uvm_reg_item——寄存器模型（五）

　　uvm_reg_item 扩展自uvm_sequence_item，也就说寄存器模型定义了transaction item. adapter 的作用是把这uvm_reg_item转换成uvm_sequence_item，再经由uvm_sequencer发送个uvm_driver，最终在总线上传输。

//------------------------------------------------------------------------------
// Title: Generic Register Operation Descriptors
//
// This section defines the abstract register transaction item. It also defines
// a descriptor for a physical bus operation that is used by <uvm_reg_adapter>
// subtypes to convert from a protocol-specific address/data/rw operation to
// a bus-independent, canonical r/w operation.
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
// CLASS: uvm_reg_item
//
// Defines an abstract register transaction item. No bus-specific information
// is present, although a handle to a <uvm_reg_map> is provided in case a user
// wishes to implement a custom address translation algorithm.
//------------------------------------------------------------------------------

class uvm_reg_item extends uvm_sequence_item;

  `uvm_object_utils(uvm_reg_item)

  // Variable: element_kind
  //
  // Kind of element being accessed: REG, MEM, or FIELD. See <uvm_elem_kind_e>.
  //
  uvm_elem_kind_e element_kind;

  uvm_object element;
  rand uvm_access_e kind;

  // Variable: value
  //
  // The value to write to, or after completion, the value read from the DUT.
  // Burst operations use the <values> property.
  //
  rand uvm_reg_data_t value[];

  // TODO: parameterize
  constraint max_values { value.size() >  && value.size() < ; }

  rand uvm_reg_addr_t offset;
  uvm_status_e status;
  uvm_reg_map local_map;
  uvm_reg_map map;
  uvm_path_e path;
  rand uvm_sequence_base parent;
  int prior = -;
  rand uvm_object extension;
  string bd_kind;
  string fname;
  int lineno;

  function new(string name="");
    super.new(name);
    value = new[];
  endfunction

  // Function: convert2string
  //
  // Returns a string showing the contents of this transaction.
  //
  virtual function string convert2string();
    string s,value_s;
    s = {"kind=",kind.name(),
         " ele_kind=",element_kind.name(),
         " ele_name=",element==null?"null":element.get_full_name() };

    if (value.size() >  && uvm_report_enabled(UVM_HIGH, UVM_INFO, "RegModel")) begin
      value_s = "'{";
      foreach (value[i])
         value_s = {value_s,$sformatf("%0h,",value[i])};
      value_s[value_s.len()-]="}";
    end
    else
      value_s = $sformatf("%0h",value[]);
    s = {s, " value=",value_s};

    if (element_kind == UVM_MEM)
      s = {s, $sformatf(" offset=%0h",offset)};
    s = {s," map=",(map==null?"null":map.get_full_name())," path=",path.name()};
    s = {s," status=",status.name()};
    return s;
  endfunction

  virtual function void do_copy(uvm_object rhs);
  endfunction

endclass

//------------------------------------------------------------------------------
//
// CLASS: uvm_reg_bus_op
//
// Struct that defines a generic bus transaction for register and memory accesses, having
// ~kind~ (read or write), ~address~, ~data~, and ~byte enable~ information.
// If the bus is narrower than the register or memory location being accessed,
// there will be multiple of these bus operations for every abstract
// <uvm_reg_item> transaction. In this case, ~data~ represents the portion
// of <uvm_reg_item::value> being transferred during this bus cycle.
// If the bus is wide enough to perform the register or memory operation in
// a single cycle, ~data~ will be the same as <uvm_reg_item::value>.
//------------------------------------------------------------------------------

typedef struct {

  // Variable: kind
  //
  // Kind of access: READ or WRITE.
  //
  uvm_access_e kind;

  // Variable: addr
  //
  // The bus address.
  //
  uvm_reg_addr_t addr;

  // Variable: data
  //
  // The data to write. If the bus width is smaller than the register or
  // memory width, ~data~ represents only the portion of ~value~ that is
  // being transferred this bus cycle.
  //
  uvm_reg_data_t data;

  // Variable: n_bits
  //
  // The number of bits of <uvm_reg_item::value> being transferred by
  // this transaction.

  int n_bits;

  /*
  constraint valid_n_bits {
     n_bits > 0;
     n_bits <= `UVM_REG_DATA_WIDTH;
  }
  */

  // Variable: byte_en
  //
  // Enables for the byte lanes on the bus. Meaningful only when the
  // bus supports byte enables and the operation originates from a field
  // write/read.
  //
  uvm_reg_byte_en_t byte_en;

  // Variable: status
  //
  // The result of the transaction: UVM_IS_OK, UVM_HAS_X, UVM_NOT_OK.
  // See <uvm_status_e>.
  //
  uvm_status_e status;

} uvm_reg_bus_op;