Files
open-roms/c64/basic/basic_shift_mem_up.s
T
2019-04-29 21:00:00 +09:30

171 lines
3.7 KiB
ArmAsm

basic_shift_mem_up_and_relink:
;; Shift memory up from basic_current_line_ptr
;; X bytes.
;; NOTE: Pointers need to be reduced by one, due to the way
;; the copyroutine works, so we do that here.
;; Work out end point of destination
txa
clc
adc basic_end_of_text_ptr+0
sta memmove_dst+0
lda basic_end_of_text_ptr+1
adc #0
sta memmove_dst+1
lda memmove_dst+0
sec
sbc #1
sta memmove_dst+0
lda memmove_dst+1
sbc #0
sta memmove_dst+1
;; End point of source is just current end of BASIC text
lda basic_end_of_text_ptr+0
sec
sbc #1
sta memmove_src+0
lda basic_end_of_text_ptr+1
sbc #0
sta memmove_src+1
;; Work out size of region to copy
lda basic_end_of_text_ptr+0
sec
sbc basic_current_line_ptr+0
sta memmove_size+0
lda basic_end_of_text_ptr+1
sbc basic_current_line_ptr+1
sta memmove_size+1
;; jsr printf
;; .byte "TOP OF BASIC = $"
;; .byte $f1,<basic_end_of_text_ptr,>basic_end_of_text_ptr
;; .byte $f0,<basic_end_of_text_ptr,>basic_end_of_text_ptr
;; .byte $0d
;; .byte "SHIFTING UP $"
;; .byte $f1,<memmove_size,>memmove_size
;; .byte $f0,<memmove_size,>memmove_size
;; .byte " BYTES FROM $"
;; .byte $f1,<memmove_src,>memmove_src
;; .byte $f0,<memmove_src,>memmove_src
;; .byte " TO $"
;; .byte $f1,<memmove_dst,>memmove_dst
;; .byte $f0,<memmove_dst,>memmove_dst
;; .byte $0d,0
;; To make life simple for the copy routine that lives in RAM,
;; we have to adjust the end pointers down one page and set Y to the low
;; byte of the copy size.
lda memmove_src+0
sec
sbc memmove_size+0
sta memmove_src+0
lda memmove_src+1
sbc #0
sta memmove_src+1
lda memmove_dst+0
sec
sbc memmove_size+0
sta memmove_dst+0
lda memmove_dst+1
sbc #0
sta memmove_dst+1
;; Now make exit easy, by being able to check for zero on size high byte when done
inc memmove_size+1
;; Then set Y to the number offset required
ldy memmove_size+0
iny
stx tokenise_work3
;; jsr printf
;; .byte "REVISED BOUNDS $"
;; .byte $f1,<memmove_size,>memmove_size
;; .byte $f0,<memmove_size,>memmove_size
;; .byte " BYTES FROM $"
;; .byte $f1,<memmove_src,>memmove_src
;; .byte $f0,<memmove_src,>memmove_src
;; .byte " TO $"
;; .byte $f1,<memmove_dst,>memmove_dst
;; .byte $f0,<memmove_dst,>memmove_dst
;; .byte $0d,0
;; Do the copy
jsr shift_mem_up
;; Now fix the pointer to the next line
;; First, we need to point the current BASIC line
;; pointer to itself, so that we can add the shift
;; to make it end up pointing to the next line
ldy #0
ldx #<basic_current_line_ptr+0
lda basic_current_line_ptr+0
jsr poke_under_roms
iny
lda basic_current_line_ptr+1
jsr poke_under_roms
relink_up_next_line:
;; inc $d020
;; jmp relink_up_next_line
;; Advance pointer by tokenise_word3 bytes
ldy #0
ldx #<basic_current_line_ptr+0
jsr peek_under_roms
sta memmove_dst+0
clc
adc tokenise_work3
sta memmove_src+0
iny
php
jsr peek_under_roms
sta memmove_dst+1
plp
adc #0
sta memmove_src+1
;; jsr printf
;; .byte "LINE ADDR = $"
;; .byte $f1,<basic_current_line_ptr,>basic_end_of_text_ptr
;; .byte $f0,<basic_current_line_ptr,>basic_end_of_text_ptr
;; .byte $d," BEFORE = $"
;; .byte $f1,<memmove_dst,>memmove_dst
;; .byte $f0,<memmove_dst,>memmove_dst
;; .byte ", AFTER = $"
;; .byte $f1,<memmove_src,>memmove_src
;; .byte $f0,<memmove_src,>memmove_src
;; .byte $d
;; .byte 0
;; Write memmove_src back to current line pointer
ldy #0
ldx #<basic_current_line_ptr
lda memmove_src+0
jsr poke_under_roms
iny
lda memmove_src+1
jsr poke_under_roms
relink_up_loop:
;; Now advance pointer to the next line,
lda memmove_src+0
sta basic_current_line_ptr+0
lda memmove_src+1
sta basic_current_line_ptr+1
;; Have we run out of lines to patch?
ldx #<basic_current_line_ptr
jsr peek_pointer_null_check
bcs relink_up_next_line
rts