Evaluator in K65 is compile-time executed expression language very similar to C/C++ expressions.

Introduction

In every place where the compiler expects a single number, you can invoke the evaluator by simply using square brackets.

data NumberFour {
  [2+2]
}

The evaluator can be also invoked freely outside any section body, e.g. to set variables:

[ FOUR = 4 ]

which can be later used freely as compiler constants and within further evaluator expressions:

data FourFiveSix {
  FOUR             // value of variable FOUR defined earlier
  [FIVE = FOUR+1]  // defines variable FIVE and returns its value
  [FIVE+1]         // uses recently set FIVE value
}

Operators

Available operators and their precedence levels are similar to operators in C and C++, operators are sorted by precedence from highest to lowest:

Precedence 2

Associativity: left-to-right

Operator Description
++
--
()
[]
.		 suffix incremen
suffix decrement
function call
array subscripting
single argument function call

Precedence 3

Associativity: right-to-left

Operator Description
++
--
+
-
!
~		 prefix increment
prefix decrement
unary plus
unary minus
logical NOT
bitwise NOT (One's Complement)

Precedence 5

Associativity: left-to-right

Operator Description
*
/
%		 multiplication
division
modulo (remainder)

Precedence 6

Associativity: left-to-right

Operator Description
+
-		 addition
subtraction

Precedence 7

Associativity: left-to-right

Operator Description
<<
>>		 bitwise left shift
bitwise right shift

Precedence 8

Associativity: left-to-right

Operator Description
<
<=
>
>=
?>
?<		 less than
less than or equal to
greater than
greater than or equal to
select greater value (maximum)
select smaller value (minimum)

Precedence 9

Associativity: left-to-right

Operator Description
==
!=		 equal to
not equal to

Precedence 10

Associativity: left-to-right

Operator Descriptiont
& bitwise AND

Precedence 11

Associativity: left-to-right

Operator Description
^ bitwise XOR (exclusive or)

Precedence 12

Associativity: left-to-right

Operator Description
| bitwise OR (inclusive or)

Precedence 13

Associativity: left-to-right

Operator Description
&& logical AND

Precedence 14

Associativity: left-to-right

Operator Description
|| logical OR

Precedence 15

Associativity: right-to-left

Operator Description
?: lternary conditional

Precedence 16

Associativity: right-to-left

Operator Description
=
+=
-=
*=
/=
%=
<<=
>>=
&=
^=
|=
 direct assignment
assignment by sum
assignment by difference
assignment by product
assignment by quotient
assignment by remainder
assignment by bitwise left shift
assignment by bitwise right shift
assignment by bitwise AND
assignment by bitwise XOR
assignment by bitwise OR

Precedence 18

Associativity: left-to-right

Operator Description
, expression list (executes in sequence, returns value of the last)

Functions

acos( x )

Arcus cosinus

addbyte( sec, b )

Add byte b to section sec

asin( x )

Arcus sinus

ceil( x )

Round up to nearest integer

clamp( x, min, max )

Clamp x to range min to max

color( r, g, b )

Return palette index for nearest color to color (r,g,b)

color( x )

Return palette index for nearest color specified in format 0xRRGGBB

cos( x )

Cosinus

error( err )

Print error message err ane terminate compilation

floor( x )

Round down to nearest integer

frac( x )

Get fractional part ( x-floor(x) )

index( tab, x )

1-dimensional indexing operator ( same as tab[x] )

index( tab, x, y )

2-dimensional indexing operator ( same as tab[x,y] )

max( a, b )

Maximum

min( a, b )

Minimum

pow( x, y )

Power function

Print message msg

rnd( )

Random value 0 <= x < 1

round( x )

Round to nearest integer

sin( x )

Sinus

size( sec )

Current size of section sec

sqrt( x )

Square root