added fast code for x*640

compiler/res/prog8lib/math.asm

@@ -774,6 +774,13 @@ stack_mul_word_320	.proc
 		rts
 		.pend
 
+stack_mul_word_640	.proc
+		; stackW = (stackLo * 2 * 320)    (stackHi doesn't matter)
+		asl  P8ESTACK_LO+1,x
+		jmp  stack_mul_word_320
+		.pend
+
+
 ; ----------- optimized multiplications (in-place A (byte) and ?? (word)) : ---------
 mul_byte_3	.proc
 		; A = A + A*2
@@ -1264,6 +1271,13 @@ mul_word_320	.proc
 		rts
 		.pend
 
+mul_word_640	.proc
+		; AY = (A * 2 * 320) (msb in Y doesn't matter)
+		asl  a
+		jmp  mul_word_320
+		.pend
+
+
 ; ----------- end optimized multiplications -----------
 
 

compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt

@@ -30,7 +30,7 @@ internal class AsmGen(private val program: Program,
 
     // for expressions and augmented assignments:
     val optimizedByteMultiplications = setOf(3,5,6,7,9,10,11,12,13,14,15,20,25,40,50,80,100)
-    val optimizedWordMultiplications = setOf(3,5,6,7,9,10,12,15,20,25,40,50,80,100,320)
+    val optimizedWordMultiplications = setOf(3,5,6,7,9,10,12,15,20,25,40,50,80,100,320,640)
     private val callGraph = CallGraph(program)
 
     private val assemblyLines = mutableListOf<String>()

examples/test.p8

@@ -1,14 +1,27 @@
+%import textio
+%zeropage basicsafe
 
 main {
 
     sub start() {
 
-        uword enemyRef = $2000
-        ubyte cur
+        uword x=22
+        x*=320
+        txt.print_uw(x)
+        txt.nl()
+
+        x=22
+        x*=640
+        txt.print_uw(x)
+        txt.nl()
+
+        ubyte a=1
+        ubyte b=22
+
+        x = (a*b)*640*a
+        txt.print_uw(x)
+        txt.nl()
 
-        cur = enemyRef[1]
-            + enemyRef[2]
-            + enemyRef[3]
 
     }
 }