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megademo: start messing with mode7 code

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This commit is contained in:
Vince Weaver 2018-10-17 14:09:01 -04:00
parent 0d0eed35e5
commit f8f60a1e42
3 changed files with 63 additions and 67 deletions
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63
megademo/island_lookup.s
View File

@ -1,63 +0,0 @@
;====================================
; do a full lookup, takes much longer
; used to be a separate function but we inlined it here
;====================
; lookup_map
;====================
; finds value in space_x.i,space_y.i
; returns color in A
; CLOBBERS: A,Y
lda SPACEX_I ; 3
sta spacex_label+1 ; self modifying code, LAST_SPACEX_I ; 4
and #CONST_MAP_MASK_X ; wrap at 64 ; 2
sta SPACEX_I ; store i patch out ; 3
tay ; copy to Y for later ; 2
lda SPACEY_I ; 3
sta spacey_label+1 ; self modifying code, LAST_SPACEY_I ; 4
and #CONST_MAP_MASK_Y ; wrap to 64x64 grid ; 2
sta SPACEY_I ; 3
asl ; 2
asl ; 2
asl ; multiply by 8 ; 2
clc ; 2
adc SPACEX_I ; add in X value ; 3
; only valid if x<8 and y<8
; SPACEX_I is also in y
cpy #$8 ; 2
;============
; 39
bcs @ocean_color ; bgt 8 ; 2nt/3
ldy SPACEY_I ; 3
cpy #$8 ; 2
;=============
; 7
bcs @ocean_color ; bgt 8 ; 2nt/3
tay ; 2
lda flying_map,Y ; load from array ; 4
bcc @update_cache ; 3
;============
; 11
@ocean_color:
and #$1f ; 2
tay ; 2
lda water_map,Y ; the color of the sea ; 4
;===========
; 8
@update_cache:
sta map_color_label+1 ; self-modifying ; 4
;===========
; 4
; rts ; 6

3
megademo/megademo.s
View File

@ -27,7 +27,8 @@ apple_iie:
;===================
jsr HOME
jsr bird_mountain
jsr mode7_flying
; jsr waterfall
; jsr arriving_there

64
megademo/mode7.s
View File

@ -947,8 +947,7 @@ screenx_loop:
nomatch:
; Get color to draw in A
.include "island_lookup.s"
jsr island_lookup
match:
mask_label:
@ -1039,7 +1038,66 @@ done_screeny:
; this is used to check if above water or grass
; the high-performance per-pixel version has been inlined
lookup_island_map:
.include "island_lookup.s"
; 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
sta SPACEX_I ; store i patch out ; 3
tay ; copy to Y for later ; 2
lda SPACEY_I ; 3
sta spacey_label+1 ; self modifying code, LAST_SPACEY_I ; 4
and #CONST_MAP_MASK_Y ; wrap to 64x64 grid ; 2
sta SPACEY_I ; 3
asl ; 2
asl ; 2
asl ; multiply by 8 ; 2
clc ; 2
adc SPACEX_I ; add in X value ; 3
; only valid if x<8 and y<8
; SPACEX_I is also in y
cpy #$8 ; 2
;============
; 39
bcs @ocean_color ; bgt 8 ; 2nt/3
ldy SPACEY_I ; 3
cpy #$8 ; 2
;=============
; 7
bcs @ocean_color ; bgt 8 ; 2nt/3
tay ; 2
lda flying_map,Y ; load from array ; 4
bcc @update_cache ; 3
;============
; 11
@ocean_color:
and #$1f ; 2
tay ; 2
lda water_map,Y ; the color of the sea ; 4
;===========
; 8
@update_cache:
sta map_color_label+1 ; self-modifying ; 4
;===========
; 4
rts ; 6