I am having trouble how to convolution of two function. The two functions have pdf as follow
f(x1)=\begin{cases} Q(\tau+1) & x_{1}=\tau\\ \phi(x1+1) & -\tau<x_{1}<\tau\\ Q(1-\tau) & x_{1}=-\tau \end{cases}
f(x2)=\begin{cases} Q(\tau+1) & x_{2}=\tau\\ \phi(x2+1) & -\tau<x_{2}<\tau\\ Q(1-\tau) & x_{2}=-\tau \end{cases}
where $Q(\tau)=\int_{\tau}^{\infty}\frac{1}{\sqrt{2\pi}}e^{-\frac{x^{2}}{2}}dx$ is Q function $\phi(x)=\frac{1}{\sqrt{2\pi}}e^{-\frac{x^{2}}{2}}$ is standard gaussain pdf. I facing problem to calculate convolution of this two function, i.e f_{$x_{1}$}*f_{$x_{2}$}. I tried with several methods but could not get the result