otxn_param

Retrieve the parameter value for a named Invoke transaction parameter

Behaviour

• Look up the value for a named parameter specified in read_ptr on the originating transaction (ttINVOKE only).
• Write the parameter's value to write_ptr

Definition

C

int64_t otxn_param (
    uint32_t write_ptr,
    uint32_t write_len,
    uint32_t read_ptr,
    uint32_t read_len
);

Example

C

uint8_t pname[] = {0xCAU, 0xFEU};
uint8_t pvalue[32];
int64_t value_len = 
    otxn_param(pvalue, 32, pname, 2);

Parameters

Name	Type	Description
write_ptr	uint32_t	Pointer to a buffer of a suitable size to store the output. Should be at least 32 bytes.
write_len	uint32_t	Length of the output buffer.
read_ptr	uint32_t	Pointer to a buffer containing the parameter's name
read_len	uint32_t	Length of the parameter's name

Return Code

Type	Description
int64_t	The number of bytes written If negative, an error: OUT_OF_BOUNDS - pointers/lengths specified outside of hook memory. DOESNT_EXIST - The specified paramater doesn't exist or is null TOO_SMALL - The parameter name can't be null TOO_BIG - The parameter name is greater than 32 bytes