Changeset 165 for soft/giet_vm/libs/mwmr_channel.c

Timestamp:

Jul 4, 2012, 2:51:18 PM (12 years ago)

Author:

alain

Message:

Introducing various modifications in kernel initialisation

File:

• soft/giet_vm/libs/mwmr_channel.c (modified) (6 diffs)

soft/giet_vm/libs/mwmr_channel.c

@@ -12 +12 @@
 // The mwmr_read() and mwmr_write() functions do not require a system call.
 // The channel itself must have been allocated in a non cacheable segment,
-// if the platform does not provide hardwate cache coherence.
+// if the platform does not provide hardware cache coherence.
 //
 // ALL MWMR channels must be defined in the mapping_info data structure, 
@@ -37 +37 @@
 //  mwmr_lock_aquire()
 // This blocking function returns only when the lock has been taken.
-// If the lock is already taken a random delay is introduced before retry.
-//////////////////////////////////////////////////////////////////////////////
-void mwmr_lock_acquire(unsigned int* plock)
+// If the lock is already taken a fixed delay is introduced before retry.
+//////////////////////////////////////////////////////////////////////////////
+void mwmr_lock_acquire(unsigned int* lock_address)
 {
+    register unsigned int*      plock = lock_address;
+    register unsigned int       delay = 100;
     asm volatile (
             "mwmr_lock_try:                                     \n"
             "ll   $2,    0(%0)                          \n" /* $2 <= lock current value */
-            "bnez $2,    mwmr_lock_delay        \n" /* retry if lock already taken */
+            "bnez $2,    mwmr_lock_delay        \n" /* retry after delay if lock busy */
             "li   $3,    1                                      \n" /* $3 <= argument for sc */
             "sc   $3,    0(%0)                          \n" /* try to get lock */
             "bnez $3,    mwmr_lock_ok           \n" /* exit if atomic */
-
             "mwmr_lock_delay:                           \n"
-            "jal  rand                                  \n" /* rand() system call */
-            "nop                                                        \n"
-            "andi $4,   $2,     0xFF                    \n"     /* $4 <= random delay < 256 cycles */
-
-            "mwmr_lock_loop:                            \n"
+            "move $4,    %1                 \n" /* $4 <= delay */
+            "mwmr_lock_loop:                \n"
+            "beqz $4,    mwmr_lock_loop         \n" /* test end delay */
             "addi $4,    $4,  -1                        \n" /* $4 <= $4 - 1 */
-            "beqz $4,    mwmr_lock_loop         \n" /* test end delay */
-            "nop                                                        \n"
-            "j           mwmr_lock_try          \n" /* retry */
+            "j           mwmr_lock_try          \n" /* retry ll */
             "nop                                                        \n"
             "mwmr_lock_ok:                                      \n"
             :
-            :"r"(plock)
+            :"r"(plock), "r"(delay)
             :"$2", "$3", "$4");
 } 
@@ -117 +114 @@
         {
             mwmr->lock = 0;
-            for ( x = rand()>>8 ; x > 0 ; x-- ) asm volatile ( "nop" );
+            for ( x = giet_rand()>>8 ; x > 0 ; x-- ) asm volatile ( "nop" );
         }
         else    // write as many items as possible, release lock and retry after delay
@@ -135 +132 @@
         }
         // random delay before retry
-        for ( x = rand()>>6 ; x > 0 ; x-- ) asm volatile ( "nop" );
+        for ( x = giet_rand()>>6 ; x > 0 ; x-- ) asm volatile ( "nop" );
     }
 } 
@@ -188 +185 @@
         {
             mwmr->lock = 0;
-            for ( x = rand()>>8 ; x > 0 ; x-- ) asm volatile ( "nop" );
+            for ( x = giet_rand()>>8 ; x > 0 ; x-- ) asm volatile ( "nop" );
         }
         else    // read as many items as possible, release lock and retry after delay
@@ -206 +203 @@
         }
         // random delay before retry
-        for ( x = rand()>>6 ; x > 0 ; x-- ) asm volatile ( "nop" );
+        for ( x = giet_rand()>>6 ; x > 0 ; x-- ) asm volatile ( "nop" );
     }
 }