Added prbs

1 files changed, 63 insertions, 0 deletions

diff --git a/R/idinput.R b/R/idinput.R
index c9831b0..330ac93 100644
--- a/R/idinput.R
+++ b/R/idinput.R
@@ -30,6 +30,8 @@ idinput<-function(n,type='rgs',band=c(0,1),levels=c(-1,1)){
     rgs(n,band,levels)
   } else if(type=="sine"){
     multisine(n,1,band,levels)
+  }else if(type=="prbs"){
+    idin.prbs(n,band,levels)
   }
 }
 
@@ -71,6 +73,67 @@ multisine <- function(N,nin=1,band,levels){
   return(u)
 }
 
+#' @export
+library(bitops)
+require(signal)
+
+idin.prbs<-function(n,band=c(0,1),levels=c(0,1)){
+  u=vector()
+  for(i in 1:18){
+    if(n / (2^i) < 1){
+      u=idin.prbs12(i,band,levels)
+      break
+    }
+  }
+  return(u[1:n])
+}
+
+idin.prbs12 <- function(N,band=c(0,1),levels=c(0,1)){
+  first=ceiling(abs(rnorm(1)*10))  #some non-zero initial state 
+  x= first
+  v = vector()  
+  n=2^N-1
+  i=1
+  clock=floor(1/band[2])
+  k=1
+  M=rbind(c(0,0,0,0),c(1,2,0,0),c(1,3,0,0),c(1,4,0,0),c(2,5,0,0),c(1,6,0,0),
+          c(1,7,0,0),c(1,2,7,8),c(4,9,0,0),c(3,10,0,0),c(9,11,0,0),
+          c(6,8,11,12),c(9,10,12,13),c(4,8,13,14),c(14,15,0,0),c(4,13,15,16),
+          c(14,17,0,0),c(11,18,0,0))
+  repeat{
+    a=M[N,1]
+    b=M[N,2]
+    c=M[N,3]
+    d=M[N,4]
+    four=c(8,12,13,14,16)
+    if(N %in% four){
+      e=bitwXor(bitwShiftR(x,N-a),bitwShiftR(x,N-b))
+      f=bitwXor(bitwShiftR(x,N-c),bitwShiftR(x,N-d))
+      newbit=bitwAnd(bitwXor(e,f),1)
+    }else{
+      newbit=bitwAnd(bitwXor(bitwShiftR(x,N-a),bitwShiftR(x,N-b)),1)
+    }
+    if(k>=clock || i==1){
+      v[i]=newbit
+      i=i+1
+      k=1
+    }else{
+      v[i]=v[i-1]
+      i=i+1
+      k=k+1
+    }
+    x=bitwOr(bitwShiftR(x,1),bitwShiftL(newbit,N-1))
+    if(x==first){
+      break
+    }
+  }
+  
+  v=sapply(v, function(x){if (x==0) levels[1] else levels[2]})
+  return(v)
+}
+
+
+
 butter_filt <- function(x,band){
   filt <- T; type <- "pass"
   if(band[1]<=2e-3){