Endian conversion...Part 2, The Endian Is Nigh!

[tantalus]

This will be my last post on the subject, but just for sharing and learning purposes here is the solution I choose to follow and what I have so far. Please take it as work in progress and it "works" for me.

*** This code is Linux targeted, you're on your own for Windows! ***

Built and tested under Debian 11 (Bullseye) x86_64 and Debian 12 (Bookworm) x86.

C static library implementation using x86_64 intrinsic instructions and a x86 work around.

Code: (Select All)

/*
* Compile:
*  gcc -O3 -static endian_swap.h -o endian_swap.o
*
* Create static library:
*  ar r libendian_swap.a endian_swap.o
*/

#ifndef ENDIAN_SWAP_H
#define ENDIAN_SWAP_H

#include <stdint.h>

inline void endian_swap16(uint16_t* v)
{
    __asm__ volatile ("movw %[src], %%ax\n"
                      "xchg %%ah, %%al\n"
                      "movw %%ax, %[dst]"
         : [dst] "=r" (*v)
         : [src] "m" (*v)
        );
}

#ifdef __x86_64__
inline void endian_swap32(uint32_t* v)
{
    __asm__ volatile ("movbel  %[src], %[dst]"
         : [dst] "=r" (*v)
         : [src] "m" (*v)
        );
}

inline void endian_swap64(uint64_t* v)
{
    __asm__ volatile ("movbeq  %[src], %[dst]"
         : [dst] "=r" (*v)
         : [src] "m" (*v)
        );
}
#else
inline void endian_swap32(uint32_t* v)
{
    __asm__ volatile ("movl  %[src], %%eax\n"
                      "bswap %%eax\n"
                      "movl  %%eax, %[dst]"
         : [dst] "=r" (*v)
         : [src] "m" (*v)
        );
}
#endif

#endif /* ENDIAN_SWAP_H */

QB64pe test program.

Code: (Select All)

DECLARE STATIC LIBRARY "endian_swap"

    sub endian_swap16(v AS _UNSIGNED INTEGER)

    sub endian_swap32(v AS _UNSIGNED LONG)

$IF 64BIT THEN

    sub endian_swap64(v AS _UNSIGNED _INTEGER64)

$END IF

END DECLARE



DIM value16 AS _UNSIGNED INTEGER

DIM value32 AS _UNSIGNED LONG

DIM value64 AS _UNSIGNED _INTEGER64



value16 = &HCEFA

value32 = &HEFBEADDE

value64 = &H0DF0FECAEFBEADDE



PRINT HEX$(value16)

PRINT HEX$(value32)

PRINT HEX$(value64)



endian_swap16 value16

endian_swap32 value32

endian_swap64 value64



PRINT HEX$(value16)

PRINT HEX$(value32)

PRINT HEX$(value64)



END