mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-04 05:05:13 +00:00
245 lines
4.2 KiB
ArmAsm
245 lines
4.2 KiB
ArmAsm
; Not quite a raster-bar, but why not
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;===========
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; CONSTANTS
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;===========
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ELEMENTS EQU 64
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NUM_ROWS EQU 20
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;=====================
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; Rasterbars
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;=====================
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;===========================
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;===========================
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; Main Loop
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;===========================
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;===========================
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draw_rasters:
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; clear rows
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ldy #(NUM_ROWS-1) ; 2
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lda #0 ; 2
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init_rows:
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sta row_color,Y ; 5
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dey ; 2
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bpl init_rows ; 2nt/3
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;================
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; set colors
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lda #COLOR_BOTH_AQUA ; aqua
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ldy SCREEN_Y
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jsr set_row_color
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lda #COLOR_BOTH_MEDIUMBLUE ; medium blue
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jsr set_row_color
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lda #COLOR_BOTH_LIGHTGREEN ; light green
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jsr set_row_color
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lda #COLOR_BOTH_DARKGREEN ; green
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jsr set_row_color
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lda #COLOR_BOTH_YELLOW ; yellow
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jsr set_row_color
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lda #COLOR_BOTH_ORANGE ; orange
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jsr set_row_color
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lda #COLOR_BOTH_PINK ; pink
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jsr set_row_color
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lda #COLOR_BOTH_RED ; red
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jsr set_row_color
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;=================
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; draw rows
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ldy #(NUM_ROWS-1) ; 2
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draw_rows_loop:
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lda row_color,Y ; 5
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beq draw_rows_skip ; skip if black ; 2nt/3
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sta COLOR ; 3
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tya ; 2
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pha ; 3
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asl ; 2
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ldy #39 ; 2
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sty V2 ; 3
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ldy #0 ; 2
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jsr hlin_double ; hlin y,V2 at A ; 63+(X*16)
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pla ; 4
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tay ; 2
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draw_rows_skip:
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dey ; 2
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bpl draw_rows_loop ; 2
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;==================
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; update y pointer
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;==================
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ldy SCREEN_Y
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iny
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cpy #ELEMENTS
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bne not_there
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ldy #0
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not_there:
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sty SCREEN_Y
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rts
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;===================
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;===================
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; set_row_color
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;===================
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;===================
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; color in A
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; Y=offset
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; Y incremented
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; A, X trashed
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set_row_color:
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sta COLOR
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tya ; wrap y offset
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and #(ELEMENTS-1)
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tax
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lda fine_sine,X ; lookup sine value
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; pre-shifted right by 4, sign-extended
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clc
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adc #18 ; add in 18 to center on screen
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sin_no_more:
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pha ; save row value
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jsr put_color ; put color at row
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pla ; restore row value
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clc ; increment row value
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adc #1
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jsr put_color ; put color at row
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iny ; increment for next time
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rts
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;==================
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; put_color
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;==================
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; A = row to set color of
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; A trashed
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put_color:
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clc
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ror ; row/2, with even/odd in carry
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tax ; put row/2 in X
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bcc even_line ; if even, skip to even
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odd_line:
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lda #$f0 ; load mask for odd
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bcs finish_line
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even_line:
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lda #$0f ; load mask for even
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finish_line:
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sta MASK
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and COLOR ; mask off color
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sta COLOR2 ; store for later
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lda MASK
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eor #$ff ; invert mask
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and row_color,X ; load existing color
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ora COLOR2 ; combine
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sta row_color,X ; store back
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rts
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;======================
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; some arrays
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;======================
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row_color:
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.byte $00,$00,$00,$00,$00, $00,$00,$00,$00,$00
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.byte $00,$00,$00,$00,$00, $00,$00,$00,$00,$00
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; arithmatically shifted right by 4
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; FIXME: exploit symmetry and get rid of 3/4 of this table
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; possibly not worth the extra code
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fine_sine:
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.byte $00 ; 0.000000
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.byte $01 ; 0.098017
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.byte $03 ; 0.195090
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.byte $04 ; 0.290285
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.byte $06 ; 0.382683
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.byte $07 ; 0.471397
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.byte $08 ; 0.555570
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.byte $0A ; 0.634393
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.byte $0B ; 0.707107
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.byte $0C ; 0.773010
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.byte $0D ; 0.831470
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.byte $0E ; 0.881921
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.byte $0E ; 0.923880
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.byte $0F ; 0.956940
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.byte $0F ; 0.980785
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.byte $0F ; 0.995185
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.byte $0F ; 1.000000
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.byte $0F ; 0.995185
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.byte $0F ; 0.980785
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.byte $0F ; 0.956940
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.byte $0E ; 0.923880
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.byte $0E ; 0.881921
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.byte $0D ; 0.831470
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.byte $0C ; 0.773010
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.byte $0B ; 0.707107
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.byte $0A ; 0.634393
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.byte $08 ; 0.555570
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.byte $07 ; 0.471397
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.byte $06 ; 0.382683
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.byte $04 ; 0.290285
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.byte $03 ; 0.195090
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.byte $01 ; 0.098017
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.byte $00 ; 0.000000
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.byte $FE ; -0.098017
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.byte $FC ; -0.195090
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.byte $FB ; -0.290285
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.byte $F9 ; -0.382683
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.byte $F8 ; -0.471397
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.byte $F7 ; -0.555570
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.byte $F5 ; -0.634393
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.byte $F4 ; -0.707107
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.byte $F3 ; -0.773010
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.byte $F2 ; -0.831470
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.byte $F1 ; -0.881921
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.byte $F1 ; -0.923880
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.byte $F0 ; -0.956940
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.byte $F0 ; -0.980785
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.byte $F0 ; -0.995185
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.byte $F0 ; -1.000000
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.byte $F0 ; -0.995185
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.byte $F0 ; -0.980785
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.byte $F0 ; -0.956940
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.byte $F1 ; -0.923880
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.byte $F1 ; -0.881921
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.byte $F2 ; -0.831470
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.byte $F3 ; -0.773010
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.byte $F4 ; -0.707107
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.byte $F5 ; -0.634393
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.byte $F7 ; -0.555570
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.byte $F8 ; -0.471397
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.byte $F9 ; -0.382683
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.byte $FB ; -0.290285
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.byte $FC ; -0.195090
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.byte $FE ; -0.098017
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