Skip to content

Latest commit

 

History

History
252 lines (166 loc) · 7.58 KB

EdgeFunctions.rst

File metadata and controls

252 lines (166 loc) · 7.58 KB
Raw

TileLink Edge Object Methods

The edge object associated with a TileLink node has several helpful methods for constructing TileLink messages and retrieving data from them.

Get

Constructor for a TLBundleA encoding a Get message, which requests data from memory. The D channel response to this message will be an AccessAckData, which may have multiple beats.

Arguments:

  • fromSource: UInt - Source ID for this transaction
  • toAddress: UInt - The address to read from
  • lgSize: UInt - Base two logarithm of the number of bytes to be read

Returns:

A (Bool, TLBundleA) tuple. The first item in the pair is a boolean indicating whether or not the operation is legal for this edge. The second is the A channel bundle.

Put

Constructor for a TLBundleA encoding a PutFull or PutPartial message, which write data to memory. It will be a PutPartial if the mask is specified and a PutFull if it is omitted. The put may require multiple beats. If that is the case, only data and mask should change for each beat. All other fields must be the same for all beats in the transaction, including the address. The manager will respond to this message with a single AccessAck.

Arguments:

  • fromSource: UInt - Source ID for this transaction.
  • toAddress: UInt - The address to write to.
  • lgSize: UInt - Base two logarithm of the number of bytes to be written.
  • data: UInt - The data to write on this beat.
  • mask: UInt - (optional) The write mask for this beat.

Returns:

A (Bool, TLBundleA) tuple. The first item in the pair is a boolean indicating whether or not the operation is legal for this edge. The second is the A channel bundle.

Arithmetic

Constructor for a TLBundleA encoding an Arithmetic message, which is an atomic operation. The possible values for the atomic field are defined in the TLAtomics object. It can be MIN, MAX, MINU, MAXU, or ADD, which correspond to atomic minimum, maximum, unsigned minimum, unsigned maximum, or addition operations, respectively. The previous value at the memory location will be returned in the response, which will be in the form of an AccessAckData.

Arguments:

  • fromSource: UInt - Source ID for this transaction.
  • toAddress: UInt - The address to perform an arithmetic operation on.
  • lgSize: UInt - Base two logarithm of the number of bytes to operate on.
  • data: UInt - Right-hand operand of the arithmetic operation
  • atomic: UInt - Arithmetic operation type (from TLAtomics)

Returns:

A (Bool, TLBundleA) tuple. The first item in the pair is a boolean indicating whether or not the operation is legal for this edge. The second is the A channel bundle.

Logical

Constructor for a TLBundleA encoding a Logical message, an atomic operation. The possible values for the atomic field are XOR, OR, AND, and SWAP, which correspond to atomic bitwise exclusive or, bitwise inclusive or, bitwise and, and swap operations, respectively. The previous value at the memory location will be returned in an AccessAckData response.

Arguments:

  • fromSource: UInt - Source ID for this transaction.
  • toAddress: UInt - The address to perform a logical operation on.
  • lgSize: UInt - Base two logarithm of the number of bytes to operate on.
  • data: UInt - Right-hand operand of the logical operation
  • atomic: UInt - Logical operation type (from TLAtomics)

Returns:

A (Bool, TLBundleA) tuple. The first item in the pair is a boolean indicating whether or not the operation is legal for this edge. The second is the A channel bundle.

Hint

Constructor for a TLBundleA encoding a Hint message, which is used to send prefetch hints to caches. The param argument determines what kind of hint it is. The possible values come from the TLHints object and are PREFETCH_READ and PREFETCH_WRITE. The first one tells caches to acquire data in a shared state. The second one tells cache to acquire data in an exclusive state. If the cache this message reaches is a last-level cache, there won't be any difference. If the manager this message reaches is not a cache, it will simply be ignored. In any case, a HintAck message will be sent in response.

Arguments:

  • fromSource: UInt - Source ID for this transaction.
  • toAddress: UInt - The address to prefetch
  • lgSize: UInt - Base two logarithm of the number of bytes to prefetch
  • param: UInt - Hint type (from TLHints)

Returns:

A (Bool, TLBundleA) tuple. The first item in the pair is a boolean indicating whether or not the operation is legal for this edge. The second is the A channel bundle.

AccessAck

Constructor for a TLBundleD encoding an AccessAck or AccessAckData message. If the optional data field is supplied, it will be an AccessAckData. Otherwise, it will be an AccessAck.

Arguments

  • a: TLBundleA - The A channel message to acknowledge
  • data: UInt - (optional) The data to send back

Returns:

The TLBundleD for the D channel message.

HintAck

Constructor for a TLBundleD encoding a HintAck message.

Arguments

  • a: TLBundleA - The A channel message to acknowledge

Returns:

The TLBundleD for the D channel message.

first

This method take a decoupled channel (either the A channel or D channel) and determines whether the current beat is the first beat in the transaction.

Arguments:

  • x: DecoupledIO[TLChannel] - The decoupled channel to snoop on.

Returns:

A Boolean which is true if the current beat is the first, or false otherwise.

last

This method take a decoupled channel (either the A channel or D channel) and determines whether the current beat is the last in the transaction.

Arguments:

  • x: DecoupledIO[TLChannel] - The decoupled channel to snoop on.

Returns:

A Boolean which is true if the current beat is the last, or false otherwise.

done

Equivalent to x.fire() && last(x).

Arguments:

  • x: DecoupledIO[TLChannel] - The decoupled channel to snoop on.

Returns:

A Boolean which is true if the current beat is the last and a beat is sent on this cycle. False otherwise.

count

This method take a decoupled channel (either the A channel or D channel) and determines the count (starting from 0) of the current beat in the transaction.

Arguments:

  • x: DecoupledIO[TLChannel] - The decoupled channel to snoop on.

Returns:

A UInt indicating the count of the current beat.

numBeats

This method takes in a TileLink bundle and gives the number of beats expected for the transaction.

Arguments:

  • x: TLChannel - The TileLink bundle to get the number of beats from

Returns:

A UInt that is the number of beats in the current transaction.

numBeats1

Similar to numBeats except it gives the number of beats minus one. If this is what you need, you should use this instead of doing numBeats - 1.U, as this is more efficient.

Arguments:

  • x: TLChannel - The TileLink bundle to get the number of beats from

Returns:

A UInt that is the number of beats in the current transaction minus one.

hasData

Determines whether the TileLink message contains data or not. This is true if the message is a PutFull, PutPartial, Arithmetic, Logical, or AccessAckData.

Arguments:

  • x: TLChannel - The TileLink bundle to check

Returns:

A Boolean that is true if the current message has data and false otherwise.