a question about fir filters

[shameem]

hi,
Does macs in a fir filters reduces to half if i use the coefficiens which are even and symmetric (i.e h = h(N-n), N is even no.). If yes, how??????
If anybody have any idea, please help me.

thanks

shameem

 

[zorro]

In that way you can replace two MACS by an addition and a MAC:

y=x[0]*h[0]+........+x[N-1]*h[N-1]
y=(x[0]+x[N-1])*h[0]+.......

In some implementations in can save resources. In many DSP processors, as an add takes the same time of a mac, nothing is saved.
Regards

Z