mirror of https://github.com/nmlgc/ReC98.git
52 lines
1.1 KiB
NASM
52 lines
1.1 KiB
NASM
; Draws the hardcoded spark sprite with the given ID, with ([x], [vram_y])
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; pointing to the top-left point. Assumptions:
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; • The GRCG is active, and set to the intended color
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; • [sprite_id] ≤ SPARK_SPRITES
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; void pascal near spark_render(int x, int vram_y, int sprite_id);
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spark_render proc near
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@@sprite_id = word ptr 4
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@@vram_y = word ptr 6
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@@x = word ptr 8
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push bp
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mov bp, sp
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push si
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push di
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mov ax, GRAM_400
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mov es, ax
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mov bx, [bp+@@x]
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mov ax, bx
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sar ax, 3 ; x /= 8
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mov dx, [bp+@@vram_y]
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shl dx, 6 ; [vram_y] * 64
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add ax, dx
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shr dx, 2 ; (([vram_y] * 64) / 4) = [vram_y] * 16
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add ax, dx
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mov di, ax ; ([vram_y] * 64) + ([vram_y] * 16) = [vram_y * ROW_SIZE]
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mov ax, bx
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and ax, 7 ; [x] & 7
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shl ax, 7 ; *= SPARK_SIZE * SPARK_SPRITES (offset of X-shifted sprite)
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mov dx, [bp+@@sprite_id]
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shl dx, 4 ; sprite_ptr = [sprite_id] * SPARK_SIZE
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add ax, dx
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add ax, offset _sSPARKS
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mov si, ax
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mov cx, SPARK_H
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@@blit_loop:
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movsw
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add di, (ROW_SIZE - SPARK_VRAM_W)
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cmp di, PLANE_SIZE
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jl short @@next_row
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sub di, PLANE_SIZE
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@@next_row:
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loop @@blit_loop
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pop di
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pop si
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pop bp
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retn 6
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spark_render endp
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even
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