more work on external BASIC ROM support

c64/basic/,imports.s

@@ -18,6 +18,11 @@
 }
 
 
+#if ROM_LAYOUT_M65
+.label map_end             = KERNAL().map_end
+.label map_NORMAL          = KERNAL().map_NORMAL
+#endif
+
 #if CONFIG_PANIC_SCREEN
 .label panic               = KERNAL().panic
 #endif

c64/basic/board_m65/4000.mega65_vectable_basic_1.s

@@ -0,0 +1,35 @@
+// #LAYOUT# M65 BASIC_0 #TAKE-FLOAT
+// #LAYOUT# M65 BASIC_1 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Definitions for communication with Mega65 segment BASIC_1 from BASIC_0
+//
+
+
+#if SEGMENT_BASIC_0
+
+	// Label definitions
+
+	.label VB1__TEST                   = $4000 + 2 * 0
+
+TEST:
+
+	jsr map_BASIC_1
+	jmp (VB1__TEST)
+
+#else
+
+	// Vector table (OpenROMs private!)
+
+	.word TEST
+
+
+TEST:
+
+	inc 53280
+	inc 53281
+
+	jmp map_NORMAL
+
+#endif

c64/basic/board_m65/mega65_map_helpers.s

@@ -0,0 +1,28 @@
+// #LAYOUT# M65 BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// ROM mapping routines for Mega65
+//
+
+// Available memory maps:
+// - NORMAL  - nothing mapped in (taken from Kernal)
+// - BASIC_1 - for calling KERNAL_1 segment code
+
+
+map_BASIC_1:
+
+	php
+	pha
+	phx
+	phy
+	phz
+
+	lda #$00
+	tay
+	taz
+
+	lda #$20
+	ldx #$42    // 0x4000 <- map 8KB from 0x22000
+
+	jmp map_end