1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <stdint.h>
void print_byte(uint8_t byte) {
for(int pos = 0; pos < 8; pos++) {
int bit_value = (byte >> (8 - 1 - pos)) & 1; // 001
char ch = '0' + bit_value;
fputc(ch, stdout);
}
}
void set_bit(uint8_t* a_buf_byte, int* a_pos_bit, int bit_value) {
*a_buf_byte |= bit_value << (8 - 1 - *a_pos_bit);
*a_pos_bit += 1;
}
void set_bits_from_string(uint8_t* a_buf_byte, int* a_pos_bit, const char* s) {
for(const char* curr = s; *curr != '\0'; curr++) {
assert(*curr == '0' || *curr == '1' || *curr == ' ');
if(*curr != ' ') {
set_bit(a_buf_byte, a_pos_bit, *curr - '0');
}
}
}
int main(int argc, char* argv[]) {
uint8_t buf[8] = {0}; // ⚠ Initialize all bytes to zero.
int pos_bytes = 0;
int pos_bit = 0; // 0 is most-significant (128's place), 7 is least significant (1's place)
// Write 0100 100 00 00 110 1011 1110 011 00 0101 100 00 00 1111 011 110 1011 1110 1010 011 110.
set_bits_from_string(&buf[0], &pos_bit, "0100 100");
print_byte(buf[0]); // 01001000 ← this is correct
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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