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Merge pull request #1032 from freechipsproject/fpga_pipeline_fpu_master

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FPU FMA FPGA retiming assist
This commit is contained in:
Andrew Waterman 2017-10-05 20:11:34 -07:00 committed by GitHub
commit 86a1953287
1 changed files with 69 additions and 2 deletions
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71
src/main/scala/tile/FPU.scala
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@ -542,7 +542,72 @@ class FPToFP(val latency: Int)(implicit p: Parameters) extends FPUModule()(p) {
io.out <> Pipe(in.valid, mux, latency-1)
}
class MulAddRecFNPipe(latency: Int, expWidth: Int, sigWidth: Int) extends Module
{
require(latency<=2)
val io = new Bundle {
val validin = Bool(INPUT)
val op = Bits(INPUT, 2)
val a = Bits(INPUT, expWidth + sigWidth + 1)
val b = Bits(INPUT, expWidth + sigWidth + 1)
val c = Bits(INPUT, expWidth + sigWidth + 1)
val roundingMode = UInt(INPUT, 3)
val detectTininess = UInt(INPUT, 1)
val out = Bits(OUTPUT, expWidth + sigWidth + 1)
val exceptionFlags = Bits(OUTPUT, 5)
val validout = Bool(OUTPUT)
}
//------------------------------------------------------------------------
//------------------------------------------------------------------------
val mulAddRecFNToRaw_preMul =
Module(new hardfloat.MulAddRecFNToRaw_preMul(expWidth, sigWidth))
val mulAddRecFNToRaw_postMul =
Module(new hardfloat.MulAddRecFNToRaw_postMul(expWidth, sigWidth))
mulAddRecFNToRaw_preMul.io.op := io.op
mulAddRecFNToRaw_preMul.io.a := io.a
mulAddRecFNToRaw_preMul.io.b := io.b
mulAddRecFNToRaw_preMul.io.c := io.c
val mulAddResult =
(mulAddRecFNToRaw_preMul.io.mulAddA *
mulAddRecFNToRaw_preMul.io.mulAddB) +&
mulAddRecFNToRaw_preMul.io.mulAddC
val valid_stage0 = Wire(Bool())
val roundingMode_stage0 = Wire(UInt(width=3))
val detectTininess_stage0 = Wire(UInt(width=1))
val postmul_regs = if(latency>0) 1 else 0
mulAddRecFNToRaw_postMul.io.fromPreMul := Pipe(io.validin, mulAddRecFNToRaw_preMul.io.toPostMul, postmul_regs).bits
mulAddRecFNToRaw_postMul.io.mulAddResult := Pipe(io.validin, mulAddResult, postmul_regs).bits
mulAddRecFNToRaw_postMul.io.roundingMode := Pipe(io.validin, io.roundingMode, postmul_regs).bits
roundingMode_stage0 := Pipe(io.validin, io.roundingMode, postmul_regs).bits
detectTininess_stage0 := Pipe(io.validin, io.detectTininess, postmul_regs).bits
valid_stage0 := Pipe(io.validin, false.B, postmul_regs).valid
//------------------------------------------------------------------------
//------------------------------------------------------------------------
val roundRawFNToRecFN = Module(new hardfloat.RoundRawFNToRecFN(expWidth, sigWidth, 0))
val round_regs = if(latency==2) 1 else 0
roundRawFNToRecFN.io.invalidExc := Pipe(valid_stage0, mulAddRecFNToRaw_postMul.io.invalidExc, round_regs).bits
roundRawFNToRecFN.io.in := Pipe(valid_stage0, mulAddRecFNToRaw_postMul.io.rawOut, round_regs).bits
roundRawFNToRecFN.io.roundingMode := Pipe(valid_stage0, roundingMode_stage0, round_regs).bits
roundRawFNToRecFN.io.detectTininess := Pipe(valid_stage0, detectTininess_stage0, round_regs).bits
io.validout := Pipe(valid_stage0, false.B, round_regs).valid
roundRawFNToRecFN.io.infiniteExc := Bool(false)
io.out := roundRawFNToRecFN.io.out
io.exceptionFlags := roundRawFNToRecFN.io.exceptionFlags
}
class FPUFMAPipe(val latency: Int, val t: FType)(implicit p: Parameters) extends FPUModule()(p) {
require(latency>0)
val io = new Bundle {
val in = Valid(new FPInput).flip
val out = Valid(new FPResult)
@ -560,7 +625,8 @@ class FPUFMAPipe(val latency: Int, val t: FType)(implicit p: Parameters) extends
when (!(cmd_fma || cmd_addsub)) { in.in3 := zero }
}
val fma = Module(new hardfloat.MulAddRecFN(t.exp, t.sig))
val fma = Module(new MulAddRecFNPipe((latency-1) min 2, t.exp, t.sig))
fma.io.validin := valid
fma.io.op := in.fmaCmd
fma.io.roundingMode := in.rm
fma.io.detectTininess := hardfloat.consts.tininess_afterRounding
@ -571,7 +637,8 @@ class FPUFMAPipe(val latency: Int, val t: FType)(implicit p: Parameters) extends
val res = Wire(new FPResult)
res.data := sanitizeNaN(fma.io.out, t)
res.exc := fma.io.exceptionFlags
io.out := Pipe(valid, res, latency-1)
io.out := Pipe(fma.io.validout, res, (latency-3) max 0)
}
class FPU(cfg: FPUParams)(implicit p: Parameters) extends FPUModule()(p) {