riscv/rocket-chip
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Fix issues with RoCC AccumulatorExample stalls on memory interface

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This commit is contained in:
Stephen Twigg 2013-09-23 00:21:43 -07:00
parent 158cee08af
commit db1e09f0d0
1 changed files with 10 additions and 3 deletions
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13
rocket/src/main/scala/rocc.scala
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@ -91,16 +91,23 @@ class AccumulatorExample(conf: RocketConfiguration) extends RoCC(conf)
val stallLoad = doLoad && !io.mem.req.ready
val stallResp = doResp && !io.resp.ready
cmd.ready := !stallReg && !stallLoad && !stallResp
val loadSent = Reg(init=Bool(false))
when(cmd.fire()) { loadSent := Bool(false) }.elsewhen(io.mem.req.fire()) {loadSent := Bool(true)}
// This ensures that, even if we hold a command at the queue, it is only processed once
io.resp.valid := cmd.valid && doResp && !stallReg && !stallLoad
cmd.ready := !stallReg && !stallLoad && !stallResp && (!doLoad || !doResp || loadSent)
// command resolved if no stalls AND not issuing a load that will need a request
// note, loadSent = true will occur when the load response comes back
io.resp.valid := cmd.valid && doResp && !stallReg && !stallLoad && (!doLoad || loadSent)
// valid response if valid command, need a response, no stalls on needed reg AND not issuing a load
io.resp.bits.rd := cmd.bits.inst.rd
io.resp.bits.data := accum
io.busy := Bool(false)
io.interrupt := Bool(false)
io.mem.req.valid := cmd.valid && doLoad && !stallReg && !stallResp
io.mem.req.valid := cmd.valid && doLoad && !stallReg && !stallResp && !loadSent
io.mem.req.bits.addr := addend
io.mem.req.bits.cmd := M_XRD // perform a load (M_XWR for stores)
io.mem.req.bits.typ := MT_D // D = 8 bytes, W = 4, H = 2, B = 1