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58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
2 years ago
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#include <stdio.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include "utils.h"
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#define INPUT_LEN 200
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const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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int main() {
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char *input = (char*)malloc(INPUT_LEN);
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char *output = (char*)malloc((INPUT_LEN / 3 + INPUT_LEN % 3) * 4);
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char buf[3];
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char sixtet;
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int i; int j;
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int n = read_bytes(input, INPUT_LEN);
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// number of byte triples (n_triples * 4 - output size)
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int n_triples = n / 3;
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// if n is not divided by 3 then we should add one more triple, we will fill remaining bytes with zeroes
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if (n % 3)
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n_triples++;
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// i - starting number of triple, j - starting number of quadriple
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for (i = 0, j = 0; i < 3 * n_triples; i += 3, j += 4) {
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// if it's the last triple (maybe not full)
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if (i == 3 * n_triples - 1) {
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buf[0] = input[i];
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if (n % 3 == 1)
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buf[1] = buf[2] = 0;
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else if (n % 3 == 2) {
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buf[1] = input[i + 1];
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buf[2] = 0;
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}
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else {
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buf[1] = input[i + 1];
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buf[2] = input[i + 2];
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}
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}
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else {
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buf[0] = input[i]; buf[1] = input[i+1]; buf[2] = input[i+2];
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}
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sixtet = (buf[0] & 0b11111100) >> 2;
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output[j] = b64[(int)sixtet];
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sixtet = ((buf[0] & 0b00000011) << 4) | ((buf[1] & 0b11110000) >> 4);
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output[j+1] = b64[(int)sixtet];
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sixtet = ((buf[1] & 0b00001111) << 2) | ((buf[2] & 0b11000000) >> 6);
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output[j+2] = b64[(int)sixtet];
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sixtet = buf[2] & 0b00111111;
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output[j+3] = b64[(int)sixtet];
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}
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for (int k = 0; k < n_triples * 4; ++k) {
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printf("%c", output[k]);
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}
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printf("\n");
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}
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