fix several bugs with storing BASIC lines

c64/basic/basic_find_line.s

@@ -11,23 +11,27 @@ basic_find_line:
 basic_find_line_loop:	
 	;; Then search for line number
 	;; Line number
+	
 	ldy #3
 	ldx #<basic_current_line_ptr
 	jsr peek_under_roms
 	cmp basic_line_number+1
+	beq +
 	bcs line_num_too_high
 	bne not_this_line
+*
+	
 	dey
 	jsr peek_under_roms
 	cmp basic_line_number+0
+	beq +
 	bcs line_num_too_high
 	bne not_this_line
-
+*
 	clc
 	rts
 not_this_line:
 	;; Not this line, so advance to next line
-	ldy #0
 	ldx #<basic_current_line_ptr
 	jsr peek_pointer_null_check
 	bcs more_lines_exist
@@ -37,11 +41,18 @@ line_num_too_high:
 	sec
 	rts
 more_lines_exist:	
-	;; A = high byte of line
+
-	pha
+	;; XXX - Add program mangled check here to be triggered
-	dey
+	;; if the link goes backwards.
+	;; Follow link to next line
+	ldy #0
+	ldx #<basic_current_line_ptr
+	jsr peek_under_roms
+	sta $0100
+	iny
 	jsr peek_under_roms
-	sta basic_current_line_ptr+0
-	pla
 	sta basic_current_line_ptr+1
+	lda $0100
+	sta basic_current_line_ptr+0
+
 	jmp basic_find_line_loop

c64/basic/basic_insert_line.s

@@ -15,8 +15,10 @@ basic_insert_line:
 	;; But first, remember where the pointer will be, so that we can
 	;; put the line in there after.
 	lda basic_current_line_ptr+0
+	sta $0438
 	pha
 	lda basic_current_line_ptr+1
+	sta $0439
 	pha
 	
 	;; Get number of bytes in tokenised line after line number
@@ -43,8 +45,10 @@ basic_insert_line:
 	
 	;; Get pointer back
 	pla
+	sta $0411
 	sta basic_current_line_ptr+1
 	pla
+	sta $0410
 	sta basic_current_line_ptr+0
 
 	inc $0427

c64/basic/basic_main_loop.s

@@ -82,6 +82,7 @@ rsl_l1:	lda $0200,x
 	ora basic_fac1_exponent
 	beq +
 ml_bad_line_number:
+	inc $0424
 	;; Syntax error
 	ldx #10
 	jmp do_basic_error
@@ -113,9 +114,19 @@ skip_spaces:
 	lda basic_fac1_mantissa+1
 	sta basic_line_number+1
 
+	lda basic_current_line_ptr+0
+	sta $0420
+	lda basic_current_line_ptr+1
+	sta $0421
+	
 	;; Delete line if present
 	jsr basic_find_line
 
+	lda basic_current_line_ptr+0
+	sta $0420
+	lda basic_current_line_ptr+1
+	sta $0421
+	
 	bcs +
 	jsr basic_delete_line
 *

c64/basic/basic_shift_mem_up.s

@@ -14,7 +14,7 @@ basic_shift_mem_up_and_relink:
 	sta memmove_dst+1
 	;; End point of source is just current end of BASIC text
 	lda basic_end_of_text_ptr+0
-	sta memmove_src
+	sta memmove_src+0
 	lda basic_end_of_text_ptr+1
 	sta memmove_src+1