Embedded SDK
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Standard Application Framework

Table of Contents

Introduction

lib_standard_app is a C framework that provides the common infrastructure every Ledger application needs:

  • An APDU I/O loop,
  • Command parsing,
  • Buffer and
  • Integer helpers,
  • BIP32 key derivation,
  • Cryptographic signing wrappers,
  • NVM storage, and
  • Exchange-swap integration.

All public symbols that have a sensible default are declared WEAK so any application can override them without relinking the whole library.

The only mandatory symbol an application must provide is:

void app_main(void);


Architecture Overview

┌────────────────────────────────────────────────────────────────────────────────────┐
│ BOOT main.c · main_std_app.h [all symbols: WEAK] │
│ │
│ arg0 == 0 → standalone_app_main() → common_app_init() → app_main() │
│ arg0 != 0 → library_app_main() [HAVE_SWAP] │
│ ├─ SIGN_TRANSACTION → swap_copy_transaction_parameters() │
│ ├─ CHECK_ADDRESS → swap_handle_check_address() │
│ └─ GET_PRINTABLE_AMOUNT → swap_handle_get_printable_amount() │
└──────────────────────────────────────────────────┬─────────────────────────────────┘
│
┌──────────────────────────────────────────────────▼─────────────────────────────────┐
│ APPLICATION app_main() — coin-application code (mandatory) │
│ │
│ io_init() │
│ for (;;) { │
│ len = io_recv_command() ◄──── I/O layer │
│ apdu_parser(buf, len) → command_t ◄──── APDU Parser │
│ dispatch(cmd) → handler() │
│ io_send_sw(sw) / io_send_response_*(…, sw) ────► I/O layer │
│ } │
└──────────────────────┬───────────────────────────────┬─────────────────────────────┘
│ │
┌───────────────────▼──────────────────┐ ┌─────────▼──────────────────────────┐ ┌───────────────────────────────────────────┐
│ I/O io.h · io.c │ │ ┌──────────────────────────────┐ │ │ HELPERS │
│ │ │ │ APDU PARSER parser.h / .c │ │ │ │
│ io_init() │ │ │ │ │ │ ┌─────────────────────────────────────┐ │
│ io_recv_command() → int │ │ │ apdu_parser(cmd, buf, len) │ │ │ │ BUFFER buffer.h/.c │ │
│ io_send_sw(sw) │ │ │ command_t { │ │ │ │ buffer_t { ptr, size, offset } │ │
│ io_send_response_buffers(…, sw) │ │ │ cla ins p1 p2 lc *data │ │ │ │ buffer_create() │ │
│ io_send_response_pointer(…, sw) │ │ │ } │ │ │ │ buffer_read_u8/u16/u32/u64() │ │
│ io_send_response_buffer(…, sw) │ │ │ offsets.h: OFFSET_* │ │ │ │ buffer_read_varint/bip32_path() │ │
│ app_ticker_event_callback() [WEAK] │ │ └──────────────────────────────┘ │ │ │ buffer_read_bytes() · peek() │ │
│ │ │ │ │ │ buffer_write_u8/u16/u32/u64() │ │
│ ── transports ──────────────────── │ │ ┌──────────────────────────────┐ │ │ │ buffer_write_bytes() │ │
│ USB · BLE · NFC · seproxyhal events │ │ │ SWAP [HAVE_SWAP] │ │ │ │ buffer_seek_set/cur/end() │ │
└──────────────────────────────────────┘ │ │ swap.h │ │ │ │ buffer_copy() · buffer_move() │ │
│ │ swap_utils.h/.c │ │ │ └─────────────┬───────────────────────┘ │
│ │ swap_err_code_helpers.h/.c │ │ │ │ uses │
│ │ │ │ │ ┌─────────────▼───────────────────────┐ │
│ │ Coin app callbacks: │ │ │ │ LOW-LEVEL R/W (internal) │ │
│ │ check_address() │ │ │ │ read.h/.c · write.h/.c │ │
│ │ get_printable_amount() │ │ │ │ read/write_u16/u32/u64_be/le() │ │
│ │ copy_tx_params() │ │ │ │ (bounds-unchecked, internal) │ │
│ │ Helpers: │ │ │ └─────────────────────────────────────┘ │
│ │ swap_str_to_u64() │ │ │ │
│ │ swap_parse_config() │ │ │ ┌─────────────────────────────────────┐ │
│ │ send_swap_error_*() │ │ │ │ BIP32 bip32.h/.c │ │
│ └──────────────────────────────┘ │ │ │ path_bip32_t { len, path[10] } │ │
└────────────────────────────────────┘ │ │ bip32_path_read() │ │
│ │ bip32_path_format[_simple]() │ │
│ └─────────────────────────────────────┘ │
│ │
│ ┌─────────────────────────────────────┐ │
│ │ ENCODING │ │
│ │ base58.h/.c │ │
│ │ base58_encode() / decode() │ │
│ │ varint.h/.c │ │
│ │ varint_read/write/size() │ │
│ │ format.h/.c │ │
│ │ format_i64() / format_u64() │ │
│ │ format_fpu64[_trimmed]() │ │
│ │ format_hex() │ │
│ └─────────────────────────────────────┘ │
│ │
│ ┌─────────────────────────────────────┐ │
│ │ CRYPTO crypto_helpers.h/.c │ │
│ │ WARN_UNUSED_RESULT · cx_err_t │ │
│ │ explicit_bzero on success/fail │ │
│ │ bip32_derive_init_privkey_256() │ │
│ │ bip32_derive_get_pubkey_256() │ │
│ │ bip32_derive_ecdsa_sign_*256() │ │
│ │ bip32_derive_eddsa_sign_*256() │ │
│ │ [+ _with_seed_ variants] │ │
│ └─────────────────────────────────────┘ │
│ │
│ ┌─────────────────────────────────────┐ │
│ │ NVM STORAGE [HAVE_APP_STORAGE] │ │
│ │ app_storage.h/.c │ │
│ │ CRC32-protected NVM area │ │
│ │ app_storage_write/read/reset() │ │
│ │ get/incr_data_version() │ │
│ │ get_size() · get_properties() │ │
│ │ get_size() · get_properties() │ │
│ └─────────────────────────────────────┘ │
└───────────────────────────────────────────┘
app_storage_write
int32_t app_storage_write(const void *buf, uint32_t nbyte, uint32_t offset)
base58_encode
int base58_encode(const uint8_t *in, size_t in_len, char *out, size_t out_len)
Definition base58.c:108
bip32_path_format
bool bip32_path_format(const uint32_t *bip32_path, size_t bip32_path_len, char *out, size_t out_len)
Definition bip32.c:49
bip32_path_read
bool bip32_path_read(const uint8_t *in, size_t in_len, uint32_t *out, size_t out_len)
Definition bip32.c:26
buffer_read_varint
bool buffer_read_varint(buffer_t *buffer, uint64_t *value)
Definition buffer.c:130
buffer_copy
bool buffer_copy(const buffer_t *buffer, uint8_t *out, size_t out_len)
Definition buffer.c:180
buffer_write_bytes
bool buffer_write_bytes(buffer_t *buffer, const uint8_t *data, size_t n)
Definition buffer.c:294
buffer_seek_set
bool buffer_seek_set(buffer_t *buffer, size_t offset)
Definition buffer.c:34
buffer_write_u8
bool buffer_write_u8(buffer_t *buffer, uint8_t value)
Definition buffer.c:230
buffer_read_bytes
WEAK bool buffer_read_bytes(buffer_t *buffer, uint8_t *out, size_t n)
Definition buffer.c:218
buffer_move
bool buffer_move(buffer_t *buffer, uint8_t *out, size_t out_len)
Definition buffer.c:191
buffer_read_u8
bool buffer_read_u8(buffer_t *buffer, uint8_t *value)
Definition buffer.c:68
buffer_create
static buffer_t buffer_create(void *ptr, size_t size)
Definition buffer.h:354
bip32_derive_init_privkey_256
static WARN_UNUSED_RESULT cx_err_t bip32_derive_init_privkey_256(cx_curve_t curve, const uint32_t *path, size_t path_len, cx_ecfp_256_private_key_t *privkey, uint8_t *chain_code)
Gets the private key from the device seed using the specified bip32 path.
Definition crypto_helpers.h:60
bip32_derive_get_pubkey_256
static WARN_UNUSED_RESULT cx_err_t bip32_derive_get_pubkey_256(cx_curve_t curve, const uint32_t *path, size_t path_len, uint8_t raw_pubkey[static 65], uint8_t *chain_code, cx_md_t hashID)
Gets the public key from the device seed using the specified bip32 path.
Definition crypto_helpers.h:127
format_u64
bool format_u64(char *out, size_t outLen, uint64_t in)
Definition format.c:65
format_hex
int format_hex(const uint8_t *in, size_t in_len, char *out, size_t out_len)
Definition format.c:156
format_i64
bool format_i64(char *dst, size_t dst_len, const int64_t value)
Definition format.c:24
format_fpu64
bool format_fpu64(char *dst, size_t dst_len, const uint64_t value, uint8_t decimals)
Definition format.c:101
io_send_response_buffers
WEAK int io_send_response_buffers(const buffer_t *rdatalist, size_t count, uint16_t sw)
Definition io.c:116
io_init
WEAK void io_init()
Definition io.c:86
io_recv_command
WEAK int io_recv_command()
Definition io.c:91
app_ticker_event_callback
WEAK void app_ticker_event_callback(void)
Definition io.c:60
io_send_sw
static int io_send_sw(uint16_t sw)
Definition io.h:112
io_send_response_buffer
static int io_send_response_buffer(const buffer_t *rdata, uint16_t sw)
Definition io.h:97
io_send_response_pointer
static int io_send_response_pointer(const uint8_t *ptr, size_t size, uint16_t sw)
Definition io.h:79
WEAK
#define WEAK
Definition macros.h:12
main
WEAK BOOT_SECTION int main(int arg0)
Definition main.c:167
standalone_app_main
WEAK void standalone_app_main(void)
Definition main.c:59
common_app_init
WEAK void common_app_init(void)
Definition main.c:48
library_app_main
WEAK void library_app_main(void)
apdu_parser
bool apdu_parser(command_t *cmd, uint8_t *buf, size_t buf_len)
Definition parser.c:25
buffer_t
Definition buffer.h:21
command_t
Definition parser.h:10
path_bip32_t
Definition bip32.h:17
swap_handle_get_printable_amount
void swap_handle_get_printable_amount(get_printable_amount_parameters_t *params)
swap_handle_check_address
void swap_handle_check_address(check_address_parameters_t *params)
swap_copy_transaction_parameters
bool swap_copy_transaction_parameters(create_transaction_parameters_t *sign_transaction_params)
SIGN_TRANSACTION
#define SIGN_TRANSACTION
Definition swap_lib_calls.h:20
CHECK_ADDRESS
#define CHECK_ADDRESS
Definition swap_lib_calls.h:21
GET_PRINTABLE_AMOUNT
#define GET_PRINTABLE_AMOUNT
Definition swap_lib_calls.h:22
swap_parse_config
bool swap_parse_config(const uint8_t *config, uint8_t config_len, char *ticker, uint8_t ticker_buf_len, uint8_t *decimals)
Definition swap_utils.c:43
swap_str_to_u64
bool swap_str_to_u64(const uint8_t *src, size_t length, uint64_t *result)
Definition swap_utils.c:29
varint_read
int varint_read(const uint8_t *in, size_t in_len, uint64_t *value)
Definition varint.c:42


Application Entry Point

Files: main.c, main_std_app.h

Provides the main() entry point (placed in .boot). On startup it detects the launch mode:

Function Description
app_exit() Stops I/O and returns to the dashboard via os_sched_exit(-1). Declared noreturn.
common_app_init() Initialises UX, seproxyhal I/O, and — when HAVE_APP_STORAGE is defined — NVM storage.
standalone_app_main() Default standalone entry; resets swap globals, calls common_app_init() then app_main().
library_app_main() Exchange library dispatcher (requires HAVE_SWAP).
Note
All four are WEAK and may be overridden by the application.


I/O Layer

Files: io.h, io.c

A portable APDU I/O layer on top of seproxyhal.
The typical receive/dispatch loop in app_main() looks like:

void app_main(void) {
io_init();
for (;;) {
int len = io_recv_command();
if (len < 0) break;
// parse and handle the APDU stored in G_io_apdu_buffer …
io_send_sw(SW_OK);
}
}
Function Description
io_init() Arms the deferred I/O start; must be called once before the first io_recv_command().
io_recv_command() Blocks until a full APDU is received into G_io_apdu_buffer; returns byte count or -1.
io_send_response_buffers(rdatalist, count, sw) Assembles a response from an array of buffer_t fragments, appends sw, and transmits.
io_send_response_pointer(ptr, size, sw) Convenience wrapper for a raw pointer.
io_send_response_buffer(rdata, sw) Convenience wrapper for a single buffer_t.
io_send_sw(sw) Sends a status-word-only response (no data).
app_ticker_event_callback() Empty WEAK hook called on each ticker event; override to receive periodic ticks.
Note
When HAVE_SWAP is active and G_swap_response_ready == true, io_send_response_buffers() signals Exchange and calls os_lib_end() instead of returning normally.


APDU Parser

Files: parser.h, parser.c

Parses a raw APDU byte buffer into a structured command_t:

typedef struct {
uint8_t cla;
uint8_t ins;
uint8_t p1;
uint8_t p2;
uint8_t lc;
uint8_t *data;
} command_t;
Function Description
apdu_parser(cmd, buf, buf_len) Fills cmd from buf. Returns false if the buffer is too short or the declared Lc doesn't match the actual remaining bytes.

Byte-offset constants (OFFSET_CLA = 0, OFFSET_INS = 1, … OFFSET_CDATA = 5) are defined in offsets.h.


Buffer Abstraction

Files: buffer.h, buffer.c

A cursor-based byte-buffer API. All operations advance (or set) the internal offset field and return false on a bounds violation.

typedef struct {
uint8_t *ptr;
size_t size;
size_t offset;
} buffer_t;
// Quick construction
buffer_t b = buffer_create(my_array, sizeof(my_array));

Reading

Function Description
buffer_can_read(b, n) Returns true if at least n unread bytes remain.
buffer_read_u8/u16/u32/u64(b, val, endianness) Reads 1/2/4/8 bytes and advances the cursor. endianness is BE or LE.
buffer_read_varint(b, val) Reads a Bitcoin-style variable-length integer.
buffer_read_bip32_path(b, out, out_len) Reads out_len big-endian 32-bit BIP32 path components.
buffer_get_path_bip32(b, path) Reads a length-prefixed BIP32 path into a path_bip32_t.
buffer_read_bytes(b, out, n) Reads n raw bytes.
buffer_peek(b, val) Reads the next byte without advancing.
buffer_peek_n(b, n, val) Reads byte at offset+n without advancing.

Writing

Function Description
buffer_write_u8/u16/u32/u64(b, val, endianness) Writes 1/2/4/8 bytes and advances.
buffer_write_bytes(b, data, n) Writes n raw bytes and advances.

Cursor control

Function Description
buffer_seek_set(b, offset) Seeks to an absolute position.
buffer_seek_cur(b, offset) Advances the cursor by offset bytes.
buffer_seek_end(b, offset) Sets the cursor to size - offset.
buffer_get_cur(b) Returns a pointer to the current position.

Output

Function Description
buffer_copy(b, out, out_len) Copies remaining bytes to out without advancing (used for APDU TX). Requires size - offset <= out_len.
buffer_move(b, out, out_len) Copies remaining bytes and advances by out_len.


BIP32 Path

Files: bip32.h, bip32.c

Parsing, serialisation, and formatting of BIP32 derivation paths.

typedef struct {
uint8_t length;
uint32_t path[MAX_BIP32_PATH];
} path_bip32_t;
MAX_BIP32_PATH
#define MAX_BIP32_PATH
Definition bip32.h:15

MAX_BIP32_PATH is 10. The hardened-child bit mask is BIP32_HARDENED_MASK (0x80000000).

Function Description
bip32_path_read(in, in_len, out, out_len) Deserialises out_len big-endian 32-bit components from in.
bip32_path_format(path, len, out, out_len) Formats the path as ‘"0&rsquo;/1/2'"` (hardened components get a trailing `'`).
bip32_path_format_simple(bip32, out, out_len) Convenience wrapper for path_bip32_t.


Cryptographic Helpers

Files: crypto_helpers.h, crypto_helpers.c

High-level wrappers that combine BIP32 key derivation with cryptographic operations. Every function:

  • Returns a cx_err_t and is annotated WARN_UNUSED_RESULT,
  • Scrubs sensitive material with explicit_bzero on both success and failure,
  • Only supports curves with 32-byte domain parameters (secp256k1, secp256r1, …).

Key derivation

Function Description
bip32_derive_init_privkey_256(curve, path, path_len, privkey, chain_code) Derives and initialises an ECFP private key.
bip32_derive_get_pubkey_256(curve, path, path_len, raw_pubkey, chain_code, hashID) Derives the private key and generates the uncompressed 65-byte public key.

ECDSA signing

Function Description
bip32_derive_ecdsa_sign_hash_256(curve, path, path_len, sign_mode, hashID, hash, hash_len, sig, sig_len, info) Signs a pre-computed hash; output is DER-encoded (30‖L‖02‖Lr‖r‖02‖Ls‖s).
bip32_derive_ecdsa_sign_rs_hash_256(curve, path, path_len, sign_mode, hashID, hash, hash_len, r, s) Like above but writes raw r and s into separate 32-byte buffers.

EdDSA signing

Function Description
bip32_derive_eddsa_sign_hash_256(curve, path, path_len, hashID, hash, hash_len, sig, sig_len) Signs with EdDSA; sig_len is updated to domain_param_size * 2.

Each function has a _with_seed_ variant that accepts a custom seed/seed_len for non-standard SLIP-21 derivations.
Pass NULL, 0 to use the standard BIP32 device seed.


Formatting Utilities

Files: format.h, format.c

Human-readable string formatting for display on device screens.

Function Description
format_i64(dst, dst_len, value) Formats a signed 64-bit integer as decimal.
format_u64(dst, dst_len, value) Formats an unsigned 64-bit integer as decimal.
format_fpu64(dst, dst_len, value, decimals) Fixed-point decimal with decimals fractional digits (e.g. 12345 with decimals=2 → "123.45").
format_fpu64_trimmed(dst, dst_len, value, decimals) Like format_fpu64() but trims trailing zeros and the decimal point.
format_hex(in, in_len, out, out_len) Uppercase hex dump; requires out_len >= 2*in_len+1. Returns bytes written or -1.


Encoding Helpers

Base58

Files: base58.h, base58.c

Bitcoin Base58 alphabet encode/decode.

Function Description
base58_encode(in, in_len, out, out_len) Binary → Base58 string; returns character count or -1. Max input: MAX_ENC_INPUT_SIZE (120 bytes).
base58_decode(in, in_len, out, out_len) Base58 string → binary; returns byte count or -1. Max input: MAX_DEC_INPUT_SIZE (164 chars).

Leading zero bytes are encoded as the ‘'1’` character (Bitcoin convention).

Variable-length integer (varint)

Files: varint.h, varint.c

Bitcoin-protocol variable-length integer (1/3/5/9 bytes).

Function Description
varint_size(value) Returns the serialised byte count for value.
varint_read(in, in_len, value) Parses a varint; returns bytes consumed or -1.
varint_write(out, offset, value) Writes a varint at out + offset; returns bytes written or -1.

Low-level integer read/write

Files: read.h, read.c, write.h, write.c

Bounds-unchecked integer accessors used internally by buffer.c and varint.c. All functions take a (ptr, offset) pair and read/write big-endian or little-endian integers of width 16, 32, or 64 bits.

Note
Callers are responsible for ensuring sufficient buffer space.


Application NVM Storage

Files: app_storage_internal.h, app_storage.c

Requires (in the application Makefile):

#define HAVE_APP_STORAGE
#define APP_STORAGE_SIZE <size_in_bytes>

Provides a CRC32-protected persistent storage area in NVM (nvm_write), placed in the .storage_section linker section. The on-disk layout is:

┌─────────────┬──────────────────────────┬────────────────────────────┐
│ CRC32 (4B) │ app_storage_header_t │ data[APP_STORAGE_SIZE] │
└─────────────┴──────────────────────────┴────────────────────────────┘
app_storage_header_s
Structure defining the header of application storage header.
Definition app_storage.h:51

The header carries

  • A "NVRA" tag,
  • Data size,
  • struct_version,
  • properties bitfield,
  • A data_version counter. The CRC is verified at every init();

if the check fails the storage is reset.

Function Description
app_storage_write(buf, nbyte, offset) Writes nbyte bytes and updates the CRC. Returns nbyte or a negative error code.
app_storage_read(buf, nbyte, offset) Reads nbyte bytes. Returns APP_STORAGE_ERR_NO_DATA_AVAILABLE if offset+nbyte exceeds the written size.
app_storage_reset() Erases the entire data area and resets the header.
app_storage_get_size() Returns the current written data size.
app_storage_get_data_version() Returns the application data version counter.
app_storage_increment_data_version() Increments (and wraps) the data version.
app_storage_get_properties() Returns the properties bitfield (APP_STORAGE_PROP_SETTINGS, APP_STORAGE_PROP_DATA).

Error codes:

  • 0: APP_STORAGE_SUCCESS,
  • -1: APP_STORAGE_ERR_INVALID_ARGUMENT,
  • -2: APP_STORAGE_ERR_NO_DATA_AVAILABLE,
  • -3: APP_STORAGE_ERR_OVERFLOW,
  • -4: APP_STORAGE_ERR_INVALID_HEADER,
  • -5: APP_STORAGE_ERR_CORRUPTED.


Exchange Swap Integration

Files: swap.h (umbrella), swap_entrypoints.h, swap_lib_calls.h, swap_utils.h, swap_utils.c, swap_error_code_helpers.h, swap_error_code_helpers.c

Requires (in the application Makefile):

#define HAVE_SWAP

Integrates with the Ledger Exchange application for atomic cross-currency swaps. When launched in library mode, main() dispatches one of three commands:

Command constant Value Description
CHECK_ADDRESS 3 Verify an address belongs to this device.
GET_PRINTABLE_AMOUNT 4 Format an amount for on-screen display.
SIGN_TRANSACTION 2 Sign the swap output transaction.

Coin application callbacks

The coin application must implement these three functions:

// Set params->result to 1 if address belongs to this device, 0 otherwise.
void swap_handle_check_address(check_address_parameters_t *params);
// Fill params->printable_amount with the formatted amount string.
void swap_handle_get_printable_amount(get_printable_amount_parameters_t *params);
// Save Exchange-validated transaction parameters for later signing verification.
// Called before BSS is reset — parameters must be heap-allocated.
bool swap_copy_transaction_parameters(create_transaction_parameters_t *params);
check_address_parameters_s
Definition swap_lib_calls.h:36
create_transaction_parameters_s
Definition swap_lib_calls.h:85
get_printable_amount_parameters_s
Definition swap_lib_calls.h:63

Runtime state

Global Type Description
G_called_from_swap volatile bool true when running as an Exchange library.
G_swap_response_ready volatile bool Set to true by the coin app when signing is complete; triggers os_lib_end() in io.c.

Helper utilities

Function Description
swap_str_to_u64(src, length, result) Converts a big-endian byte array (≤ 8 bytes) to a uint64_t amount.
swap_parse_config(config, config_len, ticker, ticker_buf_len, decimals) Parses the coin_configuration blob: length-prefixed ticker string + decimals byte.

Structured error reporting

Function Description
send_swap_error_simple(sw, common, app_specific) Sends a swap error APDU with a 2-byte structured error code and terminates (noreturn).
send_swap_error_with_buffer(sw, common, app_specific, buffer_data) Same with one extra data buffer.
send_swap_error_with_buffers(sw, common, app_specific, buffers, count) Same with up to 8 data buffers.
send_swap_error_with_string(sw, common, app_specific, format, ...) Same with a printf-style message (macro).

The 2-byte error code is

(common_code << 8) | app_specific;

Standard common codes are defined by swap_error_common_code_t:

Enumerator Value Meaning
SWAP_EC_ERROR_INTERNAL 0x00 Internal firmware error
SWAP_EC_ERROR_WRONG_AMOUNT 0x01 Amount mismatch
SWAP_EC_ERROR_WRONG_DESTINATION 0x02 Destination address mismatch
SWAP_EC_ERROR_WRONG_FEES 0x03 Fee mismatch
SWAP_EC_ERROR_WRONG_METHOD 0x04 Invalid method
SWAP_EC_ERROR_CROSSCHAIN_WRONG_MODE 0x05 Unsupported cross-chain mode
SWAP_EC_ERROR_CROSSCHAIN_WRONG_METHOD 0x06 Invalid cross-chain method
SWAP_EC_ERROR_CROSSCHAIN_WRONG_HASH 0x07 Cross-chain hash mismatch
SWAP_EC_ERROR_GENERIC 0xFF Generic / unspecified error


Utility Macros

File: macros.h

Macro Description
WEAK __attribute((weak)) — marks a function as overridable by application code.
MEMBER_SIZE(type, member) Size of a struct member without an instance.
ARRAY_LENGTH(array) Number of elements in a statically allocated array.

WEAK — allow an application to override a default SDK implementation:

// SDK default (in lib_standard_app/main.c)
WEAK void common_app_init(void) {
UX_INIT();
io_seproxyhal_init();
}
// Application override — adds custom initialisation on top
void common_app_init(void) {
UX_INIT();
io_seproxyhal_init();
my_app_nvm_init();
}
UX_INIT
#define UX_INIT()
Definition ux_nbgl.h:68

MEMBER_SIZE — size of a struct field without declaring a variable:

typedef struct {
uint8_t tag[4];
uint32_t version;
} header_t;
// Safe: no instance needed, no VLA, evaluated at compile time
uint8_t buf[MEMBER_SIZE(header_t, tag)]; // buf[4]
MEMBER_SIZE
#define MEMBER_SIZE(type, member)
Definition macros.h:6
header_t
struct header_s header_t
header_s
Definition mem_alloc.c:65

ARRAY_LENGTH — number of elements in a stack or global array:

static const uint32_t ALLOWED_PATH[] = {
0x8000002C, // 44'
0x80000000, // 0'
};
for (size_t i = 0; i < ARRAY_LENGTH(ALLOWED_PATH); i++) {
// iterate over every allowed path component
}
ARRAY_LENGTH
#define ARRAY_LENGTH(array)
Definition macros.h:30


Token Constants

File: tokens.h

Macro Value Description
MAX_TICKER_SIZE 50 Maximum buffer size for a token ticker string (including null terminator).
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