137 lines
2.7 KiB
ArmAsm
137 lines
2.7 KiB
ArmAsm
;=================
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; load RLE image
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;=================
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; Output is A:00 (assume page aligned)
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; Input is in GBASH/GBASL
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; format: first byte=xsize
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; A0,X,Y means run of X bytes of Y color
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; A1 means end of file
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; A2-AF,X means run of low nibble, X color
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; if high nibble not A: just display color
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; CV = current Y
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; CH = max xsize (usually 40)
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; TEMP = page
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; TEMPY= current X
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; 82 + 10 +
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; special short: 38+7+ 27+ 27*run +5+2
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; special long: 38+7+24+27+ 27*run +5+2
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; nospecial: 38+6+19+(cross line*58)+5+2
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load_rle_gr:
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sec ; 2
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sbc #4 ; adjust page to write to ; 2
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; to match gr_offsets
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sta TEMP ; 3
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ldy #$0 ; init Y to 0 ; 2
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sty CV ; 3
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jsr load_and_increment ; load xsize ; 6+19
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sta CH ; 3
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jsr unrle_new_y ; 6+36
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;============
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; 82
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rle_loop:
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jsr load_and_increment ; 6+19
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tax ; 2
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cmp #$A1 ; if 0xa1 ; 2
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beq rle_done ; we are done ; 3
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; -1
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and #$f0 ; mask ; 2
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cmp #$a0 ; see if special AX ; 2
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beq decompress_special ; 3
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;===========
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; 38
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; -1
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; not special, just color
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txa ; put color back in A ; 2
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ldx #$1 ; only want to print 1 ; 2
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bne decompress_run ; bra ; 3
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decompress_special:
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txa ; put read value back in A ; 2
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and #$0f ; check if was A0 ; 2
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bne decompress_color ; if A0 need to read run, color ; 3
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;===
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; 7
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decompress_large: ; -1
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jsr load_and_increment ; run length now in A ; 6+19
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decompress_color:
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tax ; put runlen into X ; 2
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jsr load_and_increment ; get color into A ; 6+19
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decompress_run:
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rle_run_loop:
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sta (BASL),y ; write out the value ; 6
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inc BASL ; 5
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dec TEMPY ; 5
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bne rle_not_eol ; if less then keep going ; 3
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;====
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; 19
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; -1
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; if here, we are > max_X
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inc CV ; 5
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inc CV ; 5
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pha ; 3
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jsr unrle_new_y ; 6+36
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pla ; 4
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;===
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;58
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rle_not_eol:
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dex ; 2
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bne rle_run_loop ; if not zero, keep looping ; 3
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;==
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; 5
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; -1
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beq rle_loop ; and branch always ; 3
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rle_done:
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lda #$15 ; move cursor somewhere sane ; 2
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sta CV ; 3
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rts ; 6
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;========================
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; common case = 19
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load_and_increment:
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lda (GBASL),Y ; 5+
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inc GBASL ; 5
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bne lai_no_oflo ; 3
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; -1
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inc GBASH ; 5
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lai_no_oflo:
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rts ; 6
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;========================
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; common case = 36
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unrle_new_y:
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ldy CV ; 3
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lda gr_offsets,Y ; 4+
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sta BASL ; 3
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lda gr_offsets+1,Y ; 4+
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clc ; 2
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adc TEMP ; adjust for page ; 3
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sta BASH ; 3
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lda CH ; 3
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sta TEMPY ; 3
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ldy #0 ; 2
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rts ; 6
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;===========
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; 36
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