106 lines
2.1 KiB
ArmAsm
106 lines
2.1 KiB
ArmAsm
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basic_shift_mem_up_and_relink:
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;; Shift memory up from basic_current_line_ptr
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;; X bytes.
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;; Work out end point of destination
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txa
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clc
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adc basic_end_of_text_ptr+0
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sta memmove_dst+0
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lda basic_end_of_text_ptr+1
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adc #0
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sta memmove_dst+1
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;; End point of source is just current end of BASIC text
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lda basic_end_of_text_ptr+0
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sta memmove_src+0
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lda basic_end_of_text_ptr+1
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sta memmove_src+1
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;; Work out size of region to copy
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lda basic_end_of_text_ptr+1
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sec
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sbc basic_current_line_ptr+1
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sta memmove_size+1
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lda basic_end_of_text_ptr+0
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sbc #0
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sta memmove_size+0
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;; To make life simple for the copy routine that lives in RAM,
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;; we have to adjust the end pointers down one page and set Y to the low
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;; byte of the copy size.
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lda memmove_src+0
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sec
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sbc memmove_size+0
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sta memmove_src+0
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lda memmove_src+1
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sbc #0
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sta memmove_src+1
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lda memmove_dst+0
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sec
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sbc memmove_size+0
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sta memmove_dst+0
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lda memmove_dst+1
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sbc #0
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sta memmove_dst+1
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;; Now make exit easy, by being able to check for zero on size high byte when done
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inc memmove_size+1
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;; Then set Y to the number offset required
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ldy memmove_size+0
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stx tokenise_work3
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;; Do the copy
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jsr shift_mem_up
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;; Now fix the pointer to the next line
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;; First, we need to point the current BASIC line
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;; pointer to itself, so that we can add the shift
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;; to make it end up pointing to the next line
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ldy #0
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ldx #<basic_current_line_ptr+0
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lda basic_current_line_ptr+0
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jsr poke_under_roms
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iny
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lda basic_current_line_ptr+1
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jsr poke_under_roms
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relink_up_next_line:
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ldy #0
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ldx #<basic_current_line_ptr+0
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jsr peek_under_roms
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clc
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adc tokenise_work3
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sta memmove_src+0
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iny
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jsr peek_under_roms
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adc #0
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sta memmove_src+1
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ldy #0
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ldx #<basic_current_line_ptr
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lda memmove_src+0
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jsr poke_under_roms
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iny
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lda memmove_src+1
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jsr poke_under_roms
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relink_up_loop:
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;; Now advance pointer to the next line,
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lda memmove_src+0
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sta basic_current_line_ptr+0
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lda memmove_src+1
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sta basic_current_line_ptr+1
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;; Have we run out of lines to patch?
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ldx #<basic_current_line_ptr
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jsr peek_pointer_null_check
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bcs relink_up_next_line
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rts
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