mirror of
https://github.com/fumiama/base16384.git
synced 2026-06-19 05:00:23 +08:00
feat(coder): add safe encode/decode
This commit is contained in:
源文雨
207
base1432.c
207
base1432.c
@@ -16,8 +16,113 @@
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "binary.h"
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union remainder {
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uint8_t buf[4];
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uint32_t val;
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};
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typedef union remainder remainder;
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int base16384_encode_safe(const char* data, int dlen, char* buf) {
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int outlen = dlen / 7 * 8;
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int offset = dlen % 7;
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switch(offset) { // 算上偏移标志字符占用的2字节
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case 0: break;
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case 1: outlen += 4; break;
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case 2:
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case 3: outlen += 6; break;
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case 4:
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case 5: outlen += 8; break;
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case 6: outlen += 10; break;
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default: break;
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}
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uint32_t* vals = (uint32_t*)buf;
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uint32_t n = 0;
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int32_t i = 0;
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for(; i < dlen - 7; i += 7) {
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register uint32_t sum = 0;
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register uint32_t shift = htobe32(*(uint32_t*)(data+i));
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sum |= (shift>>2) & 0x3fff0000;
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sum |= (shift>>4) & 0x00003fff;
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sum += 0x4e004e00;
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vals[n++] = be32toh(sum);
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shift <<= 26;
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shift &= 0x3c000000;
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sum = 0;
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shift |= (htobe32(*(uint32_t*)(data+i+4))>>6)&0x03fffffc;
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sum |= shift & 0x3fff0000;
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shift >>= 2;
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sum |= shift & 0x00003fff;
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sum += 0x4e004e00;
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vals[n++] = be32toh(sum);
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}
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remainder valbuf;
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if(dlen - i == 7) {
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register uint32_t sum = 0;
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register uint32_t shift = htobe32(*(uint32_t*)(data+i));
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sum |= (shift>>2) & 0x3fff0000;
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sum |= (shift>>4) & 0x00003fff;
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sum += 0x4e004e00;
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vals[n++] = be32toh(sum);
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shift <<= 26;
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shift &= 0x3c000000;
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sum = 0;
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memcpy(valbuf.buf, data+i+4, 3);
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shift |= (htobe32(valbuf.val)>>6)&0x03fffffc;
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sum |= shift & 0x3fff0000;
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shift >>= 2;
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sum |= shift & 0x00003fff;
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sum += 0x4e004e00;
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vals[n++] = be32toh(sum);
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return outlen;
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}
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uint8_t o = offset;
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if(o--) {
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register uint32_t sum = 0x0000003f & (data[i] >> 2);
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sum |= ((uint32_t)data[i] << 14) & 0x0000c000;
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if(o--) {
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sum |= ((uint32_t)data[i + 1] << 6) & 0x00003f00;
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sum |= ((uint32_t)data[i + 1] << 20) & 0x00300000;
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if(o--) {
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sum |= ((uint32_t)data[i + 2] << 12) & 0x000f0000;
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sum |= ((uint32_t)data[i + 2] << 28) & 0xf0000000;
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if(o--) {
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sum |= ((uint32_t)data[i + 3] << 20) & 0x0f000000;
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sum += 0x004e004e;
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// safe, because it will never go over 0x3dxx
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#ifdef WORDS_BIGENDIAN
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vals[n++] = __builtin_bswap32(sum);
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#else
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vals[n++] = sum;
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#endif
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sum = (((uint32_t)data[i + 3] << 2)) & 0x0000003c;
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if(o--) {
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sum |= (((uint32_t)data[i + 4] >> 6)) & 0x00000003;
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sum |= ((uint32_t)data[i + 4] << 10) & 0x0000fc00;
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if(o--) {
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sum |= ((uint32_t)data[i + 5] << 2) & 0x00000300;
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sum |= ((uint32_t)data[i + 5] << 16) & 0x003f0000;
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}
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}
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}
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}
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}
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sum += 0x004e004e;
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// safe, because it will never go over 0x3dxx
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#ifdef WORDS_BIGENDIAN
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vals[n] = __builtin_bswap32(sum);
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#else
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vals[n] = sum;
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#endif
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buf[outlen - 2] = '=';
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buf[outlen - 1] = offset;
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}
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return outlen;
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}
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int base16384_encode(const char* data, int dlen, char* buf) {
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int outlen = dlen / 7 * 8;
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int offset = dlen % 7;
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@@ -31,9 +136,6 @@ int base16384_encode(const char* data, int dlen, char* buf) {
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case 6: outlen += 10; break;
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default: break;
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}
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#ifdef DEBUG
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printf("outlen: %llu, offset: %u, malloc: %llu\n", outlen, offset, outlen + 8);
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#endif
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uint32_t* vals = (uint32_t*)buf;
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uint32_t n = 0;
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int32_t i = 0;
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@@ -109,9 +211,6 @@ int base16384_encode_unsafe(const char* data, int dlen, char* buf) {
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case 6: outlen += 10; break;
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default: break;
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}
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#ifdef DEBUG
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printf("outlen: %llu, offset: %u, malloc: %llu\n", outlen, offset, outlen + 8);
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#endif
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uint32_t* vals = (uint32_t*)buf;
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uint32_t n = 0;
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int32_t i = 0;
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@@ -139,6 +238,102 @@ int base16384_encode_unsafe(const char* data, int dlen, char* buf) {
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return outlen;
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}
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int base16384_decode_safe(const char* data, int dlen, char* buf) {
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int outlen = dlen;
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int offset = 0;
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if(data[dlen-2] == '=') {
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offset = data[dlen-1];
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switch(offset) { // 算上偏移标志字符占用的2字节
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case 0: break;
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case 1: outlen -= 4; break;
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case 2:
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case 3: outlen -= 6; break;
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case 4:
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case 5: outlen -= 8; break;
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case 6: outlen -= 10; break;
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default: break;
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}
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}
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outlen = outlen / 8 * 7 + offset;
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uint32_t* vals = (uint32_t*)data;
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uint32_t n = 0;
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int32_t i = 0;
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for(; i < outlen - 7; i+=7) { // n实际每次自增2
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register uint32_t sum = 0;
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register uint32_t shift = htobe32(vals[n++]) - 0x4e004e00;
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shift <<= 2;
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sum |= shift & 0xfffc0000;
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shift <<= 2;
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sum |= shift & 0x0003fff0;
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shift = htobe32(vals[n++]) - 0x4e004e00;
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sum |= shift >> 26;
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*(uint32_t*)(buf+i) = be32toh(sum);
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sum = 0;
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shift <<= 6;
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sum |= shift & 0xffc00000;
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shift <<= 2;
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sum |= shift & 0x003fff00;
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*(uint32_t*)(buf+i+4) = be32toh(sum);
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}
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remainder valbuf;
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if(outlen - i == 7) {
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register uint32_t sum = 0;
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register uint32_t shift = htobe32(vals[n++]) - 0x4e004e00;
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shift <<= 2;
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sum |= shift & 0xfffc0000;
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shift <<= 2;
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sum |= shift & 0x0003fff0;
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shift = htobe32(vals[n]) - 0x4e004e00;
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sum |= shift >> 26;
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*(uint32_t*)(buf+i) = be32toh(sum);
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sum = 0;
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shift <<= 6;
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sum |= shift & 0xffc00000;
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shift <<= 2;
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sum |= shift & 0x003fff00;
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valbuf.val = be32toh(sum);
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memcpy(buf+i+4, valbuf.buf, 3);
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} else if(offset--) {
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int cnt = dlen-2-(int)n*(int)sizeof(uint32_t);
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if (cnt > 4) cnt = 4;
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memcpy(valbuf.buf, &vals[n], cnt);
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n++;
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#ifdef WORDS_BIGENDIAN
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register uint32_t sum = __builtin_bswap32(valbuf.val);
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#else
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register uint32_t sum = valbuf.val;
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#endif
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sum -= 0x0000004e;
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buf[i++] = ((sum & 0x0000003f) << 2) | ((sum & 0x0000c000) >> 14);
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if(offset--) {
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sum -= 0x004e0000;
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buf[i++] = ((sum & 0x00003f00) >> 6) | ((sum & 0x00300000) >> 20);
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if(offset--) {
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buf[i++] = ((sum & 0x000f0000) >> 12) | ((sum & 0xf0000000) >> 28);
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if(offset--) {
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buf[i] = (sum & 0x0f000000) >> 20;
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memcpy(valbuf.buf, &vals[n], dlen-2-(int)n*(int)sizeof(uint32_t));
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#ifdef WORDS_BIGENDIAN
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sum = __builtin_bswap32(valbuf.val);
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#else
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sum = valbuf.val;
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#endif
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sum -= 0x0000004e;
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buf[i++] |= (sum & 0x0000003c) >> 2;
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if(offset--) {
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buf[i++] = ((sum & 0x00000003) << 6) | ((sum & 0x0000fc00) >> 10);
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if(offset--) {
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sum -= 0x004e0000;
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buf[i] = ((sum & 0x00000300) >> 2) | ((sum & 0x003f0000) >> 16);
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}
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}
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}
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}
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}
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}
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return outlen;
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}
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int base16384_decode(const char* data, int dlen, char* buf) {
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int outlen = dlen;
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int offset = 0;
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