dos33fsprogs/games/keen/hgr_sprite.s
2024-05-10 01:21:25 -04:00

89 lines
1.4 KiB
ArmAsm

;===========================================
; hgr draw sprite (only at 7-bit boundaries)
;===========================================
; SPRITE in INL/INH
; Location at SPRITE_X SPRITE_Y
; xsize, ysize in first two bytes
; sprite AT INL/INH
hgr_draw_sprite:
ldy #0
lda (INL),Y ; load xsize
clc
adc SPRITE_X
sta sprite_width_end_smc+1 ; self modify for end of line
iny ; load ysize
lda (INL),Y
sta sprite_ysize_smc+1 ; self modify
; point smc to sprite
lda INL ; 16-bit add
sta sprite_smc1+1
lda INH
sta sprite_smc1+2
ldx #0 ; X is pointer offset
stx CURRENT_ROW ; actual row
ldx #2
hgr_sprite_yloop:
lda CURRENT_ROW ; row
clc
adc SPRITE_Y ; add in cursor_y
; calc GBASL/GBASH
tay ; get output ROW into GBASL/H
lda hposn_low,Y
sta GBASL
lda hposn_high,Y
; eor #$00 draws on page2
; eor #$60 draws on page1
;hgr_sprite_page_smc:
; eor #$00
clc
adc DRAW_PAGE
sta GBASH
; eor #$60
; sta INH
ldy SPRITE_X
sprite_inner_loop:
sprite_smc1:
lda $f000,X ; load sprite data
sta (GBASL),Y ; store to screen
inx ; increment sprite offset
bne not_oflo
inc sprite_smc1+2
not_oflo:
iny ; increment output position
sprite_width_end_smc:
cpy #6 ; see if reached end of row
bne sprite_inner_loop ; if not, loop
inc CURRENT_ROW ; row
lda CURRENT_ROW ; row
sprite_ysize_smc:
cmp #31 ; see if at end
bne hgr_sprite_yloop ; if not, loop
rts