Conversion to little endian format in C

Question

I have an array int16_t arr[4]; . What I want to do is to convert a value in this array to little endian. For example, let us say I have 0x1d02 on the first index, but I need 0x21d there. Is there any elegant way of converting that and writing it back to the array or how are these things done? Note that I just expressed myself in hex, because its easier to see the problem.

I dont know, your 1234 is big endian, now i need that in little endian, so 3412. — Kalybor, Dec 13 '20 at 16:47
This answer goes over how to reverse a binary number in C: https://stackoverflow.com/questions/9144800/c-reverse-bits-in-unsigned-integer — Blake G, Dec 13 '20 at 16:51
Your using a signed type instead of unsigned complicates things, but that question addresses the issue. — Shawn, Dec 13 '20 at 17:30

score 0 · Answer 1 · answered Dec 13 '20 at 16:56

0

#include <byteswap.h>

arr[0] = bswap_16(arr[0]);

reference

answered Dec 13 '20 at 16:56

Bill Lynch

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Should have mentioned i work on a embedded system, thanks for your reply. – Kalybor Dec 13 '20 at 17:03
Not portable. Not available on most embedded systems. Not always "magic" libraries or macros are needed., – 0___________ Dec 13 '20 at 17:20

0___________ · Accepted Answer · 2020-12-13T17:24:37.607

0

#define BS16(x) (((x) >> 8) | ((x) << 8))

int main(void)
{
    uint16_t arr[] = {0x1122, 0x2233, 0xaabb};
    printf("%hx %hx %hx\n", BS16(arr[0]), BS16(arr[1]), BS16(arr[2]));
    arr[0] = BS16(arr[0]);
}

edited Dec 13 '20 at 17:24

answered Dec 13 '20 at 17:18

0___________

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Ty, this seems to be what im looking for. – Kalybor Dec 13 '20 at 17:31

Conversion to little endian format in C

2 Answers2