constrain(x, a, b)
Description
Constrains a number to be within a range.
Parameters
x: the number to constrain, all data types
a: the lower end of the range, all data types
b: the upper end of the range, all data types
Returns
x: if x is between a and b
a: if x is less than a
b: if x is greater than b

> ? max(100,min(200,300))
200
> ? max(100,min(200,50))
100
> ? max(100,min(200,177))
177
>

If Q$="U" Then
Dimm=Max(0,Min(7,Dimm+1))
Print"Dimm";Str$(Dimm,2,1);"mS"
EndIf
If Q$="D" Then
Dimm=Max(0,Min(7,Dimm-1))
Print"Dimm";Str$(Dimm,2,1);"mS"
EndIf

' BASIC functions and subroutines similar to Arduino math/bit/char functions
'
' Functions
' ---------
' Sq(x) square of x
' Sqrt(x) square root of x
' Pow(x, y) raise x to the power y (same as x^y)
' Constrain(x, lo, hi) constrain x between lo and hi
' Map(x, lo, hi, newlo, newhi) map x between lo and hi to newlo and newhi
' Min(x, y) minimum of x and y
' Max(x, y) maximum of x and y
' Lsh(x, n) shift x left by n bits
' Rsh(x, n) shift x right by n bits
' Inv(x) invert bits (complement of x)
' Bit(n) value of n'th bit (same as 2^n)
' BitRead(x, n) n'th bit of x
' HighByte(x) high byte of word x
' LowByte(x) low byte of word x
' IsAlpha(a) true if a is alphabetic
' IsAlnum(a) true if a is alphanumeric
' IsCntrl(a) true if a is a control character
' IsDigit(a) true if a is a digit
' IsGraph(a) true if a is a graph character
' IsPrint(a) true if a is printable
' IsPunct(a) true if a is punctuation
' IsLower(a) true if a is lower case
' IsUpper(a) true if a is upper case
' IsSpace(a) true if a is white space
'
' Subroutines
' -----------
' BitSet(x, n) set n'th bit of x
' BitClear(x, n) clear n'th bit of x
' BitToggle(x, n) toggle n'th bit of x
' BitWrite(x, n, b) set n'th bit of x to b
' RandomSeed(x) randomize with seed value x

' returns square of x
Function Sq(x)
Sq = x * x
End Function

' returns square root of x
Function Sqrt(x)
Sqrt = Sqr(x)
End Function

' returns x to the power y
Function Pow(x, y)
Pow = x ^ y
End Function

' returns value of x constrained between lo and hi
Function Constrain(x, lo, hi)
If x < lo Then
Constrain = lo
ElseIf x > hi Then
Constrain = hi
Else
Constrain = x
EndIf
End Function

' returns value of x between lo and hi mapped to range newlo and newhi
Function Map(x, lo, hi, newlo, newhi)
Map = (x - lo) * (newhi - newlo) / (hi - lo) + newlo
End Function

' returns minimum value of x and y
Function Min(x, y)
If x < y Then Min = x Else Min = y
End Function

' returns maximum value of x and y
Function Max(x, y)
If x > y Then Max = x Else Max = y
End Function

' returns x shifted left by n bits
Function Lsh(x, n)
Lsh = x * 2 ^ n
End Function

' returns x shifted right by n bits
Function Rsh(x, n)
Rsh = x \ 2 ^ n
End Function

' returns the complement of x
Function Inv(x)
Inv = -1 - x
End Function

' returns n'th bit value
Function Bit(n)
Bit = 2 ^ n
End Function

' returns n'th bit of x
Function BitRead(x, n)
BitRead = x And 2 ^ n
End Function

' set n'th bit of x
Sub BitSet(x, n)
x = x Or 2 ^ n
End Sub

' clear n'th bit of x
Sub BitClear(x, n)
x = x And -1 - (2 ^ n)
End Sub

' toggle n'th bit of x
Sub BitToggle(x, n)
x = x Xor 2 ^ n
End Sub

' set n'th bit of x to b
Sub BitWrite(x, n, b)
If b Then x = x Or 2 ^ n Else x = x And -1 - 2 ^ n
End Sub

' returns the high byte of a word
Function HighByte(x)
HighByte = x \ 256 And 255
End Function

' returns the low byte of a word
Function LowByte(x)
LowByte = x And 255
End Function

' returns random number between lo and exclusive hi
Function Random(lo, hi)
Random = lo + (hi - lo) * Rnd()
End Function

' set seed of random number generator
Sub RandomSeed(x)
Randomize x
End Sub

' returns true if a is alphabetic
Function IsAlpha(a)
IsAlpha = (a >= 65 And a <= 90) Or (a >= 97 And a <= 122)
End Function

' returns true if a is alphanumeric
Function IsAlnum(a)
IsAlnum = (a >= 48 And a <= 57) Or (a >= 64 And a <= 90) Or (a >= 97 And a <= 122)
End Function

' returns true if a is a control character
Function IsCntrl(a)
IsCntrl = (a >= 0 And a <= 31) Or a = 127
End Function

' returns true if a is a digit
Function IsDigit(a)
IsDigit = a >= 48 And a <= 57
End Function

' returns true if a is a graph character
Function IsGraph(a)
IsGraph = a >= 33 And a <= 126
End Function

' returns true if a is a printable character
Function IsPrint(a)
IsPrint = a >= 32 And a <= 126
End Function

' returns true if a is punctuation
Function IsPunct(a)
IsPunct = (a >= 33 And a <= 47) Or (a >= 58 And a <= 64) Or (a >= 91 And a <= 96) Or (a >= 123 And a <= 126)
End Function

' returns true if a is lower case
Function IsLower(a)
IsLower = a >= 97 And a <= 122
End Function

' returns true if a is upper case
Function IsUpper(a)
IsUpper = a >= 65 And a <= 90
End Function

' returns true if a is white space
Function IsSpace(a)
IsSpace = (a >= 9 And a <= 13) Or a == 32
End Function