[Core] Convert Dynamic Macro to a Core Feature (#5948)

* Convert Dynamic Macro to a Core Feature

This imports the code from Dynamic Macro into the core code, and handles it, as such.

This deprecates the old method but does not remove it, for legacy support. This way, no existing user files need to be touched.

Additionally, this reorganizes the documentation to better reflect the changes.

Also, it adds user hooks to the feature so users can customize the existing functionality.

Based heavily on and closes #2976

* Apply suggestions from code review

Co-Authored-By: fauxpark <fauxpark@gmail.com>
Co-Authored-By: noroadsleft <18669334+noroadsleft@users.noreply.github.com>

* Cleanup based on feedback

* Add short-form keycodes and document them

- add short-form keycodes to quantum/quantum_keycodes.h
- document the new aliases in docs/feature_dynamic_macros.md

* Add Dynamic Macros section and keycodes to docs/keycodes.md

* Make anti-nesting optional

* Add documentation for DYNAMIC_MACRO_NO_NESTING option

* Fix Merge artifacts

* Fix formatting typo in docs

Co-Authored-By: James Young <18669334+noroadsleft@users.noreply.github.com>

* Remove DYNAMIC_MACRO_RANGE as it's not needed

* Fix includes and layer var type

2 files changed, 298 insertions, 0 deletions

diff --git a/quantum/process_keycode/process_dynamic_macro.c b/quantum/process_keycode/process_dynamic_macro.c
new file mode 100644
index 000000000..2065f242d
--- /dev/null
+++ b/quantum/process_keycode/process_dynamic_macro.c
@@ -0,0 +1,257 @@
+/* Copyright 2016 Jack Humbert
+ * Copyright 2019 Drashna Jael're (@drashna, aka Christopher Courtney)
+ *
+ * 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/>.
+ */
+
+/* Author: Wojciech Siewierski < wojciech dot siewierski at onet dot pl > */
+#include "process_dynamic_macro.h"
+
+// default feedback method
+void dynamic_macro_led_blink(void) {
+#ifdef BACKLIGHT_ENABLE
+    backlight_toggle();
+    wait_ms(100);
+    backlight_toggle();
+#endif
+}
+
+/* User hooks for Dynamic Macros */
+
+__attribute__((weak)) void dynamic_macro_record_start_user(void) { dynamic_macro_led_blink(); }
+
+__attribute__((weak)) void dynamic_macro_play_user(int8_t direction) { dynamic_macro_led_blink(); }
+
+__attribute__((weak)) void dynamic_macro_record_key_user(int8_t direction, keyrecord_t *record) { dynamic_macro_led_blink(); }
+
+__attribute__((weak)) void dynamic_macro_record_end_user(int8_t direction) { dynamic_macro_led_blink(); }
+
+/* Convenience macros used for retrieving the debug info. All of them
+ * need a `direction` variable accessible at the call site.
+ */
+#define DYNAMIC_MACRO_CURRENT_SLOT() (direction > 0 ? 1 : 2)
+#define DYNAMIC_MACRO_CURRENT_LENGTH(BEGIN, POINTER) ((int)(direction * ((POINTER) - (BEGIN))))
+#define DYNAMIC_MACRO_CURRENT_CAPACITY(BEGIN, END2) ((int)(direction * ((END2) - (BEGIN)) + 1))
+
+/**
+ * Start recording of the dynamic macro.
+ *
+ * @param[out] macro_pointer The new macro buffer iterator.
+ * @param[in]  macro_buffer  The macro buffer used to initialize macro_pointer.
+ */
+void dynamic_macro_record_start(keyrecord_t **macro_pointer, keyrecord_t *macro_buffer) {
+    dprintln("dynamic macro recording: started");
+
+    dynamic_macro_record_start_user();
+
+    clear_keyboard();
+    layer_clear();
+    *macro_pointer = macro_buffer;
+}
+
+/**
+ * Play the dynamic macro.
+ *
+ * @param macro_buffer[in] The beginning of the macro buffer being played.
+ * @param macro_end[in]    The element after the last macro buffer element.
+ * @param direction[in]    Either +1 or -1, which way to iterate the buffer.
+ */
+void dynamic_macro_play(keyrecord_t *macro_buffer, keyrecord_t *macro_end, int8_t direction) {
+    dprintf("dynamic macro: slot %d playback\n", DYNAMIC_MACRO_CURRENT_SLOT());
+
+    layer_state_t saved_layer_state = layer_state;
+
+    clear_keyboard();
+    layer_clear();
+
+    while (macro_buffer != macro_end) {
+        process_record(macro_buffer);
+        macro_buffer += direction;
+    }
+
+    clear_keyboard();
+
+    layer_state = saved_layer_state;
+
+    dynamic_macro_play_user(direction);
+}
+
+/**
+ * Record a single key in a dynamic macro.
+ *
+ * @param macro_buffer[in] The start of the used macro buffer.
+ * @param macro_pointer[in,out] The current buffer position.
+ * @param macro2_end[in] The end of the other macro.
+ * @param direction[in]  Either +1 or -1, which way to iterate the buffer.
+ * @param record[in]     The current keypress.
+ */
+void dynamic_macro_record_key(keyrecord_t *macro_buffer, keyrecord_t **macro_pointer, keyrecord_t *macro2_end, int8_t direction, keyrecord_t *record) {
+    /* If we've just started recording, ignore all the key releases. */
+    if (!record->event.pressed && *macro_pointer == macro_buffer) {
+        dprintln("dynamic macro: ignoring a leading key-up event");
+        return;
+    }
+
+    /* The other end of the other macro is the last buffer element it
+     * is safe to use before overwriting the other macro.
+     */
+    if (*macro_pointer - direction != macro2_end) {
+        **macro_pointer = *record;
+        *macro_pointer += direction;
+    } else {
+        dynamic_macro_record_key_user(direction, record);
+    }
+
+    dprintf("dynamic macro: slot %d length: %d/%d\n", DYNAMIC_MACRO_CURRENT_SLOT(), DYNAMIC_MACRO_CURRENT_LENGTH(macro_buffer, *macro_pointer), DYNAMIC_MACRO_CURRENT_CAPACITY(macro_buffer, macro2_end));
+}
+
+/**
+ * End recording of the dynamic macro. Essentially just update the
+ * pointer to the end of the macro.
+ */
+void dynamic_macro_record_end(keyrecord_t *macro_buffer, keyrecord_t *macro_pointer, int8_t direction, keyrecord_t **macro_end) {
+    dynamic_macro_record_end_user(direction);
+
+    /* Do not save the keys being held when stopping the recording,
+     * i.e. the keys used to access the layer DYN_REC_STOP is on.
+     */
+    while (macro_pointer != macro_buffer && (macro_pointer - direction)->event.pressed) {
+        dprintln("dynamic macro: trimming a trailing key-down event");
+        macro_pointer -= direction;
+    }
+
+    dprintf("dynamic macro: slot %d saved, length: %d\n", DYNAMIC_MACRO_CURRENT_SLOT(), DYNAMIC_MACRO_CURRENT_LENGTH(macro_buffer, macro_pointer));
+
+    *macro_end = macro_pointer;
+}
+
+/* Handle the key events related to the dynamic macros. Should be
+ * called from process_record_user() like this:
+ *
+ *   bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+ *       if (!process_record_dynamic_macro(keycode, record)) {
+ *           return false;
+ *       }
+ *       <...THE REST OF THE FUNCTION...>
+ *   }
+ */
+bool process_dynamic_macro(uint16_t keycode, keyrecord_t *record) {
+    /* Both macros use the same buffer but read/write on different
+     * ends of it.
+     *
+     * Macro1 is written left-to-right starting from the beginning of
+     * the buffer.
+     *
+     * Macro2 is written right-to-left starting from the end of the
+     * buffer.
+     *
+     * &macro_buffer   macro_end
+     *  v                   v
+     * +------------------------------------------------------------+
+     * |>>>>>> MACRO1 >>>>>>      <<<<<<<<<<<<< MACRO2 <<<<<<<<<<<<<|
+     * +------------------------------------------------------------+
+     *                           ^                                 ^
+     *                         r_macro_end                  r_macro_buffer
+     *
+     * During the recording when one macro encounters the end of the
+     * other macro, the recording is stopped. Apart from this, there
+     * are no arbitrary limits for the macros' length in relation to
+     * each other: for example one can either have two medium sized
+     * macros or one long macro and one short macro. Or even one empty
+     * and one using the whole buffer.
+     */
+    static keyrecord_t macro_buffer[DYNAMIC_MACRO_SIZE];
+
+    /* Pointer to the first buffer element after the first macro.
+     * Initially points to the very beginning of the buffer since the
+     * macro is empty. */
+    static keyrecord_t *macro_end = macro_buffer;
+
+    /* The other end of the macro buffer. Serves as the beginning of
+     * the second macro. */
+    static keyrecord_t *const r_macro_buffer = macro_buffer + DYNAMIC_MACRO_SIZE - 1;
+
+    /* Like macro_end but for the second macro. */
+    static keyrecord_t *r_macro_end = r_macro_buffer;
+
+    /* A persistent pointer to the current macro position (iterator)
+     * used during the recording. */
+    static keyrecord_t *macro_pointer = NULL;
+
+    /* 0   - no macro is being recorded right now
+     * 1,2 - either macro 1 or 2 is being recorded */
+    static uint8_t macro_id = 0;
+
+    if (macro_id == 0) {
+        /* No macro recording in progress. */
+        if (!record->event.pressed) {
+            switch (keycode) {
+                case DYN_REC_START1:
+                    dynamic_macro_record_start(&macro_pointer, macro_buffer);
+                    macro_id = 1;
+                    return false;
+                case DYN_REC_START2:
+                    dynamic_macro_record_start(&macro_pointer, r_macro_buffer);
+                    macro_id = 2;
+                    return false;
+                case DYN_MACRO_PLAY1:
+                    dynamic_macro_play(macro_buffer, macro_end, +1);
+                    return false;
+                case DYN_MACRO_PLAY2:
+                    dynamic_macro_play(r_macro_buffer, r_macro_end, -1);
+                    return false;
+            }
+        }
+    } else {
+        /* A macro is being recorded right now. */
+        switch (keycode) {
+            case DYN_REC_STOP:
+                /* Stop the macro recording. */
+                if (record->event.pressed) { /* Ignore the initial release
+                                              * just after the recoding
+                                              * starts. */
+                    switch (macro_id) {
+                        case 1:
+                            dynamic_macro_record_end(macro_buffer, macro_pointer, +1, &macro_end);
+                            break;
+                        case 2:
+                            dynamic_macro_record_end(r_macro_buffer, macro_pointer, -1, &r_macro_end);
+                            break;
+                    }
+                    macro_id = 0;
+                }
+                return false;
+#ifdef DYNAMIC_MACRO_NO_NESTING
+            case DYN_MACRO_PLAY1:
+            case DYN_MACRO_PLAY2:
+                dprintln("dynamic macro: ignoring macro play key while recording");
+                return false;
+#endif
+            default:
+                /* Store the key in the macro buffer and process it normally. */
+                switch (macro_id) {
+                    case 1:
+                        dynamic_macro_record_key(macro_buffer, &macro_pointer, r_macro_end, +1, record);
+                        break;
+                    case 2:
+                        dynamic_macro_record_key(r_macro_buffer, &macro_pointer, macro_end, -1, record);
+                        break;
+                }
+                return true;
+                break;
+        }
+    }
+
+    return true;
+}
diff --git a/quantum/process_keycode/process_dynamic_macro.h b/quantum/process_keycode/process_dynamic_macro.h
new file mode 100644
index 000000000..39036541b
--- /dev/null
+++ b/quantum/process_keycode/process_dynamic_macro.h
@@ -0,0 +1,41 @@
+/* Copyright 2016 Jack Humbert
+ * Copyright 2019 Drashna Jael're (@drashna, aka Christopher Courtney)
+ *
+ * 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/>.
+ */
+
+/* Author: Wojciech Siewierski < wojciech dot siewierski at onet dot pl > */
+#pragma once
+
+#include "quantum.h"
+
+/* May be overridden with a custom value. Be aware that the effective
+ * macro length is half of this value: each keypress is recorded twice
+ * because of the down-event and up-event. This is not a bug, it's the
+ * intended behavior.
+ *
+ * Usually it should be fine to set the macro size to at least 256 but
+ * there have been reports of it being too much in some users' cases,
+ * so 128 is considered a safe default.
+ */
+#ifndef DYNAMIC_MACRO_SIZE
+#    define DYNAMIC_MACRO_SIZE 128
+#endif
+
+void dynamic_macro_led_blink(void);
+bool process_dynamic_macro(uint16_t keycode, keyrecord_t *record);
+void dynamic_macro_record_start_user(void);
+void dynamic_macro_play_user(int8_t direction);
+void dynamic_macro_record_key_user(int8_t direction, keyrecord_t *record);
+void dynamic_macro_record_end_user(int8_t direction);