Add uint to char functions (qmk#15244)

* Add uint to char functions

* appease the all mighty lint

* Further appease Lint

* Update functions

* Add doxygen comment

* Update quantum/quantum.c

Co-authored-by: Nick Brassel <[email protected]>

* Apply suggestions from code review

Co-authored-by: Nick Brassel <[email protected]>

* Add declaration for get_numeric_string

* fix formatting and bug

Co-authored-by: Nick Brassel <[email protected]>

Author: drashna

quantum/quantum.c

@@ -572,3 +572,59 @@ __attribute__((weak)) void suspend_wakeup_init_quantum(void) {
 #endif
     suspend_wakeup_init_kb();
 }
+
+/** \brief converts unsigned integers into char arrays
+ *
+ * Takes an unsigned integer and converts that value into an equivalent char array
+ * A padding character may be specified, ' ' for leading spaces, '0' for leading zeros.
+ */
+
+const char *get_numeric_str(char *buf, size_t buf_len, uint32_t curr_num, char curr_pad) {
+    buf[buf_len - 1] = '\0';
+    for (size_t i = 0; i < buf_len - 1; ++i) {
+        char c               = '0' + curr_num % 10;
+        buf[buf_len - 2 - i] = (c == '0' && i == 0) ? '0' : (curr_num > 0 ? c : curr_pad);
+        curr_num /= 10;
+    }
+    return buf;
+}
+
+/** \brief converts uint8_t into char array
+ *
+ * Takes an uint8_t, and uses an internal static buffer to render that value into a char array
+ * A padding character may be specified, ' ' for leading spaces, '0' for leading zeros.
+ *
+ * NOTE: Subsequent invocations will reuse the same static buffer and overwrite the previous
+ *       contents. Use the result immediately, instead of caching it.
+ */
+const char *get_u8_str(uint8_t curr_num, char curr_pad) {
+    static char    buf[4]   = {0};
+    static uint8_t last_num = 0xFF;
+    static char    last_pad = '\0';
+    if (last_num == curr_num && last_pad == curr_pad) {
+        return buf;
+    }
+    last_num = curr_num;
+    last_pad = curr_pad;
+    return get_numeric_str(buf, sizeof(buf), curr_num, curr_pad);
+}
+
+/** \brief converts uint16_t into char array
+ *
+ * Takes an uint16_t, and uses an internal static buffer to render that value into a char array
+ * A padding character may be specified, ' ' for leading spaces, '0' for leading zeros.
+ *
+ * NOTE: Subsequent invocations will reuse the same static buffer and overwrite the previous
+ *       contents. Use the result immediately, instead of caching it.
+ */
+const char *get_u16_str(uint16_t curr_num, char curr_pad) {
+    static char     buf[6]   = {0};
+    static uint16_t last_num = 0xFF;
+    static char     last_pad = '\0';
+    if (last_num == curr_num && last_pad == curr_pad) {
+        return buf;
+    }
+    last_num = curr_num;
+    last_pad = curr_pad;
+    return get_numeric_str(buf, sizeof(buf), curr_num, curr_pad);
+}

quantum/quantum.h

@@ -245,3 +245,7 @@ void led_set_user(uint8_t usb_led);
 void led_set_kb(uint8_t usb_led);
 bool led_update_user(led_t led_state);
 bool led_update_kb(led_t led_state);
+
+const char *get_numeric_str(char *buf, size_t buf_len, uint32_t curr_num, char curr_pad);
+const char *get_u8_str(uint8_t curr_num, char curr_pad);
+const char *get_u16_str(uint16_t curr_num, char curr_pad);