///////////////////////////////////////////////////////////////////////////////////
// File     : locks.c
// Date     : 01/12/2014
// Author   : alain greiner
// Copyright (c) UPMC-LIP6
///////////////////////////////////////////////////////////////////////////////////

#include "locks.h"
#include "giet_config.h"
#include "utils.h"

///////////////////////////////////////////////////
unsigned int _atomic_increment( unsigned int* ptr,
                                unsigned int  increment )
{
    unsigned int value;

    asm volatile (
        "1234:                         \n"
        "move $10,   %1                \n"   /* $10 <= ptr               */
        "move $11,   %2                \n"   /* $11 <= increment         */
        "ll   $12,   0($10)            \n"   /* $12 <= *ptr              */
        "addu $13,   $11,    $12       \n"   /* $13 <= *ptr + increment  */
        "sc   $13,   0($10)            \n"   /* M[ptr] <= new            */ 
        "beqz $13,   1234b             \n"   /* retry if failure         */
        "move %0,    $12               \n"   /* value <= *ptr if success */
        : "=r" (value) 
        : "r" (ptr), "r" (increment)
        : "$10", "$11", "$12", "$13", "memory" );

    return value;
}

////////////////////////////////////
void _lock_init( spin_lock_t* lock )
{
    lock->current = 0;
    lock->free    = 0;

#if GIET_DEBUG_SYS_LOCK
unsigned int    gpid = _get_procid();
unsigned int    x    = gpid >> (Y_WIDTH + P_WIDTH);
unsigned int    y    = (gpid >> P_WIDTH) & ((1<<Y_WIDTH)-1);
unsigned int    l    = gpid & ((1<<P_WIDTH)-1);
_printf("\n[SYS_LOCK DEBUG] P[%d,%d,%d] init lock %x"
                " at cycle %d (current = %d / free = %d)\n",
                x, y, l, (unsigned int)lock, 
                _get_proctime(), lock->current, lock->free );
#endif

}


////////////////////////////////////////
void _lock_acquire( spin_lock_t* lock )
{
    // get next free slot index fromlock
    unsigned int ticket = _atomic_increment( &lock->free, 1 );

#if GIET_DEBUG_SYS_LOCK
unsigned int    gpid = _get_procid();
unsigned int    x    = gpid >> (Y_WIDTH + P_WIDTH);
unsigned int    y    = (gpid >> P_WIDTH) & ((1<<Y_WIDTH)-1);
unsigned int    l    = gpid & ((1<<P_WIDTH)-1);
_printf("\n[SYS_LOCK DEBUG] P[%d,%d,%d] get ticket = %d"
                " for lock %x at cycle %d (current = %d / free = %d)\n",
                x, y, l, ticket, 
                (unsigned int)lock, _get_proctime(), lock->current, lock->free );
#endif


    // poll the spin_lock current slot index
    asm volatile("5678:                   \n"
                 "lw   $10,  0(%0)        \n"
                 "move $11,  %1           \n"
                 "bne  $10,  $11,  5678b  \n"
                 :
                 : "r"(lock), "r"(ticket)
                 : "$10", "$11" );

#if GIET_DEBUG_SYS_LOCK
_printf("\n[SYS_LOCK DEBUG] P[%d,%d,%d] get lock = %x"
                " at cycle %d (current = %d / free = %d)\n",
                x, y, l, (unsigned int)lock, 
                _get_proctime(), lock->current, lock->free );
#endif

}

////////////////////////////////////////
void _lock_release( spin_lock_t* lock )
{
    unsigned int current = lock->current;

    if ( current == (GIET_LOCK_MAX_TICKET - 1) ) current = 0;
    else                                         current = current + 1;

    asm volatile ( "sync                    \n"   /* for consistency                  */
                   "sw   %1,    0(%0)       \n"   /* release lock                     */
                   :
                   : "r"(lock), "r"(current)
                   : "memory" );
    

#if GIET_DEBUG_SYS_LOCK
unsigned int    gpid = _get_procid();
unsigned int    x    = gpid >> (Y_WIDTH + P_WIDTH);
unsigned int    y    = (gpid >> P_WIDTH) & ((1<<Y_WIDTH)-1);
unsigned int    l    = gpid & ((1<<P_WIDTH)-1);
_printf("\n[SYS_LOCK DEBUG] P[%d,%d,%d] release lock = %x"
                " at cycle %d (current = %d / free = %d)\n",
                x, y, l, (unsigned int)lock, 
                _get_proctime(), lock->current, lock->free );
#endif

}








////////////////////////////////////////////////
void _simple_lock_acquire( simple_lock_t* lock )
{
    asm volatile ( "1515:                   \n"
	               "lw   $2,    0(%0)       \n"   /* $2 <= lock current value         */
	               "bnez $2,    1515b       \n"   /* retry if lock already taken      */
                   "ll   $2,    0(%0)       \n"   /* ll_buffer <= lock current value  */
                   "bnez $2,    1515b       \n"   /* retry if lock already taken      */
                   "li   $3,    1           \n"   /* $3 <= argument for sc            */
                   "sc   $3,    0(%0)       \n"   /* try to set lock                  */
                   "beqz $3,    1515b       \n"   /* retry if sc failure              */
                   :
                   : "r"(lock)
                   : "$2", "$3", "memory" );
}

////////////////////////////////////////////////
void _simple_lock_release( simple_lock_t* lock )
{
    asm volatile ( "sync                    \n"   /* for consistency                  */
                   "sw   $0,    0(%0)       \n"   /* release lock                     */
                   :
                   : "r"(lock)
                   : "memory" );
}


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