{"id":11521,"date":"2022-09-02T10:23:43","date_gmt":"2022-09-02T10:23:43","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=11521"},"modified":"2023-09-02T11:39:38","modified_gmt":"2023-09-02T06:09:38","slug":"bitwise-operators-in-c","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/bitwise-operators-in-c\/","title":{"rendered":"Microcontroller Embedded C programming Lecture 97| Bitwise operators in ‘C’"},"content":{"rendered":"
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Bitwise operators in ‘C’<\/strong><\/span><\/h1>\n
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Bitwise operators present in ‘C’:<\/span><\/strong><\/span><\/h2>\n

There are six bitwise operators.<\/span><\/p>\n

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Figure 1. Bitwise operators in \u2018C\u2019<\/span><\/figcaption><\/figure>\n

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1. Bitwise AND (&<\/code>)<\/strong><\/span><\/p>\n

Syntax:<\/span><\/strong><\/span> result = operand1 & operand2<\/code><\/p>\n

It  performs a bitwise AND operation between each corresponding pair of bits in the operands. The result is 1 only if both bits are 1; otherwise, the result is 0.<\/p>\n

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2. Bitwise OR (|<\/code>):<\/span><\/strong><\/span><\/p>\n

Syntax:<\/span> <\/strong><\/span>result = operand1 | operand2<\/code><\/p>\n

It performs a bitwise OR operation between each corresponding pair of bits in the operands. The result is 1 if either of the bits is 1; otherwise, the result is 0.<\/p>\n

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3. Bitwise XOR (^<\/code>)<\/strong><\/span><\/p>\n

Syntax:<\/span> <\/strong><\/span>result = operand1 ^ operand2<\/code><\/p>\n

It performs a bitwise exclusive OR (XOR) operation between each corresponding pair of bits in the operands. The result is 1 if the bits are different; otherwise, the result is 0.<\/p>\n

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4. Bitwise NOT (~<\/code>)<\/span><\/strong><\/span><\/p>\n

Syntax:<\/span><\/strong><\/span> result = ~operand<\/code><\/p>\n

It performs a bitwise NOT operation on each bit of the operand. It flips all the bits, turning 0 into 1 and 1 into 0.<\/p>\n

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Left shift (<<<\/code>):<\/strong><\/span><\/p>\n

Syntax: <\/span><\/strong>result = operand << n<\/code><\/p>\n

Shifts the bits of the operand to the left by n positions. Zeros are shifted in from the right, and the leftmost bits are discarded.<\/p>\n

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Right shift (>><\/code>):<\/strong><\/span><\/p>\n

Syntax:<\/span><\/strong><\/span> result = operand >> n<\/code><\/p>\n

Shifts the bits of the operand to the right by n positions. For unsigned values, zeros are shifted in from the left. For signed values, the behavior depends on the implementation-defined rules for signed right shift.<\/p>\n

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Bitwise operators are heavily used in Embedded system programming because most of the time in Embedded system programming, ‘C’ is used.<\/span><\/span><\/p>\n

Bitwise operators are used to manipulate memory addresses, contents of peripheral registers, status registers, etc. <\/span>It is an important topic in Embedded ‘C’ programming.<\/span><\/span><\/p>\n

Bitwise operators allow us to perform operations on individual bits within a data type.<\/span><\/p>\n

Understanding the bitwise operators and their usage can improve the efficiency of code, as it directly accesses the memory and register contents.<\/span><\/p>\n

Bitwise operators have a wide range of applications in embedded systems such as setting\/clearing individual bits, masking operations, setting\/resetting flags, and more.<\/span><\/p>\n

It is crucial for an embedded system programmer to have a solid understanding of bitwise operators and their applications.<\/span><\/p>\n

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Difference between a Logical operator and a bitwise operator<\/strong><\/span><\/p>\n

If you use a double ampersand(&&<\/strong><\/span>), this is a ‘logical AND’<\/span> operator. <\/span><\/p>\n

If you use a single ampersand(&<\/strong><\/span>), this is the ‘bitwise AND’<\/span> operator.<\/span><\/p><\/blockquote>\n

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Logical operator: <\/span><\/strong><\/span><\/p>\n

Logical operator is a type of operator that performs a logical operation on two values and returns a Boolean value of true or false. These operators are used in conditional statements and control flow in programming languages. <\/span><\/p>\n

For example, the logical OR operator (||) returns true if either of its operands is true, and the logical AND operator (&&) returns true if both of its operands are true.<\/span><\/p>\n

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Bitwise operator:<\/span><\/strong><\/span><\/p>\n

A bitwise operator, on the other hand, performs a bitwise operation on the binary representation of the values, manipulating individual bits. Bitwise operators are used to perform bit manipulation tasks such as masking, shifting, and setting bits. <\/span><\/p>\n

For example, the bitwise OR operator (|) sets the bit to 1 if either of its operands has the corresponding bit set to 1, and the bitwise AND operator (&) sets the bit to 0 if either of its operands has the corresponding bit set to 0.<\/span><\/p>\n

In summary, logical operators are used to make logical comparisons between values, while bitwise operators are used to manipulate binary data.<\/span><\/p>\n

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Figure 2. Difference between logical operator and bitwise operator<\/span><\/figcaption><\/figure>\n

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To know how the operation is different.  <\/span><\/span><\/p>\n

Let’s take an example, A = 40 and B =30. What is C = A&&B ?<\/span><\/span><\/p>\n

In this case, A is 40; it is a non-zero value, so true. B is 30; also, it is a non-zero value, so it is true.  The exact value of the A and B are not considered here. So, the only thing which matters is whether the operands are true(non-zero) or false(0).<\/span><\/p>\n

Since both of these operands are non-zero, the result will be true. So, C = 1 in this case.<\/span> <\/span><\/span><\/p>\n

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How about C= A&B operation? <\/strong><\/span><\/p>\n

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Figure 3. Bitwise AND operation calculation<\/span><\/figcaption><\/figure>\n

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In this case, we do AND operation bit by bit. That’s why it is called a bitwise operation. Here, 00101000 is the binary format of the number 40, and 00011110 is the binary format of the number 30.<\/span><\/p>\n

Now, A & B is nothing but you have to perform AND operation bit by bit. So, 0  & 0<\/strong> is 0<\/strong>; 0 & 1<\/strong> is 0<\/strong>; 1 &1<\/strong> is 1<\/strong>. So, C = 00001000, this is 8. <\/span><\/p>\n

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In bitwise operation, you do the operation like AND, OR, etc., bit by bit.<\/b><\/span><\/p>\n<\/blockquote>\n

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Let’s take an example with OR. <\/span><\/p>\n

A= 40 and B =30, what is the value of C= A|B? <\/span><\/p>\n

A||B is a logical OR operation, so in this case, C =1. <\/span><\/p>\n

In the C = A|B case, you have to do the bitwise OR operation bit by bit. Here, 0|0<\/strong> is 0<\/strong>, 0|1<\/strong> is 1<\/strong>, 1|1<\/strong> is 1<\/strong>. So, C = 00111110, this turns out to be 62. <\/span><\/p>\n

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Figure 4. Bitwise OR operation calculation<\/span><\/figcaption><\/figure>\n

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Let’s explore the bitwise NOT operator.<\/span><\/span><\/p>\n

‘~’<\/b> is a bitwise NOT operator, which is a unary operator because it needs only one operand. Bitwise NOT operator you write like ~A<\/strong>. So, you cannot write A~<\/strong> (A negation). <\/span><\/span><\/p>\n

Let’s see what the value of C = ~A.<\/span><\/p>\n

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Figure 5. Bitwise NOT operation calculation<\/span><\/figcaption><\/figure>\n

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A is 40. In binary, it is 00101000. The ~ A is you have to change 0’s into 1’s and 1’s into 0’s. That’s why ~A is 11010111, so C = -41 in this case. [minus because this is a signed variable].<\/span><\/p>\n

That’s about bitwise AND, bitwise OR, and bitwise NOT.<\/span><\/p>\n

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Let’s see bitwise XOR. There is no logical XOR and only a bitwise XOR operator. <\/span><\/p>\n

 \u2018<\/span>^<\/b>\u2019 is a bitwise XOR symbol, which does bit by bit XORing. <\/span><\/span><\/p>\n

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Figure 6. Bitwise XOR calculation<\/span><\/figcaption><\/figure>\n

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The truth table of XOR is shown in Figure 6. <\/span><\/p>\n

In the case of XORing, the output will be 1 only if the two operands are different. So, when both operands are different, the only output will be 1; if both operands are equal, then the output is 0. <\/span>That’s how you should understand XOR.<\/span><\/span><\/p>\n

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Applicability of bitwise operations<\/b><\/span><\/p>\n

In an Embedded C program, most of the time you will be doing, <\/span><\/p>\n