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63 lines
2.0 KiB
63 lines
2.0 KiB
7 months ago
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This file just contains some notes about the design and usage of the PDL language.
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-------
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TERMS
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-------
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.pdl
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The file type that defines packet definitions. You may think of each pdl file
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as its own translation unit.
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Packet Views and Builders
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Generated from a packet definition. Views are used to validate packets and
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extract the fields that are defined in the pdl file. Builders check the input
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arguments and can be serialized.
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Checksum types
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checksum MyChecksumClass : 16 "path/to/the/class/"
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Checksum fields need to implement the following three methods:
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void Initialize(MyChecksumClass&);
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void AddByte(MyChecksumClass&, uint8_t);
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// Assuming a 16-bit (uint16_t) checksum:
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uint16_t GetChecksum(MyChecksumClass&);
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-------------
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LIMITATIONS
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-------------
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- Size fields for a variable length field MUST come before the definition
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of said field.
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- Payload fields must be byte-aligned unless they have an unknown size.
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Body fields are allowed to not be byte aligned.
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- No conditionals
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- Can not have to fields with the same name anywhere in the in an inheritence chain
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- Can't handle size for Body type fields yet since they might not be byte aligned.
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- Currently no arrays of custom types (might change later)
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-------
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NOTES
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-------
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All field names should be in snake_case. Types should be in CamelCase.
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The _payload_ keyword generates a getter but _body_ doesn't. Therefore, a
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_payload_ must be byte aligned.
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Supports constraints on grandparents
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Supports multiple constraints
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Every field handles its own generation.
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One pdl file will result in one header file with all the packets
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Things to cover -
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Constraints
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Inheritance vs Contains
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Custom fields with fixed size must extend and implement:
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packet::CustomFieldFixedSizeInterface
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Custom fields with variable size need the following functions:
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static void Serialize(const Type&, MutableView&);
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static std::optional<size_t> Size(Iterator);
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static Type Parse(Iterator);
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std::string ToString();
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