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// SPDX-License-Identifier: Apache-2.0
package chiselTests
import chisel3._
import chisel3.experimental.FixedPoint
import chisel3.internal.firrtl.{BinaryPoint, Width}
import chisel3.stage.ChiselStage
import chisel3.testers.BasicTester
import org.scalatest._
import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers
class FixedPointLiteralSpec extends AnyFlatSpec with Matchers {
behavior of "fixed point utilities"
they should "allow conversion between doubles and the bigints needed to represent them" in {
val initialDouble = 0.125
val bigInt = FixedPoint.toBigInt(initialDouble, 4)
val finalDouble = FixedPoint.toDouble(bigInt, 4)
initialDouble should be(finalDouble)
}
they should "have their literals support to double and to BigDecimal" in {
val d = -7.125
val lit1 = d.F(3.BP)
lit1.litToDouble should be (d)
val d2 = BigDecimal("1232123213131123.125")
val lit2 = d2.F(3.BP)
lit2.litToBigDecimal should be (d2)
// Numbers that are too big will throw exception
intercept[ChiselException] {
lit2.litToDouble
}
}
}
//noinspection TypeAnnotation,EmptyParenMethodAccessedAsParameterless
class FixedPointFromBitsTester extends BasicTester {
val uint = 3.U(4.W)
val sint = (-3).S
val fp = FixedPoint.fromDouble(3.0, 4.W, 0.BP)
val fp_tpe = FixedPoint(4.W, 1.BP)
val uint_result = FixedPoint.fromDouble(1.5, 4.W, 1.BP)
val sint_result = FixedPoint.fromDouble(-1.5, 4.W, 1.BP)
val fp_result = FixedPoint.fromDouble(1.5, 4.W, 1.BP)
val uint2fp = uint.asTypeOf(fp_tpe)
val sint2fp = sint.asTypeOf(fp_tpe)
val fp2fp = fp.asTypeOf(fp_tpe)
val uintToFp = uint.asFixedPoint(1.BP)
val sintToFp = sint.asFixedPoint(1.BP)
val fpToFp = fp.asFixedPoint(1.BP)
val negativefp = (-3.5).F(4.BP)
val positivefp = 3.5.F(4.BP)
assert(uint2fp === uint_result)
assert(sint2fp === sint_result)
assert(fp2fp === fp_result)
assert(uintToFp === uint_result)
assert(sintToFp === sint_result)
assert(fpToFp === fp_result)
assert(positivefp.abs() === positivefp)
assert(negativefp.abs() === positivefp)
assert(negativefp.abs() =/= negativefp)
val f1bp5 = 1.5.F(1.BP)
val f6bp0 = 6.0.F(0.BP)
val f6bp2 = 6.0.F(2.BP)
val f1bp5shiftleft2 = Wire(FixedPoint(Width(), BinaryPoint()))
val f6bp0shiftright2 = Wire(FixedPoint(Width(), BinaryPoint()))
val f6bp2shiftright2 = Wire(FixedPoint(Width(), BinaryPoint()))
f1bp5shiftleft2 := f1bp5 << 2
f6bp0shiftright2 := f6bp0 >> 2
f6bp2shiftright2 := f6bp2 >> 2
assert(f1bp5shiftleft2 === f6bp0)
assert(f1bp5shiftleft2 === 6.0.F(8.BP))
// shifting does not move binary point, so in first case below one bit is lost in shift
assert(f6bp0shiftright2 === 1.0.F(0.BP))
assert(f6bp2shiftright2 === 1.5.F(2.BP))
stop()
}
class FixedPointMuxTester extends BasicTester {
val largeWidthLowPrecision = 6.0.F(4.W, 0.BP)
val smallWidthHighPrecision = 0.25.F(2.W, 2.BP)
val unknownWidthLowPrecision = 6.0.F(0.BP)
val unknownFixed = Wire(FixedPoint())
unknownFixed := smallWidthHighPrecision
assert(Mux(true.B, largeWidthLowPrecision, smallWidthHighPrecision) === 6.0.F(0.BP))
assert(Mux(false.B, largeWidthLowPrecision, smallWidthHighPrecision) === 0.25.F(2.BP))
assert(Mux(false.B, largeWidthLowPrecision, unknownFixed) === 0.25.F(2.BP))
assert(Mux(true.B, unknownWidthLowPrecision, smallWidthHighPrecision) === 6.0.F(0.BP))
stop()
}
class SBP extends Module {
val io = IO(new Bundle {
val in = Input(FixedPoint(6.W, 2.BP))
val out = Output(FixedPoint(4.W, 0.BP))
})
io.out := io.in.setBinaryPoint(0)
}
class SBPTester extends BasicTester {
val dut = Module(new SBP)
dut.io.in := 3.75.F(2.BP)
assert(dut.io.out === 3.0.F(0.BP))
val test = Wire(FixedPoint(10.W, 5.BP))
// Initialize test, avoiding a "Reference test is not fully initialized" error from firrtl.
test := 0.0.F(5.BP)
val q = test.setBinaryPoint(18)
assert(q.getWidth.U === 23.U)
stop()
}
class FixedPointLitExtractTester extends BasicTester {
assert(-4.75.F(2.BP)(1) === false.B)
assert(-4.75.F(2.BP)(2) === true.B)
assert(-4.75.F(2.BP)(100) === true.B)
assert(-4.75.F(2.BP)(3, 0) === "b1101".U)
assert(-4.75.F(2.BP)(9, 0) === "b1111101101".U)
assert(-4.75.F(6.W, 2.BP)(1) === false.B)
assert(-4.75.F(6.W, 2.BP)(2) === true.B)
assert(-4.75.F(6.W, 2.BP)(100) === true.B)
assert(-4.75.F(6.W, 2.BP)(3, 0) === "b1101".U)
assert(-4.75.F(6.W, 2.BP)(9, 0) === "b1111101101".U)
stop()
}
class FixedPointSpec extends ChiselPropSpec with Utils {
property("should allow set binary point") {
assertTesterPasses { new SBPTester }
}
property("should allow fromBits") {
assertTesterPasses { new FixedPointFromBitsTester }
}
property("should mux different widths and binary points") {
assertTesterPasses { new FixedPointMuxTester }
}
property("Negative shift amounts are invalid") {
a [ChiselException] should be thrownBy extractCause[ChiselException] {
ChiselStage.elaborate(new NegativeShift(FixedPoint(1.W, 0.BP)))
}
}
property("Bit extraction on literals should work for all non-negative indices") {
assertTesterPasses(new FixedPointLitExtractTester)
}
}
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