Changeset 407 for trunk/kernel/libk/remote_fifo.c

Timestamp:

Nov 7, 2017, 3:08:12 PM (6 years ago)

Author:

alain

Message:

First implementation of fork/exec.

File:

• trunk/kernel/libk/remote_fifo.c (modified) (5 diffs)

trunk/kernel/libk/remote_fifo.c

@@ -39 +39 @@
     uint32_t  slot;
 
+    fifo->owner     = 0;
         fifo->wr_id     = 0;
         fifo->rd_id     = 0;
@@ -47 +48 @@
 }
 
-////////////////////////////////////////////// 
-error_t remote_fifo_put_item( xptr_t     fifo, 
-                              uint64_t   item,
-                              bool_t   * first )
+/////////////////////////////////////////////////
+error_t remote_fifo_put_item( xptr_t     fifo_xp, 
+                              uint64_t   item )
 {
     uint32_t        wr_id;
@@ -56 +56 @@
     uint32_t        ptw;
     uint32_t        watchdog;
-    reg_t           save_sr;
     uint32_t        nslots;
 
     // get remote cluster identifier and pointer on FIFO
-    cxy_t           cxy = (cxy_t)GET_CXY( fifo );
-    remote_fifo_t * ptr = (remote_fifo_t *)GET_PTR( fifo );
+    cxy_t           fifo_cxy = (cxy_t)GET_CXY( fifo_xp );
+    remote_fifo_t * fifo_ptr = (remote_fifo_t *)GET_PTR( fifo_xp );
 
     // initialise watchdog for contention detection
     watchdog = 0;
 
-    // no descheduling during put access
-        hal_disable_irq( &save_sr );
-        
-    // get write slot index and atomic increment 
-        wr_id = hal_remote_atomic_add( XPTR( cxy , &ptr->wr_id ) , 1 );
+    // get write slot index with atomic increment 
+        wr_id = hal_remote_atomic_add( XPTR( fifo_cxy , &fifo_ptr->wr_id ) , 1 );
 
-    // check fifo state
+    // wait until allocated slot is empty in remote FIFO
+    // max retry = CONFIG_REMOTE_FIFO_MAX_ITERATIONS  
+    // return error if watchdog is reached
     while( 1 )
     {
         // return error if contention detected by watchdog
-        if( watchdog > CONFIG_REMOTE_FIFO_MAX_ITERATIONS ) 
-        {
-            // restore scheduling
-                hal_restore_irq( save_sr );
-
-            // return error
-            return EBUSY;
-        }
+        if( watchdog > CONFIG_REMOTE_FIFO_MAX_ITERATIONS )  return EBUSY;
 
         // read remote rd_id value
-        rd_id = hal_remote_lw( XPTR( cxy , &ptr->rd_id ) );
+        rd_id = hal_remote_lw( XPTR( fifo_cxy , &fifo_ptr->rd_id ) );
 
         // compute number of full slots
@@ -92 +83 @@
         else                 nslots = (0xFFFFFFFF - rd_id) + wr_id;
 
-        // exit if fifo not full
+        // exit waiting loop as soon as fifo not full
         if ( nslots < CONFIG_REMOTE_FIFO_SLOTS )  break;
         
-        // restore interrupts
-            hal_restore_irq( save_sr );
-
-        // deschedule without blocking 
-        if( thread_can_yield() ) sched_yield( NULL );
-
-        // disable interrupts
-            hal_disable_irq( &save_sr );
+        // retry later if fifo full:
+        // - deschedule without blocking if possible
+        // - wait ~1000 cycles otherwise
+        if( thread_can_yield() ) sched_yield();
+        else                     hal_fixed_delay( 1000 );
 
         // increment watchdog
@@ -112 +100 @@
 
     // copy item to fifo
-        hal_remote_swd( XPTR( cxy , &ptr->data[ptw] ), item );
-
+        hal_remote_swd( XPTR( fifo_cxy , &fifo_ptr->data[ptw] ), item );
         hal_fence();
 
     // set the slot valid flag
-        hal_remote_sw( XPTR( cxy , &ptr->valid[ptw] ) , 1 );
+        hal_remote_sw( XPTR( fifo_cxy , &fifo_ptr->valid[ptw] ) , 1 );
         hal_fence();
-
-    // return the first RPC flag
-    *first = ( wr_id == rd_id );
-    
-    // restore scheduling
-        hal_restore_irq( save_sr );
 
     return 0;