Bits.bt

// -*- mode: c;-*-
/*
    We don't actually know what the main bank does / us.
    Here are some types relating to it, though.
    TODO: Find the main bank definition(s).
*/

/*
    list of would-be-nice-to-have-functions
    * FindFirstBitO[n|ff](From[Lef|Righ]t)
    * BiggestNumberForType
    * GetMaskForBits(ubyte d[]{0,1,1,0})
    * FindLowestCommonMask(ubyte d[])
    * BitWeld(uint64 a, uint64 b, int start=-1) //append bits from a in front of b (at first available bit)
*/

// from stackexchange or some crap
int FlipIntBits(int theNumber, int numBits) {
    local int mask = 1;
    local int i;
    for(i = 1; i < numBits; ++i)
        mask |= mask << 1;

    return ~theNumber & mask;
}

// want your own byte array? check it out:
// http://www.mathcs.emory.edu/~cheung/Courses/255/Syllabus/1-C-intro/bit-array.html

typedef struct {
    byte bit1 : 1;
    byte bit2 : 1;
    byte bit3 : 1;
    byte bit4 : 1;

    byte bit5 : 1;
    byte bit6 : 1;
    byte bit7 : 1;
    byte bit8 : 1;
} BitEight <read=BitEightRead, size=1>;

string BitEightRead(BitEight &be){
    local string s;
    SPrintf(s, "%d %d %d %d, %d %d %d %d", be.bit1, be.bit2, be.bit3, be.bit4, be.bit5, be.bit6, be.bit7, be.bit8);
    return s;
};

uint64 ReadUShortBits(uint64 pos, uint64 bitStart, uint64 readSize){
    local ushort data = ReadUShort(pos);
    // we can't adjust the size or type of what we read, so we can hardcode the mask base
    // this sure beats writing a geometric function to read bits
    local ushort mask = 0xFFFF >> (sizeof(data)*8 - readSize);
    local ushort outvalue = (( data >> (sizeof(data)*8 - (readSize + bitStart)) ) & mask);
    return outvalue;
}

uint64 ReadUByteBits(uint64 pos, uint64 bitStart, uint64 readSize){
    local ubyte data = ReadUByte(pos);
    // we can't adjust the size or type of what we read, so we can hardcode the mask base
    // this sure beats writing a geometric function to read bits
    local ubyte mask = 0xFF >> (sizeof(data)*8 - readSize);
    local ubyte outvalue = (( data >> (sizeof(data)*8 - (readSize + bitStart)) ) & mask);
    return outvalue;
}