function[out]=pcm_encode(x)
%x encode to pcm code
n=length(x);
% -4096<x<4096
for i=1:n
if x(i)>0
out(i,1)=1;
else
out(i,1)=0;
end
if abs(x(i))>=0 & abs(x(i))<32
out(i,2)=0;out(i,3)=0;out(i,4)=0;step=2;st=0;
elseif abs(x(i))>=32 & abs(x(i))<64
out(i,2)=0;out(i,3)=0;out(i,4)=1;step=2;st=32;
elseif abs(x(i))>=64 & abs(x(i))<128
out(i,2)=0;out(i,3)=1;out(i,4)=0;step=4;st=64;
elseif abs(x(i))>=128 & abs(x(i))<256
out(i,2)=0;out(i,3)=1;out(i,4)=1;step=8;st=128;
elseif abs(x(i))>=256 & abs(x(i))<512
out(i,2)=1;out(i,3)=0;out(i,4)=0;step=16;st=256;
elseif abs(x(i))>=512 & abs(x(i))<1024
out(i,2)=1;out(i,3)=0;out(i,4)=1;step=32;st=512;
elseif abs(x(i))>=1024 & abs(x(i))<2048
out(i,2)=1;out(i,3)=1;out(i,4)=0;step=64;st=1024;
elseif abs(x(i))>=2048 & abs(x(i))<4096
out(i,2)=1;out(i,3)=1;out(i,4)=1;step=128;st=2048;
else
out(i,2)=1;out(i,3)=1;out(i,4)=1;step=128;st=2048;
end
if(abs(x(i))>=4096)
out(i,2:8)=[1 1 1 1 1 1 1];
else
tmp=floor((abs(x(i))-st)/step);
t=dec2bin(tmp,4)-48; %函数dec2bin输出的是ASCII字符串，48对应0
out(i,5:8) =t(1:4);
end
end
out=reshape(out',1,8*n);
