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AsyncQueue.md

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Rocket/util/AsyncQueue

class AsyncQueue

A cross clock domain queue.

class AsyncQueue[T <: Data](gen: T, depth: Int = 8, sync: Int = 3, safe: Boolean = true) extends Crossing[T]
  • I/O, type and Paramter
name type direction description
T Data type payload type
gen T param type parameter
depth Int = 8 param size of queue
sync Int = 3 param depth of clock synchronizer
safe Boolean = true param whether enforce self-satble
enq_clock Clock I source side clock
enq_reset Bool I source side reset
enq DecoupledIO[T] I source side write port
deq_clock Clock I sink side clock
deq_reset Bool I sink side reset
deq DecoupledIO[T] O sink side write port

It is better to set safe to true if source and sink do not share the same reset.

object GrayCounter

A gray counter

  • apply (bits: Int, increment: Bool = Bool(true), clear: Bool = Bool(false), name: String = "binary") => UInt
    The actual register is binary formated.

object UIntSyncChain

A register FIFO chain.

  • apply (in: UInt, sync: Int, name: String = "gray") => UInt
    sync: the depth of the FIFO.

class AsyncValidSync

A 1-bit FIFO chain.

class AsyncValidSync(sync: Int, desc: String) extends Module
  • I/O and Paramter
name type direction description
sync Int param depth of the FIFO
desc String param name of the FIFO
in Bool I input
out Bool O output

class AsyncQueueSource

A corss clock-domain queue, the part on the soruce side.

class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int, safe: Boolean = true) extends Module
  • I/O, type and Paramter
name type direction description
T Data type payload type
gen T param type parameter
depth Int param size of queue
sync Int param depth of clock synchronizer
safe Boolean param whether enforce self-satble
enq DecoupledIO[T] I write port for source
ridx UInt I read pointer from sink (grey code)
widx UInt O write pointer for source (grey code)
mem Vec[T] O queue content for sink to read
sink_reset_n Bool I sink side reset (active low)
ridx_valid Bool I sink side read pointer valid
widx_valid Bool O source side write pointer valid

When safe is set high, source side is able to write when the read pointer is valid and synchronoized (sync+1 cycle delay).

class AsyncQueueSink

A corss clock-domain queue, the part on the sink side.

class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int, safe: Boolean = true) extends Module
  • I/O, type and Paramter
name type direction description
T Data type payload type
gen T param type parameter
depth Int param size of queue
sync Int param depth of clock synchronizer
safe Boolean param whether enforce self-satble
deq DecoupledIO[T] O read port for sink
ridx UInt O read pointer for sink (grey code)
widx UInt I write pointer from source (grey code)
mem Vec[T] I queue content for sink to read
source_reset_n Bool I sink side reset (active low)
ridx_valid Bool O sink side read pointer valid
widx_valid Bool I source side write pointer valid

When safe is set high, sink side is able to read when the write pointer is valid and synchronoized (sync+1 cycle delay).




Last updated: 09/07/2017
CC BY-NC-SA 4.0, © (2017) Wei Song
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