added missing code for some meory models

src/,,config_custom.s

@@ -39,9 +39,9 @@
 
 // Memory model
 
-#define CONFIG_MEMORY_MODEL_38K
+// #define CONFIG_MEMORY_MODEL_38K
 // #define CONFIG_MEMORY_MODEL_46K
-// #define CONFIG_MEMORY_MODEL_50K
+#define CONFIG_MEMORY_MODEL_50K
 // #define CONFIG_MEMORY_MODEL_60K
 
 

src/basic/basic_operators/helper_add_concat_46K_50K.s

@@ -0,0 +1,53 @@
+// #LAYOUT# STD *       #TAKE-HIGH
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
+// #LAYOUT# *   *       #IGNORE
+
+// This has to go $E000 or above - routines below banks out the main BASIC ROM!
+
+//
+// Helper routine for string concatenation
+//
+
+
+#if CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+
+helper_add_concat:
+
+	// Unmap BASIC lower ROM
+
+	lda #$26
+	sta CPU_R6510
+
+	// Copy data from the first string
+
+	ldy #$00
+!:
+	lda (__FAC2+1),y
+	sta (INDEX),y
+	iny
+	cpy __FAC2+0
+	bne !-
+
+	// Increase INDEX pointer by the size of the 1st string
+
+	tya
+	jsr varstr_INDEX_up_A
+
+	// Copy data from the second string
+
+	ldy #$00
+!:
+	lda (__FAC1+1),y
+	sta (INDEX),y
+	iny
+	cpy __FAC1+0
+	bne !-
+
+	// Restore default memory mapping
+
+	lda #$27
+	sta CPU_R6510
+
+	rts
+
+#endif

src/basic/basic_operators/oper_add.s

@@ -73,16 +73,38 @@ oper_add_strings:
 
 #if CONFIG_MEMORY_MODEL_60K
 	
-	// XXX
+	// Copy data from the first string
-	// XXX
+
-	// XXX
+	ldy #$00
+!:
+	ldx #<(__FAC2+1)
+	jsr peek_under_roms
+	ldx #<INDEX
+	jsr poke_under_roms
+	iny
+	cpy __FAC2+0
+	bne !-
+
+	// Increase INDEX pointer by the size of the 1st string
+
+	tya
+	jsr varstr_INDEX_up_A
+
+	// Copy data from the second string
+
+	ldy #$00
+!:
+	ldx #<(__FAC1+1)
+	jsr peek_under_roms
+	ldx #<INDEX
+	jsr poke_under_roms
+	iny
+	cpy __FAC1+0
+	bne !-
 
 #elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
-	// XXX consider optimized version without multiple JSRs
 
-	// XXX
+	jsr helper_add_concat
-	// XXX
-	// XXX
 
 #else // CONFIG_MEMORY_MODEL_38K
 

src/basic/engine/varstr_garbage_index_up_a.s

@@ -1,9 +1,11 @@
-// #LAYOUT# STD *       #TAKE
+// #LAYOUT# STD *       #TAKE-HIGH
-// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE-HIGH
 // #LAYOUT# *   *       #IGNORE
 
+// This has to go $E000 or above - it can be used by routines which bank out the main BASIC ROM!
+
 //
-// Helper routine, used by garbage collector
+// Helper routine, used by garbage collector and string concatenation
 //