dos33fsprogs/games/peasant/hgr_sprite.s
2022-01-07 14:19:15 -05:00

87 lines
1.2 KiB
ArmAsm

;===========================================
; hgr draw sprite (only at 7-bit boundaries)
;===========================================
; SPRITE in INL/INH
; Location at CURSOR_X CURSOR_Y
; xsize, ysize in first two bytes
; sprite AT INL/INH
hgr_draw_sprite:
ldy #0
lda (INL),Y ; load xsize
clc
adc CURSOR_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
; skip the xsize/ysize and point to sprite
clc
lda INL ; 16-bit add
adc #2
sta sprite_smc1+1
lda INH
adc #0
sta sprite_smc1+2
ldx #0 ; X is pointer offset
stx MASK ; actual row
hgr_sprite_yloop:
lda MASK ; row
clc
adc CURSOR_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
sta GBASH
ldy CURSOR_X
sprite_inner_loop:
sprite_smc1:
lda $d000 ; get sprite pattern
sta (GBASL),Y ; store out
inx
iny
inc sprite_smc1+1
bne sprite_noflo
inc sprite_smc1+2
sprite_noflo:
sprite_width_end_smc:
cpy #6
bne sprite_inner_loop
inc MASK ; row
lda MASK ; row
sprite_ysize_smc:
cmp #31
bne hgr_sprite_yloop
rts