riscv/rocket-chip
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Make ALU generic for zscale

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This commit is contained in:
Andrew Waterman 2015-11-24 19:17:07 -08:00
parent 5294e94794
commit e203b8b378
2 changed files with 30 additions and 22 deletions
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34
rocket/src/main/scala/dpath_alu.scala
View File

@ -43,7 +43,8 @@ object ALU
}
import ALU._
class ALUIO(implicit p: Parameters) extends CoreBundle()(p) {
class ALU(xLen: Int) extends Module {
val io = new Bundle {
val dw = Bits(INPUT, SZ_DW)
val fn = Bits(INPUT, SZ_ALU_FN)
val in2 = UInt(INPUT, xLen)
@ -52,28 +53,32 @@ class ALUIO(implicit p: Parameters) extends CoreBundle()(p) {
val adder_out = UInt(OUTPUT, xLen)
}
class ALU(implicit p: Parameters) extends Module {
val io = new ALUIO
// ADD, SUB
val sum = io.in1 + Mux(isSub(io.fn), -io.in2, io.in2)
// SLT, SLTU
val cmp = cmpInverted(io.fn) ^
Mux(cmpEq(io.fn), sum === UInt(0),
Mux(io.in1(63) === io.in2(63), sum(63),
Mux(cmpUnsigned(io.fn), io.in2(63), io.in1(63))))
Mux(io.in1(xLen-1) === io.in2(xLen-1), sum(xLen-1),
Mux(cmpUnsigned(io.fn), io.in2(xLen-1), io.in1(xLen-1))))
// SLL, SRL, SRA
val shamt = Cat(io.in2(5) & (io.dw === DW_64), io.in2(4,0)).toUInt
val shin_hi_32 = Mux(isSub(io.fn), Fill(32, io.in1(31)), UInt(0,32))
val full_shamt = io.in2(log2Up(xLen)-1,0)
val (shamt, shin_r) =
if (xLen == 32) (full_shamt, io.in1)
else {
require(xLen == 64)
val shin_hi_32 = Fill(32, isSub(io.fn) && io.in1(31))
val shin_hi = Mux(io.dw === DW_64, io.in1(63,32), shin_hi_32)
val shin_r = Cat(shin_hi, io.in1(31,0))
val shamt = Cat(full_shamt(5) & (io.dw === DW_64), full_shamt(4,0))
(shamt, Cat(shin_hi, io.in1(31,0)))
}
val shin = Mux(io.fn === FN_SR || io.fn === FN_SRA, shin_r, Reverse(shin_r))
val shout_r = (Cat(isSub(io.fn) & shin(63), shin).toSInt >> shamt)(63,0)
val shout_r = (Cat(isSub(io.fn) & shin(xLen-1), shin).toSInt >> shamt)(xLen-1,0)
val shout_l = Reverse(shout_r)
val out64 =
val out =
Mux(io.fn === FN_ADD || io.fn === FN_SUB, sum,
Mux(io.fn === FN_SR || io.fn === FN_SRA, shout_r,
Mux(io.fn === FN_SL, shout_l,
@ -82,7 +87,10 @@ class ALU(implicit p: Parameters) extends Module {
Mux(io.fn === FN_XOR, io.in1 ^ io.in2,
/* all comparisons */ cmp))))))
val out_hi = Mux(io.dw === DW_64, out64(63,32), Fill(32, out64(31)))
io.out := Cat(out_hi, out64(31,0)).toUInt
io.adder_out := sum
io.out := out
if (xLen > 32) {
require(xLen == 64)
when (io.dw === DW_32) { io.out := Cat(Fill(32, out(31)), out(31,0)) }
}
}

2
rocket/src/main/scala/rocket.scala
View File

@ -239,7 +239,7 @@ class Rocket(implicit p: Parameters) extends CoreModule()(p) {
A2_IMM -> ex_imm,
A2_FOUR -> SInt(4)))
val alu = Module(new ALU)
val alu = Module(new ALU(xLen))
alu.io.dw := ex_ctrl.alu_dw
alu.io.fn := ex_ctrl.alu_fn
alu.io.in2 := ex_op2.toUInt