59 lines
1.1 KiB
ArmAsm
59 lines
1.1 KiB
ArmAsm
;; Find the BASIC line with number basic_line_number
|
|
|
|
|
|
basic_find_line:
|
|
;; Get pointer to start of BASIC text
|
|
lda basic_start_of_text_ptr+0
|
|
sta basic_current_line_ptr+0
|
|
lda basic_start_of_text_ptr+1
|
|
sta basic_current_line_ptr+1
|
|
|
|
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
|
|
ldx #<basic_current_line_ptr
|
|
jsr peek_pointer_null_check
|
|
bcs more_lines_exist
|
|
|
|
;; no more lines exist, return failure
|
|
line_num_too_high:
|
|
sec
|
|
rts
|
|
more_lines_exist:
|
|
|
|
;; XXX - Add program mangled check here to be triggered
|
|
;; 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+1
|
|
lda $0100
|
|
sta basic_current_line_ptr+0
|
|
|
|
jmp basic_find_line_loop
|