1 files changed, 97 insertions, 0 deletions
diff --git a/quantum/unicode/ucis.h b/quantum/unicode/ucis.h
new file mode 100644
index 0000000000..5a4fa26784
--- /dev/null
+++ b/quantum/unicode/ucis.h
@@ -0,0 +1,97 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/**
+ * \file
+ *
+ * \defgroup ucis UCIS
+ * \{
+ */
+
+#ifndef UCIS_MAX_INPUT_LENGTH
+#    define UCIS_MAX_INPUT_LENGTH 32
+#endif
+
+#ifndef UCIS_MAX_CODE_POINTS
+#    define UCIS_MAX_CODE_POINTS 3
+#endif
+
+typedef struct {
+    char*    mnemonic;
+    uint32_t code_points[UCIS_MAX_CODE_POINTS];
+} ucis_symbol_t;
+
+// clang-format off
+
+#define UCIS_TABLE(...) { \
+    __VA_ARGS__,          \
+    { NULL, {} }          \
+}
+
+#define UCIS_SYM(name, ...) {    \
+    .mnemonic    = name,         \
+    .code_points = {__VA_ARGS__} \
+}
+
+// clang-format on
+
+extern const ucis_symbol_t ucis_symbol_table[];
+
+/**
+ * \brief Begin the input sequence.
+ */
+void ucis_start(void);
+
+/**
+ * \brief Whether UCIS is currently active.
+ *
+ * \return `true` if UCIS is active.
+ */
+bool ucis_active(void);
+
+/**
+ * \brief Get the number of characters in the input sequence buffer.
+ *
+ * \return The current input sequence buffer length.
+ */
+uint8_t ucis_count(void);
+
+/**
+ * \brief Add the given keycode to the input sequence buffer.
+ *
+ * \param keycode The keycode to add. Must be between `KC_A` and `KC_Z`, or `KC_1` and `KC_0`.
+ *
+ * \return `true` if the keycode was added.
+ */
+bool ucis_add(uint16_t keycode);
+
+/**
+ * \brief Remove the last character from the input sequence.
+ *
+ * \return `true` if the sequence was not empty.
+ */
+bool ucis_remove_last(void);
+
+/**
+ * Mark the input sequence as complete, and attempt to match.
+ */
+void ucis_finish(void);
+
+/**
+ * \brief Cancel the input sequence.
+ */
+void ucis_cancel(void);
+
+/**
+ * Send the code point(s) for the given UCIS index.
+ *
+ * \param index The index into the UCIS symbol table.
+ */
+void register_ucis(uint8_t index);
+
+/** \} */