```// ************************************************************************** //
//                                                                            //
//    eses                   eses                                             //
//   eses                     eses                                            //
//  eses    eseses  esesese    eses   Embedded Systems Group                  //
//  ese    ese  ese ese         ese                                           //
//  ese    eseseses eseseses    ese   Department of Computer Science          //
//  eses   eses          ese   eses                                           //
//   eses   eseses  eseseses  eses    University of Kaiserslautern            //
//    eses                   eses                                             //
//                                                                            //
// ************************************************************************** //
// ShakerSort is a symmetric version of BubbleSort. BubbleSort has the        //
// disadvantage that small elements on the right of the sequence move         //
// slowly towards the left (thus they are called turtles), while large        //
// elements on the left move rapidly to the right (thus they are called       //
// rabbits). ShakerSort therefore first bubbles the maximum of the            //
// still unsorted sequence to the right, and then the minimum to the left.    //
// ************************************************************************** //

macro aSize = 16;
macro iSize = 64;

module ShakerSort([aSize]int{iSize} ?a,b, event !ready) {
nat{aSize+1} i,j;
bool swapped;
event sorted;
for(i=0..(aSize-1))
b[i] = a[i];
i = 0;
j = 1;
weak abort {
loop {
next(swapped) = false;
w0: pause;
// bubbling up the max. of b[i..N-(i+1)]
j = i;
while(j<aSize-(i+2)) {
if(b[j] > b[j+1]) {
next(b[j]) = b[j+1];
next(b[j+1]) = b[j];
next(swapped) = true;
}
next(j) = j+1;
w1: pause;
}
if(b[j] > b[j+1]) {
next(b[j]) = b[j+1];
next(b[j+1]) = b[j];
next(swapped) = true;
}
w2: pause;
next(swapped) = false;
if(!swapped) emit(sorted);
assert(j==aSize-(i+2));
next(j) = j-1;
w3: pause;
// now, b[N-(i+1)] is the max of b[i..N-(i+1)], thus
// bubbling down the min. of b[i..N-(i+2)]
while(j>i) {
if(b[j] > b[j+1]) {
next(b[j]) = b[j+1];
next(b[j+1]) = b[j];
next(swapped) = true;
}
next(j) = j-1;
w4: pause;
}
if(b[j] > b[j+1]) {
next(b[j]) = b[j+1];
next(b[j+1]) = b[j];
next(swapped) = true;
}
w5: pause;
next(i) = i+1;
next(swapped) = false;
if(!swapped) emit(sorted);
}
} when(sorted);
}
drivenby Test01 {
for(i=0..aSize-1) a[i] = i;
for(i=0..aSize-1) assert(b[i] == i);
}
drivenby Test02 {
for(i=0..aSize-1) a[i] = aSize-1-i;