Trung tâm đào tạo thiết kế vi mạch Semicon


  • ĐĂNG KÝ TÀI KHOẢN ĐỂ TRUY CẬP NHIỀU TÀI LIỆU HƠN!
  • Đăng ký
    *
    *
    *
    *
    *
    Fields marked with an asterisk (*) are required.
semi1_solvingproblems.jpg

Verilog Operators Part 1

Email In PDF.

Arithmetic Operators

  • Binary: +, -, *, /, % (the modulus operator)
  • Unary: +, - (This is used to specify the sign)
  • Integer division truncates any fractional part
  • The result of a modulus operation takes the sign of the first operand
  • If any operand bit value is the unknown value x, then the entire result value is x
  • Register data types are used as unsigned values (Negative numbers are stored in two's complement form)
  • Example

      1 module arithmetic_operators();

      2

      3 initial begin

      4   $display (" 5  +  10 = %d", 5  + 10);

      5   $display (" 5  -  10 = %d", 5  - 10);

      6   $display (" 10 -  5  = %d", 10 - 5);

      7   $display (" 10 *  5  = %d", 10 * 5);

      8   $display (" 10 /  5  = %d", 10 / 5);

      9   $display (" 10 /  -5 = %d", 10 / -5);

     10   $display (" 10 %s  3  = %d","%", 10 % 3);

     11   $display (" +5       = %d", +5);

     12   $display (" -5       = %d", -5);

     13    #10  $finish;

     14 end

     15

     16 endmodule


      5  +  10 =  15

      5  -  10 =  -5

      10 -  5  =   5

      10 *  5  =  50

      10 /  5  =  2

      10 /  -5 = -2

      10 %  3  =   1

      +5       =  5

      -5       =  -5
    Relational Operators

    Operator

    Description

    a < b

    a less than b

    a > b

    a greater than b

    a <= b

    a less than or equal to b

    a >= b

    a greater than or equal to b

    • The result is a scalar value (example a < b)
    • 0 if the relation is false (a is bigger then b)
    • 1 if the relation is true ( a is smaller then b)
    • x if any of the operands has unknown x bits (if a or b contains X)
      Note: 
      If any operand is x or z, then the result of that test is treated as false (0)
    Example

      1 module relational_operators();

      2

      3 initial begin

      4   $display (" 5     <=  10 = %b", (5     <= 10));

      5   $display (" 5     >=  10 = %b", (5     >= 10));

      6   $display (" 1'bx  <=  10 = %b", (1'bx  <= 10));

      7   $display (" 1'bz  <=  10 = %b", (1'bz  <= 10)); 

      8    #10  $finish;

      9 end

     10

     11 endmodule

      5     <=  10 = 1

      5     >=  10 = 0

      1'bx  <=  10 = x

      1'bz  <=  10 = x

    Equality Operators

    There are two types of Equality operators. Case Equality and Logical Equality

     

    Operator

    Description

    a === b

    a equal to b, including x and z (Case equality)

    a !== b

    a not equal to b, including x and z (Case inequality)

    a == b

    a equal to b, result may be unknown (logical equality)

    a != b

    a not equal to b, result may be unknown (logical equality)

    Operands are compared bit by bit, with zero filling if the two operands do not have the same length

    • Result is 0 (false) or 1 (true)
    • For the == and != operators, the result is x, if either operand contains an x or a z
    • For the === and !== operators, bits with x and z are included in the comparison and must match for the result to be true

    Note : The result is always 0 or 1.

    Example
      1 module equality_operators();

      2

      3 initial begin

      4   // Case Equality

      5   $display (" 4'bx001 ===  4'bx001 = %b", (4'bx001 ===  4'bx001));

      6   $display (" 4'bx0x1 ===  4'bx001 = %b", (4'bx0x1 ===  4'bx001));

      7   $display (" 4'bz0x1 ===  4'bz0x1 = %b", (4'bz0x1 ===  4'bz0x1));

      8   $display (" 4'bz0x1 ===  4'bz001 = %b", (4'bz0x1 ===  4'bz001));

      9   // Case Inequality

     10   $display (" 4'bx0x1 !==  4'bx001 = %b", (4'bx0x1  ! ==  4'bx001));

     11   $display (" 4'bz0x1 !==  4'bz001 = %b", (4'bz0x1  ! ==  4'bz001)); 

     12   // Logical Equality

     13   $display (" 5       ==   10      = %b", (5       ==   10));

     14   $display (" 5       ==   5       = %b", (5       ==   5));

     15   // Logical Inequality

     16   $display (" 5       !=   5       = %b", (5        ! =   5));

     17   $display (" 5       !=   6       = %b", (5        ! =   6));

     18    #10  $finish;

     19 end

     20

     21 endmodule
      4'bx001 ===  4'bx001 = 1

      4'bx0x1 ===  4'bx001 = 0

      4'bz0x1 ===  4'bz0x1 = 1

      4'bz0x1 ===  4'bz001 = 0

      4'bx0x1 !==  4'bx001 = 1

      4'bz0x1 !==  4'bz001 = 1

      5       ==   10      = 0

      5       ==   5       = 1

      5       !=   5       = 0

      5       !=   6       = 1

    Logical Operators

    Operator

    Description

    !

    logic negation

    &&

    logical and

    ||

    logical or

    • Expressions connected by && and || are evaluated from left to right
    • Evaluation stops as soon as the result is known
    • The result is a scalar value:
      • 0 if the relation is false
      • 1 if the relation is true
      • x if any of the operands has x (unknown) bits
    Example
      1 module logical_operators();

      2

      3 initial begin

      4   // Logical AND

      5   $display ("1'b1 && 1'b1 = %b", (1'b1 && 1'b1));

      6   $display ("1'b1 && 1'b0 = %b", (1'b1 && 1'b0));

      7   $display ("1'b1 && 1'bx = %b", (1'b1 && 1'bx));

      8   // Logical OR

      9   $display ("1'b1 || 1'b0 = %b", (1'b1 || 1'b0));

     10   $display ("1'b0 || 1'b0 = %b", (1'b0 || 1'b0));

     11   $display ("1'b0 || 1'bx = %b", (1'b0 || 1'bx));

     12   // Logical Negation

     13   $display ("! 1'b1       = %b", ( !   1'b1));

     14   $display ("! 1'b0       = %b", ( !   1'b0));

     15    #10  $finish;

     16 end

     17

     18 endmodule

    1'b1 && 1'b1 = 1

     1'b1 && 1'b0 = 0

     1'b1 && 1'bx = x

     1'b1 || 1'b0 = 1

     1'b0 || 1'b0 = 0

     1'b0 || 1'bx = x

     ! 1'b1       = 0

     ! 1'b0       = 1

    Bit-wise Operators
    Bitwise operators perform a bit wise operation on two operands. They take each bit in one operand and perform the operation with the corresponding bit in the other operand. If one operand is shorter than the other, it will be extended on the left side with zeroes to match the length of the longer operand.

    Operator

    Description

    ~

    negation

    &

    and

    |

    inclusive or

    ^

    exclusive or

    ^~ or ~^

    exclusive nor (equivalence)

    • Computations include unknown bits, in the following way:
      • ~x = x
      • 0&x = 0
      • 1&x = x&x = x
      • 1|x = 1
      • 0|x = x|x = x
      • 0^x = 1^x = x^x = x
      • 0^~x = 1^~x = x^~x = x
    • When operands are of unequal bit length, the shorter operand is zero-filled in the most significant bit positions.

    Example

      1 module bitwise_operators();

      2

      3 initial begin

      4   // Bit Wise Negation

      5   $display (" ~4'b0001           = %b", (~4'b0001));

      6   $display (" ~4'bx001           = %b", (~4'bx001));

      7   $display (" ~4'bz001           = %b", (~4'bz001));

      8   // Bit Wise AND

      9   $display (" 4'b0001 &  4'b1001 = %b", (4'b0001 &  4'b1001));

     10   $display (" 4'b1001 &  4'bx001 = %b", (4'b1001 &  4'bx001));

     11   $display (" 4'b1001 &  4'bz001 = %b", (4'b1001 &  4'bz001));

     12   // Bit Wise OR

     13   $display (" 4'b0001 |  4'b1001 = %b", (4'b0001 |  4'b1001));

     14   $display (" 4'b0001 |  4'bx001 = %b", (4'b0001 |  4'bx001));

     15   $display (" 4'b0001 |  4'bz001 = %b", (4'b0001 |  4'bz001));

     16   // Bit Wise XOR

     17   $display (" 4'b0001 ^  4'b1001 = %b", (4'b0001 ^  4'b1001));

     18   $display (" 4'b0001 ^  4'bx001 = %b", (4'b0001 ^  4'bx001));

     19   $display (" 4'b0001 ^  4'bz001 = %b", (4'b0001 ^  4'bz001));

     20   // Bit Wise XNOR

     21   $display (" 4'b0001 ~^ 4'b1001 = %b", (4'b0001 ~^ 4'b1001));

     22   $display (" 4'b0001 ~^ 4'bx001 = %b", (4'b0001 ~^ 4'bx001));

     23   $display (" 4'b0001 ~^ 4'bz001 = %b", (4'b0001 ~^ 4'bz001));

     24    #10  $finish;

     25 end

     26

     27 endmodule
      ~4'b0001           = 1110

      ~4'bx001           = x110

      ~4'bz001           = x110

      4'b0001 &  4'b1001 = 0001

      4'b1001 &  4'bx001 = x001

      4'b1001 &  4'bz001 = x001

      4'b0001 |  4'b1001 = 1001

      4'b0001 |  4'bx001 = x001

      4'b0001 |  4'bz001 = x001

      4'b0001 ^  4'b1001 = 1000

      4'b0001 ^  4'bx001 = x000

      4'b0001 ^  4'bz001 = x000

      4'b0001 ~^ 4'b1001 = 0111

      4'b0001 ~^ 4'bx001 = x111

      4'b0001 ~^ 4'bz001 = x111

     Bạn Có Đam Mê Với Vi Mạch hay Nhúng      -     Bạn Muốn Trau Dồi Thêm Kĩ Năng

    Mong Muốn Có Thêm Cơ Hội Trong Công Việc

    Và Trở Thành Một Người Có Giá Trị Hơn

    Bạn Chưa Biết Phương Thức Nào Nhanh Chóng Để Đạt Được Chúng

    Hãy Để Chúng Tôi Hỗ Trợ Cho Bạn. SEMICON  

     

    Lần cập nhật cuối ( Thứ ba, 07 Tháng 9 2021 13:42 )  

    CÁC BÀI VIẾT LIÊN QUAN