binary

A helper to decode binary data into structures, with bit-size accuracy.

In C, you can declare structures like so:

typedef struct _SEQ_WR_CTL_D1_FORMAT
{
	uint32_t DAT_DLY : 4;
	uint32_t DQS_DLY : 4;
	uint32_t DQS_XTR : 1;
	uint32_t DAT_2Y_DLY : 1;
	uint32_t ADR_2Y_DLY : 1;
	uint32_t CMD_2Y_DLY : 1;
	uint32_t OEN_DLY : 4;
	uint32_t OEN_EXT : 4;
	uint32_t OEN_SEL : 2;
	uint32_t Pad0 : 2;
	uint32_t ODT_DLY : 4;
	uint32_t ODT_EXT : 1;
	uint32_t ADR_DLY : 1;
	uint32_t CMD_DLY : 1;
	uint32_t Pad1 : 1;
} SEQ_WR_CTL_D1_FORMAT;

The notation with the : (colon) operator specifies how many bits each field represents; We can convert this structure to Go with the help of tags:

type SEQ_WR_CTL_D1_FORMAT struct {
	DAT_DLY uint32 `bits:"4"`
	DQS_DLY uint32 `bits:"4"`
	DQS_XTR    uint32 `bits:"1"`
	DAT_2Y_DLY uint32 `bits:"1"`
	ADR_2Y_DLY uint32 `bits:"1"`
	CMD_2Y_DLY uint32 `bits:"1"`
	OEN_DLY    uint32 `bits:"4"`
	OEN_EXT uint32 `bits:"4"`
	OEN_SEL uint32 `bits:"2"`
	Pad0    uint32 `bits:"2"`
	ODT_DLY uint32 `bits:"4"`
	ODT_EXT uint32 `bits:"1"`
	ADR_DLY uint32 `bits:"1"`
	CMD_DLY uint32 `bits:"1"`
	Pad1    uint32 `bits:"1"`
}

In C, you can create a typed pointer that points to a byte array with this representation. In Go, you'd have to resort to the unsafe package for something like that. I use bitwise operators on scanned uint32 values in order to fill the above struct with appropriate data.

Due to the limitations of the underlying fatih/structs, the Unpack function takes a variadic argument to the fields you want to decode in the order you want to decode them. In the future, a more generic function might be available, where you would pass just a single struct with any number of nested structs, and it would linearelly decode the available data into the structs.

API

API is subject to change. While reasonable efforts will be made to keep it as it is, there might be circumstances where APIs will need to be changed.

Usage

See godoc page. Generally, it can be something like:

	n, err := b.Unpack(strap, binary.LittleEndian,
		&result.SEQ_WR_CTL_D1,
		&result.SEQ_WR_CTL_2,
		&result.SEQ_PMG_TIMING,
		&result.SEQ_RAS_TIMING,
		&result.SEQ_CAS_TIMING,
		&result.SEQ_MISC_TIMING,
		&result.SEQ_MISC_TIMING2,
		&result.SEQ_MISC1,
		&result.SEQ_MISC3,
		&result.SEQ_MISC8,
		&result.ARB_DRAM_TIMING,
		&result.ARB_DRAM_TIMING2,
	)

The variadic parameters may currently be any uint type, or a struct which reads 32 bits (uint32, 4 bytes). Support for structs that align to other uint types is possible, just takes a bit of copy pasting. As I didn't need it, I didn't write it, but feel free to add it on if you want.

Other

• support uint8, uint16, uint32, uint64 natively (without bitmasks)
• support uint32 struct with bitmasks
• support uint8, uint16, uint64 with bitmasks
• support any number of fields with encapsulating struct

License

Written by @TitPetric and licensed under the permissive WTFPL.