Basic Micro Studio Syntax Manual

Fractional Multiplication (*/)
Mod (//)
Structure - Math
Fractional multiplication will multiply a number with a fractional part. The multiplier must be a long
value which is handled by a special method. The high 16 bits are the integer portion of the multiplier,
the low 16 bits are the fractional part (expressed as a fraction of 65536). The result will be an integer
with any fractional remainder discarded (not rounded).
Example
Let us say we want to multiply the number 346 x 2.5. The multiplier must be constructed as follows:
The high 16 bits will have a value of 2. We can do this with:
mult.highword = 2
The low 16 bits will have a value that is half of 65535 or 32782 so:
mult.lowword = 32782
Then we do the fractional multiply:
a = 346 */ mult
The example will give “a” the value 865. A similar procedure will let you multiply by any fraction by
expressing that fraction with a denominator of 65535 as closely as possible.
Notice that half of 65535 is actually 32782.5; a number we can not enter as the fractional part. This
means that multiplication by exactly half is not possible. However, the difference is so small that it has
no effect on the actual outcome of the integer result.
The mod function (short for “modulo”) returns the remainder after an integer division. So, for example,
13 modulo 5 is 3 (the remainder after dividing 13 by 5).
The mod function can be used to determine if a number is odd or even, as shown here:
x var word
y var word
(code that sets the value of x)
y = x//2
if y=0 goto even ;zero indicates an even number
if y=1 goto odd ;one indicates an odd number
even
(more code)
odd
(more code)
Similarly, the mod function can be used to determine if a number is divisible by any other number.
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