float_sto

Output an XFL as a serialized object

Concepts

• Floating Point Numbers (XFL)

• Serialized Objects

Behaviour

C

• Read an XFL floating point number and optionally a field code and currency code

• Write a serialized amount to write_ptr according to the parameters provided

Javascript

• Stores a float representation into a specified field.

• Returns an error code or the updated value as an array of numbers.

Definition

C

int64_t float_sto (
    uint32_t write_ptr,
    uint32_t write_len,
    uint32_t cread_ptr,
    uint32_t cread_len,  
    uint32_t iread_ptr,
    uint32_t iread_len,  
    int64_t float1,
    uint32_t field_code
);

Javascript

function float_sto(
    currency: ByteArray | HexString | undefined,
    issuer: ByteArray | HexString | undefined,
    f1: bigint,
    field_code: number
  ): ErrorCode | ByteArray

Example

C

#define SBUF(str) (uint32_t)(str), sizeof(str)
uint8_t amt_out[48];
if (float_sto(SBUF(amt_out),
    SBUF(currency), SBUF(hook_accid), pusd_to_send, -1) < 0)
        rollback(SBUF("Peggy: Could not dump pusd amount into sto"), 1);

Javascript

const amt_out = float_sto(currency, hook_accid, pusd_to_send, -1)
if (typeof amt_out === 'number')
        rollback("Peggy: Could not dump pusd amount into sto", 1)

Parameters

C

Name	Type	Description
write_ptr	uint32_t	Pointer to a buffer of a suitable size to store the serialized amount field. Recommend at least 48 bytes.
write_len	uint32_t	The length of the output buffer.
cread_ptr	uint32_t	Pointer to a buffer contianing the currency code to serialize into the output. May be null.
cread_len	uint32_t	The length of the currency code. This must be 20 or 3 or 0 (null).
iread_ptr	uint32_t	Pointer to a buffer containing the issuer's Account ID to serialize into the output. May be null.
iread_len	uint32_t	The length of the issuer's Account ID. This must be either 20 or 0 (null).
float1	int64_t	An XFL floating point enclosing number to serialize.
field_code	uint32_t	The sf field code to prefix the serialized amount with. E.g. sfAmount. If this field is 0xFFFFFFFFU (i.e. (uint32_t)(-1)) then no field code is prepended to the output, and no issuer or currency code is appended, but serialization proceeds as a floating point amount. If this field is 0 no field code is prepended to the output, and no issuer or currency code is appended, but serialization proceeds as though the amount is an XRP native amount rather than a floating point.

📘Hint

To output an XAH amount prepopulate the field code in the output buffer then pass the output buffer incremented to the new start and 0 as field_code

Javascript

Name	Type	Description
currency	ByteArray | HexString | undefined	The current value to store into.
issuer	ByteArray | HexString | undefined	The value to store.
f1	bigint	The field code indicating where to store the float.
field_code	number	An error code or the updated value as an array of numbers.

Return Code

C

Type

Description

int64_t

The number of bytes written to the output buffer. If negative, an error: INVALID_FLOAT - the supplied float was not a valid XFL enclosing number OUT_OF_BOUNDS - pointers/lengths specified outside of hook memory. INVALID_ARGUMENT - If instructed to output as XRP or without field code then all non-write pointers and lengths should be 0 (null). TOO_SMALL - The output buffer was too small to receive the serialized object. XFL_OVERFLOW - Expressing the output caused an overflow during normalization.

Javascript

Type	Description
ErrorCode | ByteArray	Returns an error code or the updated value as an array of numbers.