allow taking address of array element

codeCore/src/prog8/code/SymbolTableMaker.kt

@@ -126,7 +126,11 @@ class SymbolTableMaker(private val program: PtProgram, private val options: Comp
     private fun makeInitialArray(value: PtArray): List<StArrayElement> {
         return value.children.map {
             when(it) {
-                is PtAddressOf -> StArrayElement(null, it.identifier.name)
+                is PtAddressOf -> {
+                    if(it.isFromArrayElement)
+                        TODO("address-of array element $it in initial array value")
+                    StArrayElement(null, it.identifier.name)
+                }
                 is PtIdentifier -> StArrayElement(null, it.name)
                 is PtNumber -> StArrayElement(it.number, null)
                 else -> throw AssemblyError("invalid array element $it")

codeCore/src/prog8/code/ast/AstExpressions.kt

@@ -24,7 +24,17 @@ sealed class PtExpression(val type: DataType, position: Position) : PtNode(posit
 
     infix fun isSameAs(other: PtExpression): Boolean {
         return when(this) {
-            is PtAddressOf -> other is PtAddressOf && other.type==type && other.identifier isSameAs identifier
+            is PtAddressOf -> {
+                if(other !is PtAddressOf)
+                    return false
+                if (other.type!==type || !(other.identifier isSameAs identifier))
+                    return false
+                if(other.children.size!=children.size)
+                    return false
+                if(children.size==1)
+                    return true
+                return arrayIndexExpr!! isSameAs other.arrayIndexExpr!!
+            }
             is PtArrayIndexer -> other is PtArrayIndexer && other.type==type && other.variable isSameAs variable && other.index isSameAs index && other.splitWords==splitWords
             is PtBinaryExpression -> other is PtBinaryExpression && other.left isSameAs left && other.right isSameAs right
             is PtContainmentCheck -> other is PtContainmentCheck && other.type==type && other.element isSameAs element && other.iterable isSameAs iterable
@@ -105,7 +115,12 @@ sealed class PtExpression(val type: DataType, position: Position) : PtNode(posit
 
 class PtAddressOf(position: Position) : PtExpression(DataType.UWORD, position) {
     val identifier: PtIdentifier
-        get() = children.single() as PtIdentifier
+        get() = children[0] as PtIdentifier
+    val arrayIndexExpr: PtExpression?
+        get() = if(children.size==2) children[1] as PtExpression else null
+
+    val isFromArrayElement: Boolean
+        get() = children.size==2
 }
 
 

codeGenCpu6502/src/prog8/codegen/cpu6502/AsmGen.kt

@@ -2417,8 +2417,7 @@ $repeatLabel""")
                     cmp  #<$number
                     bne  $jumpIfFalseLabel
                     cpy  #>$number
-                    bne  $jumpIfFalseLabel
+                    bne  $jumpIfFalseLabel""")
-                    """)
             }
             is PtIdentifier -> {
                 assignExpressionToRegister(left, RegisterOrPair.AY)
@@ -2426,18 +2425,21 @@ $repeatLabel""")
                     cmp  ${asmVariableName(right)}
                     bne  $jumpIfFalseLabel
                     cpy  ${asmVariableName(right)}+1
-                    bne  $jumpIfFalseLabel
+                    bne  $jumpIfFalseLabel""")
-                    """)
             }
             is PtAddressOf -> {
                 assignExpressionToRegister(left, RegisterOrPair.AY)
                 val name = asmSymbolName(right.identifier)
-                out("""
+                if(right.isFromArrayElement) {
-                    cmp  #<$name
+                    TODO("address-of array element $name at ${right.position}")
-                    bne  $jumpIfFalseLabel
+                    // assignmentAsmGen.assignAddressOf(target, name, right.arrayIndexExpr)
-                    cpy  #>$name
+                } else {
-                    bne  $jumpIfFalseLabel
+                    out("""
-                    """)
+                        cmp  #<$name
+                        bne  $jumpIfFalseLabel
+                        cpy  #>$name
+                        bne  $jumpIfFalseLabel""")
+                }
             }
             else -> {
                 if(left.isSimple()) {
@@ -2518,12 +2520,16 @@ $repeatLabel""")
             is PtAddressOf -> {
                 assignExpressionToRegister(left, RegisterOrPair.AY)
                 val name = asmSymbolName(right.identifier)
-                out("""
+                if(right.isFromArrayElement) {
-                    cmp  #<$name
+                    TODO("address-of array element $name at ${right.position}")
-                    bne  +
+                } else {
-                    cpy  #>$name
+                    out("""
-                    beq  $jumpIfFalseLabel
+                        cmp  #<$name
-+""")
+                        bne  +
+                        cpy  #>$name
+                        beq  $jumpIfFalseLabel
+    +""")
+                }
             }
             else -> {
                 if(left.isSimple()) {
@@ -2849,8 +2855,12 @@ $repeatLabel""")
             is PtAddressOf -> {
                 assignExpressionToRegister(right, RegisterOrPair.AY)
                 val name = asmSymbolName(left.identifier)
-                code("#>$name", "#<$name")
+                if(left.isFromArrayElement) {
-                return true
+                    TODO("address-of array element $name at ${left.position}")
+                } else {
+                    code("#>$name", "#<$name")
+                    return true
+                }
             }
             is PtIdentifier -> {
                 assignExpressionToRegister(right, RegisterOrPair.AY)
@@ -2898,8 +2908,12 @@ $repeatLabel""")
             is PtAddressOf -> {
                 assignExpressionToRegister(left, RegisterOrPair.AY)
                 val name = asmSymbolName(right.identifier)
-                code("#>$name", "#<$name")
+                if(right.isFromArrayElement) {
-                return true
+                    TODO("address-of array element $name at ${right.position}")
+                } else {
+                    code("#>$name", "#<$name")
+                    return true
+                }
             }
             is PtIdentifier -> {
                 assignExpressionToRegister(left, RegisterOrPair.AY)

codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt

@@ -49,7 +49,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     DataType.WORD -> assignVariableWord(assign.target, variable, assign.source.datatype)
                     DataType.UWORD -> {
                         if(assign.source.datatype in PassByReferenceDatatypes)
-                            assignAddressOf(assign.target, variable)
+                            assignAddressOf(assign.target, variable, null, null)
                         else
                             assignVariableWord(assign.target, variable, assign.source.datatype)
                     }
@@ -181,7 +181,8 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         when(val value = assign.source.expression!!) {
             is PtAddressOf -> {
                 val sourceName = asmgen.asmSymbolName(value.identifier)
-                assignAddressOf(assign.target, sourceName)
+                val arrayDt = value.identifier.type
+                assignAddressOf(assign.target, sourceName, arrayDt, value.arrayIndexExpr)
             }
             is PtNumber -> throw AssemblyError("source kind should have been literalnumber")
             is PtIdentifier -> throw AssemblyError("source kind should have been variable")
@@ -806,28 +807,32 @@ internal class AssignmentAsmGen(private val program: PtProgram,
 
             when (right) {
                 is PtAddressOf -> {
-                    assignExpressionToRegister(left, RegisterOrPair.AY, dt==DataType.WORD)
                     val symbol = asmgen.asmVariableName(right.identifier)
-                    if(expr.operator=="+")
+                    if(right.isFromArrayElement) {
-                        asmgen.out("""
+                        TODO("address-of array element $symbol at ${right.position}")
-                                clc
+                    } else {
-                                adc  #<$symbol
+                        assignExpressionToRegister(left, RegisterOrPair.AY, dt==DataType.WORD)
-                                tax
+                        if(expr.operator=="+")
-                                tya
+                            asmgen.out("""
-                                adc  #>$symbol
+                                    clc
-                                tay
+                                    adc  #<$symbol
-                                txa""")
+                                    tax
-                    else
+                                    tya
-                        asmgen.out("""
+                                    adc  #>$symbol
-                                sec
+                                    tay
-                                sbc  #<$symbol
+                                    txa""")
-                                tax
+                        else
-                                tya
+                            asmgen.out("""
-                                sbc  #>$symbol
+                                    sec
-                                tay
+                                    sbc  #<$symbol
-                                txa""")
+                                    tax
-                    assignRegisterpairWord(target, RegisterOrPair.AY)
+                                    tya
-                    return true
+                                    sbc  #>$symbol
+                                    tay
+                                    txa""")
+                        assignRegisterpairWord(target, RegisterOrPair.AY)
+                        return true
+                    }
                 }
                 is PtIdentifier -> {
                     val symname = asmgen.asmVariableName(right)
@@ -1619,7 +1624,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 // use subroutine
                 assignExpressionToRegister(containment.element, RegisterOrPair.A, elementDt == DataType.BYTE)
                 asmgen.saveRegisterStack(CpuRegister.A, true)
-                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position,"P8ZP_SCRATCH_W1"), varname)
+                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position,"P8ZP_SCRATCH_W1"), varname, null, null)
                 asmgen.restoreRegisterStack(CpuRegister.A, false)
                 val stringVal = (variable as PtVariable).value as PtString
                 asmgen.out("  ldy  #${stringVal.value.length}")
@@ -1632,7 +1637,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
             DataType.ARRAY_B, DataType.ARRAY_UB -> {
                 assignExpressionToRegister(containment.element, RegisterOrPair.A, elementDt == DataType.BYTE)
                 asmgen.saveRegisterStack(CpuRegister.A, true)
-                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position, "P8ZP_SCRATCH_W1"), varname)
+                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position, "P8ZP_SCRATCH_W1"), varname, null, null)
                 asmgen.restoreRegisterStack(CpuRegister.A, false)
                 asmgen.out("  ldy  #$numElements")
                 asmgen.out("  jsr  prog8_lib.containment_bytearray")
@@ -1640,7 +1645,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
             }
             DataType.ARRAY_W, DataType.ARRAY_UW -> {
                 assignExpressionToVariable(containment.element, "P8ZP_SCRATCH_W1", elementDt)
-                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position, "P8ZP_SCRATCH_W2"), varname)
+                assignAddressOf(AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, DataType.UWORD, containment.definingISub(), symbol.astNode.position, "P8ZP_SCRATCH_W2"), varname, null, null)
                 asmgen.out("  ldy  #$numElements")
                 asmgen.out("  jsr  prog8_lib.containment_wordarray")
                 return
@@ -2167,12 +2172,24 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         }
     }
 
-    private fun assignAddressOf(target: AsmAssignTarget, sourceName: String) {
+    private fun assignAddressOf(target: AsmAssignTarget, sourceName: String, arrayDt: DataType?, arrayIndexExpr: PtExpression?) {
+        val offset = if(arrayIndexExpr!=null) {
+            val constIndex = arrayIndexExpr.asConstInteger()
+            if(constIndex!=null) {
+                if(arrayDt in SplitWordArrayTypes)
+                    constIndex
+                else
+                    program.memsizer.memorySize(arrayDt!!, constIndex)  // add arrayIndexExpr * elementsize  to the address of the array variable.
+            } else {
+                TODO("address-of array element $sourceName with non-const index at ${target.position}")
+            }
+        } else 0
+
         when(target.kind) {
             TargetStorageKind.VARIABLE -> {
                 asmgen.out("""
-                        lda  #<$sourceName
+                        lda  #<$sourceName+$offset
-                        ldy  #>$sourceName
+                        ldy  #>$sourceName+$offset
                         sta  ${target.asmVarname}
                         sty  ${target.asmVarname}+1
                     """)
@@ -2181,20 +2198,20 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 throw AssemblyError("can't store word into memory byte")
             }
             TargetStorageKind.ARRAY -> {
-                asmgen.out("  lda  #<$sourceName |  ldy #>$sourceName")
+                asmgen.out("  lda  #<$sourceName+$offset |  ldy #>$sourceName+$offset")
                 assignRegisterpairWord(target, RegisterOrPair.AY)
             }
             TargetStorageKind.REGISTER -> {
                 when(target.register!!) {
-                    RegisterOrPair.AX -> asmgen.out("  ldx  #>$sourceName |  lda  #<$sourceName")
+                    RegisterOrPair.AX -> asmgen.out("  ldx  #>$sourceName+$offset |  lda  #<$sourceName+$offset")
-                    RegisterOrPair.AY -> asmgen.out("  ldy  #>$sourceName |  lda  #<$sourceName")
+                    RegisterOrPair.AY -> asmgen.out("  ldy  #>$sourceName+$offset |  lda  #<$sourceName+$offset")
-                    RegisterOrPair.XY -> asmgen.out("  ldy  #>$sourceName |  ldx  #<$sourceName")
+                    RegisterOrPair.XY -> asmgen.out("  ldy  #>$sourceName+$offset |  ldx  #<$sourceName+$offset")
                     in Cx16VirtualRegisters -> {
                         asmgen.out(
                             """
-                            lda  #<$sourceName
+                            lda  #<$sourceName+$offset
                             sta  cx16.${target.register.toString().lowercase()}
-                            lda  #>$sourceName
+                            lda  #>$sourceName+$offset
                             sta  cx16.${target.register.toString().lowercase()}+1
                         """)
                     }
@@ -3622,7 +3639,11 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 asmgen.out("  sta  ${addressLv.number.toHex()}")
             }
             addressOf != null -> {
-                asmgen.out("  sta  ${asmgen.asmSymbolName(addressOf.identifier)}")
+                if(addressOf.isFromArrayElement) {
+                    TODO("address-of array element $addressOf")
+                } else {
+                    asmgen.out("  sta  ${asmgen.asmSymbolName(addressOf.identifier)}")
+                }
             }
             addressExpr is PtIdentifier -> {
                 asmgen.storeAIntoPointerVar(addressExpr)
@@ -3632,8 +3653,12 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     val addrOf = addressExpr.left as? PtAddressOf
                     val offset = (addressExpr.right as? PtNumber)?.number?.toInt()
                     if(addrOf!=null && offset!=null) {
-                        asmgen.out("  sta  ${asmgen.asmSymbolName(addrOf.identifier)}${addressExpr.operator}${offset}")
+                        if(addrOf.isFromArrayElement) {
-                        return
+                            TODO("address-of array element $addrOf")
+                        } else {
+                            asmgen.out("  sta  ${asmgen.asmSymbolName(addrOf.identifier)}${addressExpr.operator}${offset}")
+                            return
+                        }
                     }
                 }
                 if(!asmgen.tryOptimizedPointerAccessWithA(addressExpr, addressExpr.operator, true))

codeGenIntermediate/src/prog8/codegen/intermediate/ExpressionGen.kt

@@ -3,10 +3,7 @@ package prog8.codegen.intermediate
 import prog8.code.StRomSub
 import prog8.code.StSub
 import prog8.code.ast.*
-import prog8.code.core.AssemblyError
+import prog8.code.core.*
-import prog8.code.core.DataType
-import prog8.code.core.PassByValueDatatypes
-import prog8.code.core.SignedDatatypes
 import prog8.intermediate.*
 
 internal class ExpressionCodeResult(val chunks: IRCodeChunks, val dt: IRDataType, val resultReg: Int, val resultFpReg: Int) {
@@ -69,10 +66,28 @@ internal class ExpressionGen(private val codeGen: IRCodeGen) {
                 val vmDt = irType(expr.type)
                 val symbol = expr.identifier.name
                 // note: LOAD <symbol>  gets you the address of the symbol, whereas LOADM <symbol> would get you the value stored at that location
-                val code = IRCodeChunk(null, null)
+                val result = mutableListOf<IRCodeChunkBase>()
                 val resultRegister = codeGen.registers.nextFree()
-                code += IRInstruction(Opcode.LOAD, vmDt, reg1=resultRegister, labelSymbol = symbol)
+                addInstr(result, IRInstruction(Opcode.LOAD, vmDt, reg1 = resultRegister, labelSymbol = symbol), null)
-                ExpressionCodeResult(code, vmDt, resultRegister, -1)
+                if(expr.isFromArrayElement) {
+                    val indexTr = translateExpression(expr.arrayIndexExpr!!)
+                    addToResult(result, indexTr, indexTr.resultReg, -1)
+                    if(expr.identifier.type in SplitWordArrayTypes) {
+                        result += IRCodeChunk(null, null).also {
+                            // multiply indexTr resultreg by the eltSize and add this to the resultRegister.
+                            it += IRInstruction(Opcode.ADDR, IRDataType.BYTE, reg1=resultRegister, reg2=indexTr.resultReg)
+                        }
+                    } else {
+                        val eltSize = codeGen.program.memsizer.memorySize(expr.identifier.type, 1)
+                        result += IRCodeChunk(null, null).also {
+                            // multiply indexTr resultreg by the eltSize and add this to the resultRegister.
+                            if(eltSize>1)
+                                it += IRInstruction(Opcode.MUL, IRDataType.BYTE, reg1=indexTr.resultReg, immediate = eltSize)
+                            it += IRInstruction(Opcode.ADDR, IRDataType.BYTE, reg1=resultRegister, reg2=indexTr.resultReg)
+                        }
+                    }
+                }
+                ExpressionCodeResult(result, vmDt, resultRegister, -1)
             }
             is PtMemoryByte -> {
                 val result = mutableListOf<IRCodeChunkBase>()

codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt

@@ -30,7 +30,7 @@ class StatementOptimizer(private val program: Program,
         if(functionCallStatement.target.nameInSource==listOf("txt", "print")) {
             val arg = functionCallStatement.args.single()
             val stringVar: IdentifierReference? = if(arg is AddressOf) {
-                arg.identifier
+                if(arg.arrayIndex==null) arg.identifier else null
             } else {
                 arg as? IdentifierReference
             }

compiler/src/prog8/compiler/astprocessing/BeforeAsmTypecastCleaner.kt

@@ -56,7 +56,7 @@ internal class BeforeAsmTypecastCleaner(val program: Program,
                         listOf(
                             IAstModification.ReplaceNode(
                                 typecast,
-                                AddressOf(identifier, typecast.position),
+                                AddressOf(identifier, null, typecast.position),
                                 parent
                             )
                         )

compiler/src/prog8/compiler/astprocessing/CodeDesugarer.kt

@@ -219,6 +219,8 @@ _after:
         // @(&var+1) --> msb(var)
 
         val addrOf = memread.addressExpression as? AddressOf
+        if(addrOf?.arrayIndex!=null)
+            return noModifications
         if(addrOf!=null && addrOf.identifier.inferType(program).isWords) {
             val lsb = FunctionCallExpression(IdentifierReference(listOf("lsb"), memread.position), mutableListOf(addrOf.identifier), memread.position)
             return listOf(IAstModification.ReplaceNode(memread, lsb, parent))

compiler/src/prog8/compiler/astprocessing/IntermediateAstMaker.kt

@@ -440,6 +440,8 @@ class IntermediateAstMaker(private val program: Program) {
             addr.add(PtIdentifier(name+"_lsb", dt, src.identifier.position))        // NOTE: assumes _lsb is first in memory! (immediately followed by _msb)
         else
             addr.add(transform(src.identifier))
+        if(src.arrayIndex!=null)
+            addr.add(transformExpression(src.arrayIndex!!.indexExpr))
         return addr
     }
 

compiler/src/prog8/compiler/astprocessing/StatementReorderer.kt

@@ -304,8 +304,8 @@ internal class StatementReorderer(
         val eltsize = program.memsizer.memorySize(ArrayToElementTypes.getValue(sourceVar.datatype))
         val memcopy = FunctionCallStatement(IdentifierReference(listOf("sys", "memcopy"), assign.position),
             mutableListOf(
-                AddressOf(sourceIdent, assign.position),
+                AddressOf(sourceIdent, null, assign.position),
-                AddressOf(identifier, assign.position),
+                AddressOf(identifier, null, assign.position),
                 NumericLiteral.optimalInteger(numelements*eltsize, assign.position)
             ), false, assign.position
         )

compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt

@@ -265,7 +265,7 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                                 if(identifier?.isSubroutineParameter(program)==false) {
                                     modifications += IAstModification.ReplaceNode(
                                             identifier,
-                                            AddressOf(identifier, arg.position),
+                                            AddressOf(identifier, null, arg.position),
                                             call as Node)
                                 }
                             } else if(arg is NumericLiteral) {
@@ -286,7 +286,7 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                         if(arg is IdentifierReference && DataType.UWORD == param.type) {
                             modifications += IAstModification.ReplaceNode(
                                 arg,
-                                AddressOf(arg, arg.position),
+                                AddressOf(arg, null, arg.position),
                                 call as Node
                             )
                         }
@@ -312,7 +312,7 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                                     if(identifier?.isSubroutineParameter(program)==false) {
                                         modifications += IAstModification.ReplaceNode(
                                             call.args[index],
-                                            AddressOf(identifier, pair.second.position),
+                                            AddressOf(identifier, null, pair.second.position),
                                             call as Node)
                                         break
                                     }
@@ -325,7 +325,7 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
                         if(pair.second is IdentifierReference && DataType.UWORD in pair.first.possibleDatatypes) {
                             modifications += IAstModification.ReplaceNode(
                                 call.args[index],
-                                AddressOf(pair.second as IdentifierReference, pair.second.position),
+                                AddressOf(pair.second as IdentifierReference, null, pair.second.position),
                                 call as Node
                             )
                         }

compiler/test/codegeneration/TestAsmGenSymbols.kt

@@ -52,13 +52,13 @@ class TestAsmGenSymbols: StringSpec({
 
         val tgt = AssignTarget(IdentifierReference(listOf("tgt"), Position.DUMMY), null, null, Position.DUMMY)
         val assign1 = Assignment(tgt, IdentifierReference(listOf("localvar"), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign2 = Assignment(tgt, AddressOf(IdentifierReference(listOf("locallabel"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign2 = Assignment(tgt, AddressOf(IdentifierReference(listOf("locallabel"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign3 = Assignment(tgt, AddressOf(IdentifierReference(listOf("var_outside"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign3 = Assignment(tgt, AddressOf(IdentifierReference(listOf("var_outside"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign4 = Assignment(tgt, AddressOf(IdentifierReference(listOf("label_outside"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign4 = Assignment(tgt, AddressOf(IdentifierReference(listOf("label_outside"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign5 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","localvar"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign5 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","localvar"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign6 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","locallabel"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign6 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","locallabel"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign7 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","var_outside"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign7 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","var_outside"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
-        val assign8 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","label_outside"), Position.DUMMY), Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
+        val assign8 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","label_outside"), Position.DUMMY), null, Position.DUMMY), AssignmentOrigin.USERCODE, Position.DUMMY)
 
         val statements = mutableListOf(varInSub, var2InSub, labelInSub, assign1, assign2, assign3, assign4, assign5, assign6, assign7, assign8)
         val subroutine = Subroutine("start", mutableListOf(), emptyList(), emptyList(), emptyList(), emptySet(), null, false, false, false, statements, Position.DUMMY)

compilerAst/src/prog8/ast/AstToSourceTextConverter.kt

@@ -429,6 +429,7 @@ class AstToSourceTextConverter(val output: (text: String) -> Unit, val program:
     override fun visit(addressOf: AddressOf) {
         output("&")
         addressOf.identifier.accept(this)
+        addressOf.arrayIndex?.accept(this)
     }
 
     override fun visit(inlineAssembly: InlineAssembly) {

compilerAst/src/prog8/ast/antlr/Antlr2Kotlin.kt

@@ -469,8 +469,15 @@ private fun Prog8ANTLRParser.ExpressionContext.toAst() : Expression {
     if(directmemory()!=null)
         return DirectMemoryRead(directmemory().expression().toAst(), toPosition())
 
-    if(addressof()!=null)
+    if(addressof()!=null) {
-        return AddressOf(addressof().scoped_identifier().toAst(), toPosition())
+        val addressOf = addressof()
+        val identifier = addressOf.scoped_identifier()
+        val array = addressOf.arrayindexed()
+        return if(identifier!=null)
+            AddressOf(addressof().scoped_identifier().toAst(), null, toPosition())
+        else
+            AddressOf(array.scoped_identifier().toAst(), array.arrayindex().toAst(), toPosition())
+    }
 
     throw FatalAstException(text)
 }

compilerAst/src/prog8/ast/expressions/AstExpressions.kt

@@ -49,7 +49,7 @@ sealed class Expression: Node {
                 (other is TypecastExpression && other.implicit==implicit && other.type==type && other.expression isSameAs expression)
             }
             is AddressOf -> {
-                (other is AddressOf && other.identifier.nameInSource == identifier.nameInSource)
+                (other is AddressOf && other.identifier.nameInSource == identifier.nameInSource && other.arrayIndex==arrayIndex)
             }
             is RangeExpression -> {
                 (other is RangeExpression && other.from==from && other.to==to && other.step==step)
@@ -369,25 +369,34 @@ class TypecastExpression(var expression: Expression, var type: DataType, val imp
     }
 }
 
-data class AddressOf(var identifier: IdentifierReference, override val position: Position) : Expression() {
+data class AddressOf(var identifier: IdentifierReference, var arrayIndex: ArrayIndex?, override val position: Position) : Expression() {
     override lateinit var parent: Node
 
     override fun linkParents(parent: Node) {
         this.parent = parent
-        identifier.parent=this
+        identifier.linkParents(this)
+        arrayIndex?.linkParents(this)
     }
 
     override val isSimple = true
 
     override fun replaceChildNode(node: Node, replacement: Node) {
-        require(replacement is IdentifierReference && node===identifier)
+        if(node===identifier) {
-        identifier = replacement
+            require(replacement is IdentifierReference)
-        replacement.parent = this
+            identifier = replacement
+            replacement.parent = this
+        } else if(node===arrayIndex) {
+            require(replacement is ArrayIndex)
+            arrayIndex = replacement
+            replacement.parent = this
+        } else {
+            throw FatalAstException("invalid replace, no child node $node")
+        }
     }
 
-    override fun copy() = AddressOf(identifier.copy(), position)
+    override fun copy() = AddressOf(identifier.copy(), arrayIndex?.copy(), position)
     override fun constValue(program: Program): NumericLiteral? = null
-    override fun referencesIdentifier(nameInSource: List<String>) = identifier.nameInSource==nameInSource
+    override fun referencesIdentifier(nameInSource: List<String>) = identifier.nameInSource==nameInSource || arrayIndex?.referencesIdentifier(nameInSource)==true
     override fun inferType(program: Program) = InferredTypes.knownFor(DataType.UWORD)
     override fun accept(visitor: IAstVisitor) = visitor.visit(this)
     override fun accept(visitor: AstWalker, parent: Node)= visitor.visit(this, parent)

compilerAst/src/prog8/ast/walk/AstWalker.kt

@@ -458,6 +458,7 @@ abstract class AstWalker {
     fun visit(addressOf: AddressOf, parent: Node) {
         track(before(addressOf, parent), addressOf, parent)
         addressOf.identifier.accept(this, addressOf)
+        addressOf.arrayIndex?.accept(this)
         track(after(addressOf, parent), addressOf, parent)
     }
 

compilerAst/src/prog8/ast/walk/IAstVisitor.kt

@@ -173,6 +173,7 @@ interface IAstVisitor {
 
     fun visit(addressOf: AddressOf) {
         addressOf.identifier.accept(this)
+        addressOf.arrayIndex?.accept(this)
     }
 
     fun visit(inlineAssembly: InlineAssembly) {

docs/source/todo.rst

@@ -1,7 +1,7 @@
 TODO
 ====
 
-- allow taking address of array variable (now gives parser error)
+- implement codegen TODO's "address-of array element"  (part of:  allow taking address of array element (now gives parser error):  &array[10] )
 - ir: the @split arrays are currently also split in _lsb/_msb arrays in the IR, and operations take multiple (byte) instructions that may lead to verbose and slow operation and machine code generation down the line.
 
 - [on branch: shortcircuit] investigate McCarthy evaluation again? this may also reduce code size perhaps for things like if a>4 or a<2 ....

examples/test.p8

@@ -1,37 +1,53 @@
 %import textio
+%import floats
+
 %zeropage basicsafe
 
 main {
     sub start() {
-        uword zz = $ea45
+        ubyte[] barray = [11,22,33]
-        txt.print_uwhex(zz, true)
+        uword[] warray = [$1234,$5678,$abcd]
+        uword[] @split split_warray = [$1234,$5678,$abcd]
+        float[] float_array = [11.11,22.22,33.33]
+
+        txt.print("incr of 1: ")
+        txt.print_uw(&barray)
+        txt.spc()
+        txt.print_uw(&barray[0])
+        txt.spc()
+        txt.print_uw(&barray[1])
+        txt.spc()
+        txt.print_uw(&barray[2])
         txt.nl()
 
-        ;@(&zz) = $11
+        txt.print("incr of 2: ")
-        setlsb(zz, 0)
+        txt.print_uw(&warray)
-        txt.print_uwhex(zz, true)
+        txt.spc()
-        txt.nl()
+        txt.print_uw(&warray[0])
-        ;@(&zz+1) = $22
+        txt.spc()
-        setmsb(zz, 0)
+        txt.print_uw(&warray[1])
-        txt.print_uwhex(zz, true)
+        txt.spc()
-        txt.nl()
+        txt.print_uw(&warray[2])
         txt.nl()
 
-        uword[] @split array = [$1234,$5678,$abcd]     ; TODO also with @split
+        txt.print("incr of 1: ")
+        txt.print_uw(&split_warray)
+        txt.spc()
+        txt.print_uw(&split_warray[0])
+        txt.spc()
+        txt.print_uw(&split_warray[1])
+        txt.spc()
+        txt.print_uw(&split_warray[2])
+        txt.nl()
 
-        ubyte one = 1
+        txt.print("incr of 4 or 5: ")
-        ubyte two = 2
+        txt.print_uw(&float_array)
-        txt.print_uwhex(array[1], true)
+        txt.spc()
-        txt.nl()
+        txt.print_uw(&float_array[0])
-        txt.print_uwhex(array[2], true)
+        txt.spc()
-        txt.nl()
+        txt.print_uw(&float_array[1])
-        ;@(&array+one*2) = $ff
+        txt.spc()
-        ;@(&array+two*2+1) = $ff
+        txt.print_uw(&float_array[2])
-        setlsb(array[one],0)
-        setmsb(array[two],0)
-        txt.print_uwhex(array[1], true)
-        txt.nl()
-        txt.print_uwhex(array[2], true)
         txt.nl()
     }
 }

parser/antlr/Prog8ANTLR.g4

@@ -197,7 +197,7 @@ typecast : 'as' datatype;
 
 directmemory : '@' '(' expression ')';
 
-addressof : <assoc=right> ADDRESS_OF scoped_identifier ;
+addressof : <assoc=right> ADDRESS_OF (scoped_identifier | arrayindexed) ;
 
 
 functioncall : scoped_identifier '(' expression_list? ')'  ;