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/* NSC -- new scala compiler
* Copyright 2005 LAMP/EPFL
* @author Martin Odersky
*/
// $Id$
package scala.tools.nsc.symtab.classfile;
/** Variable length byte arrays, with methods for basic pickling and unpickling.
* @param data: The initial buffer
* @param from: The first index where defined data are found
* @param to : The first index where new data can be written
*/
class PickleBuffer(data: Array[byte], from: int, to: int) {
var bytes = data;
var readIndex = from;
var writeIndex = to;
/** Double bytes array */
private def dble: unit = {
val bytes1 = new Array[byte](bytes.length * 2);
System.arraycopy(bytes, 0, bytes1, 0, writeIndex);
bytes = bytes1
}
def ensureCapacity(capacity: int) = while (bytes.length < writeIndex + capacity) dble;
// -- Basic output routines --------------------------------------------
/** Write a byte of data */
def writeByte(b: int): unit = {
if (writeIndex == bytes.length) dble;
bytes(writeIndex) = b.asInstanceOf[byte];
writeIndex = writeIndex + 1
}
/** Write a natural number in big endian format, base 128.
* All but the last digits have bit 0x80 set.*/
def writeNat(x: int): unit = {
def writeNatPrefix(x: int): unit = {
val y = x >>> 7;
if (y != 0) writeNatPrefix(y);
writeByte((x & 0x7f) | 0x80);
}
val y = x >>> 7;
if (y != 0) writeNatPrefix(y);
writeByte(x & 0x7f)
}
/** Write a natural number at `pos'
* If number is more than one byte, shift rest of array to make space. */
def patchNat(pos: int, x: int): unit = {
def patchNatPrefix(x: int): unit = {
writeByte(0);
System.arraycopy(bytes, pos, bytes, pos+1, writeIndex - (pos+1));
bytes(pos) = ((x & 0x7f) | 0x80).asInstanceOf[byte];
val y = x >>> 7;
if (y != 0) patchNatPrefix(y)
}
bytes(pos) = (x & 0x7f).asInstanceOf[byte];
val y = x >>> 7;
if (y != 0) patchNatPrefix(y);
}
/** Write a long number in signed big endian format, base 256. */
def writeLong(x: long): unit = {
val y = x >> 8;
val z = x & 0xff;
if (-y != (z >> 7)) writeLong(y);
writeByte(z.asInstanceOf[int]);
}
// -- Basic input routines --------------------------------------------
/** Read a byte */
def readByte(): int = {
val x = bytes(readIndex); readIndex = readIndex + 1; x
}
/** Read a natural number in big endian format, base 128.
* All but the last digits have bit 0x80 set.*/
def readNat(): int = {
var b = 0;
var x = 0;
do {
b = readByte();
x = (x << 7) + (b & 0x7f);
} while ((b & 0x80) != 0);
x
}
/** Read a long number in signed big endian format, base 256. */
def readLong(len: int): long = {
var x = 0L;
var i = 0;
while (i < len) {
x = (x << 8) + (readByte() & 0xff);
i = i + 1
}
val leading = 64 - (len << 3);
x << leading >> leading
}
/** Perform operation `op' until readIndex == end. Concatenate results into a list. */
def until[T](end: int, op: () => T): List[T] =
if (readIndex == end) List() else op() :: until(end, op);
/** Create an index */
def createIndex: Array[int] = {
val index = new Array[int](readNat());
for (val i <- Iterator.range(0, index.length)) {
index(i) = readIndex;
readByte();
readIndex = readNat() + readIndex
}
index
}
}
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