source: bootcd/isolinux/syslinux-6.03/gpxe/src/drivers/bus/isa_ids.c

#include <stdint.h>
#include <stdio.h>
#include <byteswap.h>
#include <gpxe/isa_ids.h>

/* 
 * EISA and ISAPnP IDs are actually mildly human readable, though in a
 * somewhat brain-damaged way.
 *
 */
char * isa_id_string ( unsigned int vendor, unsigned int product ) {
        static char buf[7];
        int i;

        /* Vendor ID is a compressed ASCII string */
        vendor = bswap_16 ( vendor );
        for ( i = 2 ; i >= 0 ; i-- ) {
                buf[i] = ( 'A' - 1 + ( vendor & 0x1f ) );
                vendor >>= 5;
        }
        
        /* Product ID is a 4-digit hex string */
        sprintf ( &buf[3], "%04x", bswap_16 ( product ) );

        return buf;
}