ms = interval;
-            while (ms--) wait_ms(1);
-        }
-    }
-}
-
-void send_string_with_delay_P(const char *str, uint8_t interval) {
-    while (1) {
-        char ascii_code = pgm_read_byte(str);
-        if (!ascii_code) break;
-        if (ascii_code == SS_QMK_PREFIX) {
-            ascii_code = pgm_read_byte(++str);
-            if (ascii_code == SS_TAP_CODE) {
-                // tap
-                uint8_t keycode = pgm_read_byte(++str);
-                tap_code(keycode);
-            } else if (ascii_code == SS_DOWN_CODE) {
-                // down
-                uint8_t keycode = pgm_read_byte(++str);
-                register_code(keycode);
-            } else if (ascii_code == SS_UP_CODE) {
-                // up
-                uint8_t keycode = pgm_read_byte(++str);
-                unregister_code(keycode);
-            } else if (ascii_code == SS_DELAY_CODE) {
-                // delay
-                int     ms      = 0;
-                uint8_t keycode = pgm_read_byte(++str);
-                while (isdigit(keycode)) {
-                    ms *= 10;
-                    ms += keycode - '0';
-                    keycode = pgm_read_byte(++str);
-                }
-                while (ms--) wait_ms(1);
-            }
-        } else {
-            send_char(ascii_code);
-        }
-        ++str;
-        // interval
-        {
-            uint8_t ms = interval;
-            while (ms--) wait_ms(1);
-        }
-    }
-}
-
-void send_char(char ascii_code) {
-#if defined(AUDIO_ENABLE) && defined(SENDSTRING_BELL)
-    if (ascii_code == '\a') {  // BEL
-        PLAY_SONG(bell_song);
-        return;
-    }
-#endif
-
-    uint8_t keycode    = pgm_read_byte(&ascii_to_keycode_lut[(uint8_t)ascii_code]);
-    bool    is_shifted = PGM_LOADBIT(ascii_to_shift_lut, (uint8_t)ascii_code);
-    bool    is_altgred = PGM_LOADBIT(ascii_to_altgr_lut, (uint8_t)ascii_code);
-    bool    is_dead    = PGM_LOADBIT(ascii_to_dead_lut, (uint8_t)ascii_code);
-
-    if (is_shifted) {
-        register_code(KC_LSFT);
-    }
-    if (is_altgred) {
-        register_code(KC_RALT);
-    }
-    tap_code(keycode);
-    if (is_altgred) {
-        unregister_code(KC_RALT);
-    }
-    if (is_shifted) {
-        unregister_code(KC_LSFT);
-    }
-    if (is_dead) {
-        tap_code(KC_SPACE);
-    }
-}
-
 void set_single_persistent_default_layer(uint8_t default_layer) {
 #if defined(AUDIO_ENABLE) && defined(DEFAULT_LAYER_SONGS)
     PLAY_SONG(default_layer_songs[default_layer]);
diff --git a/quantum/quantum.h b/quantum/quantum.h
index 36a983d575..b1600dd724 100644
--- a/quantum/quantum.h
+++ b/quantum/quantum.h
@@ -61,7 +61,7 @@
 #include "action_util.h"
 #include "action_tapping.h"
 #include "print.h"
-#include "send_string_keycodes.h"
+#include "send_string.h"
 #include "suspend.h"
 #include <stddef.h>
 #include <stdlib.h>
@@ -231,31 +231,6 @@ extern layer_state_t layer_state;
 #    define waitInputPinDelay() wait_cpuclock(GPIO_INPUT_PIN_DELAY)
 
 #endif
-#define SEND_STRING(string) send_string_P(PSTR(string))
-#define SEND_STRING_DELAY(string, interval) send_string_with_delay_P(PSTR(string), interval)
-
-// Look-Up Tables (LUTs) to convert ASCII character to keycode sequence.
-extern const uint8_t ascii_to_keycode_lut[128];
-extern const uint8_t ascii_to_shift_lut[16];
-extern const uint8_t ascii_to_altgr_lut[16];
-extern const uint8_t ascii_to_dead_lut[16];
-// clang-format off
-#define KCLUT_ENTRY(a, b, c, d, e, f, g, h) \
-    ( ((a) ? 1 : 0) << 0 \
-    | ((b) ? 1 : 0) << 1 \
-    | ((c) ? 1 : 0) << 2 \
-    | ((d) ? 1 : 0) << 3 \
-    | ((e) ? 1 : 0) << 4 \
-    | ((f) ? 1 : 0) << 5 \
-    | ((g) ? 1 : 0) << 6 \
-    | ((h) ? 1 : 0) << 7 )
-// clang-format on
-
-void send_string(const char *str);
-void send_string_with_delay(const char *str, uint8_t interval);
-void send_string_P(const char *str);
-void send_string_with_delay_P(const char *str, uint8_t interval);
-void send_char(char ascii_code);
 
 // For tri-layer
 void          update_tri_layer(uint8_t layer1, uint8_t layer2, uint8_t layer3);
diff --git a/quantum/send_string.c b/quantum/send_string.c
new file mode 100644
index 0000000000..0e8902ca3f
--- /dev/null
+++ b/quantum/send_string.c
@@ -0,0 +1,252 @@
+/* Copyright 2021
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <ctype.h>
+
+#include "quantum.h"
+
+#include "send_string.h"
+
+// clang-format off
+
+/* Bit-Packed look-up table to convert an ASCII character to whether
+ * [Shift] needs to be sent with the keycode.
+ */
+__attribute__((weak)) const uint8_t ascii_to_shift_lut[16] PROGMEM = {
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+
+    KCLUT_ENTRY(0, 1, 1, 1, 1, 1, 1, 0),
+    KCLUT_ENTRY(1, 1, 1, 1, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 1, 0, 1, 0, 1, 1),
+    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
+    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
+    KCLUT_ENTRY(1, 1, 1, 1, 1, 1, 1, 1),
+    KCLUT_ENTRY(1, 1, 1, 0, 0, 0, 1, 1),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 1, 1, 1, 1, 0)
+};
+
+/* Bit-Packed look-up table to convert an ASCII character to whether
+ * [AltGr] needs to be sent with the keycode.
+ */
+__attribute__((weak)) const uint8_t ascii_to_altgr_lut[16] PROGMEM = {
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0)
+};
+
+/* Bit-Packed look-up table to convert an ASCII character to whether
+ * [Space] needs to be sent after the keycode
+ */
+__attribute__((weak)) const uint8_t ascii_to_dead_lut[16] PROGMEM = {
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0),
+    KCLUT_ENTRY(0, 0, 0, 0, 0, 0, 0, 0)
+};
+
+/* Look-up table to convert an ASCII character to a keycode.
+ */
+__attribute__((weak)) const uint8_t ascii_to_keycode_lut[128] PROGMEM = {
+    // NUL   SOH      STX      ETX      EOT      ENQ      ACK      BEL
+    XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
+    // BS    TAB      LF       VT       FF       CR       SO       SI
+    KC_BSPC, KC_TAB,  KC_ENT,  XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
+    // DLE   DC1      DC2      DC3      DC4      NAK      SYN      ETB
+    XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
+    // CAN   EM       SUB      ESC      FS       GS       RS       US
+    XXXXXXX, XXXXXXX, XXXXXXX, KC_ESC,  XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX,
+
+    //       !        "        #        $        %        &        '
+    KC_SPC,  KC_1,    KC_QUOT, KC_3,    KC_4,    KC_5,    KC_7,    KC_QUOT,
+    // (     )        *        +        ,        -        .        /
+    KC_9,    KC_0,    KC_8,    KC_EQL,  KC_COMM, KC_MINS, KC_DOT,  KC_SLSH,
+    // 0     1        2        3        4        5        6        7
+    KC_0,    KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,
+    // 8     9        :        ;        <        =        >        ?
+    KC_8,    KC_9,    KC_SCLN, KC_SCLN, KC_COMM, KC_EQL,  KC_DOT,  KC_SLSH,
+    // @     A        B        C        D        E        F        G
+    KC_2,    KC_A,    KC_B,    KC_C,    KC_D,    KC_E,    KC_F,    KC_G,
+    // H     I        J        K        L        M        N        O
+    KC_H,    KC_I,    KC_J,    KC_K,    KC_L,    KC_M,    KC_N,    KC_O,
+    // P     Q        R        S        T        U        V        W
+    KC_P,    KC_Q,    KC_R,    KC_S,    KC_T,    KC_U,    KC_V,    KC_W,
+    // X     Y        Z        [        \        ]        ^        _
+    KC_X,    KC_Y,    KC_Z,    KC_LBRC, KC_BSLS, KC_RBRC, KC_6,    KC_MINS,
+    // `     a        b        c        d        e        f        g
+    KC_GRV,  KC_A,    KC_B,    KC_C,    KC_D,    KC_E,    KC_F,    KC_G,
+    // h     i        j        k        l        m        n        o
+    KC_H,    KC_I,    KC_J,    KC_K,    KC_L,    KC_M,    KC_N,    KC_O,
+    // p     q        r        s        t        u        v        w
+    KC_P,    KC_Q,    KC_R,    KC_S,    KC_T,    KC_U,    KC_V,    KC_W,
+    // x     y        z        {        |        }        ~        DEL
+    KC_X,    KC_Y,    KC_Z,    KC_LBRC, KC_BSLS, KC_RBRC, KC_GRV,  KC_DEL
+};
+
+// clang-format on
+
+// Note: we bit-pack in "reverse" order to optimize loading
+#define PGM_LOADBIT(mem, pos) ((pgm_read_byte(&((mem)[(pos) / 8])) >> ((pos) % 8)) & 0x01)
+
+void send_string(const char *str) { send_string_with_delay(str, 0); }
+
+void send_string_P(const char *str) { send_string_with_delay_P(str, 0); }
+
+void send_string_with_delay(const char *str, uint8_t interval) {
+    while (1) {
+        char ascii_code = *str;
+        if (!ascii_code) break;
+        if (ascii_code == SS_QMK_PREFIX) {
+            ascii_code = *(++str);
+            if (ascii_code == SS_TAP_CODE) {
+                // tap
+                uint8_t keycode = *(++str);
+                tap_code(keycode);
+            } else if (ascii_code == SS_DOWN_CODE) {
+                // down
+                uint8_t keycode = *(++str);
+                register_code(keycode);
+            } else if (ascii_code == SS_UP_CODE) {
+                // up
+                uint8_t keycode = *(++str);
+                unregister_code(keycode);
+            } else if (ascii_code == SS_DELAY_CODE) {
+                // delay
+                int     ms      = 0;
+                uint8_t keycode = *(++str);
+                while (isdigit(keycode)) {
+                    ms *= 10;
+                    ms += keycode - '0';
+                    keycode = *(++str);
+                }
+                while (ms--) wait_ms(1);
+            }
+        } else {
+            send_char(ascii_code);
+        }
+        ++str;
+        // interval
+        {
+            uint8_t ms = interval;
+            while (ms--) wait_ms(1);
+        }
+    }
+}
+
+void send_string_with_delay_P(const char *str, uint8_t interval) {
+    while (1) {
+        char ascii_code = pgm_read_byte(str);
+        if (!ascii_code) break;
+        if (ascii_code == SS_QMK_PREFIX) {
+            ascii_code = pgm_read_byte(++str);
+            if (ascii_code == SS_TAP_CODE) {
+                // tap
+                uint8_t keycode = pgm_read_byte(++str);
+                tap_code(keycode);
+            } else if (ascii_code == SS_DOWN_CODE) {
+                // down
+                uint8_t keycode = pgm_read_byte(++str);
+                register_code(keycode);
+            } else if (ascii_code == SS_UP_CODE) {
+                // up
+                uint8_t keycode = pgm_read_byte(++str);
+                unregister_code(keycode);
+            } else if (ascii_code == SS_DELAY_CODE) {
+                // delay
+                int     ms      = 0;
+                uint8_t keycode = pgm_read_byte(++str);
+                while (isdigit(keycode)) {
+                    ms *= 10;
+                    ms += keycode - '0';
+                    keycode = pgm_read_byte(++str);
+                }
+                while (ms--) wait_ms(1);
+            }
+        } else {
+            send_char(ascii_code);
+        }
+        ++str;
+        // interval
+        {
+            uint8_t ms = interval;
+            while (ms--) wait_ms(1);
+        }
+    }
+}
+
+void send_char(char ascii_code) {
+#if defined(AUDIO_ENABLE) && defined(SENDSTRING_BELL)
+    if (ascii_code == '\a') {  // BEL
+        PLAY_SONG(bell_song);
+        return;
+    }
+#endif
+
+    uint8_t keycode    = pgm_read_byte(&ascii_to_keycode_lut[(uint8_t)ascii_code]);
+    bool    is_shifted = PGM_LOADBIT(ascii_to_shift_lut, (uint8_t)ascii_code);
+    bool    is_altgred = PGM_LOADBIT(ascii_to_altgr_lut, (uint8_t)ascii_code);
+    bool    is_dead    = PGM_LOADBIT(ascii_to_dead_lut, (uint8_t)ascii_code);
+
+    if (is_shifted) {
+        register_code(KC_LSFT);
+    }
+    if (is_altgred) {
+        register_code(KC_RALT);
+    }
+    tap_code(keycode);
+    if (is_altgred) {
+        unregister_code(KC_RALT);
+    }
+    if (is_shifted) {
+        unregister_code(KC_LSFT);
+    }
+    if (is_dead) {
+        tap_code(KC_SPACE);
+    }
+}
\ No newline at end of file
diff --git a/quantum/send_string.h b/quantum/send_string.h
new file mode 100644
index 0000000000..570522eb0e
--- /dev/null
+++ b/quantum/send_string.h
@@ -0,0 +1,47 @@
+/* Copyright 2021
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+
+#include "progmem.h"
+#include "send_string_keycodes.h"
+
+#define SEND_STRING(string) send_string_P(PSTR(string))
+#define SEND_STRING_DELAY(string, interval) send_string_with_delay_P(PSTR(string), interval)
+
+// Look-Up Tables (LUTs) to convert ASCII character to keycode sequence.
+extern const uint8_t ascii_to_keycode_lut[128];
+extern const uint8_t ascii_to_shift_lut[16];
+extern const uint8_t ascii_to_altgr_lut[16];
+extern const uint8_t ascii_to_dead_lut[16];
+
+// clang-format off
+#define KCLUT_ENTRY(a, b, c, d, e, f, g, h) \
+    ( ((a) ? 1 : 0) << 0 \
+    | ((b) ? 1 : 0) << 1 \
+    | ((c) ? 1 : 0) << 2 \
+    | ((d) ? 1 : 0) << 3 \
+    | ((e) ? 1 : 0) << 4 \
+    | ((f) ? 1 : 0) << 5 \
+    | ((g) ? 1 : 0) << 6 \
+    | ((h) ? 1 : 0) << 7 )
+// clang-format on
+
+void send_string(const char *str);
+void send_string_with_delay(const char *str, uint8_t interval);
+void send_string_P(const char *str);
+void send_string_with_delay_P(const char *str, uint8_t interval);
+void send_char(char ascii_code);