source: doc/papers/concurrency/examples/Format.c

#include <stdio.h>

typedef struct {
        int restart, g, b;
        char ch;
} Fmt;

void comain( Fmt * f ) {
        static void * states[] = {&&s0, &&s1};
        goto *states[f->restart];
  s0: f->restart = 1;
        for ( ;; ) {
                for ( f->g = 0; f->g < 5; f->g += 1 ) {                 // groups
                        for ( f->b = 0; f->b < 4; f->b += 1 ) {         // blocks
                                do {
                                        return;  s1: ;
                                } while ( f->ch == '\n' );                              // ignore
                                printf( "%c", f->ch );                                  // print character
                        }
                        printf( " " );                                                          // block separator
                }
                printf( "\n" );                                                                 // group separator
        }
}

int main() {
        Fmt fmt = { 0 };
        comain( &fmt );                                                                         // prime
        for ( ;; ) {
                scanf( "%c", &fmt.ch );                                                 // direct read into communication variable
          if ( feof( stdin ) ) break;
                comain( &fmt );
        }
        if ( fmt.g != 0 || fmt.b != 0 ) printf( "\n" );
}

// Local Variables: //
// tab-width: 4 //
// compile-command: "gcc-8 Format.c" //
// End: //