105 lines
2.4 KiB
C++
105 lines
2.4 KiB
C++
#include "big_int.hpp"
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#include "tl/expected.hpp"
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#include <charconv>
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#pragma clang diagnostic push
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#pragma ide diagnostic ignored "clion-misra-cpp2008-6-4-5"
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inline uint8_t hex(char c) {
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switch(c) {
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case '0': return 0U;
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case '1': return 1U;
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case '2': return 2U;
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case '3': return 3U;
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case '4': return 4U;
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case '5': return 5U;
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case '6': return 6U;
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case '7': return 7U;
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case '8': return 8U;
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case '9': return 9U;
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case 'a': return 10U;
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case 'b': return 11U;
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case 'c': return 12U;
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case 'd': return 13U;
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case 'e': return 14U;
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case 'f': return 15U;
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case 'A': return 10U;
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case 'B': return 11U;
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case 'C': return 12U;
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case 'D': return 13U;
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case 'E': return 14U;
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case 'F': return 15U;
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default:
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return 0xffU;
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}
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}
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#pragma clang diagnostic pop
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tl::expected<BigInt,BigInt::eError>
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BigInt::from_string(const std::string& str) {
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BigInt b;
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uint8_t hval=0U;
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uint8_t nibble;
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size_t i = str.size()+1U;
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for(auto c : str) {
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nibble = hex(c);
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if (nibble ==0xFFU) {
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return tl::make_unexpected(eError::PARSE_ERROR);
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}
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if ( i%2U != 0U ) {
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hval = nibble << 4U;
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} else {
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hval |= nibble;
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b.data[256U - (i/2U)]= hval;
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hval = 0U;
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}
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i--;
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}
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return b;
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}
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BigInt BigInt::from_int(uint64_t value)
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{
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BigInt b;
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b.data[248U]=static_cast<uint8_t>(value >> 56 & 0xffU);
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b.data[249U]=static_cast<uint8_t>(value >> 48 & 0xffU);
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b.data[250U]=static_cast<uint8_t>(value >> 40U & 0xffU);
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b.data[251U]=static_cast<uint8_t>(value >> 32U & 0xffU);
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b.data[252U]=static_cast<uint8_t>(value >> 24U & 0xffU);
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b.data[253U]=static_cast<uint8_t>(value >> 16U & 0xffU);
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b.data[254U]=static_cast<uint8_t>(value >> 8U & 0xffU);
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b.data[255U]=static_cast<uint8_t>(value & 0xffU);
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return b;
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}
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constexpr char hex_char [] = "0123456789abcdef";
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std::string BigInt::to_string() const
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{
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std::string s;
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uint8_t b;
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uint8_t first_digit = 0U;
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for (size_t i = 0U; i<256U;i++) {
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b = data[i];
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if (first_digit==0U) {
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if (b==0U) {
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continue;
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} else if (b>0xfU) {
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s.push_back(hex_char[b >> 4]);
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} else {
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/* nothing to do here */
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}
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s.push_back(hex_char[b & 0xf]);
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first_digit = b;
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} else {
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s.push_back(hex_char[b >> 4]);
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s.push_back(hex_char[b & 0xf]);
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}
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}
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return s;
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}
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bool operator == (const BigInt& rhs, const BigInt& lhs)
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{ return rhs.data == lhs.data; }
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