4 template <typename t_element, size_t t_size>
5 struct mpmc_boundq_1_alt
9 // elements should generally be cache-line-size padded :
10 t_element m_array[t_size];
12 // rdwr counts the reads & writes that have started
13 atomic<unsigned int> m_rdwr;
14 // "read" and "written" count the number completed
15 atomic<unsigned int> m_read;
16 atomic<unsigned int> m_written;
27 //-----------------------------------------------------
29 t_element * read_fetch() {
30 unsigned int rdwr = m_rdwr.load(mo_acquire);
33 rd = (rdwr>>16) & 0xFFFF;
36 if ( wr == rd ) // empty
39 if ( m_rdwr.compare_exchange(rdwr,rdwr+(1<<16),mo_acq_rel) )
45 while ( (m_written.load(mo_acquire) & 0xFFFF) != wr ) {
49 t_element * p = & ( m_array[ rd % t_size ] );
55 m_read.fetch_add(1,mo_release);
58 //-----------------------------------------------------
60 t_element * write_prepare() {
61 unsigned int rdwr = m_rdwr.load(mo_acquire);
64 rd = (rdwr>>16) & 0xFFFF;
67 if ( wr == ((rd + t_size)&0xFFFF) ) // full
70 if ( m_rdwr.compare_exchange(rdwr,(rd<<16) | ((wr+1)&0xFFFF),mo_acq_rel) )
76 while ( (m_read.load(mo_acquire) & 0xFFFF) != rd ) {
80 t_element * p = & ( m_array[ wr % t_size ] );
87 m_written.fetch_add(1,mo_release);
90 //-----------------------------------------------------