From 18d997ed13856dd112300baa244e9cc238d825eb Mon Sep 17 00:00:00 2001
From: qinjun-li <liqinjun1994@gmail.com>
Date: Sun, 8 Dec 2024 19:01:27 +0800
Subject: [PATCH] [rtl] Pipe result in float adder.

---
 t1/src/FloatModule.scala     |  6 +++---
 t1/src/mask/MaskReduce.scala | 27 +++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/t1/src/FloatModule.scala b/t1/src/FloatModule.scala
index da0651e1d..ea4abad8a 100644
--- a/t1/src/FloatModule.scala
+++ b/t1/src/FloatModule.scala
@@ -10,7 +10,7 @@ import chisel3.util.experimental.decode.TruthTable
 import hardfloat._
 
 @instantiable
-class FloatAdder(expWidth: Int, sigWidth: Int) extends Module {
+class FloatAdder(expWidth: Int, sigWidth: Int, latency: Int) extends Module {
   @public
   val io       = IO(new Bundle {
     val a              = Input(UInt((expWidth + sigWidth).W))
@@ -26,8 +26,8 @@ class FloatAdder(expWidth: Int, sigWidth: Int) extends Module {
   addRecFN.io.roundingMode   := io.roundingMode
   addRecFN.io.detectTininess := false.B
 
-  io.out            := fNFromRecFN(8, 24, addRecFN.io.out)
-  io.exceptionFlags := addRecFN.io.exceptionFlags
+  io.out            := Pipe(true.B, fNFromRecFN(8, 24, addRecFN.io.out), latency).bits
+  io.exceptionFlags := Pipe(true.B, addRecFN.io.exceptionFlags, latency).bits
 }
 
 /** float compare module
diff --git a/t1/src/mask/MaskReduce.scala b/t1/src/mask/MaskReduce.scala
index 288a190f5..4e26d4c67 100644
--- a/t1/src/mask/MaskReduce.scala
+++ b/t1/src/mask/MaskReduce.scala
@@ -35,7 +35,8 @@ class MaskReduce(parameter: T1Parameter) extends Module {
   val validInst:      Bool                     = IO(Input(Bool()))
   val pop:            Bool                     = IO(Input(Bool()))
 
-  val maskSize: Int = parameter.laneNumber * parameter.datapathWidth / 8
+  val floatAdderLatency: Int = 1
+  val maskSize:          Int = parameter.laneNumber * parameter.datapathWidth / 8
 
   // todo: uop decode
   val order:    Bool = in.bits.uop === "b101".U
@@ -49,7 +50,7 @@ class MaskReduce(parameter: T1Parameter) extends Module {
   val logicUnit:   Instance[LaneLogic]            = Instantiate(new LaneLogic(parameter.datapathWidth))
   // option unit for flot reduce
   val floatAdder:  Option[Instance[FloatAdder]]   =
-    Option.when(parameter.fpuEnable)(Instantiate(new FloatAdder(8, 24)))
+    Option.when(parameter.fpuEnable)(Instantiate(new FloatAdder(8, 24, floatAdderLatency)))
   val flotCompare: Option[Instance[FloatCompare]] =
     Option.when(parameter.fpuEnable)(Instantiate(new FloatCompare(8, 24)))
 
@@ -73,6 +74,7 @@ class MaskReduce(parameter: T1Parameter) extends Module {
   val floatType:  Bool = reqReg.uop(2) || reqReg.uop(1, 0).andR
   val NotAdd:     Bool = reqReg.uop(1)
   val widen:      Bool = reqReg.uop === "b001".U || reqReg.uop(2, 1) === "b11".U
+  val floatAdd:   Bool = floatType && !NotAdd
   // eew1HReg(0) || (eew1HReg(1) && !widen)
   val needFold:   Bool = false.B
   val writeEEW:   UInt = Mux(pop, 2.U, reqReg.eew + widen)
@@ -82,16 +84,21 @@ class MaskReduce(parameter: T1Parameter) extends Module {
   // crossFold: reduce between lane
   // lastFold: reduce in data path
   // orderRed: order reduce
-  val idle :: crossFold :: lastFold :: orderRed :: Nil = Enum(4)
+  val idle :: crossFold :: lastFold :: orderRed :: waitRes :: Nil = Enum(5)
   val state: UInt = RegInit(idle)
 
   val stateIdle:  Bool = state === idle
   val stateCross: Bool = state === crossFold
   val stateLast:  Bool = state === lastFold
   val stateOrder: Bool = state === orderRed
+  val stateWait:  Bool = state === waitRes
 
+  // wait float
+  val waitCount: UInt = RegInit(0.U(log2Ceil(floatAdderLatency.max(2)).W))
+  when(stateWait) { waitCount := waitCount + 1.U }
+  val resFire:   Bool = stateWait && waitCount === (floatAdderLatency - 1).U
   updateResult :=
-    stateLast || ((stateCross || stateOrder) && sourceValid)
+    stateLast || ((stateCross || stateOrder) && sourceValid && !floatAdd) || resFire
 
   // state update
   in.ready := stateIdle
@@ -102,9 +109,21 @@ class MaskReduce(parameter: T1Parameter) extends Module {
   }
 
   when(stateCross) {
+    when(floatAdd) {
+      state     := waitRes
+      waitCount := 0.U
+    }.elsewhen(groupLastReduce) {
+      state    := Mux(reqReg.lastGroup && needFold, lastFold, idle)
+      outValid := reqReg.lastGroup && !needFold
+    }
+  }
+
+  when(stateWait && resFire) {
     when(groupLastReduce) {
       state    := Mux(reqReg.lastGroup && needFold, lastFold, idle)
       outValid := reqReg.lastGroup && !needFold
+    }.otherwise {
+      state := crossFold
     }
   }