#version 450

layout (local_size_x = 16, local_size_y = 16) in;

layout (binding = 0) readonly buffer Host
{
 uint data[];
} host;

layout (binding = 1, rgba8) writeonly uniform image2D resultImage;

layout (push_constant) uniform constants
{
 vec4  gamma;
 ivec2 pitch;
} cfg;

 const ivec2 sh02 = ivec2(0,2);
 const ivec4 sh1212 = ivec4(1,2,1,2);
 const ivec4 sh1345 = ivec4(1,3,4,5);

 const ivec3 sh345 = ivec3(3,4,5);
 const ivec3 sh678 = ivec3(6,7,8);
 
 const ivec4 sh6789 = ivec4(6,7,8,9);
 const ivec4 sh6543 = ivec4(6,5,4,3);
 const ivec4 sh9101112 = ivec4(9,10,11,12);
 
 const ivec2 i2_1 = ivec2(1,1);
 const ivec3 i3_1 = ivec3(1,1,1);
 const ivec4 i4_1 = ivec4(1,1,1,1);

int getElementIndex(ivec2 p) //[0..5]
{
 ivec2 t1=(p.xy & i2_1) << sh02;
 ivec4 t2=((p.xxyy >> sh1212) & i4_1) << sh1345;

 t1=t1 | t2.xy | t2.zw;
 return t1.x | t1.y;
}

int getPipeIndex(ivec2 p) //[6..8]
{
 ivec3 t=(((p.xxx >> sh345) ^ (p.yyy >> sh345) ^ ivec3(p.x>>4,0,0)) & i3_1) << sh678;
 
 return t.x | t.y | t.z;
}

int getBankIndex(ivec2 p) //[9..12]
{
 ivec4 bank=(((p.xxxx >> sh6789) ^ (p.yyyy >> sh6543) ^ ivec4(0,p.y>>6,0,0)) & i4_1) << sh9101112;

 ivec2 t=bank.xy | bank.zw;
 return t.x | t.y;
}

void main()
{   
    ivec2 pixelCoords = ivec2(gl_GlobalInvocationID.xy);
    
    int element_index=getElementIndex(pixelCoords);    
    int pipe=getPipeIndex(pixelCoords);
    int bank=getBankIndex(pixelCoords);
    
    //const ivec4 shmt = ivec4(7,6,6,3);
    const ivec2 shmt = ivec2(7,6);
    //const ivec2 bmod = ivec2(1,1);
    
    //ivec4 mt=(pixelCoords.xyxy >> shmt);
    ivec2 mt=(pixelCoords.xy >> shmt);
    ivec2 total_offset=(mt.xy*cfg.pitch);
    //+(mt.zw % bmod);
    
    int offset = element_index | pipe | bank | ((total_offset.x+total_offset.y) << 13); 

    uint pack=host.data[offset];
    
    ////const uvec4 shift = uvec4(16,8,0,24);
    ////const uvec4 mask4 = uvec4(255,255,255,255);
    
    ////uvec4 pix_int=(uvec4(pack,pack,pack,pack) >> shift) & mask4;
    
    //0,8,16,24
    //R,G, B,A
    
    //16,8,0,24
    //BGRA

    ////vec4 pixel = vec4(pix_int) / mask4;

    vec4 pixel=unpackUnorm4x8(pack);

    pixel=pixel.bgra;

    pixel = pow(pixel, cfg.gamma);                        

    imageStore(resultImage, pixelCoords, pixel);
}