added target() function

compiler/src/prog8/functions/BuiltinFunctions.kt

@@ -6,6 +6,9 @@ import prog8.ast.expressions.*
 import prog8.ast.statements.StructDecl
 import prog8.ast.statements.VarDecl
 import prog8.compiler.CompilerException
+import prog8.compiler.target.C64Target
+import prog8.compiler.target.CompilationTarget
+import prog8.compiler.target.Cx16Target
 import kotlin.math.*
 
 
@@ -142,6 +145,7 @@ private val functionSignatures: List<FSignature> = listOf(
     FSignature("clear_irqd"  , false, emptyList(), null),
     FSignature("read_flags"  , false, emptyList(), DataType.UBYTE),
     FSignature("progend"     , true, emptyList(), DataType.UWORD),
+    FSignature("target"      , true, emptyList(), DataType.UBYTE, ::builtinTarget),
     FSignature("swap"        , false, listOf(FParam("first", NumericDatatypes), FParam("second", NumericDatatypes)), null),
     FSignature("memcopy"     , false, listOf(
                             FParam("from", IterableDatatypes + DataType.UWORD),
@@ -480,6 +484,17 @@ private fun builtinSgn(args: List<Expression>, position: Position, program: Prog
     return NumericLiteralValue(DataType.BYTE, constval.number.toDouble().sign.toInt().toShort(), position)
 }
 
+private fun builtinTarget(args: List<Expression>, position: Position, program: Program): NumericLiteralValue {
+    if (args.isNotEmpty())
+        throw SyntaxError("target requires no arguments", position)
+    val target = when(CompilationTarget.instance) {
+        is C64Target -> 64
+        is Cx16Target -> 16
+        else -> throw CompilerException("unrecognised compilation target")
+    }
+    return NumericLiteralValue(DataType.UBYTE, target, position)
+}
+
 private fun numericLiteral(value: Number, position: Position): NumericLiteralValue {
     val floatNum=value.toDouble()
     val tweakedValue: Number =

docs/source/programming.rst

@@ -912,6 +912,13 @@ set_irqd()  /  clear_irqd()
 swap(x, y)
     Swap the values of numerical variables (or memory locations) x and y in a fast way.
 
+target()
+    Returns byte value designating the target machine that the program was compiled for.
+    The following return values are currently defined:
+
+    - 16 = compiled for CommanderX16 with 65C02 CPU
+    - 64 = compiled for Commodore-64 with 6502/6510 CPU
+
 progend()
     Returns the last address of the program in memory + 1.
     Can be used to load dynamic data after the program, instead of hardcoding something.

docs/source/todo.rst

@@ -2,7 +2,6 @@
 TODO
 ====
 
-- add target() function that returns 16=cx16, 64=C64
 - Cx16 target: support full-screen 640x480 and 320x240 graphics? That requires our own custom graphics routines though to draw lines.
 - hoist all variable declarations up to the subroutine scope *before* even the constant folding takes place (to avoid undefined symbol errors when referring to a variable from another nested scope in the subroutine)
 - make it possible to use cpu opcodes such as 'nop' as variable names by prefixing all asm vars with something such as '_'

examples/test.p8

@@ -83,8 +83,7 @@ _y  .byte 0
     }
 
     sub start () {
-        ubyte ss = withasm(derp(1), 33,66)
-        txt.print_ub(ss)
+        txt.print_ub(target())
         txt.chrout('\n')
 
 ;        cx16.r0 = 65535