uvm_reg_model——寄存器模型（一）

　　对于一个复杂设计，寄存器模型要能够模拟任意数量的寄存器域操作。UVM提供标准的基类库，UVM的寄存器模型来自于继承自VMM的RAL（Register Abstract Layer），现在可以先将寄存器模型进行XML建模，再通过脚本工具直接生产寄存器模型。首先来看看uvm_reg_model的代码，该文件用来保存Register Layer的全局变量和文件include。

//------------------------------------------------------------------------------
// TITLE: Global Declarations for the Register Layer
//------------------------------------------------------------------------------
//
// This section defines globally available types, enums, and utility classes.
//
//------------------------------------------------------------------------------

`ifndef UVM_REG_MODEL__SV
`define UVM_REG_MODEL__SV

typedef class uvm_reg_field;
typedef class uvm_vreg_field;
typedef class uvm_reg;
typedef class uvm_reg_file;
typedef class uvm_vreg;
typedef class uvm_reg_block;
typedef class uvm_mem;
typedef class uvm_reg_item;
typedef class uvm_reg_map;
typedef class uvm_reg_map_info;
typedef class uvm_reg_sequence;
typedef class uvm_reg_adapter;
typedef class uvm_reg_indirect_data;

除了声明了基本的寄存器模型外，还定义了一些全局变量和枚举的定义：

// Type: uvm_hdl_path_slice
//
// Slice of an HDL path
//
// Struct that specifies the HDL variable that corresponds to all
// or a portion of a register.
//
// path    - Path to the HDL variable.
// offset  - Offset of the LSB in the register that this variable implements
// size    - Number of bits (toward the MSB) that this variable implements
//
// If the HDL variable implements all of the register, ~offset~ and ~size~
// are specified as -1. For example:
//|
//| r1.add_hdl_path('{ '{"r1", -1, -1} });
//|
//
typedef struct {
   string path;
   int offset;
   int size;
} uvm_hdl_path_slice;

typedef uvm_resource_db#(uvm_reg_cvr_t) uvm_reg_cvr_rsrc_db;

//--------------------
// Group: Enumerations
//--------------------

// Enum: uvm_status_e
//
// Return status for register operations
//
// UVM_IS_OK      - Operation completed successfully
// UVM_NOT_OK     - Operation completed with error
// UVM_HAS_X      - Operation completed successfully bit had unknown bits.
//

   typedef enum {
      UVM_IS_OK,
      UVM_NOT_OK,
      UVM_HAS_X
   } uvm_status_e;

// Enum: uvm_path_e
//
// Path used for register operation
//
// UVM_FRONTDOOR    - Use the front door
// UVM_BACKDOOR     - Use the back door
// UVM_PREDICT      - Operation derived from observations by a bus monitor via
//                    the <uvm_reg_predictor> class.
// UVM_DEFAULT_PATH - Operation specified by the context
//
   typedef enum {
      UVM_FRONTDOOR,
      UVM_BACKDOOR,
      UVM_PREDICT,
      UVM_DEFAULT_PATH
   } uvm_path_e;

// Enum: uvm_check_e
//
// Read-only or read-and-check
//
// UVM_NO_CHECK   - Read only
// UVM_CHECK      - Read and check
//
   typedef enum {
      UVM_NO_CHECK,
      UVM_CHECK
   } uvm_check_e;

// Enum: uvm_endianness_e
//
// Specifies byte ordering
//
// UVM_NO_ENDIAN      - Byte ordering not applicable
// UVM_LITTLE_ENDIAN  - Least-significant bytes first in consecutive addresses
// UVM_BIG_ENDIAN     - Most-significant bytes first in consecutive addresses
// UVM_LITTLE_FIFO    - Least-significant bytes first at the same address
// UVM_BIG_FIFO       - Most-significant bytes first at the same address
//
   typedef enum {
      UVM_NO_ENDIAN,
      UVM_LITTLE_ENDIAN,
      UVM_BIG_ENDIAN,
      UVM_LITTLE_FIFO,
      UVM_BIG_FIFO
   } uvm_endianness_e;

// Enum: uvm_elem_kind_e
//
// Type of element being read or written
//
// UVM_REG      - Register
// UVM_FIELD    - Field
// UVM_MEM      - Memory location
//
   typedef enum {
      UVM_REG,
      UVM_FIELD,
      UVM_MEM
   } uvm_elem_kind_e;

// Enum: uvm_access_e
//
// Type of operation begin performed
//
// UVM_READ     - Read operation
// UVM_WRITE    - Write operation
//
   typedef enum {
      UVM_READ,
      UVM_WRITE,
      UVM_BURST_READ,
      UVM_BURST_WRITE
   } uvm_access_e;

// Enum: uvm_hier_e
//
// Whether to provide the requested information from a hierarchical context.
//
// UVM_NO_HIER - Provide info from the local context
// UVM_HIER    - Provide info based on the hierarchical context

   typedef enum {
      UVM_NO_HIER,
      UVM_HIER
   } uvm_hier_e;

// Enum: uvm_predict_e
//
// How the mirror is to be updated
//
// UVM_PREDICT_DIRECT  - Predicted value is as-is
// UVM_PREDICT_READ    - Predict based on the specified value having been read
// UVM_PREDICT_WRITE   - Predict based on the specified value having been written
//
   typedef enum {
      UVM_PREDICT_DIRECT,
      UVM_PREDICT_READ,
      UVM_PREDICT_WRITE
   } uvm_predict_e;

// Enum: uvm_coverage_model_e
//
// Coverage models available or desired.
// Multiple models may be specified by bitwise OR'ing individual model identifiers.
//
// UVM_NO_COVERAGE      - None
// UVM_CVR_REG_BITS     - Individual register bits
// UVM_CVR_ADDR_MAP     - Individual register and memory addresses
// UVM_CVR_FIELD_VALS   - Field values
// UVM_CVR_ALL          - All coverage models
//
   typedef enum uvm_reg_cvr_t {
      UVM_NO_COVERAGE      = 'h0000,
      UVM_CVR_REG_BITS     = 'h0001,
      UVM_CVR_ADDR_MAP     = 'h0002,
      UVM_CVR_FIELD_VALS   = 'h0004,
      UVM_CVR_ALL          = -
   } uvm_coverage_model_e;

// Enum: uvm_reg_mem_tests_e
//
// Select which pre-defined test sequence to execute.
//
// Multiple test sequences may be selected by bitwise OR'ing their
// respective symbolic values.
//
// UVM_DO_REG_HW_RESET      - Run <uvm_reg_hw_reset_seq>
// UVM_DO_REG_BIT_BASH      - Run <uvm_reg_bit_bash_seq>
// UVM_DO_REG_ACCESS        - Run <uvm_reg_access_seq>
// UVM_DO_MEM_ACCESS        - Run <uvm_mem_access_seq>
// UVM_DO_SHARED_ACCESS     - Run <uvm_reg_mem_shared_access_seq>
// UVM_DO_MEM_WALK          - Run <uvm_mem_walk_seq>
// UVM_DO_ALL_REG_MEM_TESTS - Run all of the above
//
// Test sequences, when selected, are executed in the
// order in which they are specified above.
//
typedef enum bit [:] {
  UVM_DO_REG_HW_RESET      = 'h0000_0000_0000_0001,
  UVM_DO_REG_BIT_BASH      = 'h0000_0000_0000_0002,
  UVM_DO_REG_ACCESS        = 'h0000_0000_0000_0004,
  UVM_DO_MEM_ACCESS        = 'h0000_0000_0000_0008,
  UVM_DO_SHARED_ACCESS     = 'h0000_0000_0000_0010,
  UVM_DO_MEM_WALK          = 'h0000_0000_0000_0020,
  UVM_DO_ALL_REG_MEM_TESTS = 'hffff_ffff_ffff_ffff
} uvm_reg_mem_tests_e;

包含其他文件的include:

`include "reg/uvm_reg_item.svh"
`include "reg/uvm_reg_adapter.svh"
`include "reg/uvm_reg_predictor.svh"
`include "reg/uvm_reg_sequence.svh"
`include "reg/uvm_reg_cbs.svh"
`include "reg/uvm_reg_backdoor.svh"
`include "reg/uvm_reg_field.svh"
`include "reg/uvm_vreg_field.svh"
`include "reg/uvm_reg.svh"
`include "reg/uvm_reg_indirect.svh"
`include "reg/uvm_reg_fifo.svh"
`include "reg/uvm_reg_file.svh"
`include "reg/uvm_mem_mam.svh"
`include "reg/uvm_vreg.svh"
`include "reg/uvm_mem.svh"
`include "reg/uvm_reg_map.svh"
`include "reg/uvm_reg_block.svh"

`include "reg/sequences/uvm_reg_hw_reset_seq.svh"
`include "reg/sequences/uvm_reg_bit_bash_seq.svh"
`include "reg/sequences/uvm_mem_walk_seq.svh"
`include "reg/sequences/uvm_mem_access_seq.svh"
`include "reg/sequences/uvm_reg_access_seq.svh"
`include "reg/sequences/uvm_reg_mem_shared_access_seq.svh"
`include "reg/sequences/uvm_reg_mem_built_in_seq.svh"
`include "reg/sequences/uvm_reg_mem_hdl_paths_seq.svh"