Gamevar operators: Difference between revisions
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Helixhorned (talk | contribs) warn dividing negative numbers, since EDuke32 CON currently implements an incorrect optimization (right shifting negative numbers by X isn't the same as dividing them by 2^X) |
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|<code>/</code> | |<code>/</code> | ||
|÷ | |÷ | ||
|division with rounding toward 0 | |division with rounding toward 0 for nonnegative dividends | ||
|Ensure that <value> does not equal 0 at any time. | |Ensure that <value> does not equal 0 at any time. '''The rounding mode of negative dividends is undefined.''' | ||
|- | |- | ||
|mod | |mod |
Revision as of 08:25, 19 April 2012
<operator>var <gamevar> <value>
<operator>varvar <gamevar> <value>
Gamevar operators are commands that perform various mathematical and bitwise logical operations on gamevars. The first argument must be a writable gamevar and is taken as the destination as well and the first operand (2-address code).
For example:
setvar temp 1 // assigns a value of 1 to the gamevar temp. addvar temp 1 // adds 1 to temp, causing its value to become 2. mulvar temp 2 // multiplies temp by 2, causing its value to become 4.
Operator | C/C++ | Math | Description | Notes | |
---|---|---|---|---|---|
set | =
|
= | assignment | ||
add | +
|
+ | addition | ||
sub | -
|
– | subtraction | ||
mul | *
|
× | multiplication | ||
div | /
|
÷ | division with rounding toward 0 for nonnegative dividends | Ensure that <value> does not equal 0 at any time. The rounding mode of negative dividends is undefined. | |
mod | %
|
modulo, remainder | Ensure that <value> does not equal 0 at any time; It is undefined whether the sign of the result follows the divisor or the dividend (for now). | ||
and | &
|
bitwise AND | The bits in the result are set only if they were set in both of the values being operated on. Ex.: 01001010 AND | ||
or | |
|
bitwise OR | The bits in the result are set only if they were set in either of the values being operated on. Ex.: 01001010 OR | ||
xor | ^
|
bitwise XOR | The bits in the result are set if only one of the values being operated on has those bits set. Ex.: 01001010 XOR |
Commands with an additional "var" suffix take gamevars rather than constants or defined labels for their inputs. As an alternate short form, "varvar" can be dropped from these commands; for example ife serves an an alias for ifvarvare.