variable support cleanup

src/basic/engine_editor/delete_line.s

@@ -0,0 +1,78 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Delete the current BASIC line, which is assumed to have already been found with find_line.
+// Consists of copying memory down and lline linkage update.
+//
+
+delete_line:
+
+	// jsr printf
+	// .text "DELETING LINE AT $"
+	// .byte $f1,<OLDTXT,>OLDTXT
+	// .byte $f0,<OLDTXT,>OLDTXT
+	// .byte $0d,0
+
+	// Get address of next line
+	ldy #$00
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<OLDTXT
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_OLDTXT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (OLDTXT),y
+#endif
+
+	sta __tokenise_work3
+	iny
+
+#if CONFIG_MEMORY_MODEL_60K	
+	jsr peek_under_roms
+#elif CONFIG_MEMORY_MODEL_46K || CONFIG_MEMORY_MODEL_50K
+	jsr peek_under_roms_via_OLDTXT
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (OLDTXT),y
+#endif
+
+	sta __tokenise_work4
+
+	// Work out length of this line by looking at the pointer
+	lda __tokenise_work3
+	sec
+	sbc OLDTXT+0
+	sta __tokenise_work3
+	lda __tokenise_work4
+	sbc OLDTXT+1
+	sta __tokenise_work4
+
+	// jsr printf
+	// .text "LINE LENGTH IS $"
+	// .byte $f0,<__tokenise_work4,>__tokenise_work4
+	// .byte $f0,<__tokenise_work3,>__tokenise_work3
+	// .byte $0d,0
+	
+	lda __tokenise_work4
+	sbc #0
+	cmp #$00
+	beq !+
+
+	// Line length is <0 or >255 bytes.
+	// Either way, things are bad, so abort.
+
+	jmp do_MEMORY_CORRUPT_error
+!:
+	// Length can now be safely assumed to be in the low
+	// byte only, i.e., stored in __tokenise_work3
+
+	ldx __tokenise_work3
+
+	// Shuffle everything down
+	jsr shift_txt_down
+
+	// Finish by fixing program linkage and calculating new 
+
+	jmp update_LINKPRG_VARTAB_do_clr