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package Chisel
import scala.math.log
import scala.math.abs
import scala.math.ceil
import scala.math.max
import scala.math.min
import Literal._
import ChiselError._
/* Factory for literal values to be used by Bits and SInt factories. */
object Lit {
def apply[T <: Bits](n: String)(gen: => T): T = {
makeLit(Literal(n, -1))(gen)
}
def apply[T <: Bits](n: String, width: Int)(gen: => T): T = {
makeLit(Literal(n, width))(gen)
}
def apply[T <: Bits](n: String, base: Char)(gen: => T): T = {
makeLit(Literal(-1, base, n))(gen)
}
def apply[T <: Bits](n: String, base: Char, width: Int)(gen: => T): T = {
makeLit(Literal(width, base, n))(gen)
}
def apply[T <: Bits](n: BigInt)(gen: => T): T = {
makeLit(Literal(n, signed = gen.isInstanceOf[SInt]))(gen)
}
def apply[T <: Bits](n: BigInt, width: Int)(gen: => T): T = {
val lit = Literal(n, width, signed = gen.isInstanceOf[SInt])
makeLit(lit)(gen)
}
def makeLit[T <: Bits](x: Literal)(gen: => T): T = {
gen.makeLit(x.value, x.width)
}
}
class Literal(val value: BigInt, val width: Int) { }
object Literal {
private def bigMax(x: BigInt, y: BigInt): BigInt = if (x > y) x else y;
def sizeof(x: BigInt): Int = {
val y = bigMax(BigInt(1), x.abs).toDouble;
val res = max(1, (ceil(log(y + 1)/log(2.0))).toInt);
res
}
private def sizeof(base: Char, x: String): Int = {
var res = 0;
var first = true;
val size =
if(base == 'b') {
1
} else if(base == 'h') {
4
} else if(base == 'o') {
3
} else {
-1
}
for(c <- x)
if (c == '_') {
} else if(first) {
first = false;
res += sizeof(c.asDigit);
} else if (c != '_') {
res += size;
}
res
}
val hexNibbles = "0123456789abcdef";
def toHexNibble(x: String, off: Int): Char = {
var res = 0;
for (i <- 0 until 4) {
val idx = off + i;
val c = if (idx < 0) '0' else x(idx);
res = 2 * res + (if (c == '1') 1 else 0);
}
hexNibbles(res)
}
val pads = Vector(0, 3, 2, 1);
def toHex(x: String): String = {
var res = "";
val numNibbles = (x.length-1) / 4 + 1;
val pad = pads(x.length % 4);
for (i <- 0 until numNibbles) {
res += toHexNibble(x, i*4 - pad);
}
res
}
def toLitVal(x: String): BigInt = {
BigInt(x.substring(2, x.length), 16)
}
def toLitVal(x: String, shamt: Int): BigInt = {
var res = BigInt(0);
for(c <- x)
if(c != '_'){
if(!(hexNibbles + "?").contains(c.toLower)) ChiselError.error({"Literal: " + x + " contains illegal character: " + c});
res = res * shamt + c.asDigit;
}
res
}
def removeUnderscore(x: String): String = {
var res = ""
for(c <- x){
if(c != '_'){
res = res + c
}
}
res
}
def parseLit(x: String): (String, String, Int) = {
var bits = "";
var mask = "";
var width = 0;
for (d <- x) {
if (d != '_') {
if(!"01?".contains(d)) ChiselError.error({"Literal: " + x + " contains illegal character: " + d});
width += 1;
mask = mask + (if (d == '?') "0" else "1");
bits = bits + (if (d == '?') "0" else d.toString);
}
}
(bits, mask, width)
}
def stringToVal(base: Char, x: String): BigInt = {
if(base == 'x') {
toLitVal(x, 16);
} else if(base == 'd') {
BigInt(x.toInt)
} else if(base == 'h') {
toLitVal(x, 16)
} else if(base == 'b') {
toLitVal(x, 2)
} else if(base == 'o') {
toLitVal(x, 8)
} else {
BigInt(-1)
}
}
/** Derive the bit length for a Literal
*
*/
def bitLength(b: BigInt): Int = {
// Check for signedness
// We have seen unexpected values (one too small) when using .bitLength on negative BigInts,
// so use the positive value instead.
val usePositiveValueForBitLength = false
(if (usePositiveValueForBitLength && b < 0) {
-b
} else {
b
}).bitLength
}
/** Creates a *Literal* instance from a scala integer.
*/
def apply(x: BigInt, width: Int = -1, signed: Boolean = false): Literal = {
// Check for signedness
// We get unexpected values (one too small) when using .bitLength on negative BigInts,
// so use the positive value instead.
val bl = bitLength(x)
val xWidth = if (signed) {
bl + 1
} else {
max(bl, 1)
}
val w = if(width == -1) xWidth else width
val xString = (if (x >= 0) x else (BigInt(1) << w) + x).toString(16)
if(xWidth > width && width != -1) {
// Is this a zero-width wire with value 0
if (!(x == 0 && width == 0 && Driver.isSupportW0W)) {
ChiselError.error({"width " + width + " is too small for literal " + x + ". Smallest allowed width is " + xWidth});
}
}
apply("h" + xString, w)
}
def apply(n: String, width: Int): Literal =
apply(width, n(0), n.substring(1, n.length));
def apply(width: Int, base: Char, literal: String): Literal = {
if (!"dhbo".contains(base)) {
ChiselError.error("no base specified");
}
new Literal(stringToVal(base, literal), width)
}
}
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