9.3. 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.
9.3.1. 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.
9.3.2. 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.
9.3.3. 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 (fromTLAtomics)
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.
9.3.4. 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 (fromTLAtomics)
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.
9.3.5. 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.
9.3.6. 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.
9.3.7. 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.
9.3.8. 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.
9.3.9. 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.
9.3.10. 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.
9.3.11. 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.
9.3.12. 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.
9.3.13. 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.
9.3.14. 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.