74 lines
3.5 KiB
C++
74 lines
3.5 KiB
C++
#include "bitfields.h"
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#include <string.h>
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/// Takes a pointer, offset bitcount and data bitcount, returning the unsigned int read from the
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/// givens. offsetBits may be > 7, in which case offsetBits / 8 is added to the pointer
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/// automatically. This function assumes Most Significant Bits first. If dataBits > 64, only the
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/// last 64 bits are returned.
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unsigned long long Bit::getMSB(char *pointer, unsigned int offsetBits, unsigned int dataBits){
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// If the offset is a whole byte or more, add the whole bytes to the pointer instead.
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pointer += offsetBits >> 3;
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// The offset is now guaranteed less than a whole byte.
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offsetBits &= 0x07;
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unsigned long long retVal = 0;
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// Now we parse the remaining bytes
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while (dataBits){
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// Calculate how many bits we're reading from this byte
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// We assume all except for the offset
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unsigned int curBits = 8 - offsetBits;
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// If that is too much, we use the remainder instead
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if (curBits > dataBits){curBits = dataBits;}
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// First, shift the current return value by the amount of bits we're adding
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retVal <<= curBits;
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// Next, add those bits from the current pointer position at the correct offset, increasing the
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// pointer by one
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retVal |= ((int)(*(pointer++)) << offsetBits) >> (8 - curBits);
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// Finally, set the offset to zero and remove curBits from dataBits.
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offsetBits = 0;
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dataBits -= curBits;
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}// Loop until we run out of dataBits, then return the result
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return retVal;
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}
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/// Takes a pointer, offset bitcount and data bitcount, setting to given value.
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/// offsetBits may be > 7, in which case offsetBits / 8 is added to the pointer automatically.
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/// This function assumes Most Significant Bits first.
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/// WARNING: UNFINISHED. DO NOT USE.
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/// \todo Finish writing this - untested atm.
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void Bit::setMSB(char *pointer, unsigned int offsetBits, unsigned int dataBits, unsigned long long value){
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// Set the pointer to the last byte we need to be setting
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pointer += (offsetBits + dataBits) >> 3;
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// The offset is now guaranteed less than a whole byte.
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offsetBits = (offsetBits + dataBits) & 0x07;
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unsigned long long retVal = 0;
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// Now we set the remaining bytes
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while (dataBits){
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// Calculate how many bits we're setting in this byte
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// We assume all that will fit in the current byte
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unsigned int curBits = offsetBits;
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// If that is too much, we use the remainder instead
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if (curBits > dataBits){curBits = dataBits;}
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// Set the current pointer position at the correct offset, increasing the pointer by one
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retVal |= ((int)(*(pointer++)) << offsetBits) >> (8 - curBits);
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*pointer = (((*pointer) << offsetBits) >> offsetBits) | ((value & 0xFF) << (8 - offsetBits));
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--pointer;
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// Finally, shift the current value by the amount of bits we're adding
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value >>= offsetBits;
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//... and set the offset to eight and remove curBits from dataBits.
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offsetBits = 8;
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dataBits -= curBits;
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}// Loop until we run out of dataBits, then return the result
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}
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/// Parses a string reference to a boolean.
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/// Returns true if the string, with whitespace removed and converted to lowercase, prefix-matches
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/// any of: "1", "yes", "true", "cont". Returns false otherwise.
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bool Util::stringToBool(std::string &str){
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std::string tmp;
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tmp.reserve(4);
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for (unsigned int i = 0; i < str.size() && tmp.size() < 4; ++i){
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if (!::isspace(str[i])){tmp.push_back((char)tolower(str[i]));}
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}
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return (strncmp(tmp.c_str(), "1", 1) == 0 || strncmp(tmp.c_str(), "yes", 3) == 0 ||
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strncmp(tmp.c_str(), "true", 4) == 0 || strncmp(tmp.c_str(), "cont", 4) == 0);
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}
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