Changes between Version 67 and Version 68 of Writing Rules/Tlmt

Timestamp:

Nov 15, 2008, 6:12:57 PM (15 years ago)

Author:

alain

Comment:

--

Writing Rules/Tlmt

@@ -15 +15 @@
 compliant with the new TLM2.0 OSCI standard. 
 These rules enforce the PDES (Parallel Discrete Event Simulation) principles. In the TLM-T approach, 
-we don't use anymore the SystemC global time, as each PDES process involved in 
+we don't use the SystemC global time, as each PDES process involved in 
 the simulation has its own local time. PDES processes (implemented as SC_THREADS) synchronize through 
 messages piggybacked with time information. 
@@ -44 +44 @@
 = C) TLM-T VCI Transaction =
 
-The TLM2.0 standard allows the user to redefine both the payload and the phases of a transaction.
-Two classes are defined in '''soclib_vci_types''' :  a '''tlmt_vci_transaction''' and a '''tlmt_phase".
-
-A payload of type '''soclib_vci_types::tlm_payload_type''' corresponds to a '''tlmt_vci_transaction'''.
-It contains three groups of information: 
- * TLM2.0 related fields
- * TLM-T related fields 
- * VCI related fields 
+The TLM2.0 standard allows the user to redefine both the payload and the phases of the transaction.
+Two classes have been defined in '''soclib_vci_types''' :  a '''tlmt_vci_transaction''' and a '''tlmt_phase".
+
+The payload of a '''tlmt_vci_transaction''' contains three groups of information: 
+ * TLM2.0 generic fields
+ * TLM-T specific fields 
+ * VCI specific fields 
 {{{
 class tlmt_vci_transaction
@@ -57 +56 @@
         ...
 private:
+
   // TLM2.0 related fields and common structure
 
   sc_dt::uint64        m_address;               // address
-  unsigned char*       m_data;                  // buf
-  unsigned int         m_length;                // nword
+  unsigned char*       m_data;                  // data buffer
+  unsigned int         m_length;                // number of bytes
   tlmt_response_status m_response_status;       // rerror
-  bool                 m_dmi;                   // nothing
-  unsigned char*       m_byte_enable;           // be
-  unsigned int         m_byte_enable_length; 
+  unsigned char*       m_byte_enable;           // be buffer
   unsigned int         m_streaming_width;       // 
 
@@ -81 +79 @@
 }}}
 
-The TLM2.0 compliant accessors allow to set the TLM2.0 related fields, such as the transaction address, the byte enable
-array pointer and its associated size in bytes, and the data array pointer and its associated size in bytes. The byte
-enable array allows to build versatile packets thanks to a powerful but slow data masking scheme. Further experiments are
-currently done to evaluate the performance degradation incurred by the byte formatting.
+The TLM2.0 compliant accessors allow to set the TLM2.0 related fields, such as the transaction address, the data & byte enable
+arrays pointers and its associated size in bytes. 
+
+NB : The byte array approach defined by TLM2.0 can degrade the simulation speed,
+as the existing SoCLib models use uint32_t arrays to model both the embedded memory and the caches... 
+Experiments are currently in progress to evaluate the performance degradation incurred by this byte formatting.
 It is therefore  possible that the types of the '''m_data''' and '''m_byte_enable''' of the '''tlmt_vci_transaction'''
 will be changed to '''uint32*''' in a near future.