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megademo: mode7: more minor cleanups

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This commit is contained in:
Vince Weaver 2018-10-17 14:13:10 -04:00
parent b18ce38a6e
commit e510dc388c
1 changed files with 7 additions and 18 deletions
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25
megademo/mode7.s
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@ -947,7 +947,7 @@ screenx_loop:
nomatch:
; Get color to draw in A
jsr island_lookup
jsr lookup_island_map
match:
mask_label:
@ -1036,19 +1036,7 @@ done_screeny:
; returns color in A
; CLOBBERS: A,Y
; this is used to check if above water or grass
; the high-performance per-pixel version has been inlined
lookup_island_map:
; rts ; 6
;====================
; lookup_map
;====================
; finds value in space_x.i,space_y.i
; returns color in A
; CLOBBERS: A,Y
island_lookup:
lda SPACEX_I ; 3
sta spacex_label+1 ; self modifying code, LAST_SPACEX_I ; 4
and #CONST_MAP_MASK_X ; wrap at 64 ; 2
@ -1072,28 +1060,28 @@ island_lookup:
;============
; 39
bcs @ocean_color ; bgt 8 ; 2nt/3
bcs ocean_color ; bgt 8 ; 2nt/3
ldy SPACEY_I ; 3
cpy #$8 ; 2
;=============
; 7
bcs @ocean_color ; bgt 8 ; 2nt/3
bcs ocean_color ; bgt 8 ; 2nt/3
tay ; 2
lda flying_map,Y ; load from array ; 4
bcc @update_cache ; 3
bcc update_cache ; 3
;============
; 11
@ocean_color:
ocean_color:
and #$1f ; 2
tay ; 2
lda water_map,Y ; the color of the sea ; 4
;===========
; 8
@update_cache:
update_cache:
sta map_color_label+1 ; self-modifying ; 4
;===========
@ -1135,6 +1123,7 @@ water_map:
.byte $22,$22,$22,$22, $22,$22,$22,$22
.byte $22,$22,$22,$22, $ee,$22,$22,$22
.include "starry_sky.scroll"
.include "multiply_fast.s"