PicBasic mathematical and logical operations

PicBasic supports a number of mathematical and logical functions which make calculations easy in programs. The operations are performed on integer numbers only with 16-bit precision and there is no floating-point number format. Also, all math operations are performed strictly from left to right. The operators supported are

              addition

              subtraction

*              multiplication

**            most significant bit (MSB) of multiplication

/              division

//             remainder in a division MIN        limit to minimum value MAX      limit to maximum value

&            bitwise AND

|               bitwise OR

^              bitwise XOR

&/           bitwise AND NOT

|/              bitwise OR NOT

^/             bitwise XOR NOT

Multiplication is done on 16     16 bit numbers, resulting in a 32-bit result. The “*” operator returns the lower 16-bits of the 32-bit result. Similarly, the “**” operator returns the upper 16-bits of the result. For example,

W2     W1 * W0        ‘ Multiply W1 with W0. The lower 16-bits of the result

‘ are placed in W2

or,

W2     W1 ** W0      ‘ Multiply W1 with W0. The upper 16-bits of the result

‘ are placed in W2

or,

W2     W1 * 100        ‘ Multiply W1 with 100. Place the lower 16-bits of the

‘ result in W2. Note that this is the multiplication

‘ found in most programming languages

Similarly with division,

or,

W2     W1 / W0     ‘ Divide W1 by W0. The result is placed in W2

W2     W1 // W0    ‘ Divide W1 by W0. The remainder is placed in W2

MIN is used to limit the result to the minimum value defined. For example, B1     B0 MIN 100

Sets B1 to the smaller of B0 and 100, i.e. B1 cannot be greater than 100.

Similarly, MAX is used to limit the result to the maximum value defined. For example, B1     B0 MAX 100

sets B1 to the larger of B0 and 100, i.e. B1 will be between 100 and 255.

Bitwise logical operations operate on the entire byte and these operations can be used to extract bits from bytes or to set and clear bits of a byte. For example, to extract the least significant bit of B0 we can write

B0     B0 & 000001

Similarly, to set bit 2 of B1 to be 1 we can write

B1     B1 | 000100

To store the upper four bits of B2 in B1 we can write

B1     B2 & %11110000