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Operator documentation fixes

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Karol Stasiak 2018-01-10 13:17:09 +01:00
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doc/lang/operators.md
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@ -2,6 +2,8 @@
Unlike in high-level languages, operators in Millfork have limited applicability.
Not every well-formed expression is actually compilable.
Most expressions involving single bytes compile,
but for larger types usually you need to use in-place modification operators.
Further improvements to the compiler may increase the number of acceptable combinations.
## Precedence
@ -54,22 +56,28 @@ Such expressions have the property that the only register they may clobber is Y.
* `+`, `-`:
`byte + byte`
`word + word`
`long + long`
`constant word + constant word`
`constant long + constant long`
* `*`: 8-bit multiplication
* `*`: multiplication; the size of the result is the same as the size of the arguments
`byte * constant byte`
`constant byte * byte`
`constant byte * byte`
`constant word * constant word`
`constant long * constant long`
There are no division, remainder or modulo operators.
## Bitwise operators
* `|`, `^`, `&`: OR, EXOR and AND
`byte | byte`
`byte | byte`
`constant word | constant word`
`constant long | constant long`
* `<<`, `>>`: bit shifting; shifting right pads the result with zeroes
`byte << constant byte`
* `<<`, `>>`: bit shifting; shifting pads the result with zeroes
`byte << constant byte`
`constant word << constant byte`
`constant long << constant byte`
* `>>>>`: shifting a 9-bit value and returning a byte; `a >>>> b` is equivalent to `(a & $1FF) >> b`, but the latter doesn't compile yet
`word >>>> constant byte`
@ -80,8 +88,8 @@ These operators work using the decimal arithmetic and will not work on Ricoh CPU
* `+'`, `-'`: decimal addition/subtraction
`byte +' byte`
`word +' word`
`long +' long`
`constant word +' constant word`
`constant long +' constant long`
* `*'`: decimal multiplication
`constant *' constant`
@ -114,7 +122,7 @@ Currently, `>`, `<`, `<=`, `>=` operators perform unsigned comparison
if none of the types of their arguments is signed,
and fail to compile otherwise. This will be changed in the future.
## Assignment operators
## Assignment and in-place modification operators
* `=`: normal assignment
`mutable byte = byte`
@ -139,4 +147,5 @@ and fail to compile otherwise. This will be changed in the future.
* `*=`: multiplication in place
`mutable byte *= constant byte`
There are no `*'=` operator yet.
There is no `*'=` operator yet.