source: Hardware/WARP_v3/Rev1.1/Config_CPLD/src/spi_boot_OpenCores_src/sw/misc/bit_reverse.c

// Altera requires configuration bytes to be sent LSB first but the
// SD Card reads bytes MSB first
// This code reverses the bits of the altera bitstream so
// it will come out correct when read from the SD card
// $Log: bit_reverse.c,v $
// Revision 1.1  2006/01/06 14:44:17  mbl
// initial version
//



#include "stdio.h"
#include "string.h"

FILE*   fileOut;
FILE*   fileIn;

void    outIOerror(char* pfn);
void    inIOerror(char* pfn);

int main(int argc, char* arg[])
{
    unsigned char input, output;
    unsigned char in_mask, out_mask;
    int i;

    fileOut = fopen(arg[2],"wb");
    if (fileOut == NULL)
    {
        outIOerror(arg[2]);
        exit(-1);
    }

    printf("Opening input file %s\n", arg[1]);
        fileIn = fopen(arg[1],"rb");
        if (fileIn == NULL)
        {
            inIOerror(arg[1]);
            exit(-1);
        }

        while (!feof(fileIn) && fgets((char*)&input, 2 ,fileIn) != NULL)
        {
            in_mask = 1;
            out_mask = 0x80;
        output = 0;

            for ( i=0; i < 8; ++i )
            {
            if (input & in_mask) 
            {
                output |= out_mask;
            }
            out_mask = out_mask >> 1;
            in_mask = in_mask << 1;
            }
        fwrite((void*)&output,sizeof(char),1,fileOut);
    }

    fclose(fileIn);
    fclose(fileOut);
    printf("\n%s has been created\n", arg[2]);
    exit(0);
}

void outIOerror(char *pfn)
{
    printf("I/O Error while writing to file=%s\n",pfn);
}

void inIOerror(char *pfn)
{
    printf("I/O Error while reading file=%s\n",pfn);
}