76 lines
1.7 KiB
ArmAsm
76 lines
1.7 KiB
ArmAsm
;; Insert the tokenised line stored at $0200.
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;; First work out where in the list to put it
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;; (basic_find_line with the line number can be used to work
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;; out the insertion point, as it should abort once it finds a
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;; line number too high).
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;; Then all we have to do is push the rest of the BASIC text up,
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;; and update the pointers in all following basic lines.
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basic_insert_line:
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;; ASSUMES basic_find_line has been called to set the insert point.
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;; We need to insert space for the link link token, the line number,
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;; and the zero-terminated line itself. This means 2+2+1 plus length
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;; of tokenised string after the line number
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;; But first, remember where the pointer will be, so that we can
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;; put the line in there after.
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lda basic_current_line_ptr+0
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pha
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lda basic_current_line_ptr+1
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pha
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;; Get number of bytes in tokenised line after line number
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lda tokenise_work2
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sec
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sbc tokenise_work1
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;; Add on the four bytes space we need
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clc
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adc #5
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pha
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tax
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;; Make the space
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jsr basic_shift_mem_up_and_relink
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;; Now increase top of BASIC mem
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pla
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clc
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adc basic_end_of_text_ptr+0
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sta basic_end_of_text_ptr+0
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lda basic_end_of_text_ptr+1
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adc #0
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sta basic_end_of_text_ptr+1
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;; Get pointer back
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pla
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sta basic_current_line_ptr+1
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pla
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sta basic_current_line_ptr+0
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inc $0427
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;; Write the line number
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ldy #2
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ldx #<basic_current_line_ptr
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lda basic_line_number+0
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jsr poke_under_roms
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iny
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lda basic_line_number+1
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jsr poke_under_roms
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;; Now store the line body itself
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line_store_loop:
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ldx tokenise_work1
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lda $0200,x
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inc tokenise_work1
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ldx #<basic_current_line_ptr
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iny
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jsr poke_under_roms
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lda tokenise_work1
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cmp tokenise_work2
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bne line_store_loop
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sec
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rts
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