Refactor input to use stdio drivers for Keyboard and TCP

keyboard_stdio.cpp

@@ -0,0 +1,46 @@
+#include "keyboard_stdio.h"
+#include "pico/stdio/driver.h"
+#include "pico/sync.h"
+
+#define KBD_BUF_SIZE 128
+
+// Circular buffer for keyboard input
+static char kbd_buf[KBD_BUF_SIZE];
+static volatile int write_idx = 0;
+static volatile int read_idx = 0;
+static critical_section_t kbd_crit;
+
+void keyboard_stdio_push_char(char c) {
+    critical_section_enter_blocking(&kbd_crit);
+    int next_write = (write_idx + 1) % KBD_BUF_SIZE;
+    if (next_write != read_idx) { // Only write if not full
+        kbd_buf[write_idx] = c;
+        write_idx = next_write;
+    }
+    critical_section_exit(&kbd_crit);
+}
+
+static int keyboard_in_chars(char *buf, int len) {
+    int count = 0;
+    critical_section_enter_blocking(&kbd_crit);
+    while (count < len && read_idx != write_idx) {
+        buf[count++] = kbd_buf[read_idx];
+        read_idx = (read_idx + 1) % KBD_BUF_SIZE;
+    }
+    critical_section_exit(&kbd_crit);
+    return count > 0 ? count : PICO_ERROR_NO_DATA;
+}
+
+static stdio_driver_t kbd_driver = {
+    .out_chars = NULL,
+    .out_flush = NULL,
+    .in_chars = keyboard_in_chars,
+#if PICO_STDIO_ENABLE_CRLF_SUPPORT
+    .crlf_enabled = false
+#endif
+};
+
+void keyboard_stdio_init(void) {
+    critical_section_init(&kbd_crit);
+    stdio_set_driver_enabled(&kbd_driver, true);
+}