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8bitworkshop/presets/verilog/rototexture.ice

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$include('ntsc.ice')
// SL 2020-04-22
// A rotating texture using BRAM
// -------------------------
algorithm frame_display(
input uint10 pix_x,
input uint10 pix_y,
input uint1 pix_active,
input uint1 pix_vblank,
output! uint$color_depth$ pix_r,
output! uint$color_depth$ pix_g,
output! uint$color_depth$ pix_b
) <autorun> {
uint8 frame = 0;
uint8 angle = 0;
int20 u = 0;
int20 v = 0;
int20 cos = 0;
int20 sin = 0;
int20 cornerx = 320;
int20 cornery = 240;
//int20 cornerx = -320;
//int20 cornery = -240;
int20 corneru = 0;
int20 cornerv = 0;
int20 deltau_x = 0;
int20 deltau_y = 0;
int20 deltav_x = 0;
int20 deltav_y = 0;
brom uint18 tbl[$32*32$] = {
$$write_image_in_table('tile.tga',6)
};
brom int10 cosine[256] = {
$$for i=0,255 do
$math.floor(511.0 * math.cos(2*math.pi*i/255))$,
$$end
};
pix_r := 0; pix_g := 0; pix_b := 0;
// ---------- show time!
while (1) {
// display frame
while (pix_vblank == 0) {
if (pix_active) {
pix_b = tbl.rdata[0,6]<<2;
pix_g = tbl.rdata[6,6]<<2;
pix_r = tbl.rdata[12,6]<<2;
// update u,v
if (pix_x == 0) {
u = corneru;
v = cornerv;
} else {
if (pix_x == 255) {
corneru = corneru + deltau_y;
cornerv = cornerv + deltav_y;
} else {
u = u + deltau_x;
v = v + deltav_x;
}
}
// tbl bram access
tbl.addr = ((u>>11)&31) + (((v>>11)&31)<<5);
// access during loop (one cycle to go back)
}
}
// prepare next (we are in vblank, there is time)
cosine.addr = frame;
frame = frame + 1;
++:
angle = ((512+cosine.rdata) >> 2);
cosine.addr = angle;
++: // sine bram access
cos = cosine.rdata;
cosine.addr = angle + 64;
++: // sine bram access
sin = cosine.rdata;
// prepare scanline with mapping
corneru = - ((cornerx * cos) - (cornery * sin));
cornerv = - ((cornerx * sin) + (cornery * cos));
//corneru = ((cornerx * cos) - (cornery * sin));
//cornerv = ((cornerx * sin) + (cornery * cos));
deltau_x = cos;
deltau_y = - sin;
deltav_x = sin;
deltav_y = cos;
u = corneru;
v = cornerv;
// wait for sync
while (pix_vblank == 1) {}
}
}
// -------------------------
algorithm main(
output! uint$color_depth$ video_r,
output! uint$color_depth$ video_g,
output! uint$color_depth$ video_b,
output! uint1 video_hs,
output! uint1 video_vs
)
<@clock,!reset>
{
uint1 active = 0;
uint1 vblank = 0;
uint10 pix_x = 0;
uint10 pix_y = 0;
ntsc ntsc_driver (
ntsc_hs :> video_hs,
ntsc_vs :> video_vs,
active :> active,
vblank :> vblank,
ntsc_x :> pix_x,
ntsc_y :> pix_y
);
frame_display display (
pix_x <: pix_x,
pix_y <: pix_y,
pix_active <: active,
pix_vblank <: vblank,
pix_r :> video_r,
pix_g :> video_g,
pix_b :> video_b
);
// forever
while (1) {
}
}