52 lines
1.2 KiB
C
52 lines
1.2 KiB
C
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#include <stddef.h>
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#include <stdint.h>
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#include "types.h"
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#include "base64.h"
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static const char base64t[64] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/',
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};
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char *base64_to(char *dst,const u8 *src,size_t slen)
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{
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if (!slen) {
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*dst = '\0';
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return dst;
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}
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for(size_t i = 0; i < slen;) {
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u32 threebytes = 0;
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threebytes |= (i < slen ? (unsigned char)src[i++] : (unsigned char)0) << (2 * 8);
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threebytes |= (i < slen ? (unsigned char)src[i++] : (unsigned char)0) << (1 * 8);
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threebytes |= (i < slen ? (unsigned char)src[i++] : (unsigned char)0) << (0 * 8);
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*dst++ = base64t[(threebytes >> (3 * 6)) & 63];
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*dst++ = base64t[(threebytes >> (2 * 6)) & 63];
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*dst++ = base64t[(threebytes >> (1 * 6)) & 63];
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*dst++ = base64t[(threebytes >> (0 * 6)) & 63];
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}
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switch (slen % 3) {
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case 0 : break;
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case 1 : {
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*(dst-2) = '=';
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*(dst-1) = '=';
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break;
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}
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case 2 : {
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*(dst-1) = '=';
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break;
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}
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}
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*dst = '\0';
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return dst;
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}
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