72 lines
2.3 KiB
Scala
72 lines
2.3 KiB
Scala
// See LICENSE.SiFive for license details.
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package uncore.axi4
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import Chisel._
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import diplomacy._
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class AXI4RAM(address: AddressSet, executable: Boolean = true, beatBytes: Int = 4) extends LazyModule
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{
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val node = AXI4SlaveNode(AXI4SlavePortParameters(
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Seq(AXI4SlaveParameters(
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address = List(address),
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regionType = RegionType.UNCACHED,
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executable = executable,
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supportsRead = TransferSizes(1, beatBytes),
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supportsWrite = TransferSizes(1, beatBytes),
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interleavedId = Some(0))),
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beatBytes = beatBytes))
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// We require the address range to include an entire beat (for the write mask)
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require ((address.mask & (beatBytes-1)) == beatBytes-1)
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lazy val module = new LazyModuleImp(this) {
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val io = new Bundle {
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val in = node.bundleIn
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}
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def bigBits(x: BigInt, tail: List[Boolean] = List.empty[Boolean]): List[Boolean] =
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if (x == 0) tail.reverse else bigBits(x >> 1, ((x & 1) == 1) :: tail)
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val mask = bigBits(address.mask >> log2Ceil(beatBytes))
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val in = io.in(0)
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val mem = SeqMem(1 << mask.filter(b=>b).size, Vec(beatBytes, Bits(width = 8)))
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val r_addr = Cat((mask zip (in.ar.bits.addr >> log2Ceil(beatBytes)).toBools).filter(_._1).map(_._2).reverse)
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val w_addr = Cat((mask zip (in.aw.bits.addr >> log2Ceil(beatBytes)).toBools).filter(_._1).map(_._2).reverse)
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in.aw.ready := in. w.valid && in.b.ready
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in. w.ready := in.aw.valid && in.b.ready
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in. b.valid := in.w.valid && in.aw.valid
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in.b.bits.id := in.aw.bits.id
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in.b.bits.resp := AXI4Parameters.RESP_OKAY
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val wdata = Vec.tabulate(beatBytes) { i => in.w.bits.data(8*(i+1)-1, 8*i) }
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when (in.b.fire()) {
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mem.write(w_addr, wdata, in.w.bits.strb.toBools)
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}
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val r_full = RegInit(Bool(false))
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val r_id = Reg(UInt())
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when (in. r.fire()) { r_full := Bool(false) }
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when (in.ar.fire()) { r_full := Bool(true) }
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in. r.valid := r_full
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in.ar.ready := in.r.ready || !r_full
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when (in.ar.fire()) {
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r_id := in.ar.bits.id
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}
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val ren = in.ar.fire()
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def holdUnless[T <: Data](in : T, enable: Bool): T = Mux(!enable, RegEnable(in, enable), in)
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val rdata = holdUnless(mem.read(r_addr, ren), RegNext(ren))
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in.r.bits.id := r_id
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in.r.bits.resp := AXI4Parameters.RESP_OKAY
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in.r.bits.data := Cat(rdata.reverse)
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in.r.bits.last := Bool(true)
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}
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}
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