added hooks for ST, TI and TI$ variables

src/basic/engine/fetch_variable.s

@@ -68,9 +68,9 @@ fetch_variable_type_float:
 #endif
 
 #if HAS_OPCODES_65C02
-	bra fetch_variable_find_addr
+	bra fetch_variable_special
 #else
-	jmp fetch_variable_find_addr
+	jmp fetch_variable_special
 #endif
 
 fetch_variable_type_integer:
@@ -89,6 +89,32 @@ fetch_variable_type_string:
 
 	// FALLTROUGH
 
+fetch_variable_special:
+
+	lda VARNAM+0
+	cmp #$54                           // 'T'
+	beq !+
+	cmp #$53                           // 'S'
+	bne fetch_variable_find_addr
+
+	// First character is 'S', check the second one
+
+	lda VARNAM+1
+	cmp #$54                           // 'T'
+	bne fetch_variable_find_addr
+
+	jmp fetch_variable_ST
+!:
+	// First character is 'T', check the second one
+
+	lda VARNAM+1
+	cmp #$49
+	beq_16 fetch_variable_TI
+	cmp #$C9
+	beq_16 fetch_variable_TI_string
+
+	// FALLTROUGH
+
 fetch_variable_find_addr:
 
 	// Now try to find variable address between VARTAB and ARYTAB, see

src/basic/engine/fetch_variable_ST.s

@@ -0,0 +1,10 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+fetch_variable_ST:
+
+	// XXX implement this
+
+	jmp do_NOT_IMPLEMENTED_error

src/basic/engine/fetch_variable_TI.s

@@ -0,0 +1,10 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+fetch_variable_TI:
+
+	// XXX implement this
+
+	jmp do_NOT_IMPLEMENTED_error

src/basic/engine/fetch_variable_TI_string.s

@@ -0,0 +1,10 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+fetch_variable_TI_string:
+
+	// XXX implement this
+
+	jmp do_NOT_IMPLEMENTED_error

src/basic/engine/varstr_alloc.s

@@ -20,6 +20,9 @@
 // - fills-in pointer in the string descriptor
 //
 
+// NOTE: if FAC1 or FAC2 contains a value (not a string descriptor - these are going to be updated
+//       if garbage collector starts), then preserve __FAC1+1/+2 and __FAC2+1/+2 somewhere, as there
+//       is a small chance they'll get damaged!
 
 varstr_alloc: