/* BSD 2-Clause License - see OPAL/LICENSE for details. */
package org.opalj
package br
package fpcf
package properties

import org.opalj.br.fpcf.analyses.ContextProvider
import org.opalj.util.elidedAssert

package object pointsto {
    // we encode allocation sites (method, pc, emptyArray, typeid tuples) as longs
    // MSB 20 bit TypeID | 1 bit is empty array | 16 bit PC | 27 bit ContextID LSB
    type AllocationSite = Long

    @inline def allocationSiteToLong(
        context:      Context,
        pc:           Int,
        tpe:          ReferenceType,
        isEmptyArray: Boolean = false
    ): Long = {
        val contextId = if (context eq NoContext) 0x3FFFFFF else context.id
        val typeId = tpe.id
        val emptyArray = if (isEmptyArray) 1L else 0L
        elidedAssert(pc >= -0x10000 && pc <= 0xFFFF)
        elidedAssert(contextId >= 0 && contextId <= 0x3FFFFFF)
        elidedAssert(typeId >= -0x80000 && typeId <= 0x7FFFF)
        contextId.toLong | ((pc.toLong & 0x1FFFF) << 26) | (emptyArray << 43) | (typeId.toLong << 44)
    }

    @inline def allocationSiteLongToTypeId(encodedAllocationSite: AllocationSite): Int = {
        (encodedAllocationSite >> 44).toInt
    }

    @inline def isEmptyArrayAllocationSite(encodedAllocationSite: AllocationSite): Boolean = {
        (encodedAllocationSite >> 43) % 2 == -1
    }

    @inline def longToAllocationSite(
        encodedAllocationSite: AllocationSite
    )(
        implicit contextProvider: ContextProvider
    ): (Context, PC, Int) /* method, pc, typeid */ = {
        val contextID = encodedAllocationSite.toInt & 0x3FFFFFF
        val pc = (encodedAllocationSite >> 26).toInt & 0x1FFFF
        (
            contextProvider.contextFromId(if (contextID == 0x3FFFFFF) -1 else contextID),
            if (pc > 0xFFFF) pc | 0xFFFF0000 else pc,
            (encodedAllocationSite >> 44).toInt
        )
    }
}