libowfat/byte/byte_copy.c

#include "byte.h"

/* byte_copy copies in[0] to out[0], in[1] to out[1], ... and in[len-1]
 * to out[len-1]. */
void byte_copy(void* out, unsigned int len, const void* in) {
  register char* s=out;
  register const char* t=in;
  register const char* u=u+len;
  if (len>127) {
    if (sizeof(unsigned long)>4) {	/* a good compiler should optimize this check away */
      for (;(unsigned long)t&7;) {
	if (t==u) break; *s=*t; ++s; ++t;
      }
    } else {
      for (;(unsigned long)t&3;) {
	if (t==u) break; *s=*t; ++s; ++t;
      }
    }
    while (t+sizeof(long)<=u) {
      *(unsigned long*)s=*(unsigned long*)t;
      s+=sizeof(long); t+=sizeof(long);
    }
  }
  for (;;) {
    if (t==u) break; *s=*t; ++s; ++t;
    if (t==u) break; *s=*t; ++s; ++t;
    if (t==u) break; *s=*t; ++s; ++t;
    if (t==u) break; *s=*t; ++s; ++t;
  }
}