78 lines
2.3 KiB
C
78 lines
2.3 KiB
C
#include <stddef.h>
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#include <stdint.h>
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#include "types.h"
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#include "base32.h"
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static const char base32t[32] = {
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'a', 'b', 'c', 'd', // 0
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'e', 'f', 'g', 'h', // 1
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'i', 'j', 'k', 'l', // 2
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'm', 'n', 'o', 'p', // 3
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'q', 'r', 's', 't', // 4
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'u', 'v', 'w', 'x', // 5
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'y', 'z', '2', '3', // 6
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'4', '5', '6', '7', // 7
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};
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/*
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+--first octet--+-second octet--+--third octet--+--forth octet--+--fifth octet--+
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|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|
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+---------+-----+---+---------+-+-------+-------+-+---------+---+-----+---------+
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|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|
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+-1.index-+-2.index-+-3.index-+-4.index-+-5.index-+-6.index-+-7.index-+-8.index-+
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*/
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// masks:
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// 0xFF 0x7F 0x3F 0x1F 0x0F 0x07 0x03 0x01
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// 255 127 63 31 15 7 3 1
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char *base32_to(char *dst, const u8 *src, size_t slen)
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{
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//printf("slen = %d\n", slen);
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//printhex(base32t, 32);
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//printhex(base32f, 256);
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// base32 eats in 5bit pieces;
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// closest we can provide is 40, which is 5 bytes
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size_t i;
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for (i = 0; i + 4 < slen; i += 5) {
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//printf("ei!\n");
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//char *od = dst;
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*dst++ = base32t[src[i+0] >> 3];
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*dst++ = base32t[((src[i+0] & 7) << 2) | (src[i+1] >> 6)];
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*dst++ = base32t[(src[i+1] >> 1) & 31];
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*dst++ = base32t[((src[i+1] & 1) << 4) | (src[i+2] >> 4)];
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*dst++ = base32t[((src[i+2] & 15) << 1) | (src[i+3] >> 7)];
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*dst++ = base32t[((src[i+3]) >> 2) & 31];
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*dst++ = base32t[((src[i+3] & 3) << 3) | (src[i+4] >> 5)];
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*dst++ = base32t[src[i+4] & 31];
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//printhex(od, 8);
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}
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//char *od = dst;
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if (i < slen) {
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//printf("oi!0\n");
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*dst++ = base32t[src[i+0] >> 3];
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if (i + 1 < slen) {
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//printf("oi!1\n");
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*dst++ = base32t[((src[i+0] & 7) << 2) | (src[i+1] >> 6)];
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*dst++ = base32t[(src[i+1] >> 1) & 31];
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if (i + 2 < slen) {
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//printf("oi!2\n");
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*dst++ = base32t[((src[i+1] & 1) << 4) | (src[i+2] >> 4)];
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if (i + 3 < slen) {
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//printf("oi!3\n");
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*dst++ = base32t[((src[i+2] & 15) << 1) | (src[i+3] >> 7)];
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*dst++ = base32t[(src[i+3] >> 2) & 31];
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*dst++ = base32t[(src[i+3] & 3) << 3];
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}
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else {
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*dst++ = base32t[(src[i+2] & 15) << 1];
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}
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}
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else
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*dst++ = base32t[(src[i+1] & 1) << 4];
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}
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else
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*dst++ = base32t[(src[i+0] & 7) << 2];
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}
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//printhex(od, dst-od);
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*dst = 0;
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return dst;
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}
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