Library mcertikos.mcslock.MMCSLockAbsIntroCSource

// macros only for MCS_LOCK
#define BUSY 1
#define FREE 0
#define INVALID_MCS_NODE TOTAL_CPU
#define TRUE 1
#define FALSE 0

// num of CPUs and procs
#define TOTAL_CPU 8

// macros for num of chans and num of cvs
#define READ_Q_START 0
#define MSG_Q_START (READ_Q_START + TOTAL_CPU) // 8
#define SLEEP_Q_START (MSG_Q_START + TOTAL_CPU) // 16
#define num_cv 255
#define TDQ_SIZE (SLEEP_Q_START + num_proc * num_cv + 1) // 16 + 64 * 255 + 1 = 16337
#define num_chan TDQ_SIZE // 16337

// macros for lock index
#define ID_AT 0
#define ID_TCB 1
#define ID_SC 2
#define ID_range 3
#define ID_AT_range 1
#define ID_TCB_range num_chan // 16337
#define ID_SC_range num_cv // 255
#define lock_TCB_range (ID_AT_range + ID_TCB_range) // 1 + 16337 = 16338
#define lock_range (ID_AT_range + ID_TCB_range + ID_SC_range) // 1 + 16337 + 255 = 16593
#define lock_AT_start 0
#define lock_TCB_start ID_AT_range // 1
#define lock_SC_start lock_TCB_range // 16338
#define WRONG 123456789

// defined in MBoot layer
extern void boot_loader(unsigned int mbi_adr);
extern unsigned int get_CPU_ID(void);

extern void mcs_init_node_log(unsigned int lock_index);
extern void mcs_init_node_log(unsigned int lock_index);
extern void mcs_GET_NEXT_log(unsigned int lock_index, unsigned int cpuid);
extern void mcs_SET_NEXT_log(unsigned int lock_index, unsigned int cpuid, unsigned int prev_id);
extern void mcs_GET_BUSY_log(unsigned int lock_index, unsigned int cpuid);
extern void mcs_SET_BUSY_log(unsigned int lock_index, unsigned int cpuid);

// defined in MMCSLockIntro layer
extern void mcs_init_node(unsigned int lock_index);
extern void mcs_log(unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_GET_NEXT(unsigned int lock_index, unsigned int cpuid);
extern void mcs_SET_NEXT(unsigned int lock_index, unsigned int cpuid, unsigned int prev_id);
extern unsigned int mcs_GET_BUSY(unsigned int lock_index, unsigned int cpuid);
extern void mcs_SET_BUSY(unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_SWAP_TAIL(unsigned int bound, unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_CAS_TAIL(unsigned int lock_index, unsigned int cpuid);

// defined in MMCSAbsLockIntro layer
extern void mcs_lock_init(unsigned int mbi_adr);
extern unsigned int mcs_get_next(unsigned int lock_index, unsigned int cpuid);
extern void mcs_set_next(unsigned int lock_index, unsigned int cpuid, unsigned int prev_id);
extern unsigned int mcs_get_busy(unsigned int lock_index, unsigned int cpuid);
extern void mcs_set_busy(unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_swap_tail(unsigned int bound, unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_cas_tail(unsigned int lock_index, unsigned int cpuid);
extern unsigned int mcs_lock_get_index(unsigned int lock_id, unsigned int offset);

// Data Type 
typedef struct _mcs_node{
    unsigned int next;
    unsigned int busy;
}mcs_node;

typedef struct _mcs_lock{
    unsigned int last;
    mcs_node node_pool[TOTAL_CPU];
}mcs_lock;

mcs_lock MCS_LOCK_LOC[lock_range];


void
mcs_wait_lock(unsigned int bound, unsigned int lock_id, unsigned int offset)
{
    unsigned int lock_index, cpuid, prev_id, current_busy, busy_var;

    // pre-setting 
    lock_index = mcs_lock_get_index(lock_id, offset);
    cpuid = get_CPU_ID();
    prev_id = mcs_swap_tail(bound, lock_index, cpuid);

    if(prev_id == INVALID_MCS_NODE){
        return;
    } else {
        busy_var = BUSY;
        mcs_set_next(lock_index, cpuid, prev_id);
        
        // busy waiting
        current_busy = mcs_get_busy(lock_index, cpuid);
        while(current_busy == busy_var){
            current_busy = mcs_get_busy(lock_index, cpuid);
        }
        return;
    }
} 

void
mcs_pass_lock(unsigned int lock_id, unsigned int offset)
{
    unsigned int lock_index, cpuid, current_next, cas_res, null_var;

    // pre-setting
    lock_index = mcs_lock_get_index(lock_id, offset);
    cpuid = get_CPU_ID();
    cas_res = mcs_cas_tail(lock_index, cpuid);
    
    if(cas_res == 1){
        return;
    } else {
        null_var = INVALID_MCS_NODE;
        current_next = mcs_get_next(lock_index, cpuid);
        while (current_next == null_var){
            current_next = mcs_get_next(lock_index, cpuid);
        }
        mcs_set_busy(lock_index, cpuid);
        return;
    }
}