Apply strict build.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
2026-05-28 17:11:23 +02:00 · 2026-03-08 19:27:23 +01:00
parent 802a706587
commit 8e6c6c1fcc
34 changed files with 277 additions and 204 deletions
--- a/pico_keys_sdk_import.cmake
+++ b/pico_keys_sdk_import.cmake
@@ -467,6 +467,64 @@ function(add_impl_library target)
    target_compile_definitions(${target} INTERFACE LIB_${TARGET_UPPER}=1)
 endfunction()

+# Apply strict warning flags to a caller-provided source list.
+# Usage:
+#   pico_keys_apply_strict_flags(SOURCES ${SOURCES} FILTER_REGEX "/src/fido/")
+function(pico_keys_apply_strict_flags)
+    set(options)
+    set(oneValueArgs FILTER_REGEX)
+    set(multiValueArgs SOURCES)
+    cmake_parse_arguments(PKAS "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+    if(NOT PKAS_SOURCES)
+        return()
+    endif()
+
+    set(PICO_KEYS_STRICT_FLAGS
+        -Wextra
+        -pipe
+        -funsigned-char
+        -fstrict-aliasing
+        -Wchar-subscripts
+        -Wundef
+        -Wshadow
+        -Wcast-align
+        -Wwrite-strings
+        -Wunused
+        -Wuninitialized
+        -Wpointer-arith
+        -Wredundant-decls
+        -Winline
+        -Wformat
+        -Wformat-security
+        -Wswitch-enum
+        -Winit-self
+        -Wmissing-include-dirs
+        -Wempty-body
+        -fdiagnostics-color=auto
+        -Wmissing-prototypes
+        -Wstrict-prototypes
+        -Wold-style-definition
+        -Wbad-function-cast
+        -Wnested-externs
+        -Wmissing-declarations
+        -Werror
+    )
+
+    if(NOT ENABLE_EMULATION)
+        list(APPEND PICO_KEYS_STRICT_FLAGS -D_FORTIFY_SOURCE=2)
+    endif()
+
+    foreach(src IN LISTS PKAS_SOURCES)
+        if(PKAS_FILTER_REGEX)
+            if(NOT src MATCHES "${PKAS_FILTER_REGEX}")
+                continue()
+            endif()
+        endif()
+        set_property(SOURCE "${src}" APPEND PROPERTY COMPILE_OPTIONS ${PICO_KEYS_STRICT_FLAGS})
+    endforeach()
+endfunction()
+
 if(USB_ITF_HID)
    list(APPEND PICO_KEYS_SOURCES
        ${CMAKE_CURRENT_LIST_DIR}/src/usb/hid/hid.c
--- a/src/apdu.c
+++ b/src/apdu.c
@@ -33,13 +33,15 @@ bool is_chaining = false;
 uint8_t chain_buf[2038];
 uint8_t *chain_ptr = NULL;

-int process_apdu() {
+int process_apdu(void) {
    led_set_mode(MODE_PROCESSING);
    if (CLA(apdu) & 0x10) {
+        size_t chain_used = 0;
        if (!is_chaining) {
            chain_ptr = chain_buf;
        }
-        if (chain_ptr - chain_buf + apdu.nc >= sizeof(chain_buf)) {
+        chain_used = (size_t)(chain_ptr - chain_buf);
+        if (chain_used + apdu.nc >= sizeof(chain_buf)) {
            return SW_CLA_NOT_SUPPORTED();
        }
        memcpy(chain_ptr, apdu.data, apdu.nc);
@@ -222,7 +224,7 @@ done:   ;
    return NULL;
 }

-void apdu_finish() {
+void apdu_finish(void) {
    put_uint16_t_be(apdu.sw, apdu.rdata + apdu.rlen);
    // timeout_stop();
 #ifndef ENABLE_EMULATION
@@ -233,7 +235,7 @@ void apdu_finish() {
 #endif
 }

-uint16_t apdu_next() {
+uint16_t apdu_next(void) {
    if (apdu.sw != 0) {
        if (apdu.rlen <= apdu.ne) {
            return apdu.rlen + 2;
@@ -255,7 +257,7 @@ uint16_t apdu_next() {
    return 0;
 }

-int bulk_cmd(int (*cmd)()) {
+int bulk_cmd(int (*cmd)(void)) {
    uint8_t *p = apdu.data;
    uint8_t *rapdu = apdu.rdata;
    uint16_t rapdu_size = 0;
--- a/src/apdu.h
+++ b/src/apdu.h
@@ -29,9 +29,9 @@

 typedef struct app {
    const uint8_t *aid;
-    int (*process_apdu)();
+    int (*process_apdu)(void);
    int (*select_aid)(struct app *, uint8_t);
-    int (*unload)();
+    int (*unload)(void);
 } app_t;

 extern bool app_exists(const uint8_t *aid, size_t aid_len);
@@ -40,7 +40,7 @@ extern int select_app(const uint8_t *aid, size_t aid_len);

 typedef struct cmd {
    uint8_t ins;
-    int (*cmd_handler)();
+    int (*cmd_handler)(void);
 } cmd_t;

 extern uint8_t num_apps;
@@ -69,11 +69,11 @@ PACK(struct apdu {
 extern struct apdu apdu;

 extern uint16_t set_res_sw(uint8_t sw1, uint8_t sw2);
-extern int process_apdu();
+extern int process_apdu(void);
 extern uint16_t apdu_process(uint8_t, const uint8_t *buffer, uint16_t buffer_size);
-extern void apdu_finish();
-extern uint16_t apdu_next();
+extern void apdu_finish(void);
+extern uint16_t apdu_next(void);
 extern void *apdu_thread(void *);
-extern int bulk_cmd(int (*cmd)());
+extern int bulk_cmd(int (*cmd)(void));

 #endif
--- a/src/board.h
+++ b/src/board.h
@@ -26,7 +26,7 @@ extern int gettimeofday(struct timeval *tp, struct timezone *tzp);
 #include <sys/time.h>
 #endif

-static inline uint32_t board_millis() {
+static inline uint32_t board_millis(void) {
    struct timeval start;
    gettimeofday(&start, NULL);
    return start.tv_sec * 1000 + start.tv_usec / 1000;
--- a/src/eac.c
+++ b/src/eac.c
@@ -37,16 +37,16 @@ static uint8_t sm_iv[16];
 uint16_t sm_session_pin_len = 0;
 uint8_t sm_session_pin[16];

-bool is_secured_apdu() {
+bool is_secured_apdu(void) {
    return CLA(apdu) & 0xC;
 }

-void sm_derive_key(const uint8_t *input,
-                   size_t input_len,
-                   uint8_t counter,
-                   const uint8_t *nonce,
-                   size_t nonce_len,
-                   uint8_t *out) {
+static void sm_derive_key(const uint8_t *input,
+                          size_t input_len,
+                          uint8_t counter,
+                          const uint8_t *nonce,
+                          size_t nonce_len,
+                          uint8_t *out) {
    uint8_t *b = (uint8_t *) calloc(1, input_len + nonce_len + 4);
    if (input) {
        memcpy(b, input, input_len);
@@ -82,11 +82,11 @@ void sm_set_protocol(MSE_protocol proto) {
    }
 }

-MSE_protocol sm_get_protocol() {
+MSE_protocol sm_get_protocol(void) {
    return sm_protocol;
 }

-uint8_t *sm_get_nonce() {
+uint8_t *sm_get_nonce(void) {
    return sm_nonce;
 }

@@ -99,7 +99,7 @@ int sm_sign(uint8_t *in, size_t in_len, uint8_t *out) {
                               out);
 }

-int sm_unwrap() {
+int sm_unwrap(void) {
    uint8_t sm_indicator = (CLA(apdu) >> 2) & 0x3;
    if (sm_indicator == 0) {
        return PICOKEY_OK;
@@ -144,7 +144,7 @@ int sm_unwrap() {
    return PICOKEY_OK;
 }

-int sm_wrap() {
+int sm_wrap(void) {
    uint8_t sm_indicator = (CLA(apdu) >> 2) & 0x3;
    if (sm_indicator == 0) {
        return PICOKEY_OK;
@@ -210,7 +210,7 @@ int sm_wrap() {
    return PICOKEY_OK;
 }

-uint16_t sm_get_le() {
+uint16_t sm_get_le(void) {
    uint16_t tag = 0x0;
    uint8_t *tag_data = NULL, *p = NULL;
    uint16_t tag_len = 0;
@@ -228,7 +228,7 @@ uint16_t sm_get_le() {
    return 0;
 }

-void sm_update_iv() {
+void sm_update_iv(void) {
    uint8_t tmp_iv[16], sc_counter[16];
    memset(tmp_iv, 0, sizeof(tmp_iv)); //IV is always 0 for encryption of IV based on counter
    mbedtls_mpi_write_binary(&sm_mSSC, sc_counter, sizeof(sc_counter));
@@ -236,7 +236,7 @@ void sm_update_iv() {
    memcpy(sm_iv, sc_counter, sizeof(sc_counter));
 }

-int sm_verify() {
+int sm_verify(void) {
    uint8_t input[USB_BUFFER_SIZE];
    memset(input, 0, sizeof(input));
    uint16_t input_len = 0;
--- a/src/eac.h
+++ b/src/eac.h
@@ -28,16 +28,16 @@ typedef enum MSE_protocol {

 extern void sm_derive_all_keys(const uint8_t *input, size_t input_len);
 extern void sm_set_protocol(MSE_protocol proto);
-extern MSE_protocol sm_get_protocol();
-extern uint8_t *sm_get_nonce();
+extern MSE_protocol sm_get_protocol(void);
+extern uint8_t *sm_get_nonce(void);
 extern int sm_sign(uint8_t *in, size_t in_len, uint8_t *out);
-int sm_verify();
-void sm_update_iv();
-uint16_t sm_get_le();
-extern int sm_unwrap();
+int sm_verify(void);
+void sm_update_iv(void);
+uint16_t sm_get_le(void);
+extern int sm_unwrap(void);
 uint16_t sm_remove_padding(const uint8_t *data, uint16_t data_len);
-extern int sm_wrap();
-extern bool is_secured_apdu();
+extern int sm_wrap(void);
+extern bool is_secured_apdu(void);
 extern uint8_t sm_session_pin[16];
 extern uint16_t sm_session_pin_len;

--- a/src/fs/file.c
+++ b/src/fs/file.c
@@ -26,15 +26,6 @@ extern const uintptr_t end_data_pool;
 extern const uintptr_t start_data_pool;
 extern const uintptr_t end_rom_pool;
 extern const uintptr_t start_rom_pool;
-extern int flash_write_data_to_file(file_t *file, const uint8_t *data, uint16_t len);
-extern int flash_program_block(uintptr_t addr, const uint8_t *data, size_t len);
-extern uintptr_t flash_read_uintptr(uintptr_t addr);
-extern uint16_t flash_read_uint16(uintptr_t addr);
-extern uint8_t flash_read_uint8(uintptr_t addr);
-extern uint8_t *flash_read(uintptr_t addr);
-extern int flash_clear_file(file_t *ef);
-extern void low_flash_available(void);
-
 #ifndef ENABLE_EMULATION
 file_t sef_phy = {.fid = EF_PHY, .parent = 5, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH | FILE_PERSISTENT, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = {0xff}};
 file_t *ef_phy = &sef_phy;
@@ -55,7 +46,8 @@ void process_fci(const file_t *pe, int fmd) {
    res_APDU[res_APDU_size++] = 2;
    if (pe->data) {
        if ((pe->type & FILE_DATA_FUNC) == FILE_DATA_FUNC) {
-            uint16_t len = (uint16_t)((int (*)(const file_t *, int))(pe->data))(pe, 0);
+            int (*data_fn)(const file_t *, int) = (int (*)(const file_t *, int))(uintptr_t)pe->data;
+            uint16_t len = (uint16_t)data_fn(pe, 0);
            res_APDU_size += put_uint16_t_be(len, res_APDU + res_APDU_size);
        }
        else {
@@ -115,7 +107,7 @@ file_t dynamic_file[MAX_DYNAMIC_FILES];

 bool card_terminated = false;

-bool is_parent(const file_t *child, const file_t *parent) {
+static bool is_parent(const file_t *child, const file_t *parent) {
    if (child == parent) {
        return true;
    }
@@ -166,7 +158,7 @@ file_t *search_file(const uint16_t fid) {
    return search_dynamic_file(fid);
 }

-uint8_t make_path_buf(const file_t *pe, uint8_t *buf, uint8_t buflen, const file_t *top) {
+static uint8_t make_path_buf(const file_t *pe, uint8_t *buf, uint8_t buflen, const file_t *top) {
    if (!buflen) {
        return 0;
    }
@@ -177,7 +169,7 @@ uint8_t make_path_buf(const file_t *pe, uint8_t *buf, uint8_t buflen, const file
    return make_path_buf(&file_entries[pe->parent], buf + 2, buflen - 2, top) + 2;
 }

-uint8_t make_path(const file_t *pe, const file_t *top, uint8_t *path) {
+static uint8_t make_path(const file_t *pe, const file_t *top, uint8_t *path) {
    uint8_t buf[MAX_DEPTH * 2], *p = path;
    put_uint16_t_be(pe->fid, buf);
    uint8_t depth = make_path_buf(&file_entries[pe->parent], buf + 2, sizeof(buf) - 2, top) + 2;
@@ -243,7 +235,7 @@ void initialize_flash(bool hard) {

 extern uintptr_t last_base;
 extern uint32_t num_files;
-void scan_region(bool persistent)
+static void scan_region(bool persistent)
 {
    uintptr_t endp = end_data_pool, startp = start_data_pool;
    if (persistent) {
@@ -279,9 +271,10 @@ void scan_region(bool persistent)
        }
    }
 }
-void scan_flash() {
+void scan_flash(void) {
    initialize_flash(false); //soft initialization
-    uint32_t r1 = (uint32_t)(*(uintptr_t *) flash_read(end_rom_pool)), r2 = (uint32_t)(*(uintptr_t *) flash_read(end_rom_pool + sizeof(uintptr_t)));
+    uint32_t r1 = (uint32_t)flash_read_uintptr(end_rom_pool);
+    uint32_t r2 = (uint32_t)flash_read_uintptr(end_rom_pool + sizeof(uintptr_t));
    if ((r1 == 0xffffffff || r1 == 0xefefefef) && (r2 == 0xffffffff || r2 == 0xefefefef)) {
        printf("First initialization (or corrupted!)\n");
        uint8_t empty[sizeof(uintptr_t) * 2 + sizeof(uint32_t)];
--- a/src/fs/file.h
+++ b/src/fs/file.h
@@ -115,7 +115,7 @@ extern file_t *search_by_name(uint8_t *name, uint16_t namelen);
 extern file_t *search_by_path(const uint8_t *pe_path, uint8_t pathlen, const file_t *parent);
 extern bool authenticate_action(const file_t *ef, uint8_t op);
 extern void process_fci(const file_t *pe, int fmd);
-extern void scan_flash();
+extern void scan_flash(void);
 extern void initialize_flash(bool);

 extern file_t file_entries[];
@@ -142,11 +142,26 @@ extern int meta_delete(uint16_t fid);
 extern int meta_add(uint16_t fid, const uint8_t *data, uint16_t len);
 extern int delete_file(file_t *ef);

-extern uint32_t flash_free_space();
-extern uint32_t flash_used_space();
-extern uint32_t flash_total_space();
-extern uint32_t flash_num_files();
-extern uint32_t flash_size();
+extern uint32_t flash_free_space(void);
+extern uint32_t flash_used_space(void);
+extern uint32_t flash_total_space(void);
+extern uint32_t flash_num_files(void);
+extern uint32_t flash_size(void);
+
+extern void flash_set_bounds(uintptr_t start, uintptr_t end);
+extern int flash_write_data_to_file(file_t *file, const uint8_t *data, uint16_t len);
+extern int flash_program_block(uintptr_t addr, const uint8_t *data, size_t len);
+extern int flash_program_halfword(uintptr_t addr, uint16_t data);
+extern int flash_program_word(uintptr_t addr, uint32_t data);
+extern int flash_program_uintptr(uintptr_t addr, uintptr_t data);
+extern uintptr_t flash_read_uintptr(uintptr_t addr);
+extern uint16_t flash_read_uint16(uintptr_t addr);
+extern uint8_t flash_read_uint8(uintptr_t addr);
+extern uint8_t *flash_read(uintptr_t addr);
+extern int flash_erase_page(uintptr_t addr, size_t page_size);
+extern bool flash_check_blank(const uint8_t *p_start, size_t size);
+extern void do_flash(void);
+extern void low_flash_init(void);

 #ifndef ENABLE_EMULATION
 extern file_t *ef_phy;
--- a/src/fs/flash.c
+++ b/src/fs/flash.c
@@ -54,15 +54,6 @@ uint32_t FLASH_SIZE_BYTES = (2 * 1024 * 1024);
 //To avoid possible future allocations, data region starts at the end of flash and goes upwards to the center region
 uintptr_t end_flash, end_rom_pool, start_rom_pool, end_data_pool, start_data_pool;

-extern int flash_program_block(uintptr_t addr, const uint8_t *data, size_t len);
-extern int flash_program_halfword(uintptr_t addr, uint16_t data);
-extern int flash_program_uintptr(uintptr_t, uintptr_t);
-extern uintptr_t flash_read_uintptr(uintptr_t addr);
-extern uint16_t flash_read_uint16(uintptr_t addr);
-extern uint8_t *flash_read(uintptr_t addr);
-
-extern void low_flash_available(void);
-
 uintptr_t last_base;
 uint32_t num_files = 0;

@@ -76,7 +67,7 @@ void flash_set_bounds(uintptr_t start, uintptr_t end) {
    last_base = end_data_pool;
 }

-uintptr_t allocate_free_addr(uint16_t size, bool persistent) {
+static uintptr_t allocate_free_addr(uint16_t size, bool persistent) {
    if (size > FLASH_SECTOR_SIZE) {
        return 0x0; //ERROR
    }
@@ -144,7 +135,7 @@ int flash_clear_file(file_t *file) {
    return PICOKEY_OK;
 }

-int flash_write_data_to_file_offset(file_t *file, const uint8_t *data, uint16_t len, uint16_t offset) {
+static int flash_write_data_to_file_offset(file_t *file, const uint8_t *data, uint16_t len, uint16_t offset) {
    if (!file) {
        return PICOKEY_ERR_NULL_PARAM;
    }
@@ -198,22 +189,22 @@ int flash_write_data_to_file(file_t *file, const uint8_t *data, uint16_t len) {
    return flash_write_data_to_file_offset(file, data, len, 0);
 }

-uint32_t flash_free_space() {
+uint32_t flash_free_space(void) {
    return (uint32_t)(last_base - start_data_pool);
 }

-uint32_t flash_used_space() {
+uint32_t flash_used_space(void) {
    return (uint32_t)(end_data_pool - last_base);
 }

-uint32_t flash_total_space() {
+uint32_t flash_total_space(void) {
    return (uint32_t)(end_data_pool - start_data_pool);
 }

-uint32_t flash_num_files() {
+uint32_t flash_num_files(void) {
    return num_files;
 }

-uint32_t flash_size() {
+uint32_t flash_size(void) {
    return FLASH_SIZE_BYTES;
 }
--- a/src/fs/low_flash.c
+++ b/src/fs/low_flash.c
@@ -76,8 +76,6 @@ extern uint32_t FLASH_SIZE_BYTES;

 #define TOTAL_FLASH_PAGES 6

-extern void flash_set_bounds(uintptr_t start, uintptr_t end);
-
 extern const uintptr_t start_data_pool;
 extern const uintptr_t end_rom_pool;

@@ -105,7 +103,7 @@ bool flash_available = false;


 //this function has to be called from the core 0
-void do_flash() {
+void do_flash(void) {
    if (mutex_try_enter(&mtx_flash, NULL) == true) {
        if (locked_out == true && flash_available == true && ready_pages > 0) {
            //printf(" DO_FLASH AVAILABLE\n");
@@ -181,10 +179,10 @@ void do_flash() {
 }

 #ifdef PICO_RP2040
-void phymarker_write();
+void phymarker_write(void);
 #endif
 //this function has to be called from the core 0
-void low_flash_init() {
+void low_flash_init(void) {
 #ifdef PICO_RP2040
    phymarker_write();
 #endif
@@ -206,21 +204,21 @@ void low_flash_init() {

    FLASH_SIZE_BYTES = (1 << rxbuf[3]);
 #ifdef PICO_RP2350
-    __attribute__((aligned(4))) uint8_t workarea[4 * 1024];
-    int rc = rom_load_partition_table(workarea, sizeof(workarea), false);
+    __attribute__((aligned(4))) uint32_t workarea[1024];
+    int rc = rom_load_partition_table((uint8_t *)workarea, sizeof(workarea), false);
    if (rc) {
        reset_usb_boot(0, 0);
    }

    uint8_t boot_partition = 1;
-    rc = rom_get_partition_table_info((uint32_t*)workarea, 0x8, PT_INFO_PARTITION_LOCATION_AND_FLAGS | PT_INFO_SINGLE_PARTITION | (boot_partition << 24));
+    rc = rom_get_partition_table_info(workarea, 0x8, PT_INFO_PARTITION_LOCATION_AND_FLAGS | PT_INFO_SINGLE_PARTITION | (boot_partition << 24));

    if (rc != 3) {
        data_start_addr = (FLASH_SIZE_BYTES >> 1);
        data_end_addr = FLASH_SIZE_BYTES;
    } else {
-        uint16_t first_sector_number = (((uint32_t*)workarea)[1] & PICOBIN_PARTITION_LOCATION_FIRST_SECTOR_BITS) >> PICOBIN_PARTITION_LOCATION_FIRST_SECTOR_LSB;
-        uint16_t last_sector_number = (((uint32_t*)workarea)[1] & PICOBIN_PARTITION_LOCATION_LAST_SECTOR_BITS) >> PICOBIN_PARTITION_LOCATION_LAST_SECTOR_LSB;
+        uint16_t first_sector_number = (workarea[1] & PICOBIN_PARTITION_LOCATION_FIRST_SECTOR_BITS) >> PICOBIN_PARTITION_LOCATION_FIRST_SECTOR_LSB;
+        uint16_t last_sector_number = (workarea[1] & PICOBIN_PARTITION_LOCATION_LAST_SECTOR_BITS) >> PICOBIN_PARTITION_LOCATION_LAST_SECTOR_LSB;
        data_start_addr = first_sector_number * FLASH_SECTOR_SIZE;
        data_end_addr = (last_sector_number + 1) * FLASH_SECTOR_SIZE;
        if (data_end_addr > FLASH_SIZE_BYTES) {
@@ -259,7 +257,7 @@ void low_flash_available(void) {
    mutex_exit(&mtx_flash);
 }

-page_flash_t *find_free_page(uintptr_t addr) {
+static page_flash_t *find_free_page(uintptr_t addr) {
    uintptr_t addr_alg = addr & -FLASH_SECTOR_SIZE;
    page_flash_t *p = NULL;
    for (int r = 0; r < TOTAL_FLASH_PAGES; r++) {
@@ -406,7 +404,7 @@ uintptr_t __phymarker_start = (uintptr_t)0x10100000;

 const uint64_t PHYSICAL_MARKER_MAGIC = 0x5049434F4B455953ULL; // "PICOKEYS"

-void phymarker_write() {
+void phymarker_write(void) {
    const uint64_t magic = *(uint64_t *)__phymarker_start;
    if (magic == PHYSICAL_MARKER_MAGIC) {
        return;
--- a/src/fs/otp.c
+++ b/src/fs/otp.c
@@ -260,6 +260,7 @@ typedef esp_err_t otp_ret_t;
 #endif

 bool otp_is_secure_boot_enabled(uint8_t *bootkey) {
+    (void)bootkey;
 #ifdef PICO_RP2350
    const uint8_t *crit1 = otp_buffer(OTP_DATA_CRIT1_ROW);
    if ((crit1[0] & (1 << OTP_DATA_CRIT1_SECURE_BOOT_ENABLE_LSB)) == 0) {
@@ -511,7 +512,7 @@ static otp_ret_t otp_migrate_key(uint16_t new_row, uint16_t old_row, uint16_t le
    return BOOTROM_ERROR_INVALID_STATE;
 }

-void otp_migrate_chaff() {
+static void otp_migrate_chaff(void) {
    otp_migrate_key(OTP_MKEK_ROW, OTP_OLD_MKEK_ROW, 32);
    otp_migrate_key(OTP_DEVK_ROW, OTP_OLD_DEVK_ROW, 32);
    otp_lock_page(OTP_MKEK_ROW >> 6);
@@ -564,7 +565,7 @@ void init_otp_files(void) {
    }
    OTP_READ(OTP_KEY_2, otp_key_2);

-    for (int i = 0; i < sizeof(write_otp)/sizeof(uint16_t); i++) {
+    for (size_t i = 0; i < sizeof(write_otp) / sizeof(write_otp[0]); i++) {
        if (write_otp[i] != 0xFFFF) {
 #if defined(PICO_RP2350)
            otp_lock_page(write_otp[i] >> 6);
--- a/src/fs/phy.c
+++ b/src/fs/phy.c
@@ -165,12 +165,12 @@ int phy_unserialize_data(const uint8_t *data, uint16_t len, phy_data_t *phy) {
    return PICOKEY_OK;
 }

-int phy_init() {
+int phy_init(void) {
    memset(&phy_data, 0, sizeof(phy_data_t));
    return phy_load();
 }

-int phy_save() {
+int phy_save(void) {
    uint8_t tmp[PHY_MAX_SIZE] = {0};
    uint16_t tmp_len = 0;
    int ret = phy_serialize_data(&phy_data, tmp, &tmp_len);
@@ -182,7 +182,7 @@ int phy_save() {
    return PICOKEY_OK;
 }

-int phy_load() {
+int phy_load(void) {
    if (file_has_data(ef_phy)) {
        return phy_unserialize_data(file_get_data(ef_phy), file_get_size(ef_phy), &phy_data);
    }
--- a/src/fs/phy.h
+++ b/src/fs/phy.h
@@ -104,9 +104,9 @@ typedef struct phy_data {
 #ifndef ENABLE_EMULATION
 extern int phy_serialize_data(const phy_data_t *phy, uint8_t *data, uint16_t *len);
 extern int phy_unserialize_data(const uint8_t *data, uint16_t len, phy_data_t *phy);
-extern int phy_init();
-extern int phy_save();
-extern int phy_load();
+extern int phy_init(void);
+extern int phy_save(void);
+extern int phy_load(void);
 extern phy_data_t phy_data;
 #endif

--- a/src/led/led.c
+++ b/src/led/led.c
@@ -35,11 +35,11 @@ void led_set_mode(uint32_t mode) {
    led_mode = mode;
 }

-uint32_t led_get_mode() {
+uint32_t led_get_mode(void) {
    return led_mode;
 }

-void led_blinking_task() {
+void led_blinking_task(void) {
 #if defined(PICO_PLATFORM) || defined(ESP_PLATFORM)
    static uint32_t start_ms = 0;
    static uint32_t stop_ms = 0;
@@ -81,7 +81,7 @@ void led_blinking_task() {
 #endif
 }

-void led_off_all() {
+void led_off_all(void) {
 #if defined(PICO_PLATFORM) || defined(ESP_PLATFORM)
    led_driver->set_color(LED_COLOR_OFF, 0, 0);
 #endif
@@ -93,11 +93,11 @@ extern led_driver_t led_driver_ws2812;
 extern led_driver_t led_driver_neopixel;
 extern led_driver_t led_driver_pimoroni;

-void led_driver_init_dummy() {
+static void led_driver_init_dummy(void) {
    // Do nothing
 }

-void led_driver_color_dummy(uint8_t color, uint32_t led_brightness, float progress) {
+static void led_driver_color_dummy(uint8_t color, uint32_t led_brightness, float progress) {
    (void)color;
    (void)led_brightness;
    (void)progress;
@@ -109,7 +109,7 @@ led_driver_t led_driver_dummy = {
    .set_color = led_driver_color_dummy,
 };

-void led_init() {
+void led_init(void) {
    led_driver = &led_driver_dummy;
 #if defined(PICO_PLATFORM) || defined(ESP_PLATFORM)
    // Guess default driver
--- a/src/led/led.h
+++ b/src/led/led.h
@@ -62,13 +62,13 @@ enum  {
 };

 extern void led_set_mode(uint32_t mode);
-extern uint32_t led_get_mode();
-extern void led_blinking_task();
-extern void led_off_all();
-extern void led_init();
+extern uint32_t led_get_mode(void);
+extern void led_blinking_task(void);
+extern void led_off_all(void);
+extern void led_init(void);

 typedef struct {
-    void (*init)();
+    void (*init)(void);
    void (*set_color)(uint8_t color, uint32_t led_brightness, float progress);
 } led_driver_t;

--- a/src/led/led_cyw43.c
+++ b/src/led/led_cyw43.c
@@ -21,7 +21,7 @@

 #include "pico/cyw43_arch.h"

-void led_driver_init_cyw43() {
+void led_driver_init_cyw43(void) {
    cyw43_arch_init();
 }

--- a/src/led/led_neopixel.c
+++ b/src/led/led_neopixel.c
@@ -45,7 +45,7 @@ tNeopixel pixel[] = {
    #define NEOPIXEL_PIN GPIO_NUM_27
 #endif

-void led_driver_init_neopixel() {
+void led_driver_init_neopixel(void) {
    uint8_t gpio = NEOPIXEL_PIN;
    if (phy_data.led_gpio_present) {
        gpio = phy_data.led_gpio;
--- a/src/led/led_pico.c
+++ b/src/led/led_pico.c
@@ -32,7 +32,7 @@ static uint8_t gpio = 0;
 #endif

 #if defined(PICO_PLATFORM) || defined(ESP_PLATFORM)
-void led_driver_init_pico() {
+static void led_driver_init_pico(void) {
    if (phy_data.led_gpio_present) {
        gpio = phy_data.led_gpio;
    }
@@ -40,7 +40,8 @@ void led_driver_init_pico() {
    gpio_set_dir(gpio, GPIO_OUT);
 }

-void led_driver_color_pico(uint8_t color, uint32_t led_brightness, float progress) {
+static void led_driver_color_pico(uint8_t color, uint32_t led_brightness, float progress) {
+    (void)color;
    (void)led_brightness;
    gpio_put(gpio, progress >= 0.5);
 }
--- a/src/led/led_pimoroni.c
+++ b/src/led/led_pimoroni.c
@@ -35,7 +35,7 @@ uint8_t pixel[][3] = {
    {0, 0, 0}  // 7: white
 };

-void led_driver_init_pimoroni() {
+static void led_driver_init_pimoroni(void) {
    if (phy_data.led_gpio_present) {
        gpio = phy_data.led_gpio;
    }
@@ -47,7 +47,8 @@ void led_driver_init_pimoroni() {
    gpio_set_dir(gpio+1, GPIO_OUT);
 }

-void led_driver_color_pimoroni(uint8_t color, uint32_t led_brightness, float progress) {
+static void led_driver_color_pimoroni(uint8_t color, uint32_t led_brightness, float progress) {
+    (void)led_brightness;
    if (progress < 0.5) {
        color = LED_COLOR_OFF;
    }
--- a/src/led/led_ws2812.c
+++ b/src/led/led_ws2812.c
@@ -69,7 +69,7 @@ static inline void ws2812_program_init(PIO pio, uint sm, uint offset, uint pin,
    pio_sm_set_enabled(pio, sm, true);
 }

-void led_driver_init_ws2812() {
+static void led_driver_init_ws2812(void) {
    PIO pio = pio0;
    int sm = 0;
    uint offset = pio_add_program(pio, &ws2812_program);
@@ -115,7 +115,7 @@ static inline void ws2812_put_pixel(uint32_t u32_pixel) {
    pio_sm_put_blocking(pio0, 0, u32_pixel << 8u);
 }

-void led_driver_color_ws2812(uint8_t color, uint32_t led_brightness, float progress) {
+static void led_driver_color_ws2812(uint8_t color, uint32_t led_brightness, float progress) {
    if (!(phy_data.opts & PHY_OPT_DIMM)) {
        progress = progress >= 0.5 ? 1 : 0;
    }
--- a/src/main.c
+++ b/src/main.c
@@ -41,12 +41,11 @@
 #endif

 #include "random.h"
+#include "hwrng.h"
 #include "apdu.h"
 #include "usb.h"
 #include "mbedtls/sha256.h"

-extern void do_flash();
-extern void low_flash_init();
 extern void init_otp_files(void);

 app_t apps[16];
@@ -105,7 +104,7 @@ int select_app(const uint8_t *aid, size_t aid_len) {

 int (*button_pressed_cb)(uint8_t) = NULL;

-void execute_tasks();
+static void execute_tasks(void);

 static bool req_button_pending = false;

@@ -146,12 +145,12 @@ int gettimeofday(struct timeval* tp, struct timezone* tzp)
 #endif
 #if !defined(ENABLE_EMULATION)
 #ifdef ESP_PLATFORM
-bool picok_board_button_read() {
+static bool picok_board_button_read(void) {
    int boot_state = gpio_get_level(BOOT_PIN);
    return boot_state == 0;
 }
 #elif defined(PICO_PLATFORM)
-bool __no_inline_not_in_flash_func(picok_get_bootsel_button)() {
+static bool __no_inline_not_in_flash_func(picok_get_bootsel_button)(void) {
    const uint CS_PIN_INDEX = 1;

    // Must disable interrupts, as interrupt handlers may be in flash, and we
@@ -168,7 +167,7 @@ bool __no_inline_not_in_flash_func(picok_get_bootsel_button)() {

    // The HI GPIO registers in SIO can observe and control the 6 QSPI pins.
    // Note the button pulls the pin *low* when pressed.
-#if PICO_RP2040
+#ifdef PICO_RP2040
    #define CS_BIT (1u << 1)
 #else
    #define CS_BIT SIO_GPIO_HI_IN_QSPI_CSN_BITS
@@ -185,11 +184,11 @@ bool __no_inline_not_in_flash_func(picok_get_bootsel_button)() {

    return button_state;
 }
-bool picok_board_button_read(void) {
+static bool picok_board_button_read(void) {
  return picok_get_bootsel_button();
 }
 #else
-bool picok_board_button_read(void) {
+static bool picok_board_button_read(void) {
    return true; // always unpressed
 }
 #endif
@@ -236,7 +235,7 @@ bool wait_button(void) {
    return timeout || cancel_button;
 }

-__attribute__((weak)) int picokey_init() {
+__attribute__((weak)) int picokey_init(void) {
    return 0;
 }

@@ -273,7 +272,7 @@ time_t get_rtc_time(void) {

 struct apdu apdu;

-void init_rtc() {
+static void init_rtc(void) {
 #ifdef PICO_PLATFORM
    struct timespec tv = {0};
    tv.tv_sec = 1577836800; // 2020-01-01
@@ -281,9 +280,7 @@ void init_rtc() {
 #endif
 }

-extern void hwrng_task();
-extern void usb_task();
-void execute_tasks()
+static void execute_tasks(void)
 {
 #if !defined(ENABLE_EMULATION) && !defined(ESP_PLATFORM)
    tud_task(); // tinyusb device task
@@ -292,7 +289,8 @@ void execute_tasks()
    led_blinking_task();
 }

-void core0_loop() {
+static void core0_loop(void *arg) {
+    (void)arg;
    while (1) {
        execute_tasks();
        hwrng_task();
@@ -331,7 +329,7 @@ pico_unique_board_id_t pico_serial;
 extern tinyusb_config_t tusb_cfg;
 extern const uint8_t desc_config[];
 TaskHandle_t hcore0 = NULL, hcore1 = NULL;
-int app_main() {
+int app_main(void) {
 #else
 #ifndef PICO_PLATFORM
 #define pico_get_unique_board_id(a) memset(a, 0, sizeof(*(a)))
@@ -405,7 +403,7 @@ int main(void) {
 #ifdef ESP_PLATFORM
    xTaskCreatePinnedToCore(core0_loop, "core0", 4096*ITF_TOTAL*2, NULL, CONFIG_TINYUSB_TASK_PRIORITY - 1, &hcore0, ESP32_CORE0);
 #else
-    core0_loop();
+    core0_loop(NULL);
 #endif

    return 0;
--- a/src/pico_keys.h
+++ b/src/pico_keys.h
@@ -71,6 +71,7 @@
 #endif

 extern bool wait_button(void);
+extern int picokey_init(void);

 extern void low_flash_init_core1(void);

--- a/src/rescue.c
+++ b/src/rescue.c
@@ -29,8 +29,8 @@ extern char __flash_binary_start;
 extern char __flash_binary_end;
 #endif

-int rescue_process_apdu();
-int rescue_unload();
+static int rescue_process_apdu(void);
+static int rescue_unload(void);

 const uint8_t rescue_aid[] = {
    8,
@@ -55,7 +55,7 @@ extern uint8_t PICO_PRODUCT;
 extern uint8_t PICO_VERSION_MAJOR;
 extern uint8_t PICO_VERSION_MINOR;

-int rescue_select(app_t *a, uint8_t force) {
+static int rescue_select(app_t *a, uint8_t force) {
    a->process_apdu = rescue_process_apdu;
    a->unload = rescue_unload;
    res_APDU_size = 0;
@@ -76,7 +76,7 @@ INITIALIZER ( rescue_ctor ) {
    register_app(rescue_select, rescue_aid);
 }

-int rescue_unload() {
+static int rescue_unload(void) {
    return PICOKEY_OK;
 }

@@ -112,7 +112,7 @@ static int load_internal_keydev(mbedtls_ecp_keypair *ecp, mbedtls_ecp_group_id e
    return PICOKEY_OK;
 }

-int cmd_keydev_sign() {
+static int cmd_keydev_sign(void) {
    uint8_t p1 = P1(apdu);
    if (p1 == 0x01) {
        if (apdu.nc != 32) {
@@ -210,7 +210,7 @@ int cmd_keydev_sign() {
 }

 // Blocking CORE1
-void led_3_blinks() {
+static void led_3_blinks(void) {
 #ifndef ENABLE_EMULATION
    uint32_t mode = led_get_mode();
    led_set_mode(MODE_PROCESSING);
@@ -219,7 +219,7 @@ void led_3_blinks() {
 #endif
 }

-int cmd_write() {
+static int cmd_write(void) {
    if (apdu.nc < 2) {
        return SW_WRONG_LENGTH();
    }
@@ -268,7 +268,7 @@ int cmd_write() {
    return SW_OK();
 }

-int cmd_read() {
+static int cmd_read(void) {
    if (apdu.nc != 0) {
        return SW_WRONG_LENGTH();
    }
@@ -340,7 +340,7 @@ int cmd_read() {
 }

 #if defined(PICO_RP2350) || defined(ESP_PLATFORM)
-int cmd_secure() {
+static int cmd_secure(void) {
    if (apdu.nc != 0) {
        return SW_WRONG_LENGTH();
    }
@@ -358,7 +358,7 @@ int cmd_secure() {
 #endif

 #ifdef PICO_PLATFORM
-int cmd_reboot_bootsel() {
+static int cmd_reboot_bootsel(void) {
    if (apdu.nc != 0) {
        return SW_WRONG_LENGTH();
    }
@@ -398,7 +398,7 @@ static const cmd_t cmds[] = {
    { 0x00, 0x0 }
 };

-int rescue_process_apdu() {
+static int rescue_process_apdu(void) {
    if (CLA(apdu) != 0x80) {
        return SW_CLA_NOT_SUPPORTED();
    }
--- a/src/rng/hwrng.c
+++ b/src/rng/hwrng.c
@@ -18,10 +18,10 @@
 #include <stdint.h>
 #include <string.h>
 #include <stdio.h>
+#include "hwrng.h"

 #if defined(PICO_PLATFORM)
 #include "pico/stdlib.h"
-#include "hwrng.h"
 #include "bsp/board.h"
 #include "pico/rand.h"
 #elif defined(ESP_PLATFORM)
@@ -35,7 +35,7 @@
 #include "board.h"
 #endif

-void hwrng_start() {
+static void hwrng_start(void) {
 #if defined(ENABLE_EMULATION)
    srand(time(0));
 #elif defined(ESP_PLATFORM)
@@ -46,13 +46,13 @@ void hwrng_start() {
 static uint64_t random_word = 0xcbf29ce484222325;
 static uint8_t hwrng_mix_round = 0;

-static void hwrng_mix_init() {
+static void hwrng_mix_init(void) {
    random_word = 0xcbf29ce484222325;
    hwrng_mix_round = 0;
 }

 /* Here, we assume a little endian architecture.  */
-static int hwrng_mix_process() {
+static int hwrng_mix_process(void) {
    if (hwrng_mix_round == 0) {
        hwrng_mix_init();
    }
@@ -119,7 +119,7 @@ static uint32_t hwrng_buf_del(struct hwrng_buf *rb) {

 static struct hwrng_buf ring_buffer;

-void *hwrng_task() {
+void *hwrng_task(void) {
    struct hwrng_buf *rb = &ring_buffer;

    int n;
@@ -154,7 +154,7 @@ void hwrng_flush(void) {
    }
 }

-uint32_t hwrng_get() {
+uint32_t hwrng_get(void) {
    struct hwrng_buf *rb = &ring_buffer;
    uint32_t v;

@@ -166,7 +166,7 @@ uint32_t hwrng_get() {
    return v;
 }

-void hwrng_wait_full() {
+void hwrng_wait_full(void) {
    struct hwrng_buf *rb = &ring_buffer;
 #ifdef ESP_PLATFORM
    uint8_t core = xTaskGetCurrentTaskHandle() == hcore1 ? 1 : 0;
--- a/src/rng/hwrng.h
+++ b/src/rng/hwrng.h
@@ -20,8 +20,9 @@
 #include <stdint.h>

 void hwrng_init(uint32_t *buf, uint8_t size);
-uint32_t hwrng_get();
+uint32_t hwrng_get(void);
 void hwrng_flush(void);
-void hwrng_wait_full();
+void hwrng_wait_full(void);
+void *hwrng_task(void);

 #endif
--- a/src/rng/random.c
+++ b/src/rng/random.c
@@ -24,6 +24,7 @@
 #include <string.h>

 #include "hwrng.h"
+#include "random.h"

 #define RANDOM_BYTES_LENGTH 32
 static uint32_t random_word[RANDOM_BYTES_LENGTH / sizeof(uint32_t)];
--- a/src/usb/ccid/ccid.c
+++ b/src/usb/ccid/ccid.c
@@ -97,21 +97,22 @@ static uint8_t itf_num;
 static usb_buffer_t *ccid_rx = NULL, *ccid_tx = NULL;

 int driver_process_usb_packet_ccid(uint8_t itf, uint16_t rx_read);
+void ccid_init(void);
+void ccid_task(void);
+#ifdef ENABLE_EMULATION
+void tud_vendor_rx_cb(uint8_t itf, const uint8_t *buffer, uint16_t bufsize);
+#endif

-void ccid_write_offset(uint8_t itf, uint16_t size, uint16_t offset) {
+static void ccid_write_offset(uint8_t itf, uint16_t size, uint16_t offset) {
    ccid_tx[itf].w_ptr += size + offset;
    ccid_tx[itf].r_ptr += offset;
 }

-void ccid_write(uint8_t itf, uint16_t size) {
-    ccid_write_offset(itf, size, 0);
-}
-
 ccid_header_t **ccid_response = NULL;
 ccid_header_t **ccid_resp_fast = NULL;
 ccid_header_t **ccid_header = NULL;

-uint8_t sc_itf_to_usb_itf(uint8_t itf) {
+static uint8_t sc_itf_to_usb_itf(uint8_t itf) {
    if (itf == ITF_SC_CCID) {
        return ITF_CCID;
    }
@@ -121,7 +122,7 @@ uint8_t sc_itf_to_usb_itf(uint8_t itf) {
    return itf;
 }

-void ccid_init_buffers() {
+static void ccid_init_buffers(void) {
    if (ITF_SC_TOTAL == 0) {
        return;
    }
@@ -142,7 +143,7 @@ void ccid_init_buffers() {
    }
 }

-int driver_init_ccid(uint8_t itf) {
+static int driver_init_ccid(uint8_t itf) {
    ccid_header[itf] = (ccid_header_t *) (ccid_rx[itf].buffer + ccid_rx[itf].r_ptr);
    ccid_resp_fast[itf] = (ccid_header_t *) (ccid_tx[itf].buffer + sizeof(ccid_tx[itf].buffer) - 64);
 //    apdu.header = &ccid_header->apdu;
@@ -157,6 +158,8 @@ int driver_init_ccid(uint8_t itf) {
 }

 void tud_vendor_rx_cb(uint8_t itf, const uint8_t *buffer, uint16_t bufsize) {
+    (void)buffer;
+    (void)bufsize;
    uint32_t len = tud_vendor_n_available(itf);
    do {
        uint16_t tlen = 0;
@@ -173,7 +176,7 @@ void tud_vendor_rx_cb(uint8_t itf, const uint8_t *buffer, uint16_t bufsize) {
    } while (len > 0);
 }

-int driver_write_ccid(uint8_t itf, const uint8_t *tx_buffer, uint16_t buffer_size) {
+static int driver_write_ccid(uint8_t itf, const uint8_t *tx_buffer, uint16_t buffer_size) {
    if (*tx_buffer != 0x81) {
        DEBUG_PAYLOAD(tx_buffer, buffer_size);
    }
@@ -193,7 +196,7 @@ int driver_write_ccid(uint8_t itf, const uint8_t *tx_buffer, uint16_t buffer_siz
    return (int)written;
 }

-int ccid_write_fast(uint8_t itf, const uint8_t *buffer, uint16_t buffer_size) {
+static int ccid_write_fast(uint8_t itf, const uint8_t *buffer, uint16_t buffer_size) {
    return driver_write_ccid(itf, buffer, buffer_size);
 }

@@ -316,7 +319,7 @@ int driver_process_usb_packet_ccid(uint8_t itf, uint16_t rx_read) {
    return 0;
 }

-void driver_exec_timeout_ccid(uint8_t itf) {
+static void driver_exec_timeout_ccid(uint8_t itf) {
    ccid_resp_fast[itf]->bMessageType = CCID_DATA_BLOCK_RET;
    ccid_resp_fast[itf]->dwLength = 0;
    ccid_resp_fast[itf]->bSlot = 0;
@@ -341,7 +344,7 @@ void driver_exec_finished_cont_ccid(uint8_t itf, uint16_t size_next, uint16_t of
    ccid_write_offset(itf, size_next+10, offset);
 }

-void ccid_task() {
+void ccid_task(void) {
    for (int itf = 0; itf < ITF_SC_TOTAL; itf++) {
        int status = card_status(sc_itf_to_usb_itf(itf));
        if (status == PICOKEY_OK) {
@@ -358,7 +361,7 @@ void ccid_task() {
    }
 }

-void ccid_init() {
+void ccid_init(void) {
    ccid_init_buffers();
 }

--- a/src/usb/emulation/emulation.c
+++ b/src/usb/emulation/emulation.c
@@ -60,7 +60,7 @@ extern int cbor_parse(uint8_t cmd, const uint8_t *data, size_t len);
 pthread_t hcore0, hcore1;

 #ifndef _MSC_VER
-int msleep(long msec) {
+static int msleep(long msec) {
    struct timespec ts;
    int res;

@@ -80,7 +80,7 @@ int msleep(long msec) {
 }
 #endif

-int emul_init(char *host, uint16_t port) {
+int emul_init(const char *host, uint16_t port) {
    struct sockaddr_in serv_addr;
    fprintf(stderr, "\n Starting emulation envionrment\n");
 #ifdef _MSC_VER
@@ -167,7 +167,7 @@ int emul_init(char *host, uint16_t port) {
    return 0;
 }

-socket_t get_sock_itf(uint8_t itf) {
+static socket_t get_sock_itf(uint8_t itf) {
 #ifdef USB_ITF_CCID
    if (itf == ITF_CCID) {
        return ccid_sock;
@@ -333,7 +333,7 @@ uint16_t emul_read(uint8_t itf) {
    return emul_rx_size;
 }

-void emul_task() {
+void emul_task(void) {
 #ifdef USB_ITF_CCID
    emul_read(ITF_CCID);
 #endif
--- a/src/usb/emulation/emulation.h
+++ b/src/usb/emulation/emulation.h
@@ -25,11 +25,12 @@
 #include <stdbool.h>

 #define USB_BUFFER_SIZE 4096
-extern int emul_init(char *host, uint16_t port);
+extern int emul_init(const char *host, uint16_t port);
 extern uint8_t emul_rx[USB_BUFFER_SIZE];
 extern uint16_t emul_rx_size, emul_tx_size;
 extern uint16_t driver_write_emul(uint8_t itf, const uint8_t *buffer, uint16_t buffer_size);
 extern uint16_t emul_read(uint8_t itf);
+extern void emul_task(void);

 #ifdef USB_ITF_HID
 typedef uint8_t hid_report_type_t;
--- a/src/usb/hid/ctap_hid.h
+++ b/src/usb/hid/ctap_hid.h
@@ -158,6 +158,9 @@ typedef struct {

 extern void add_keyboard_buffer(const uint8_t *, size_t, bool);
 extern void append_keyboard_buffer(const uint8_t *data, size_t data_len);
+extern int driver_init_hid(void);
+extern int ctap_error(uint8_t error);
+extern uint16_t *get_send_buffer_size(uint8_t itf);

 extern bool is_nk;

--- a/src/usb/hid/hid.c
+++ b/src/usb/hid/hid.c
@@ -31,10 +31,10 @@ static portMUX_TYPE mutex = portMUX_INITIALIZER_UNLOCKED;
 #include "apdu.h"
 #include "usb.h"

-extern void init_fido();
+extern void init_fido(void);
 bool is_nk = false;
-uint8_t (*get_version_major)() = NULL;
-uint8_t (*get_version_minor)() = NULL;
+uint8_t (*get_version_major)(void) = NULL;
+uint8_t (*get_version_minor)(void) = NULL;

 static usb_buffer_t *hid_rx = NULL, *hid_tx = NULL;

@@ -51,12 +51,18 @@ static uint16_t *send_buffer_size = NULL;
 static write_status_t *last_write_result = NULL;

 CTAPHID_FRAME *ctap_req = NULL, *ctap_resp = NULL;
-void send_keepalive();
+static void send_keepalive(void);
 int driver_process_usb_packet_hid(uint16_t read);
 int driver_write_hid(uint8_t itf, const uint8_t *buffer, uint16_t buffer_size);
-int driver_process_usb_nopacket_hid();
+static int driver_process_usb_nopacket_hid(void);
+void hid_init(void);
+void hid_task(void);
+#ifdef ENABLE_EMULATION
+uint16_t tud_hid_get_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t *buffer, uint16_t reqlen);
+void tud_hid_set_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t const *buffer, uint16_t bufsize);
+#endif

-void hid_init() {
+void hid_init(void) {
    if (ITF_HID_TOTAL == 0) {
        return;
    }
@@ -74,7 +80,7 @@ void hid_init() {
    }
 }

-int driver_init_hid() {
+int driver_init_hid(void) {
 #ifndef ENABLE_EMULATION
    static bool _init = false;
    if (_init == false) {
@@ -98,10 +104,6 @@ int driver_init_hid() {
    return 0;
 }

-uint16_t *get_send_buffer_size(uint8_t itf) {
-    return &send_buffer_size[itf];
-}
-
 //--------------------------------------------------------------------+
 // USB HID
 //--------------------------------------------------------------------+
@@ -127,7 +129,7 @@ uint16_t tud_hid_get_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t
    return reqlen;
 }

-uint32_t hid_write_offset(uint16_t size, uint16_t offset) {
+static uint32_t hid_write_offset(uint16_t size, uint16_t offset) {
    if (hid_tx[ITF_HID_CTAP].buffer[offset] != 0x81) {
        DEBUG_PAYLOAD(&hid_tx[ITF_HID_CTAP].buffer[offset], size);
    }
@@ -136,7 +138,7 @@ uint32_t hid_write_offset(uint16_t size, uint16_t offset) {
    return size;
 }

-uint32_t hid_write(uint16_t size) {
+static uint32_t hid_write(uint16_t size) {
    return hid_write_offset(size, 0);
 }

@@ -309,7 +311,7 @@ uint8_t thread_type = 0; //1 is APDU, 2 is CBOR
 extern bool cancel_button;
 extern int cbor_process(uint8_t last_cmd, const uint8_t *data, size_t len);

-int driver_process_usb_nopacket_hid() {
+int driver_process_usb_nopacket_hid(void) {
    if (last_packet_time > 0 && last_packet_time + 500 < board_millis()) {
        ctap_error(CTAP1_ERR_MSG_TIMEOUT);
        last_packet_time = 0;
@@ -321,6 +323,10 @@ int driver_process_usb_nopacket_hid() {
 extern const uint8_t fido_aid[], u2f_aid[], oath_aid[];
 extern void *cbor_thread(void *);

+uint16_t *get_send_buffer_size(uint8_t itf) {
+    return &send_buffer_size[itf];
+}
+
 int driver_process_usb_packet_hid(uint16_t read) {
    int apdu_sent = 0;
    if (read >= 5) {
@@ -549,7 +555,7 @@ int driver_process_usb_packet_hid(uint16_t read) {
    return apdu_sent;
 }

-void send_keepalive() {
+static void send_keepalive(void) {
    if (thread_type == 1) {
        return;
    }
@@ -593,7 +599,7 @@ void driver_exec_finished_cont_hid(uint8_t itf, uint16_t size_next, uint16_t off
    }
 }

-void hid_task() {
+void hid_task(void) {
 #ifdef ENABLE_EMULATION
    uint16_t rx_len = emul_read(ITF_HID);
    if (rx_len) {
--- a/src/usb/usb.c
+++ b/src/usb/usb.c
@@ -40,7 +40,6 @@ static uint8_t card_locked_itf = 0; // no locked
 static void *(*card_locked_func)(void *) = NULL;
 #ifndef ENABLE_EMULATION
 static mutex_t mutex;
-extern void usb_desc_setup();
 #endif
 #if !defined(PICO_PLATFORM) && !defined(ENABLE_EMULATION) && !defined(ESP_PLATFORM)
 #ifdef _MSC_VER
@@ -53,14 +52,14 @@ pthread_t hcore0, hcore1;
    uint8_t ITF_HID_CTAP = ITF_INVALID, ITF_HID_KB = ITF_INVALID;
    uint8_t ITF_HID = ITF_INVALID, ITF_KEYBOARD = ITF_INVALID;
    uint8_t ITF_HID_TOTAL = 0;
-    extern void hid_init();
+    extern void hid_init(void);
 #endif

 #ifdef USB_ITF_CCID
    uint8_t ITF_SC_CCID = ITF_INVALID, ITF_SC_WCID = ITF_INVALID;
    uint8_t ITF_CCID = ITF_INVALID, ITF_WCID = ITF_INVALID;
    uint8_t ITF_SC_TOTAL = 0;
-    extern void ccid_init();
+    extern void ccid_init(void);
 #endif
 uint8_t ITF_TOTAL = 0;

@@ -75,7 +74,7 @@ queue_t card_to_usb_q = {0};
 extern tusb_desc_device_t desc_device;
 extern char *string_desc_itf[4], *string_desc_arr[];
 #endif
-void usb_init()
+void usb_init(void)
 {
 #ifndef ENABLE_EMULATION
    if (phy_data.vidpid_present) {
@@ -158,15 +157,15 @@ void usb_init()
 }

 uint32_t timeout = 0;
-void timeout_stop() {
+void timeout_stop(void) {
    timeout = 0;
 }

-void timeout_start() {
+void timeout_start(void) {
    timeout = board_millis();
 }

-bool is_busy() {
+bool is_busy(void) {
    return timeout > 0;
 }

@@ -187,8 +186,7 @@ void usb_send_event(uint32_t flag) {
 #endif
 }

-extern void low_flash_init();
-void card_init_core1() {
+void card_init_core1(void) {
    low_flash_init_core1();
 }

@@ -210,7 +208,7 @@ void card_start(uint8_t itf, void *(*func)(void *)) {
    }
 }

-void card_exit() {
+void card_exit(void) {
    if (card_locked_itf != ITF_TOTAL || card_locked_func != NULL) {
        usb_send_event(EV_EXIT);
        uint32_t m;
@@ -238,10 +236,10 @@ void card_exit() {
    card_locked_itf = ITF_TOTAL;
    card_locked_func = NULL;
 }
-extern void hid_task();
-extern void ccid_task();
-extern void emul_task();
-void usb_task() {
+extern void hid_task(void);
+extern void ccid_task(void);
+extern void emul_task(void);
+void usb_task(void) {
 #ifdef USB_ITF_HID
    hid_task();
 #endif
--- a/src/usb/usb.h
+++ b/src/usb/usb.h
@@ -73,23 +73,24 @@ enum {
 #define TUSB_SMARTCARD_CCID_EPS 3
 #endif

-extern void usb_task();
+extern void usb_task(void);
 extern queue_t usb_to_card_q;
 extern queue_t card_to_usb_q;

 extern void card_start(uint8_t, void *(*func)(void *));
-extern void card_exit();
+extern void card_exit(void);
 extern int card_status(uint8_t itf);
-extern void usb_init();
+extern void usb_init(void);

 extern uint16_t finished_data_size;
 extern void usb_set_timeout_counter(uint8_t itf, uint32_t v);
-extern void card_init_core1();
+extern void card_init_core1(void);

 extern void usb_send_event(uint32_t flag);
-extern void timeout_stop();
-extern void timeout_start();
-extern bool is_busy();
+extern void timeout_stop(void);
+extern void timeout_start(void);
+extern bool is_busy(void);
+extern void usb_desc_setup(void);

 #ifdef USB_ITF_HID
 extern void driver_exec_finished_hid(uint16_t size_next);
--- a/src/usb/usb_descriptors.c
+++ b/src/usb/usb_descriptors.c
@@ -160,7 +160,7 @@ uint8_t const *tud_hid_descriptor_report_cb(uint8_t itf) {
 }
 #endif

-void usb_desc_setup() {
+void usb_desc_setup(void) {
    desc_config[4] = ITF_TOTAL;
    TUSB_DESC_TOTAL_LEN = TUD_CONFIG_DESC_LEN;
    uint8_t *p = desc_config + TUD_CONFIG_DESC_LEN;