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/**
* Gets a bitmasked value in from an integer. If the shift is omitted, it will
* be deduced from the mask.
*
* @arg 0 - the variable
* @arg 1 - mask
* @arg 2 - shift
*/
function script bitwise_get {
.@shift = getarg(2, 0);
if (getargcount() < 3) {
// guess the shift from the mask:
for (.@shift = 0; .@shift < 32; ++.@shift) {
if ((getarg(1) & (1 << .@shift)) != 0) {
break;
}
}
}
return (getarg(0) & getarg(1)) >> .@shift;
}
/**
* sets a bitmasked value in a variable
*
* @arg 0 - the target variable
* @arg 1 - mask
* @arg 2 - shift
* @arg 3 - new value
* @return a reference to the variable
*/
function script bitwise_set {
if (getargcount() < 4) {
// guess the shift from the mask:
for (.@shift = 0; .@shift < 32; ++.@shift) {
if ((getarg(1) & (1 << .@shift)) != 0) {
break;
}
}
return set(getarg(0), (getarg(0) & ~(getarg(1))) | (getarg(2, 0) << .@shift));
}
return set(getarg(0), (getarg(0) & ~(getarg(1))) | (getarg(3, 0) << getarg(2, 0)));
}
// bitmask_count(<int>)
// returns the number of bits set in <int> (up to 4096?)
function script bitmask_count {
.@n = getarg(0); // Number evaluated
.@p=0; // Bits set/unset
.@s=0; // Stack and Check
.@m=0; // Memory
// Loop only as needed
while (.@s < .@n) {
.@s=2**.@m;
if (.@n & .@s)
.@p++;
.@m++;
}
return .@p;
}
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