76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
#include "varint.h"
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#include <stdlib.h>
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varint varint_encode(unsigned long long value){
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varint result;
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if (value <= 240){
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result = (varint)malloc(1);
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result[0] = (char)value;
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}
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else if (value <= 2287)
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{
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result = (varint)malloc(2);
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result[0] = (char)(((value - 240) >> 8) + 241);
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result[1] = (char)(value - 240);
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}
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else if (value <= 67823)
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{
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result = (varint)malloc(3);
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result[0] = 249;
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result[1] = (char)((value - 2288) >> 8);
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result[2] = (char)(value - 2288);
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}
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else
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{
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unsigned long long header = 255;
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unsigned long long match = 0x00FFFFFFFFFFFFFFUL;
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while (value <= match)
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{
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--header;
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match >>= 8;
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}
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int max = (int)(header - 247);
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result = (varint)malloc(max + 1);
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result[0] = (char) header;
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for (int i = 0; i < max; ++i)
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result[i+1] = (char)(value >> (i << 3));
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}
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return result;
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}
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unsigned long long varint_decode(varint varint){
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unsigned long long header = (unsigned char)varint[0];
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if(header <= 240){
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free(varint);
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return header;
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}
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if(header <= 248){
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unsigned long long result = 240UL + ((header - 241) << 8) + (unsigned char)varint[1];
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free(varint);
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return result;
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}
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if(header == 249){
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unsigned long long result = 2288UL + ((unsigned char)varint[1] << 8) + (unsigned char)varint[2];
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free(varint);
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return result;
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}
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unsigned long result = (unsigned char)varint[1] | ((unsigned char)varint[2] << 8) | ((unsigned char)varint[3]);
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int compare = 2;
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int head = (int)(header - 247);
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while(head > ++compare) result |= (unsigned char)varint[compare + 2] << (compare << 3);
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free(varint);
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return result;
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}
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unsigned long long zigzag_encode(signed long long value){
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union sig_ll convert = {value};
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return (convert.signature.value << 1) ^ (unsigned long long)convert.signature.sig;
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}
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signed long long zigzag_decode(unsigned long long value){
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union sig_ll convert = {value << 63};
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return (signed long long)((value >> 1) ^ (unsigned long long)convert.signature.sig);
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}
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