I was making the point that certain applications go directly to hardware yet don't effect the multitasking OS. They return and OS is still stable as it was. Even the examples of audio playback in Compute! magazines are directly writing to hardware registers rather than making APi calls.
You haven't answered Protracker 1 vs Octamed 4 vs Deluxe Music 2.0 interactions.
On modern GPU and using NVIDIA's Cg shaders
const static float3x3 m = float3x3(
0.2209, 0.3390, 0.4184,
0.1138, 0.6780, 0.7319,
0.0102, 0.1130, 0.2969);
inline float4 PS3_LogLuv_Encode(in float3 rgb)
{
float4 res; // float4(Ue, Ve, LeHigh, LeLow)
float3 Xp_Y_XYZp = mul(rgb,m);
Xp_Y_XYZp = max(Xp_Y_XYZp, float3(1e-6, 1e-6, 1e-6));
res.xy = Xp_Y_XYZp.xy / Xp_Y_XYZp.z;
float Le = 2 * log2(Xp_Y_XYZp.y) + 128;
res.z = Le / 256;
res.w = frac(Le);
return res;
}
Running this code through NVShaderPerf gives 5 cycles for 9 instructions. When inserted at the end of a longer shader where there is plenty of room for instruction pairing, the total overhead for the LogLuv conversion will be less than this, perhaps around 3 cycles.
This code snippet is use to enable HDR and hardware AA on PS3. The other exercise is to do the conversion from LogLuv back to RGB.
This type of optimisation works on Geforce 7. I like PS3 devs for taking care of Geforce 7 and other DirectX9c class GPUs.
If you have any modern GPU enquires, one should visit Beyond3D's forums i.e. you have professional game developers lurking in that particular forums.
On Amiga, without OpenGL shaders it's difficult to test shader code snippets from PS3 and XNA forums.
