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Add swizzle method to Encoding

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This commit is contained in:
Andrew Waterman 2017-06-21 00:44:13 -07:00
parent 3e04a99f61
commit 8989f5654c
1 changed files with 15 additions and 0 deletions
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15
src/main/scala/uncore/util/Ecc.scala
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@ -19,12 +19,20 @@ abstract class Code
def width(w0: Int): Int
def encode(x: UInt): UInt
def decode(x: UInt): Decoding
/** Copy the bits in x to the right bit positions in an encoded word,
* so that x === decode(swizzle(x)).uncorrected; but don't generate
* the other code bits, so decode(swizzle(x)).error might be true.
* For codes for which this operation is not trivial, throw an
* UnsupportedOperationException. */
def swizzle(x: UInt): UInt
}
class IdentityCode extends Code
{
def width(w0: Int) = w0
def encode(x: UInt) = x
def swizzle(x: UInt) = x
def decode(y: UInt) = new Decoding {
def uncorrected = y
def corrected = y
@ -37,6 +45,7 @@ class ParityCode extends Code
{
def width(w0: Int) = w0+1
def encode(x: UInt) = Cat(x.xorR, x)
def swizzle(x: UInt) = Cat(false.B, x)
def decode(y: UInt) = new Decoding {
val uncorrected = y(y.getWidth-2,0)
val corrected = uncorrected
@ -66,6 +75,11 @@ class SECCode extends Code
}
y.asUInt
}
def swizzle(x: UInt) = {
val y = for (i <- 1 to width(x.getWidth))
yield (if (isPow2(i)) false.B else x(mapping(i)))
y.asUInt
}
def decode(y: UInt) = new Decoding {
val n = y.getWidth
require(n > 0 && !isPow2(n))
@ -93,6 +107,7 @@ class SECDEDCode extends Code
def width(k: Int) = sec.width(k)+1
def encode(x: UInt) = par.encode(sec.encode(x))
def swizzle(x: UInt) = par.swizzle(sec.swizzle(x))
def decode(x: UInt) = new Decoding {
val secdec = sec.decode(x(x.getWidth-2,0))
val pardec = par.decode(x)