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mode7: add some timing info

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This commit is contained in:
Vince Weaver 2017-12-31 17:07:45 -05:00
parent f0ef7095d7
commit f6601e3d16
2 changed files with 18 additions and 18 deletions
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mode7/mode7.dsk
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36
mode7/starfield_demo.s
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@ -54,35 +54,35 @@ starfield_loop:
; start at 15 and count down (rather than 0 and count up)
ldx #(NUMSTARS-1)
ldx #(NUMSTARS-1) ; 2
draw_stars:
stx XX
stx XX ; 3
;================
; calculate color
;================
lda #$ff ; want if z<16, color = 5
sta COLOR ; if 16<z<32 color = 13
lda #$ff ; want if z<16, color = 5 ; 2
sta COLOR ; if 16<z<32 color = 13 ; 3
; if 32<z<64 color = 15
ldy XX
lda star_z,Y
tay ; put star_z[i] in Y for later
ldy XX ; 3
lda star_z,Y ; 5
tay ; put star_z[i] in X for later ; 2
cmp #32
bpl done_color
cmp #32 ; 2
bpl done_color ; 2nt/3
cmp #16 ; 15 -1 16 0 17 1
bpl second_color
cmp #16 ; 15 -1 16 0 17 1 ; 2
bpl second_color ; 2nt/3
lda #$55
sta COLOR
lda #$55 ; 2
sta COLOR ; 3
jmp done_color
jmp done_color ; 3
second_color:
lda #$dd
sta COLOR
lda #$dd ; 2
sta COLOR ; 3
done_color:
@ -91,8 +91,8 @@ done_color:
; put 1/stars[i].z in NUM1H:NUM1L and multiply
lda z_table,Y
sta NUM1L ; F
lda z_table,Y ; 4
sta NUM1L ; F ; 3
; adjust for 58+
; all this logic to avoid having a 128 byte table of mostly zero