97 lines
2.0 KiB
ArmAsm
97 lines
2.0 KiB
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# * KERNAL_0 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// CHROUT routine - screen support, INS key handling
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//
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chrout_screen_INS:
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// First check if last character of the logical line is space
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jsr screen_check_space_ends_line
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beq chrout_screen_ins_possible
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// Not space, we cannot insert anything
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bne_16 chrout_screen_done
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chrout_screen_ins_possible:
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// Move chars towards end of the line
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jsr screen_get_logical_line_end_ptr
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// Special handling for cursor in second line
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ldx TBLX
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lda LDTBL+0, x
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bpl chrout_screen_ins_second_line
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// Perform character copy
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jsr chrout_screen_ins_copy_loop
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// Put space in the inserted gap
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lda #$20
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sta (PNT), y
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// If line does not end with space now, try to grow the logical line
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jsr screen_check_space_ends_line
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beq chrout_screen_ins_done
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jsr screen_grow_logical_line
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// FALLTROUGH
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chrout_screen_ins_done:
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// End of processing
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jmp chrout_screen_calc_lptr_done
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chrout_screen_ins_second_line:
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// Adapt PNTR for copying
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lda PNTR
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sec
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sbc #40
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sta PNTR
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// Perform character copy
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jsr chrout_screen_ins_copy_loop
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// Put space in the inserted gap
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lda #$20
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sta (PNT), y
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// End of processing
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bne chrout_screen_ins_done // branch always
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chrout_screen_ins_copy_loop:
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// Note: While the following routine is obvious to any skilled
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// in the art as the most obvious simple and efficient solution,
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// if the screen writes are before the colour writes, it results
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// in a relatively long verbatim stretch of bytes when compared to
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// the C64 KERNAL. Thus we have swapped the order, just to reduce
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// the potential for any argument of copyright infringement, even
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// though we really do not believe that the routine can be copyrighted
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// due to the lack of creativity.
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dey
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lda (USER),y
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iny
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sta (USER),y
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dey
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lda (PNT),y
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iny
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sta (PNT),y
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dey
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cpy PNTR
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bne chrout_screen_ins_copy_loop
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// Increase insert mode count (which causes quote-mode like behaviour)
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inc INSRT
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// Return from loop
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rts
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