how to implement the decimal fraction in an equation

[sevid]

hi,all
i want to know how to RTL the expression listed as follows:
Y = 0.299R + 0.587G + 0.114B (1)

someone implement it in terms of this methodology:
always@(posedge clk)
if (ena)
begin
y1 <= #1 10'h132 * r + 10'h259 * g + 10'h074 * b;
end
always@(posedge clk)
if (ena)
begin
Y <= #1 (y1[19:10] & {10{!y1[21]}}) | {10{(!y1[21] && y1[20])}};
end
and the result generated is same as that calculated directly by (1),my questions are :
1. who can tell me the arithmetic of the implementation above.
2. any other methods to get it,pls tell me.

thanks in advance
sevid

 

[yln2k2]

Hi ,

I asked one of my friend who is a Designer .

The above aeqation is multiplied by 1024 and devide the same by 1024 ( which is equavalent to right shit by 10bits are discard 9:0) .


Thanks & Regards
yln

 

[sevid]

thanks

you are right.
i think what he wants is only to save the hardware,and it is a good methodology we should always use.

thanks a lot.
sevid