small ST/TI/TI$ cleanup

src/basic/engine_variables/fetch_variable.s

@@ -93,28 +93,15 @@ fetch_variable_type_string:
 
 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
+	jsr is_var_TI_string
 	beq_16 fetch_variable_TI_string
 
+	jsr is_var_TI
+	beq_16 fetch_variable_TI
+
+	jsr is_var_ST
+	beq_16 fetch_variable_ST
+
 	// FALLTROUGH
 
 fetch_variable_find_addr:

src/basic/engine_variables/is_var_ST.s

@@ -0,0 +1,17 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+is_var_ST:
+
+	// Always start with VARNAM+1, there is a sligtly bigger chance it won't match
+
+	lda VARNAM+1
+	cmp #$54       // 'T'
+	bne !+
+
+	lda VARNAM+0
+	cmp #$53       // 'S'
+!:
+	rts

src/basic/engine_variables/is_var_TI.s

@@ -0,0 +1,17 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+is_var_TI:
+
+	// Always start with VARNAM+1, there is a sligtly bigger chance it won't match
+
+	lda VARNAM+1
+	cmp #$49       // 'I'
+	bne !+
+
+	lda VARNAM+0
+	cmp #$54       // 'T'
+!:
+	rts

src/basic/engine_variables/is_var_TI_string.s

@@ -0,0 +1,17 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+is_var_TI_string:
+
+	// Always start with VARNAM+1, there is a sligtly bigger chance it won't match
+
+	lda VARNAM+1
+	cmp #$C9       // 'I...$'
+	bne !+
+
+	lda VARNAM+0
+	cmp #$54       // 'T'
+!:
+	rts