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mode7: rasterbars: adjust lookup table to handle the shifting

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This commit is contained in:
Vince Weaver 2018-01-31 00:38:28 -05:00
parent f57854e43a
commit b4e9a5412f
1 changed files with 68 additions and 94 deletions
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162
mode7/rasterbars.s
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@ -135,9 +135,11 @@ not_there:
jmp raster_loop ; 3
;===================
;===================
; set_row_color
;===================
;===================
; color in A
; Y=offset
; Y incremented
@ -145,44 +147,15 @@ not_there:
set_row_color:
sta COLOR
tya ; wrap y offset
tya ; wrap y offset
and #(ELEMENTS-1)
tax
lda fine_sine,X ; lookup sign value
cpx #33 ; check if > pi and
bpl sin_negative ; need to make negative
lda fine_sine,X ; lookup sine value
; pre-shifted right by 4, sign-extended
sin_positive:
clc ; shift right by 4, zero-extend
ror
clc
ror
clc
ror
clc
ror
clc
adc #18 ; add in 18 to center on screen
; lsr ; shift once more
jmp sin_no_more
; FIXME: precalculate as we shift same each time
sin_negative:
sec
ror
sec
ror
sec
ror
sec
ror
clc
adc #18
; lsr
sin_no_more:
pha
@ -261,69 +234,70 @@ row_color:
.byte $00,$00,$00,$00,$00, $00,$00,$00,$00,$00
.byte $00,$00,$00,$00,$00, $00,$00,$00,$00,$00
; arithmatically shifted right by 4
fine_sine:
.byte $00 ; 0.000000
.byte $19 ; 0.098017
.byte $31 ; 0.195090
.byte $4A ; 0.290285
.byte $61 ; 0.382683
.byte $78 ; 0.471397
.byte $8E ; 0.555570
.byte $A2 ; 0.634393
.byte $B5 ; 0.707107
.byte $C5 ; 0.773010
.byte $D4 ; 0.831470
.byte $E1 ; 0.881921
.byte $EC ; 0.923880
.byte $F4 ; 0.956940
.byte $FB ; 0.980785
.byte $FE ; 0.995185
.byte $FF ; 1.000000
.byte $FE ; 0.995185
.byte $FB ; 0.980785
.byte $F4 ; 0.956940
.byte $EC ; 0.923880
.byte $E1 ; 0.881921
.byte $D4 ; 0.831470
.byte $C5 ; 0.773010
.byte $B5 ; 0.707107
.byte $A2 ; 0.634393
.byte $8E ; 0.555570
.byte $78 ; 0.471397
.byte $61 ; 0.382683
.byte $4A ; 0.290285
.byte $31 ; 0.195090
.byte $19 ; 0.098017
.byte $01 ; 0.098017
.byte $03 ; 0.195090
.byte $04 ; 0.290285
.byte $06 ; 0.382683
.byte $07 ; 0.471397
.byte $08 ; 0.555570
.byte $0A ; 0.634393
.byte $0B ; 0.707107
.byte $0C ; 0.773010
.byte $0D ; 0.831470
.byte $0E ; 0.881921
.byte $0E ; 0.923880
.byte $0F ; 0.956940
.byte $0F ; 0.980785
.byte $0F ; 0.995185
.byte $0F ; 1.000000
.byte $0F ; 0.995185
.byte $0F ; 0.980785
.byte $0F ; 0.956940
.byte $0E ; 0.923880
.byte $0E ; 0.881921
.byte $0D ; 0.831470
.byte $0C ; 0.773010
.byte $0B ; 0.707107
.byte $0A ; 0.634393
.byte $08 ; 0.555570
.byte $07 ; 0.471397
.byte $06 ; 0.382683
.byte $04 ; 0.290285
.byte $03 ; 0.195090
.byte $01 ; 0.098017
.byte $00 ; 0.000000
.byte $E7 ; -0.098017
.byte $CF ; -0.195090
.byte $B6 ; -0.290285
.byte $9F ; -0.382683
.byte $88 ; -0.471397
.byte $72 ; -0.555570
.byte $5E ; -0.634393
.byte $4B ; -0.707107
.byte $3B ; -0.773010
.byte $2C ; -0.831470
.byte $1F ; -0.881921
.byte $14 ; -0.923880
.byte $0C ; -0.956940
.byte $05 ; -0.980785
.byte $02 ; -0.995185
.byte $00 ; -1.000000
.byte $02 ; -0.995185
.byte $05 ; -0.980785
.byte $0C ; -0.956940
.byte $14 ; -0.923880
.byte $1F ; -0.881921
.byte $2C ; -0.831470
.byte $3B ; -0.773010
.byte $4B ; -0.707107
.byte $5E ; -0.634393
.byte $72 ; -0.555570
.byte $88 ; -0.471397
.byte $9F ; -0.382683
.byte $B6 ; -0.290285
.byte $CF ; -0.195090
.byte $E7 ; -0.098017
.byte $FE ; -0.098017
.byte $FC ; -0.195090
.byte $FB ; -0.290285
.byte $F9 ; -0.382683
.byte $F8 ; -0.471397
.byte $F7 ; -0.555570
.byte $F5 ; -0.634393
.byte $F4 ; -0.707107
.byte $F3 ; -0.773010
.byte $F2 ; -0.831470
.byte $F1 ; -0.881921
.byte $F1 ; -0.923880
.byte $F0 ; -0.956940
.byte $F0 ; -0.980785
.byte $F0 ; -0.995185
.byte $F0 ; -1.000000
.byte $F0 ; -0.995185
.byte $F0 ; -0.980785
.byte $F0 ; -0.956940
.byte $F1 ; -0.923880
.byte $F1 ; -0.881921
.byte $F2 ; -0.831470
.byte $F3 ; -0.773010
.byte $F4 ; -0.707107
.byte $F5 ; -0.634393
.byte $F7 ; -0.555570
.byte $F8 ; -0.471397
.byte $F9 ; -0.382683
.byte $FB ; -0.290285
.byte $FC ; -0.195090
.byte $FE ; -0.098017