206 lines
3.3 KiB
ArmAsm
206 lines
3.3 KiB
ArmAsm
;===========================================
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; hgr draw sprite (only at 7-bit boundaries)
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;===========================================
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; can handle sprites bigger than a 256 byte page
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; Note this is optimized for blue/orange sprites
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; it treats black0 as transparent
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; SPRITE in INL/INH
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; Location at SPRITE_X SPRITE_Y
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; xsize, ysize in first two bytes
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; sprite AT INL/INH
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; orange = color5 1 101 0101 1 010 1010
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hgr_draw_sprite_big:
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lda SPRITE_X
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ror
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bcs hgr_draw_sprite_big_odd
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hgr_draw_sprite_big_even:
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ldy #0
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lda (INL),Y ; load xsize
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clc
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adc SPRITE_X
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sta big_sprite_width_end_smc+1 ; self modify for end of line
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iny ; load ysize
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lda (INL),Y
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sta big_sprite_ysize_smc+1 ; self modify
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; point smc to sprite
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lda INL ; 16-bit add
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sta big_sprite_smc1+1
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lda INH
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sta big_sprite_smc1+2
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ldx #0 ; X is pointer offset
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stx CURRENT_ROW ; actual row
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ldx #2
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hgr_big_sprite_yloop:
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lda CURRENT_ROW ; row
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clc
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adc SPRITE_Y ; add in cursor_y
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; calc GBASL/GBASH
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tay ; get output ROW into GBASL/H
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lda hposn_low,Y
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sta GBASL
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lda hposn_high,Y
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clc
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adc DRAW_PAGE
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sta GBASH
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ldy SPRITE_X
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big_sprite_inner_loop:
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big_sprite_smc1:
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lda $f000,X ; load sprite data
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beq big_sprite_transparent
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sta (GBASL),Y ; store to screen
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big_sprite_transparent:
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inx ; increment sprite offset
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; if > 1 page
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bne big_sprite_no_page_cross
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inc big_sprite_smc1+2
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big_sprite_no_page_cross:
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iny ; increment output position
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big_sprite_width_end_smc:
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cpy #6 ; see if reached end of row
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bne big_sprite_inner_loop ; if not, loop
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inc CURRENT_ROW ; row
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lda CURRENT_ROW ; row
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big_sprite_ysize_smc:
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cmp #31 ; see if at end
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bne hgr_big_sprite_yloop ; if not, loop
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rts
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hgr_draw_sprite_big_odd:
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ldy #0
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lda (INL),Y ; load xsize
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clc
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adc SPRITE_X
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sta osprite_width_end_smc+1 ; self modify for end of line
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iny ; load ysize
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lda (INL),Y
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sta osprite_ysize_smc+1 ; self modify
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; point smc to sprite
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lda INL ; 16-bit add
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sta osprite_smc1+1
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lda INH
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sta osprite_smc1+2
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ldx #0 ; X is pointer offset
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stx CURRENT_ROW ; actual row
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ldx #2
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ohgr_sprite_yloop:
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lda CURRENT_ROW ; row
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clc
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adc SPRITE_Y ; add in cursor_y
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; calc GBASL/GBASH
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tay ; get output ROW into GBASL/H
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lda hposn_low,Y
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sta GBASL
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lda hposn_high,Y
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clc
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adc DRAW_PAGE
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sta GBASH
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ldy SPRITE_X
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clc
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php ; store 0 carry on stack
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osprite_inner_loop:
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osprite_smc1:
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lda $f000,X ; load sprite data
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bne osprite_not_transparent
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; we can't just skip if 0 because we might shift a bit in
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; from previous byte
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plp
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bcs osprite_oops
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clc
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php
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bcc osprite_transparent_done
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osprite_not_transparent:
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plp ; restore carry from last
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osprite_oops:
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rol ; rotate in carry
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asl ; one more time, bit6 in carry
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php ; save on stack
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sec ; assume blur/orange
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ror ; rotate it back down
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sta (GBASL),Y ; store to screen
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osprite_transparent_done:
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inx ; increment sprite offset
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; if > 1 page
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bne osprite_no_page_cross
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inc osprite_smc1+2
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osprite_no_page_cross:
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iny ; increment output position
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osprite_width_end_smc:
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cpy #6 ; see if reached end of row
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bne osprite_inner_loop ; if not, loop
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plp ; restore stack
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inc CURRENT_ROW ; row
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lda CURRENT_ROW ; row
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osprite_ysize_smc:
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cmp #31 ; see if at end
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bne ohgr_sprite_yloop ; if not, loop
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rts
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