151 lines
3.2 KiB
ArmAsm
151 lines
3.2 KiB
ArmAsm
basic_shift_mem_down_and_relink:
|
|
// Shift memory down to basic_current_line_pointer
|
|
// from X bytes further along.
|
|
|
|
// Destination is basic_current_line_ptr
|
|
lda basic_current_line_ptr+0
|
|
sta memmove_dst+0
|
|
lda basic_current_line_ptr+1
|
|
sta memmove_dst+1
|
|
|
|
// Source is that plus X
|
|
txa
|
|
pha // also keep for later
|
|
clc
|
|
adc basic_current_line_ptr+0
|
|
sta memmove_src+0
|
|
lda basic_current_line_ptr+1
|
|
adc #0
|
|
sta memmove_src+1
|
|
|
|
// Size is distance from source to end of BASIC text.
|
|
lda basic_end_of_text_ptr+0
|
|
sec
|
|
sbc memmove_src+0
|
|
sta memmove_size+0
|
|
lda basic_end_of_text_ptr+1
|
|
sbc memmove_src+1
|
|
sta memmove_size+1
|
|
|
|
// jsr printf
|
|
// .text "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
|
|
// .text "SHIFTING DOWN $"
|
|
// .byte $f1,<memmove_size,>memmove_size
|
|
// .byte $f0,<memmove_size,>memmove_size
|
|
// .text " BYTES FROM $"
|
|
// .byte $f1,<memmove_src,>memmove_src
|
|
// .byte $f0,<memmove_src,>memmove_src
|
|
// .text " TO $"
|
|
// .byte $f1,<memmove_dst,>memmove_dst
|
|
// .byte $f0,<memmove_dst,>memmove_dst
|
|
// .byte $0d,0
|
|
|
|
// The copy routine that copies under the ROMs is as simple
|
|
// as possible to be as small as possible, so we have
|
|
// to adjust the pointers and counts so that the simple
|
|
// increment and decrement bounds checks work.
|
|
|
|
// Specifically we want Y pre-set so that the end of the
|
|
// copy ends when Y = $00.
|
|
// So if copying 1 byte, we want Y=$FF
|
|
// This means we have to then reduce the source and
|
|
// target pointers by the same amount
|
|
|
|
lda memmove_size+0
|
|
eor #$ff
|
|
sta tokenise_work3
|
|
sta memmove_size+0
|
|
|
|
lda memmove_src+0
|
|
sec
|
|
sbc tokenise_work3
|
|
sta memmove_src+0
|
|
lda memmove_src+1
|
|
sbc #0
|
|
sta memmove_src+1
|
|
|
|
lda memmove_dst+0
|
|
sec
|
|
sbc tokenise_work3
|
|
sta memmove_dst+0
|
|
lda memmove_dst+1
|
|
sbc #0
|
|
sta memmove_dst+1
|
|
|
|
// Increase copy page count so we can post-decrement compare with $00
|
|
inc memmove_size+1
|
|
|
|
// jsr printf
|
|
// .text "REVISED BOUNDS $"
|
|
// .byte $f1,<memmove_size,>memmove_size
|
|
// .byte $f0,<memmove_size,>memmove_size
|
|
// .text " BYTES FROM $"
|
|
// .byte $f1,<memmove_src,>memmove_src
|
|
// .byte $f0,<memmove_src,>memmove_src
|
|
// .text " TO $"
|
|
// .byte $f1,<memmove_dst,>memmove_dst
|
|
// .byte $f0,<memmove_dst,>memmove_dst
|
|
// .byte $0d,0
|
|
|
|
// Get Y value ready for the copy
|
|
ldy memmove_size+0
|
|
|
|
jsr shift_mem_down
|
|
|
|
// Get length of deletion back
|
|
pla
|
|
sta tokenise_work3
|
|
|
|
// Check if we still have any lines left
|
|
ldy #0
|
|
ldx #<basic_current_line_ptr
|
|
jsr peek_pointer_null_check
|
|
bcs relink_down_next_line
|
|
// Nope, so just return
|
|
clc
|
|
rts
|
|
|
|
|
|
relink_down_next_line:
|
|
// inc $d020
|
|
// jmp relink_down_next_line
|
|
|
|
// Subtract tokenise_work3 from the pointer
|
|
ldy #0
|
|
ldx #<basic_current_line_ptr+0
|
|
jsr peek_under_roms
|
|
sec
|
|
sbc tokenise_work3
|
|
sta memmove_src+0
|
|
iny
|
|
jsr peek_under_roms
|
|
sbc #0
|
|
sta memmove_src+1
|
|
|
|
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_down_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_down_next_line
|
|
|
|
clc
|
|
rts
|
|
|