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45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
#ifndef _BASE14_H_
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#define _BASE14_H_
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// base14.h
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// fumiama 20220319
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// encode_len calc min buf size to fill encode result
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int encode_len(int dlen) {
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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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return outlen + 8; // 冗余的8B用于可能的结尾的覆盖
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}
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// decode_len calc min buf size to fill decode result
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int decode_len(int dlen, int offset) {
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int outlen = dlen;
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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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return outlen / 8 * 7 + offset + 1; // 多出1字节用于循环覆盖
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}
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// encode data and write result into buf
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int encode(const char* data, int dlen, char* buf, int blen);
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// decode data and write result into buf
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int decode(const char* data, int dlen, char* buf, int blen);
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#endif |