Introduction

Smart contract documentation format description.

Overview

Contract documentation has following sections:

  • Specifications - Specifications and standards that contract implements. See corresponding spec documentation for function descriptions;

  • Types - Common types that are used through various contract functions;

  • Logs - Log binary format, that is used across contract functions;

  • Functions:

    • Initialization - Contract initialization function;

    • Read functions - read only contract functions, that do not affect instance state;

    • Write functions - write contract functions, that affect instance state.

Each contract function documentation has the following format:

  • Name and description;

  • Parameters in binary;

  • Logs;

  • Errors.

Binary format

Following format is used to describe binary data:

  • ::= assigns name to a byte group that follows it;

  • () logical group of bytes;

  • : separates group name on the left and group type on the right;

  • | alternative group variant, usually used with tag;

  • = indicates allowed value this variant;

  • u8, u16, u32, u64 number types, u for unsigned, i for signed, number indicates number size in bits;

  • LE number is expected in little endian format. Least significant byte comes first, most significant comes last;

  • * inside logical group indicates how many times it should be repeated;

  • // comment separator, does not affect data format, ends at line break;

  • ; comment separator within a logical group, does not affect data format. Ends at the bracket that closes the group.

Example:

IpfsCid ::= (size: u32 as LE) (buffer: u8 * size)

New logical group is assigned a name IpfsCid to use as a type later. First group is named size, it expects a 4 byte number in little endian format. Next group is named buffer, it expects size bytes. So, if size is 16, it must be followed by exactly 16 bytes.

Little endian transformation examples:

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